RFC 1115 (rfc1115) - Page 2 of 8
Privacy enhancement for Internet electronic mail: Part III - algorithms, modes, and identifiers
Alternative Format: Original Text Document
RFC 1115 Mail Privacy: Algorithms August 1989 1. Executive Summary This RFC provides definitions, references, and citations for algorithms, usage modes, and associated identifiers used in RFC-1113 and RFC-1114 in support of privacy-enhanced electronic mail in the Internet community. As some parts of this material are cited by both RFC-1113 and RFC-1114, and as it is anticipated that some of the definitions herein may be changed, added, or replaced without affecting the citing RFCs, algorithm-specific material has been placed into this separate RFC. The text is organized into three primary sections; dealing with symmetric encryption algorithms, asymmetric encryption algorithms, and integrity check algorithms. 2. Symmetric Encryption Algorithms and Modes This section identifies alternative symmetric encryption algorithms and modes which may be used to encrypt DEKs, MICs, and message text, and assigns them character string identifiers to be incorporated in encapsulated header fields to indicate the choice of algorithm employed. (Note: all alternatives presently defined in this category correspond to different usage modes of the DEA-1 (DES) algorithm, rather than to other algorithms per se.) 2.1. DES Modes The Block Cipher Algorithm DEA-1, defined in ANSI X3.92-1981 [3] may be used for message text, DEKs, and MICs. The DEA-1 is equivalent to the Data Encryption Standard (DES), as defined in FIPS PUB 46 [4]. The ECB and CBC modes of operation of DEA-1 are defined in ISO IS 8372 [5]. 2.1.1. DES in ECB mode (DES-ECB) The string "DES-ECB" indicates use of the DES algorithm in Electronic Codebook (ECB) mode. This algorithm/mode combination is used for DEK and MIC encryption. 2.1.2. DES in EDE mode (DES-EDE) The string "DES-EDE" indicates use of the DES algorithm in Encrypt-Decrypt-Encrypt (EDE) mode as defined by ANSI X9.17 [2] for key encryption and decryption with pairs of 64-bit keys. This algorithm/mode combination is used for DEK and MIC encryption. Linn
