Table of Contents       
Email Security Glossary of Terms and Abbreviations:  A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z
Some Email and Cryptography Standards and Publications: IETF-RFCs   Internet-Drafts   FIPS-Publications   Other Standards

Additional Research Papers, Publications and References:   Research-Publications    White-Papers    Presentations

Glossary by William Leibzon - Last Revised: Dec 30, 2004
(if you find errors in description or have suggestion for new term to be added, please send email to william@leibzon.org)

Email Security Glossary of Terms and Abbreviations
A ABNF

Augmented Backus-Naur Form - syntax used for defining structure of various elements of IETF protocols, see [RFC2234]

 

 ACCREDITATION A process by which an email sender can get certified by some agency that it meets certain criteria (like a mail list with all users confirmed opt-in). The accreditation agency then publishes a list of accredited entities (with accreditation information) and/or provides accreditation confirmation by some other means. Getting an email certificate from certificate authority can be be a form of accreditation.
AES Advanced Encryption Standard. A new cryptographic standard algorithm (known in cryptography as Rijndael) chosen by NIST in November 2000, see [FIPS197]
ANSI American National Standards Institute, see http://www.ansi.org
ARPA Defense Advanced Research Projects Agency (now they use DARPA as abbreviation) - part of DISA, they sponsored the development of a network (called ARPANET) that later evolved into Internet.
ASCII American Standard Code for Information Interchange - 7 bit format consisting of 128 characters which is a de facto world-wide standard used by computers to represent all the upper and lower-case Latin letters, numbers, punctuation, etc.
ASN.1 Abstract Syntax Notation One (CCITT recommendation X.208) - syntax for compact representation of structured data objects. This is the data format used for most PKCS objects. For more info see http://luca.ntop.org/Teaching/Appunti/asn1.html 
ASRG Anti-Spam Research Group of the Internet Research Task Force (IRTF),  see http://asrg.sp.am 
ASTA Anti-Spam Technical Alliance - a group of largest ISPs (AOL, Earthlink, Microsoft, Yahoo) who coordinate their actions to combat SPAM
AUTORESPONSE A message generated automatically by program that acts on behalf of email recipient. Examples of such responses are: information on change of email address, information on person's temporary unavailability (i.e. VACATION message), acknowledgement of receipt of an email message, etc.

B

 BASE64 An encoding of binary data, which is using only 64 characters (A-Z, a-z, 0-9, +, / and =) and can be sent as part of any text message in ASCII character set. See [RFC2045] and [RFC3548].  Note that PEM format files used by OpenSSL are BASE64 representation of DER encoded X.509 certificates.
  BATV Bounce Address Tag Validation. Proposal to add signatures information in the local part of RFC2821 MAIL FROM (known as bounce address). See [Draft-BATV] and http://mipassoc.org/batv/index.html
BAYESIAN FILTER This is an email filtering system based on Bayesian Logic, which is a mathematics and logic theory based on work of Thomas Bayes who worked on logic of decision making based on statistical probability inference. Spam filters that use this system determine probability if an email message is spam by doing comparison of the message contents to known spam messages with rating system applied to individual keywords and then summed up to produce message score.
BCP Best Current Practice RFCs - an IETF document series that specifies IETF recommended procedure that is not directly a protocol standard. See http://www.faqs.org/rfcs/bcp-index.html 
BER Specification of Basic Encoding Rules for ASN.1 (CCITT recommendation X.209). For more information see http://luca.ntop.org/Teaching/Appunti/asn1.html 
BLACKLIST A list of domains, hosts, IP addresses and/or e-mail addresses from which e-mail is blocked. These can be either maintained locally by each recipient or run by an external organization (see below). These are early  variants of Email Reputation Systems.
   BLOCKLIST A synonym term for BLACKLIST (which the author of this glossary prefers to use)
   RBL Real Time BlockList - blacklist with access to it available to other parties through the Internet
   DNSBL DNS BlockList - usually IP-addresses blocklist maintained centrally which can be checked by the DNS protocol (returning address within 127.0.0.x if an entry is in the list), see [Draft-DNSBL]
BOGON IP Term "bogon" comes from "bogus number" - as applied to ip addreses it specifies ip that should not be used on public Internet (but such IP maybe used on some local networks). Those are ip addresses in unallocated, unassigned or special reserved ip address blocks and use of these ips on public Internet  can often be for malicious purposes or in order to make it more difficult to find the entity responsible (since there is no whois data for the ip). See http://www.completewhois.com/bogons/
BOT [1] A term derived from "robot" and meaning automated computer system visiting websites and doing tasks on its own. Most commonly used in reference to web spiders (for example "google bot") which are systems trying to visit web sites to be able to reference them in search engines. 
BOT [2] A term derived from "robot" and meaning an application running on hacked or compromised (by means of virus) computer being remotely controlled by somebody other than its owner.  This use of BOT is synonymous with DRONE and ZOMBIE. For more info see  http://www.nanog.org/mtg-0410/pdf/kristoff.pdf
   BOTNET A large number of BOTs [2] / DRONES / ZOMBIES which are controlled by a single entity. There are now reportedly BOTNETS consisting of 100,000s of individual PCs but most often BOTNET consists of several thousands of BOTs. Many BOTNETSs are controlled from special channels on IRC and are often used for orchestrated attacks such as DDOS or for distributed generation and distribution of SPAM. Spammers and miscreants buy and sell BOTNETS on their blackmarket.  
BOUNCE If message delivery has failed for some reason then the email message should be returned back to the original sender (or an agent it designates to receive returned email) and such process of returning message after delivery failure is called BOUNCING and the message being returned is a BOUNCE.
   BOUNCE
   ADDRESS		 Also known as "Return-Path", "Envelope From" and "SMTP2821 MAIL FROM". This is an address transmitted at SMTP session during MAIL FROM command and represents an address that in case of delivery failure an MTA (or more likely an MDA) would need to send message back to.

C

 CAN-SPAM CAN-SPAM Act of 2003 - law passed by US Congress that makes unlawful to send unsolicited commercial email with purpose to deceive or with false source data (not very effective so far in stopping even what it defined as illegal... and because it makes it legal to send SPAM in other cases, some have called it "You can SPAM act"). See http://www.spamlaws.com/federal/108s877.html

 

