RFC 1320 (rfc1320) - Page 2 of 20

The MD4 Message-Digest Algorithm

RFC 1320              MD4 Message-Digest Algorithm            April 1992


   The MD4 algorithm is being placed in the public domain for review and
   possible adoption as a standard.

   This document replaces the October 1990 RFC 1186 [2].  The main
   difference is that the reference implementation of MD4 in the
   appendix is more portable.

   For OSI-based applications, MD4's object identifier is

   md4 OBJECT IDENTIFIER ::=
     {iso(1) member-body(2) US(840) rsadsi(113549) digestAlgorithm(2) 4}

   In the X.509 type AlgorithmIdentifier [3], the parameters for MD4
   should have type NULL.

2. Terminology and Notation

   In this document a "word" is a 32-bit quantity and a "byte" is an
   eight-bit quantity. A sequence of bits can be interpreted in a
   natural manner as a sequence of bytes, where each consecutive group
   of eight bits is interpreted as a byte with the high-order (most
   significant) bit of each byte listed first. Similarly, a sequence of
   bytes can be interpreted as a sequence of 32-bit words, where each
   consecutive group of four bytes is interpreted as a word with the
   low-order (least significant) byte given first.

   Let x_i denote "x sub i". If the subscript is an expression, we
   surround it in braces, as in x_{i+1}. Similarly, we use ^ for
   superscripts (exponentiation), so that x^i denotes x to the i-th
   power.

   Let the symbol "+" denote addition of words (i.e., modulo-2^32
   addition). Let X