Cryptography standards

Last updated October 12, 2025

There are a number of standards related to cryptography . Standard algorithms and protocols provide a focus for study; standards for popular applications attract a large amount of cryptanalysis.

Encryption standards

Data Encryption Standard (DES, now obsolete)
Advanced Encryption Standard (AES)
RSA the original public key algorithm
OpenPGP

Hash standards

MD5 128-bit (obsolete)
SHA-1 160-bit (obsolete)
SHA-2 available in 224, 256, 384, and 512-bit variants
HMAC keyed hash
PBKDF2 Key derivation function (RFC 2898)

Digital signature standards

Digital Signature Standard (DSS), based on the Digital Signature Algorithm (DSA)
RSA
Elliptic Curve DSA

Public-key infrastructure (PKI) standards

X.509 Public Key Certificates

Wireless Standards

Wired Equivalent Privacy (WEP), severely flawed and superseded by WPA
Wi-Fi Protected Access (WPA) better than WEP, a 'pre-standard' partial version of 802.11i
802.11i a.k.a. WPA2, uses AES and other improvements on WEP
A5/1 and A5/2 cell phone encryption for GSM

U.S. Government Federal Information Processing Standards (FIPS)

FIPS PUB 31 Guidelines for Automatic Data Processing Physical Security and Risk Management 1974
FIPS PUB 46-3 Data Encryption Standard (DES) 1999
FIPS PUB 73 Guidelines for Security of Computer Applications 1980
FIPS PUB 74 Guidelines for Implementing and Using the NBS Data Encryption Standard 1981
FIPS PUB 81 DES Modes of Operation 1980
FIPS PUB 102 Guideline for Computer Security Certification and Accreditation 1983
FIPS PUB 112 Password Usage 1985, defines 10 factors to be considered in access control systems that are based on passwords
FIPS PUB 113 Computer Data Authentication 1985, specifies a Data Authentication Algorithm (DAA) based on DES, adopted by the Department of Treasury and the banking community to protect electronic fund transfers.
FIPS PUB 140-2 Security Requirements for Cryptographic Modules 2001, defines four increasing security levels
FIPS PUB 171 Key Management Using ANSI X9.17 (ANSI X9.17-1985) 1992, based on DES
FIPS PUB 180-2 Secure Hash Standard (SHS) 2002 defines the SHA family
FIPS PUB 181 Automated Password Generator (APG) 1993
FIPS PUB 185 Escrowed Encryption Standard (EES) 1994, a key escrow system that provides for decryption of telecommunications when lawfully authorized.
FIPS PUB 186-2 Digital Signature Standard (DSS) 2000
FIPS PUB 190 Guideline for the Use of Advanced Authentication Technology Alternatives 1994
FIPS PUB 191 Guideline for the Analysis of local area network Security 1994
FIPS PUB 196 Entity Authentication Using Public Key Cryptography 1997
FIPS PUB 197 Advanced Encryption Standard (AES) 2001
FIPS PUB 198 The Keyed-Hash Message Authentication Code (HMAC) 2002

Internet Requests for Comments (RFCs)

Classified Standards

EKMS NSA's Electronic Key Management System
FNBDT NSA's secure narrow band voice standard
Fortezza encryption based on portable crypto token in PC Card format
STE secure telephone
STU-III older secure telephone
TEMPEST prevents compromising emanations

Other

IPsec Virtual Private Network (VPN) and more
IEEE P1363 covers most aspects of public-key cryptography
Transport Layer Security (formerly SSL)
SSH secure Telnet and more
Content Scramble System (CSS, the DVD encryption standard, broken by DeCSS)
Kerberos authentication standard
RADIUS authentication standard
ANSI X9.59 electronic payment standard
Common Criteria Trusted operating system standard
CRYPTREC Japanese Government's cryptography recommendations