 Caller ID [1] In telephony this refers to a system for displaying phone number and name of the calling party 
Caller ID [2] In email security this may refer to a Microsoft email authentication proposal, for more info see CID
CAUCE Coalition Against Unsolicited Commercial Email - an ad hoc, all volunteer organization, created by netizens to advocate for a legislative solution to the problem of UCE (a/k/a "spam"), see http://www.cauce.org
CBV Call-Back Verification - a technique used by some systems to distinguish valid sender email addresses from invalid ones such that  a receiving mail server connects back to MTA of a sender domain (as identified by MX records) to verify that such address exists before accepting the email.
CCITT International Telegraph and Telephone Consultative Committee - a predecessor organization of the ITU-T
CID Caller-ID - in email security this refers to a Microsoft proposal for verification of email sender based on RFC2822 headers Sender, From, Resent-Sender, Resent-From. This proposal used DNS XML records and it has now been superseded by Sender-ID which uses SPF records.
CMS Cryptographic Message Syntax  -  standard for cryptographic email message data, see [RFC2630], [RFC3369]
CNAME Canonical Name - a DNS RR that is used for listing Canonical ("Real") name of a certain host, this allows to alias one dns name to another. See http://www.dns.net/dnsrd/rr.html and [RFC1035]
COLLISION This term is used in cryptography as reference to when two distinct data sets produce identical HASH digest.  Good cryptographic hash function would make it very computationally difficult to purposely create a collision.
C/R Challenge/Response - a technique used by some systems to determine good senders from bad ones. Assumes that all senders are bad unless they have been verified by having responded to a challenge sent by receiving system the first time it got email from the sender. All senders who have responded are placed on local WHITELIST and their email is then allowed through to recipient.
CRYPTOGRAPHY A process by which a piece of data is transformed into another seemingly unrecognizable piece of data by means of a special function. The result can be transformed back into the original only by somebody who possesses the correct decryption KEY.
CSV Certified Server Validation (formerly Client SMTP Validation) - a verification of SMTP session HELO/HELO identity which involves checking if the incoming SMTP server's ip address is listed as a valid SMTP client based on DNS SRV record of the domain in HELO. See http://www.csvmail.com and http://mipassoc.org/csv/ and [Draft-CSV]

D

 DH Diffie-Hellman Public Key Encryption Algorithm, see [RFC2631]
  DER Distinguished Encoding Rules (from CCITT recommendation X.509 section 8.7) - set of encoding rules based on ASN.1. DER is often a reference to the format of  binary ASN.1 PKCS and/or X.509 objects. See http://luca.ntop.org/Teaching/Appunti/asn1.html 
DES Data Encryption Standard as set by NIST and first introduced back in December 1977. See [FIPS46-3]
DIGEST [1] For mail lists, newsgroups and other discussion forums this refers to a collection of multiple messages on that discussion forum for a certain period of time (one-day is daily digest, one-week is weekly digest, one-month is monthly digest, etc).
DIGEST [2] In cryptography digest (which is referred to as cryptographic message digest or digital fingerprint) is a hash of message data, which is what is used when cryptographic signature is created (the encrypted message digest is in fact the signature).
DISA Defense Information Systems Agency - an agency within US Military responsible for providing network and information services to other military agencies, see http://www.disa.mil 
DK DomainKeys - a proposal by Yahoo such that sending MTAs would add a special header with RSA signature which can be verified by retrieving a public key from dns TXT record. See [Draft-DK] and http://antispam.yahoo.com/domainkeys
DMP Designated Mailers Protocol -  "A proposal for identifying computer systems authorized to act as Simple Mail Transfer Protocol (SMTP) clients for an email domain", this is one of the earlier proposals that SPF is based on. For more information see http://www.pan-am.ca/dmp/
DNA Domain Name Accreditation - one of the proposals aimed at identifying domain accreditation service. See [Draft-DNA]
DNS Domain Name System - distributed data lookup system used on the internet as means of identifying network end-points (hosts) by name (these names are referred to as domains) and finding their attributes (these are referred to as Resource Records - most well known of which are IP addresses and MX records). This protocol has proven to be very robust for small size data lookups. See [RFC1035] and http://www.dns.net/dnsrd/
   DNS HOST DNS HOST or HOSTNAME is a final end-point naming identifier in the DNS system which would refer to actual physical HOST system. Note that the same HOST can have more than one hostnames.
   DNS RR DNS Resource Record - dns record type, these include "A" (IP), "MX", "SRV", "PTR", "TXT" and others
   DNS ZONE Collection of related dns records - usually these are all dns records for same domain, but zones can have records that spawn multiple domains.
   DNSSEC DNS Security - An attempt to secure DNS system which involves cryptographic signatures for all DNSSEC secure zones. See [Draft-DNSSEC]
DOMAIN Domain Name (or just Domain) is a very common term for internet infrastructure that refers to naming of all internet end-points which have  names like c.b.a, i.e. its long name separated by a number of ".". The naming system is hierarchical and ICANN is de-jure (but not necessarily de-facto for every internet user) authority that decides on the list of  "a" or root TLDs. Name delegation in each TLD is done by different Registrars and in the end each ISP (or directly end-user) has been delegated one or more Domains which user can either directly use as FQDN or set up HOSTNAMES for each system.
DOS Denial of Service (DoS) - an attack against a system that involves sending a large number of typically the same queries so as to overload the target system
   DDOS Distributed Denial of Service - a most common form of DoS that involves using multiple sources (many thousands) controlled by attacker. Quite often the sources of such attacks are either directly hacked computers or computers that had become zombies and are now part of BOTNET
DRIP

Designated Relays Inquiry Protocol - proposal similar to DMP but using a different dns syntax ("A" RR records), see [Draft-DRIP]
DRONE

Robot drone - in computer security this is synonymous with ZOMBIE and BOT [2] and means hacked or otherwise compromised (for example by virus) computer being remotely controlled by somebody other than its owner.
   DRONE Army

A large number of DRONES controlled by single entity, see BOTNET and ZOMBIE ARMY
DS [1]  Designated Sender - a generic term used to describe systems like RMX, DMP, SPF and Caller-ID, where the domain owners can designates which hosts can send email using their domain names.
   DSS [1] Designated Sender Scheme - same as DS [1]
   DSP Designated Sender Protocol - an early name for DMP
DS [2] Digital Signature - generic term for any kind of cryptographic signature
   DSA Digital Signature Algorithm - general term for algorithms used for creating digital signatures. These algorithms include RSA, Deffie-Hellman, ECDSA, HMAC and others.
   DSS [2] Digital Signature Standard - see [FIPS186-2]
DSN Delivery Status Notification - message delivery status (usually failure to deliver) message send by MTA to message sender, see [RFC3461]
DVCS Internet X.509 Public Key Infrastructure Data Validation and Certification Server Protocol, see [RFC3029]

E

 ECC Elliptic Curve Cryptography - see [SEC1] and [RFC3278]

 

 

 

 

 ECDSA The Elliptic Curve Digital Signature Algorithm - cryptography algorithm used in ECC (see above)
EES Escrowed Encryption Standard - used by certain branches of US government for encryption of telecommunication data intercepted for law enforcement use. Based on SKIPJACK symmetric-key encryption/decryption algorithm, see [FIPS185]
EDI Electronic Data Interchange, see [FIPS161-2]
EHLO Extended HELO - an extended format for HELO command given by the initiator of an ESMTP session.
ENCODING [1] As a verb this refers to a process of transforming data, usually so that arbitrary binary data could be represented in ASCII format and as such safely included email. MIME format of email data may require encoding when including 8-bit data block and BASE64 encoding is often used for this purpose
ENCODING [2] As a noun this refers to format and algorithm of the system used for encoding the data (see above). Some examples of such systems are: MIME w/BASE64, UUENCODE, BinHex
EMAIL Electronic Mail - generic term used to describe messaging system on the Internet
ESS Enhanced Security Services for S/MIME - see [RFC2634]
ESMTP Extended Simple Mail Transfer Protocol - extends original SMTP (which was described in [RFC821]) with syntax that allows additional extensions. ESMTP is what almost every SMTP server now supports, its base syntax is described in [RFC2821].
ESP Encapsulating Security Payload -see [RFC1829]

F

 FILTER An email filter is a process that sorts emails based on certain criteria, typically as an attempt to sort out the unwanted and bad email such as spam and viruses.

