RFC 2419 (rfc2419) - Page 2 of 12
The PPP DES Encryption Protocol, Version 2 (DESE-bis)
Alternative Format: Original Text Document
RFC 2419 PPP DES Encryption v2 September 1998 6. Encryption .................................................. 6 6.1. Padding Considerations .................................... 7 6.2. Generation of the Ciphertext .............................. 8 6.3. Retrieval of the Plaintext ................................ 8 6.4. Recovery after Packet Loss ................................ 8 7. MRU Considerations .......................................... 9 8. Differences from RFC 1969 ................................... 9 8.1. When to Pad ............................................... 9 8.2. Assigned Numbers .......................................... 9 8.3. Minor Editorial Changes ................................... 9 9. Security Considerations ..................................... 9 10. References ................................................. 10 11. Authors' Addresses ......................................... 11 12. Full Copyright Statement ................................... 12 1. Introduction 1.1. Motivation The purpose of this memo is two-fold: to show how one specifies the necessary details of a "data" or "bearer" protocol given the context of the generic PPP Encryption Control Protocol, and also to provide at least one commonly-understood means of secure data transmission between PPP implementations. The DES encryption algorithm is a well studied, understood and widely implemented encryption algorithm. The DES cipher was designed for efficient implementation in hardware, and consequently may be relatively expensive to implement in software. However, its pervasiveness makes it seem like a reasonable choice for a "model" encryption protocol. Source code implementing DES in the "Electronic Code Book Mode" can be found in [7]. US export laws forbid the inclusion of compilation-ready source code in this document. 1.2. Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [8]. 2. General Overview The purpose of encrypting packets exchanged between two PPP implementations is to attempt to insure the privacy of communication conducted via the two implementations. The encryption process depends on the specification of an encryption algorithm and a shared Sklower & Meyer Standards Track