 

 

 FIPS Federal Information Processing Standards - standards set by NIST for information and telecommunication infrastructure of US Government for use in information processing systems. See http://www.itl.nist.gov/fipspubs/
FINGERPRINT In cryptography a fingerprint is a HASH of public key. It is often used to verify that a public key is correct.
   Digital
   Fingerprint 		 This is sometimes used to refer to a cryptographic hash of email message, the other term used for this is DIGEST of email message. For more info see DIGEST [2].
F/OSS Free and Open Source Software - open-source software is software with source code freely available and anyone has the right to modify and redistribute such software. See http://www.fsf.org/philosophy/free-sw.html
FQDN Fully Qualified Domain Name - refers to a properly specified domain that is a proper hostname, i.e. its a domain that has a DNS RR other then "NS" ("NS" is delegation record used to identify when domain information can be found in another zone or another dns server and listing such a server).
FTC Federal Trade Commission - a division of United States Government responsible for promoting fair trade and making sure consumers are not hurt by bad business practices. Part of their responsibility includes regulations on use of email as per CAN-SPAM act.
FTP

File Transfer Protocol - commonly used file exchange internet protocol (one of oldest TCP/IP protocols), see [RFC959] 

G

 GATEWAY A device or a system that manages traffic coming and going between two different disjoint networks

 

    GW-MTA Gateway Message Transfer Agent - a gateway MTA that accepts a message and further retransmits it to a foreign mail system outside of the Internet protocol space
GNU "Gnu's Not Unix" - a project by Free Software Foundation to develop Free and Open Source programs and utilities for Unix operating system (including free version of Unix itself). See http://www.gnu.org 
GPL GNU Public License - a very very popular license often used by people who create free and open source programs and packages. Its features include requirement that any modified version of program also be GNU licensed. See http://www.gnu.org/licenses/licenses.html 
GPG GNU Privacy Guard - a popular open-source program for encrypting and signing email based on PGP specification, some also use this as synonym term for PGP. See http://www.gnupg.org/ 
GREYLISTING A technique where for some (or all) email SMTP connections an MTA responds with temporary failure error requiring delivery to  be retried at later time. Normally this is used so that delivery attempts from previously unknown source could be correlated to better decide if that new source is likely to be good or bad. See http://www.greylisting.org/

H

 HASH In math hash function refers to a way of converting a large data block into a much smaller data block that represents the original and which is then called a HASH. For cryptography it's important that given a hash data one could not easily find another data that would produce the same hash. Currently the most widely used cryptographic hash function algorithms are MD5 and SHA-1.

 

 

 HELO The command that initiates an SMTP conversation. New extended version of this command used in ESMTP is EHLO. See [RFC821] and [RFC2821]
HIJACKING In computer security this term describes taking computer resource(s) by somebody other than its legal owner without resource owner's permission or consent - this is similar to stealing but when applied to computer resources. This maybe done either to be able to directly control and use the resource or as a way to pretend to be the resource owner possibly to get access to important information.
   Hijacked PC Hijacked Personal Computer - this is synonymous with Zombie PC and describes a computer where special BOT [2] program has been installed (often as a result of virus infection) which allows the system to be remotely controlled by somebody else than computer owner. Such computers are often used to distribute spam (see zombies and botnet) or used as a source for DDOS attacks.
   Hijacked IPs This term describes group of ip addresses (an ip block) that are being controlled and/or used without permission by somebody other than the legal entity to which the ip block was allocated. See http://www.completewhois.com/hijacked/
HMAC Keyed-Hash Message Authentication Code - it is a type of message authentication using both cryptographic hash together in combination with secret KEY, see [FIPS198]. HMAC-MD5 (based on MD5 hash algorithm) and more recently HMAC-SHA1 (based on SHA1) are used in IPSec and TLS
HOST A computer attached to the Internet. A host may have one or more dns names (hostnames) and may have one or more ip addresses. Hosts with more than one interface and ip addresses in different networks can function as a router or a gateway.
   HOSTNAME Host Name -a synonym for DNS HOST
HTML Hyper Text Markup Language - text syntax for WWW documents. See http://www.w3.org
HTTP Hyper Text Transfer Protocol - base internet protocol for WWW. See http://www.w3.org

I

 IANA Internet Assigned Numbers Authority - they maintain a list of unique internet identifies, including protocol numbers, service numbers, dns parameters, etc. - see http://www.iana.org

 

 

 ICANN Internet Corporation for Assigned Names and Numbers - the parent organization for IANA and organization responsible for general internet policies - see http://www.icann.org
I-D Internet Draft -  a working document of IETF, usually a proposal for protocol extension or new protocol. Not all Internet Drafts become RFCs but all new RFCs were once Internet Drafts.
IEEE Institute of Electrical and Electronics Engineers - see http://www.ieee.org
IETF Internet Engineering Task Force - organization of engineers who develop internet protocol standards, see http://www.ietf.org 
   IETF WG IETF Work Group - a group of engineers within IETF working on standard in specific area as defined by WG Charter (all work within IETF is done in WGs)
   IETF BOF BoF is an acronym for "birds of feather" - a term used to describe group of people with common interests. At IETF a BOF is a meeting on which formation of the new IETF Working Group is discussed
IIM Identified Internet Mail - a proposal by Cisco such that sending MTAs would add a special header with RSA signature and public key and they key can be verified by looking up its fingerprint in a special key registration server database. See [Draft-IIM] and http://www.identifiedmail.com
IKE Internet Key Exchange - refers to protocol or service for exchanging public keys between different internet end-notes and used for IPSEC, see [RFC2409]
IM Instant Messaging - a form of messaging service where small text messages can be sent directly from one person's computer to another. See http://www.jabber.org, http://www.icq.com, http://www.aim.com and http://messenger.msn.com
IMAP Internet Mail Access Protocol - a protocol that can be used by MUA to get access to email box located at ISP mail server where MDA has delivered email, currently used version of this protocol is IMAP4, for more info see [RFC3501]
INTERNET Term comes from "Interconnected Network" and refers to a network that connects many other networks (run by ISPs) and end-points to make one global network (as such some people now refer to Internet as "International Network"). If you're seeing this page you use Internet.
IP Internet Protocol - protocol used by internet end-nodes to exchange data
   IPv4 Internet Protocol version 4 (in this case 4 is protocol number, its not really 4th generation of protocol). Its one major drawback is the use of 32-bit ip addresses which will not be enough given the number of people who want to use Internet. Protocol core specification is described in [RFC791]
   IPv6 Internet Protocol version 6 (6 is protocol number, it is actually the 2nd generation internet protocol and as such was referred to as IP-NG) which is currently beginning to get deployed. It uses 128-bit ip addresses system unlike 32-bit with IPv4 and also includes a number of other advanced features. See [RFC2460]
   IP Address IP Addresses are identifiers of end-point network nodes for systems connected to the internet. There are two types of ip addresses - 32bit ip addresses used with IPv4 and 128bit addresses for IPv6.
   IPSEC IP Security - an effort to secure core internet infrastructure by means of public key cryptography. One of its major problems is distribution of public keys which is attempted to be solved by IKE. Support for IPSEC is a required part for IPv6 but use of IPSEC is not required by all IPv6 hosts. For more info see [RFC2411] and http://www.ietf.org/html.charters/ipsec-charter.html 
IPR Intellectual Property Rights - patent or patent application for some technology or algorithm. IPR have negative effect if they apply to technology that becomes standard as license is then required to use the technology which often limits its use only to companies that agree to terms imposed by such license.
IRC Internet Relay Chat - a protocol used for real-time user chat computer networks (which are hence called "irc networks"), largest networks have tens of thousands of users chatting connected to series of interconnected servers. See http://www.irchelp.org
IRTF Internet Research Task Force - a sister organization to IETF which does research in areas of internet technologies and can often involve early work that later is picked up by IETF WG. See http://www.irtf.org 
ISO International Standards Organization (an official name is actually "International Organization for Standardization") - see http://www.iso.org
ISOC Internet Society - an open organization whose mission is developing the Internet for the benefit of people throughout the world, they sponsor activities of IETF and RFC Editor. See http://www.isoc.org
ISP Internet Service Provider - a term used to describe a company providing internet access to the public. Each ISP runs its own network and connected together (with other organization's networks) they all make up what we call Internet
ITU International Telecommunication Union - an UN organization that sets policies, procedures and standards for international telecommunications. See http://www.itu.int 
   ITU-T International Telecommunication Union Standardization Bureau - the telecommunications standardization sector of the ITU

J

 JOE-JOB This term is used to describe what happens when a spammer chooses the e-mail address of an unsuspecting user as the spoofed source e-mail. The spoofed user then receives bounces (from failed delivery attempts) and angry complaints from people who did not want to receive those emails.

K

 KEY A KEY is a common term in cryptography signifying a piece of data necessary to create and/or verify encrypted data. For most cryptography systems only one key is used to encrypt and decrypt the data but for public key cryptography one key is used to encrypt and another key can be used to decrypt. 
     PUBLIC KEY For public key cryptography this signifies a piece of data given to the public so that anyone could encrypt message that is thereafter sent to the recipient who possessing the private key is the only one who can decrypt it. Note that for message SIGNING the roles of keys are reversed and private key is the one used to "sign" the message signature by sender who also publishes the other key in public allowing everyone else to be able to decrypt the signature and verify the message really came from listed sender. For more info see http://www.pgpi.org/doc/pgpintro/
   PRIVATE KEY For public key cryptography this signifies a piece of data used to decrypt a previously encrypted message. For message signing this is the key that only the signer has and uses to create cryptographic message signatures. For more information see http://www.pgpi.org/doc/pgpintro/
   SYMMETRIC
   KEY		 A symmetric key is one that can be used for both encryption and decryption of the same message. This is also sometimes called "single key" and "private key" (but this one can be confusing with private keys in public key cryptography, see above). For message signing it would be necessary for both sender and recipient to know this key and to have kept it private from everyone else.
KEA Key Exchange Algorithm - a general term used to describe various proposals for automated exchange of cryptographic keys such as ones used for IKE

L

 LDA Local Delivery Agent  - mail system component that delivers the message to the local message store. This is used either as a synonym for MDA or to describe an actual mail delivery component of it.

 

 

 LDAP Lightweight Directory Access Protocol - a protocol to access and update what is usually shared primarily read-only type of database based X.500 structure. As part of its use it became de-facto standard for sharing email address-books and similar directories. For more information see  http://www.kingsmountain.com/ldapRoadmap.shtml 
LMAP Lightweight MTA Authentication Protocol - refers to working group within ASRG that took place at the end of 2003 to try to unify multiple  proposals (RMX, DMP, SPF, DRIP, MTAMARK) that focused on per-hop authentication based on SMTP client ip. While no unified protocol was agreed upon, the result was a draft discussing this approach to email authentication, see [Draft-LMAP].

M

 MAAWG Messaging Anti-Abuse Working Group - see http://www.maawg.org 

 

 

 MAIL BOMB A type of DOS attack that involves sending a large number of email messages to the victim's email address or to the victim's email server in an attempt to overload the server or to make email box unusable and difficult to find good messages among the bad ones
MAIL LIST While it means simply a list of email addresses, usually it refers to discussion forum where each person on mail list can send an email that would be forwarded to every other person on the same list.
MAPS Mail Anti-abuse Prevention System - a first blacklist originally started by Pail Vixie and now operated by independent company as commercial reputation service. See http://www.mail-abuse.org
MARID MTA Authorization Records In DNS - an IETF WG that existed between April and September 2004 to discuss standardization of LMAP / Designated Sender related proposals. It came close to standardizing SPF, but was disbanded because of pressure from Microsoft to standardize SenderID which had technical problems that were never resolved and had Microsoft claimed IPR with license offered that was incompatible with OpenSource software
MASS Mail Authentication Signature Service - an IETF BoF and possible future WG. Bof proceedings and presentations are at http://www.ietf.org/proceedings/04aug/230.htm and comparison of proposals is at http://www.elan.net/~william/emailsecurity/emailsignatures-comparisonmatrix.htm. For public mail list subscription info see  http://www.imc.org/ietf-mailsig/index.html 
MD5

Message Digest #5 Algorithm (designed by Ronald Rivest along with RSA encryption), see [RFC1321]
MDN

Mail Disposition Notification - a type of DSN that can be sent indicating successful delivery
META [1] General term that comes from Greek and means "with" or  "about", in computer systems it is usually used to mean "additional information" or "related information".
   META TAG [1] In HTML "<META>" tags are used in the "<HEAD>" section and provide references to and short description of topic(s) that are related to content of the web page.
   META TAG [2] When used to refer to subject of email messages this is a reference to topic of discussion which is usually put inside "[ ...]"  in  "Subject:" header, mail lists often add this automatically.
META [2] Message Enhancements for Transmission Authorization - META Signatures is a proposal for automated email cryptographic signatures that are to be added by MTAs with flexible syntax to support signatures that can be verified after common email modifications (such as with mail lists) and authorization support for dns and http verification of public key or fingerprint or based on existing X.509 certificate or from PGP key server. See http://www.metasignatures.org
MIME Multipurpose Internet Mail Extensions - IETF standard for email content allowing multiple types of objects to be included as part of text data message, see [RFC2045], [RFC2046], [RFC2047], [RFC2048], [RFC2049]
MISCREANTS Refers to those who use vulnerabilities of computer systems and networks with intent to harm other users. Miscreants may hack systems and use BOTNETS to attack those who do not agree with them, some of them get employed by spammers to attack organizations and individuals who are engaged in anti-spam activities.
MDA Mail Delivery Agent - system that is the end-point of SMTP transmission. It delivers email message into a storage device where it can then be picked up or directly accessed by an MUA.
MRA Mail Redirection Agent - an intermediate MTA or other SMTP participating entity that changes destination or source of email message in transit. Forwarders and Mail Lists are two well known types of Mail Redirection Systems. See [Draft-Redirected]
MSA Mail Submission Agent - program on the sender side that initiates email transmission
MTA Mail Transfer Agent - any server utilizing SMTP protocol to send and receive email messages.
MTS Message Tracking Server - a tracking server provides messages tracking data to a tracking client and is a repository of the information about a message passing through a particular MTA. See [RFC3885], [RFC3886], [RFC3887], [RFC3888].
MUA Mail User Agent - program used by users to read email (same program is also usually an MSA)
MOSS MIME Objects Security Services - first, now obsolete IETF standard for encryption of MIME emails
MTAMARK Proposal that allows ip address owners to mark (indicate) in INADDR by means of TXT record if a particular ip address can or can not be the source of SMTP transmission, see [Draft-MTAMARK]
MX Mail Exchange - a type of DNS RR that identifies MTAs that are supposed to receive e-mail destined to addresses in particular domain.

N

 NANAE News.Admin.Net-Abuse.Email - a USENET newsgroup dedicated to discussions of email abuse and spam, see http://groups.google.com/group/news.admin.net-abuse.email and http://www.nanae.org

 

 NANOG North American Network Operators Group  - a discussion forum for network operators involved in running Internet Infrastructure. Despite that email security and spam issues are off-topic, such discussions happen there almost every day. See http://www.nanog.org 
NCSA National Center for Supercomputer Applications - they were involved as part of research sponsored by NSF in development of WWW and other important components of today's Internet infrastructure. See http://www.ncsa.uiuc.edu
NDN Non-Delivery Notification - a type of DSN that is sent when email can not be delivered
NIST National Institute of Standards and Technology - US government organization responsible for setting and publishing standards and researching technologies used by US government. They published specifications for several cryptography algorithms such as DES or AES. See http://www.nist.gov
   CRNS NIST Computer Security Resource Center of Computer Security Division, see http://crns.nist.gov
NNTP Network News Transfer Protocol - protocol for transfer of USENET messages over TCP/IP and providing access to them to internet users.
NOFWS No Folding White Space - a canonicalization algorithm used in DK, IIM and META Signatures when creating the message digest. Using this algorithm allows message digest verification to work even after some common transformations (additions and deletions of extra empty line before message body is common with mail lists for example) that sometimes happen at MTA message handling.
NSA National Security Agency - an agency in US government responsible for collection and analysis of communication and security in US government and military communications. They have sponsored developments of number of cryptographic algorithms. See http://www.nsa.gov 
NSF National Science Foundation - an agency in US Government that sponsored development of early internet in 1980s and early 1990s as way to connect research networks of different universities. See http://www.nsf.gov 
NSSN National Standards System Network (affiliated with ANSI), see http://www.nssn.org

O

 OPT-IN A general term used to indicate when a person has agreed to receive emails from some mail list or other type of discussion forum, ie. when he/she has asked to be subscribed

 

    Confirmed
   OPT-IN		 A term indicating that opt-in subscription was confirmed by the user. Typically it involves sending a verification email to the user requesting some action (such as replying to the verification email or
visiting some website). Positive action from the user is interpreted as a decision to subscribe.
   Double
   OPT-IN		 A term primarily used by companies sending large amount of email who insist that users have requested to be on their list - in most of the cases this is not so and users receive email unsolicited.
OSI [1] Open Systems Interconnect Reference Model - developed by ISO in 1984 it is now considered primary architectural model of intercomputer communications. It describes how information from an application on one system moves through a network to another system and separates tasks involved in that process into several layers: Application, Presentation, Session, Transport, Network, Data Link and Physical connection. See http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/introint.htm
OSI [2] Open Source Initiative - an effort to promote development and use of free and open software products, see http://www.opensource.org
OSS Open Source Software - usually used in the same context as F/OSS although technically it just means the software which source code is available and can be used and modified by somebody other than its original author but not that its necessarily free.

P

 PATH Email path is an ordered list of mail systems that some message can pass through on the way from sender to recipient. Email path may consist of just two servers or may involve many MTAs and MRAs (i.e. mail lists, forwarding and other systems). See [EMAILPATH]

 

 

    Path
   Authentication		 A technical name used to describe the type of email authentication seen in proposals like RMX, DMP, CID and its successors SPF and SID. In this authentication each system on the email message PATH authenticates the previous system on the PATH based on the attributes of that system (rather than on attributes of the message itself) and together this forms complete scheme.
PEM Privacy Enhancement for Internet Electronic Mail - first (and no longer used) IETF standard for email encryption, see [RFC1421], [RFC1422], [RFC1423], [RFC1424]
PGP Pretty Good Privacy - first email encryption and signing standard, created by Phil Zimmermann, see http://www.pgp.com, http://www.pgpi.com and http://www.philzimmermann.com. The most commonly used implementation of PGP is GNU Privacy Guard (GPG). 
   OpenPGP An Open Specification for Pretty Good Privacy - IETF standard for PGP signed messages. Extends PGP to do encryption on MIME parts similar to S/MIME, see [RFC2440], [RFC3156]. Also used to refer to IETF WG with same name, see http://www.ietf.org/html.charters/openpgp-charter.html
   PGP/MIME Often used as reference to OpenPGP (PGP/MIME is MIME type for PGP signatures)
PHISHING Internet scam where spoofed e-mails are sent that trick consumers into going to criminal-run website that looks like some other official site (like a bank site) and asks users to provide account information, username and passwords, bank account numbers, social security numbers, etc.
PKCS Public-Key Cryptography Standards
   PKCS1 Public-Key Cryptography Standard #1 - RSA Encryption, see info on RSA below, see [RFC2313]
   PKCS7 Public-Key Cryptography Standard #7 -  Standard for cryptographic messages, see CMS above, see [RFC2315]
   PKCS10 Public-Key Cryptography Standard #10 - Certificate Request Syntax, see [RFC2314]
PKI Public Key Infrastructure - general term describing use of public key encryption technology with protocols and systems necessary to support it for many users
   PKIX An IETF WG that focuses on creating standards for X.509 based public key infrastructure, see http://www.ietf.org/html.charters/pkix-charter.html 
POP [1] Post Office Protocol - a protocol by which an MUA can download emails stored on ISP or organization mail server. Current version is POP3 and it is widely used supported by MUAs, see [RFC1939] 
POP [2] Point of Presence - network node setup by an ISP to handle connectivity in a particular city or region
POSTMASTER Email address of the mail service administrator - all domains are required to have postmaster
PRA Purported Responsible Address - an email address from "Resent-Sender:" header or if not found then from "Resent-From:" or if not found then from "Sender:" or if not found then from "From:" header. As specified in RFC2822 this should provide an email address of the user responsible for initiating the current email transmission. Its notable that Microsoft has incorrectly taken this to be an address associated with the last MTA mail message passed through and is improperly using in its CID and SID proposals to provide per-hop authentication of the MTA based on its ip address.
PTR Domain Name Pointer - a DNS RR that is used primarily to associate an ip address with a hostname (which is then sometimes called a "reverse dns [host]name for ip")

R

 REGEX Regular Expressions - a standard system for expressing pattern matching formulas that are widely supported by many libraries. For more info see http://sitescooper.org/tao_regexps.html

 

 

 

 RELAY In email this refers to a  MTA system that without any modification to email message or its destination or source addresses retransmits the message to another MTA system.
   OPEN RELAY This refers to a RELAY system that does not have any authorization in place to decide on which messages should be retransmitted. While such systems are now rare, previously they were present in abundance (no authorization for relaying was default installation 5-10 years ago) and were often misused for purposes of helping to redistribute unwanted email.
REPUTATION Reputation is data collected by independent party on various email senders, what kind of email messages they sent and what are their policies dealing with abuse. This independent party (reputation provider) then makes the data available to recipients who can make more informed decision on acceptance or rejection of email messages from authenticated sender based on their reputation.
RFC Request for Comments - refers to IETF RFCs which are not really "requests for comments" but rather a publication usually specifying some technical standard or specification on how various technologies are to be used on the Internet.
RMX Reverse MX - a proposal by Hadmut Danisch for a new DNS RR to be used to indicate the list of ip addresses of systems authorized to use a given domain in SMTP2821 MAIL FROM address, this proposal became the basis for more comprehensive SPF protocol. For more information see http://www.danisch.de/work/security/antispam.html and [Draft-RMX]
RSA Public Key Encryption Algorithm named after its inventors Rivest, Shamir and Adleman, see [RFC2313] and [RFC3447]
Rijndael Rijndael is a block cipher, designed by Joan Daemen and Vincent Rijmen (its name is derived from their last names). It became base algorithm for AES, see http://csrc.nist.gov/CryptoToolkit/aes/rijndael/

S

 SCVP Simple Certificate Validation Protocol, see [Draft-Malpani] document
  SCV Sender Callout Verification - this is the same as Callback Verification, see CBV
SECG Standards for Efficient Cryptography Group - see http://www.secg.org 
SENDER ID Microsoft sponsored email authentication proposal based on CID but uses SPF records, see SID
SES Signed Envelope Sender - a proposal that describes how cryptographic message signature can be added in envelope MAIL FROM address. The signature is not based on public key cryptography but on HMAC and requires the use of a special verification server. See http://ses.codeshare.ca
SGML Standard Generalized Markup Language - a format and syntax for text documents that allows to add special meaning and processing semantics. SGML is derived from work on IBM Generalized Markup language and is now an ISO standard (ISO8879), it is most often used as a way to construct other markup languages each for their own field or for specific purpose, for example both HTML and XML are derivatives of SGML. See http://www.w3.org/MarkUp/SGML/
SHA Secure Hash Algorithm - this refers to standards for creating a cryptographic digest as set out by NIST
   SHA-1 Secure Hash Algorithm #1 - a superior and more secure hash/digest algorithm that is now starting to be used as replacement for MD5. The "#1" comes from FIPS180 as it was the FIPS180-1 that first specified this standard and algorithm (original FIPS180 had what some now call SHA0 but that algorithm was found to have flaws). SHA1 is a 160-bit digest algorithm and for IETF standards some of which are now based on SHA1, the technical details are described in [RFC3174]
   SHA-2 SHA224, SHA256, SHA384 and SHA512 are new more secure versions that use the same algorithm as SHA1 to produce longer digest (thus less prone to possible collisions).  224, 256, 384 and 512 refer to number of bits in the resulting digest. SHA-2 refers to that they all were first mentioned in FIPS180-2 document (the last and current version of SHA standard)
SHS Secure Hash Standard - usually used as synonym for SHA, see [FIPS180-2]
SID Sender-ID - in email security this refers to a Microsoft proposal for verification of email sender based on PRA address derived from headers Sender, From, Resent-Sender, Resent-From, which unlike its predecessor Caller-ID is using SPF DNS records. The proposal has serious flaws both in how it is using PRA (which provides original email sender and not address of last hop) and in that it  is using SPF v1 records that are published specifically for MAIL FROM (bounce address) authentication. Another controversy regarding SID revolves in that Microsoft claims IPR and license they proposed is not compatible with GPL and most other open-source software licenses.
SKIPJACK An encryption algorithm developed by NSA and proposed for clipper chip and also in some key exchange algorithm proposals. See http://csrc.nist.gov/encryption/skipjack/skipjack.pdf
S/MIME Secure MIME - X.509 based IETF standard developed with references to earlier PEM and MOSS work for transmission of signed and encrypted email. See http://www.ietf.org/html.charters/smime-charter.html  
   S/MIME v2 S/MIME version 2.0 - S/MIME standard for email signing and encryption using RSA algorithm for encryption and MD5 algorithm for hash, see [RFC2311], [RFC2312], [RFC2313], [RFC2314], [RFC2315] 
   S/MIME v3 S/MIME version 3.0 - S/MIME standard for email signing and encryption using Deffie-Hellman algorithm for encryption and SHA-1 algorithm for hash, see [RFC2633], [RFC2634]
SMTP Simple Mail Transfer Protocol - internet email delivery protocol, see [RFC821], [RFC822], [RFC1425], [RFC2821], [RFC2822]
SOA Start Of Authority - this is DNS record that marks the beginning of a zone and contains information about zone including hostmaster address, and caching information such as TTL and expire time
SPAM General term used to describe unwanted email communication sent in mass quantities usually for purpose of commercial advertising. The continued widespread sending of such emails despite overwhelming opposition of people who receive them has caused hatred of people and companies involved in this activity and large amount of effort both technical and legal to stop it.
   UBE Unsolicited Bulk Email - often used as synonym for SPAM, more specifically unsolicited emails (commercial or otherwise) sent in large quantities
   UCE Unsolicited Commercial Email - often used as synonym for SPAM, more specifically this is unsolicited emails with commercial advertisement (which may or may not be sent in mass). 
SPAM-L Old and quite popular mail list dedicated to discussions of email abuse and spam, see http://www.claws-and-paws.com/spam-l/ 
SPAMHAUS [1] Organization or group of people (or maybe even one person) responsible for sending lots of unsolicited emails (SPAM) and who are doing it as their primary business activity. Some people believe that although billions of spam emails are sent every day the number of organizations and people responsible for 99% of all that is only several hundred. See http://www.spamhaus.org/rokso/
SPAMHAUS [2] A website dedicated to finding and exposing spammers and their activity and stopping its effect on the internet, they provide very a popular blacklist called SBL (see below). See http://www.spamhaus.org
   SBL Spamhaus Block List - see http://www.spamhaus.org/sbl/
SPEWS Spam Prevention Early Warning System -  an anonymous group dedicated to exposing and stopping spammers and those organizations that provide them services. See http://www.spews.org 
SPF [1] Sender Policy Framework (previously known as Sender Permitted From). Specification of format for dns records that allows domain owner and SMTP operator to specify policies that are followed by those using that domain in email messages and the list of MTA ip addresses that can be source of such email. Based largely on DMP and RMX proposals. See http://spf.pobox.com and [Draft-SPF]
SPF [2] Shortest Path First algorithm (Dijkstra SPF algorithm) - used in some routing protocols (such as OSPF) to determine best routing path for network traffic 
SPOOFING Falsifying the identity of the message sender or falsifying the source of the transmission
SRS Sender Rewriting Scheme - a system of retaining original bounce address within new bounce address added by MRA when it wants to become directly responsible for receiving bounces. This is needed for SPF to work with all forwarders. For more information see http://spf.pobox.com/srs.html and http://www.libsrs.org/ and http://www.libsrs2.org/
SRV DNS Service Records - for a domain or host this is a general DNS RR type which can be used as  mechanism for locating services it supports and finding which hosts and protocols are to be used for such services. See [RFC2052]
SSL Secure Socket Layer - a protocol extension developed by Netscape in 1995-1996 for secure HTTP transmission which is using public key cryptography. This became a predecessor for TLS which is a generic protocol layer allowing use of a similar technology with other internet protocols. See http://wp.netscape.com/eng/ssl3/ 
SUBMITTER A person or entity that submits mail to MSA (i.e. the very first entity that starts mail transmission)
   Responsible
   Submitter		 An entity that is most recently responsible for injecting or re-injecting message into transport stream - this is not necessarily the original submitter but includes forwarders and redirecting agents that re-inject the message. An SMTP extension of "SUBMITTER" has been proposed to have this information passed along as part of SMTP2821 session. See [Draft-Submitter]

T

 TARPIT An MTA system which when it identifies an incoming e-mail as undesirable begins to purposely respond slowly (instead of immediately rejecting it and closing connection). Some use it as a way to cause spammer server(s) to slow down so they are no longer able to send large amounts of email.

 

 TCP

Transmission Control Protocol - protocol that most of internet other protocol's use for intercommunications, it provides a system for negotiating a data transmission channel between two network end-points with error correction and retransmission on failure. See [RFC793]
   TCP/IP TCP over IP protocol - UDP is also often considered to be part of it and together the provide the base set of protocols of today's Internet, see [RFC791], [RFC793], [RFC768]
TLD Top Level Domain - on the internet all domains have naming system like "d.c.b.a" where a, b, c, d are levels in domain naming tree. The "a" part is the first level and thus called "top level domain". Some well known top level domains are ".com",  ".net", ".org", ".uk", ".de", ".name", ".biz", etc.
TLS Tansport Layer Security - a standard for providing encryption of cryptography based security for TCP/IP communication channel (usually TCP session). Other protocols use this as layer to provide secure connection such as with HTTPS. See [RFC2246]
TROJAN Trojan Horse - a term from Greek mythology which in computer security is used as reference to a distractive or malicious program that is disguised as legitimate software or part of it. This is one of the ways a system can become a  zombie - it may involve hacking a website carrying good software and replacing it (or adding to it) a trojan zombie code, or a person may receive an email attachment which lists itself as good software (like virus cleaning software) but in reality is zombie trojan.
TTL Time To Live - all DNS records have these values which specify the amount of time DNS servers and applications are allowed to cache the record
TUA Tracking User Agent - an entity that initiates message tracking request, see [RFC3888]

U

 UBE Unsolicited Bulk Email, see SPAM

 

    UCE Unsolicited Commercial Email, see SPAM
UDP User Datagram Protocol - a basic protocol of Internet, unlike TCP it does not provide any special handling for establishing session or for error-corrections, but this works well for those protocols where one data packet is all that is needed in most cases (like DNS). See [RFC768].
UNIX An operating system developed at AT&T Bell Labs in 1960s and 1970s which successors are now used in many servers and workstations. Originally the name used was UNICS - "Uniplexed Information and Computing System" but this was soon changed to UNIX because it sounds better - in fact the "IX" ending is now famous and often used as way to name systems similar in the design to original UNIX such as Linux, AIX, IRIX, Minix and others. See http://en.wikipedia.org/wiki/Unix
URI Universal Resource Identifier - a specification for identifying element of the internet infrastructure, these developed from "http://", "news://" and similar protocol and location naming conventions used by web browsers, where they are called URL. See [RFC2396]
   URL Universal Resource Locator - this is a subset of URI (in reality predecessor of it) that is used by web browsers. In most cases URL and URI are actually used as synonyms with URL being more well known by end-users and URI being used more in technical and standard specifications.
USENET Unix User Network - originally a system for individual (not directly connected) Unix computers to exchange and share messages (usually through telephone connections). Now almost all usenet messages are distributed on the Internet and this refers to a set of protocols for generating, storing, retrieving and exchanging news "articles" (the structure of which resembles internet mail messages).

V

 VERP Variable Envelope Return Paths - a way of including recipient address as part of RFC2821 MAIL FROM  (bounce address), this is used by mail lists in order to better handle bounce messages and be able to automatically unsubscribe users with bad addresses. See http://cr.yp.to/proto/verp.txt
  VIRUS In computer security a virus is a self-replicating program that spreads by inserting copies of itself  into other programs or documents (or entirely replacing other programs). There are now many email viruses that add themselves as attachments to emails supposedly sent from friends and associates. Some of these viruses also contain TROJAN BOT code that turns infected computer into remotely controlled ZOMBIE and these are then used by spammers for distributing unsolicited emails.

W

 W3 Word Wide Web Consortium -  an organization working on standards for WWW protocols and language, including HTML, HTTP and others. See http://www.w3.org

 

 WHITELIST A locally or remotely maintained list of good email senders (this is either an email address list or list of domains). 
WHOIS A protocol used on the internet that allows to find the person or entity responsible for given internet resource (primarily used for domains and ip addresses) and associated technical, administrative, abuse and other contacts, see [RFC954]. For whois queries see http://www.completewhois.com 
WORM In email security a worm is a self-replicating computer virus that spreads by sending copies of itself via email. Well known examples with many variants are MyDoom, Nimda and Netsky.
WWW Word Wide Web - a general name used to refer to web browsing, see W3, HTTP, HTML

X

 X.509 A ITU approved (CCITT recommendation X.509-88) hierarchical standard for Public Key Infrastructure, see [RFC2459] and also see http://www.ietf.org/html.charters/pkix-charter.html
  XML Extensible Markup Language - a simple and flexible text format derived from SGML (and considered by some a superset of HTML) capable of being used as general data language for many protocols and applications. See http://www.w3.org/XML/
X-TOKEN In email this is a general term for any non-standard primarily site-specific header or its parameter. The convention is that all such parameters should have a name that starts with "x-" or "X-".

Z

 ZOMBIE In computer security this means a hacked or compromised (possibly by virus) system being remotely controlled by somebody other than its owner. These are often used by spammers to distribute SPAM and may also get used for DDOS attacks (primarily with IRC controlled zombies).  This term is synonymous with DRONE and BOT [2]
     ZOMBIENET Zombie Network,  also known as Zombie Army - this refers to large number ZOMBIE computers which are controlled by single entity. Spammers and their associates create large zombie networks to send their emails and for other purposes, they also sell either complete zombie networks or number of zombie computers on their blackmarket. This term is synonymous with BOTNET and DRONE ARMY.
   ZOMBIE PC Primarily used to reference Windows Personal Computer that became a ZOMBIE. Microsoft Windows with its numerous security holes and large installed user base is the primary type of Zombie systems.

Some Email and Cryptography Standards and Publications

IETF RFCs
Access all IETF RFCs from official IETF site: http://www.ietf.org/rfc.html
Access all IETF RFCs from FAQs.Org: http://www.faqs.org/faqs/
Access email and related RFCs from IMC: http://www.imc.org/rfcs.html
Access email and related RFCs from All Things Email: http://ref.allthingsemail.org/rfcs/index.html 
Access partial list of security RFCs from DFN CERT: http://www.cert.dfn.de/eng/resource/rfc/ 
Access list of dns security and related RFCs from DNSSEC.NET: http://www.dnssec.net/rfc.php
[RFC768] Postel, J. "User Datagram Protocol", August 1980 - http://www.ietf.org/rfc/rfc768.txt
[RFC791] "DARPA Internet Program Protocol Specifications: Internet Protocol", September 1981 - http://www.ietf.org/rfc/rfc791.txt
[RFC793] "DARPA Internet Program Protocol Specifications: Transmission Control Protocol", September 1981 - http://www.ietf.org/rfc/rfc793.txt 
[RFC821]

Postel, J. "Simple Mail Transfer Protocol", August 1982 - http://www.ietf.org/rfc/rfc821.txt (obsoluted by  [RFC2821])
[RFC822]

Crocker, D. "Standard For The Format of ARPA Internet Text Messages", August 1982 - http://www.ietf.org/rfc/rfc822.txt (obsoluted by [RFC2822]
[RFC954] Harrenstien, K. "NICNAME/WHOIS",  October 1982 - http://www.ietf.org/rfc/rfc812.txt
[RFC959] Postel, J. "File Transfer Protocol (FTP)", October 1985 - http://www.ietf.org/rfc/rfc959.txt
[RFC1035] Mockapetris, P. "Domain Names - Implementation and Specification", November 1987 - http://www.ietf.org/rfc/rfc1035.txt
[RFC1321]

Rivest, R. "The MD5 Message-Digest Algorithm", April 1992 - http://www.ietf.org/rfc/rfc1321.txt 
[RFC1421]

Linn, J. "Privacy Enhancement for Internet Electronic Mail: Part I: Message Encryption and Authentication Procedures", February 1993 - http://www.ietf.org/rfc/rfc1421.txt 
[RFC1422]

Kent, S. "Privacy Enhancement for Internet Electronic Mail: Part II: Certificate-Based Key Management", February 1993 - http://www.ietf.org/rfc/rfc1422.txt 
[RFC1423]

Balenson, D. "Privacy Enhancement for Internet Electronic Mail: Part III: Algorithms, Modes, and Identifiers", February 1993 - http://www.ietf.org/rfc/rfc1423.txt
[RFC1424]

Kaliski, B. "Privacy Enhancement for Internet Electronic Mail: Part IV: Key Certification and Related Services", February 1993 - http://www.ietf.org/rfc/rfc1424.txt 
[RFC1425]

Klensin, J. "SMTP Service Extensions", February 1993 - http://www.ietf.org/rfc/rfc1425.txt 
[RFC1829] Karn, P. "The ESP DES-CBC Transform", August 1985 - http://www.ietf.org/rfc/rfc1829.txt
[RFC1939] Myers, J. "Post Office Protocol - Version 3", May 1996 - http://www.ietf.org/rfc/rfc1939.txt
[RFC2045]

Freed, N. "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", November 1996 - http://www.ietf.org/rfc/rfc2045.txt
[RFC2046]

Freed, N. "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types", November 1996 - http://www.ietf.org/rfc/rfc2046.txt 
[RFC2047]

Moore, K. "MIME (Multipurpose Internet Mail Extensions) Part Three: Message Header Extensions for Non-ASCII Text", November 1996 - http://www.ietf.org/rfc/rfc2047.txt 
[RFC2048]

Freed, N. "Multipurpose Internet Mail Extensions (MIME) Part Four: Registration Procedures", November 1996 - http://www.ietf.org/rfc/rfc2048.txt
[RFC2049]

Freed, N. "Multipurpose Internet Mail Extensions (MIME) Part Five: Conformance Criteria and Examples", November 1996 - http://www.ietf.org/rfc/rfc2049.txt 
[RFC2052] Gulbrandsen, A., Vixie P. "A DNS RR for specifying the location of services (DNS SRV)", October 1996 - http://www.ietf.org/rfc/rfc2052.txt 
[RFC2060] Crispin, M. "Internet Message Access Protocol - Version 4rev1", December 1996 - http://www.ietf.org/rfc/rfc2060.txt  (obsoluted by [RFC3501])
[RFC2231] Freed, N., Moore K. "MIME Parameter Value and Encoded Word Extensions: Character Sets, Languages, and Continuations", November 1997 - http://www.ietf.org/rfc/rfc2231.txt
[RFC2234] Crocker, D. (Ed.) "Augmented BNF for Syntax Specifications: ABNF", November 1997 - http://www.ietf.org/rfc/rfc2234.txt 
[RFC2246] Dierks, T.  "The TLS Protocol Version 1.0", January 1999 - http://www.ietf.org/rfc/rfc2246.txt
[RFC2311]

Dusse, S. "S/MIME Version 2 Message Specification", March 1998 - http://www.ietf.org/rfc/rfc2311.txt  
[RFC2312]

Dusse, S. "S/MIME Version 2 Certificate Handling",  March 1998 - http://www.ietf.org/rfc/rfc2312.txt 
[RFC2313]

Kalinski, B. "PKCS #1: RSA Encryption Version 1.5",  March 1998 - http://www.ietf.org/rfc/rfc2313.txt (obsoluted by [RFC2437] and [RFC3447])
[RFC2314]

Kalinski, B. "PKCS #10: Certification Request Syntax Version 1.5",  March 1998 - http://www.ietf.org/rfc/rfc2314.txt 
[RFC2315]

Kalinski, B. "PKCS #7: Cryptographic Message Syntax, Version 1.5",  March 1998 - http://www.ietf.org/rfc/rfc2315.txt  (obsoluted by new standard, see [RFC3369])
[RFC2396] Berners-Lee T., "Uniform Resource Identifiers (URI): Generic Syntax", August 1998 -  http://www.ietf.org/rfc/rfc2396.txt
[RFC2409] Harkins, D., Carrel, D. "The Internet Key Exchange (IKE)", Nov 1998 - http://www.ietf.org/rfc/rfc2409.txt
[RFC2411] Thayer, R. "IP Security Document Roadmap", November 1998 - http://www.ietf.org/rfc/rfc2411.txt
[RFC2437] Kaliski, B., Staddon J. "PKCS #