Network Working Group R. Rivest
`Request for Comments: 1321 MIT Laboratory for Computer Science
` and RSA Data Security, Inc.
` April 1992
`
` The MD5 Message-Digest Algorithm
`
`Status of this Memo
`
` This memo provides information for the Internet community. It does
` not specify an Internet standard. Distribution of this memo is
` unlimited.
`
`Acknowlegements
`
` We would like to thank Don Coppersmith, Burt Kaliski, Ralph Merkle,
` David Chaum, and Noam Nisan for numerous helpful comments and
` suggestions.
`
`Table of Contents
`
` 1. Executive Summary 1
` 2. Terminology and Notation 2
` 3. MD5 Algorithm Description 3
` 4. Summary 6
` 5. Differences Between MD4 and MD5 6
` References 7
` APPENDIX A - Reference Implementation 7
` Security Considerations 21
` Author’s Address 21
`
`1. Executive Summary
`
` This document describes the MD5 message-digest algorithm. The
` algorithm takes as input a message of arbitrary length and produces
` as output a 128-bit "fingerprint" or "message digest" of the input.
` It is conjectured that it is computationally infeasible to produce
` two messages having the same message digest, or to produce any
` message having a given prespecified target message digest. The MD5
` algorithm is intended for digital signature applications, where a
` large file must be "compressed" in a secure manner before being
` encrypted with a private (secret) key under a public-key cryptosystem
` such as RSA.
`
`Rivest [Page 1]
`
`CSCO-1017
`
`

`

`
`RFC 1321 MD5 Message-Digest Algorithm April 1992
`
` The MD5 algorithm is designed to be quite fast on 32-bit machines. In
` addition, the MD5 algorithm does not require any large substitution
` tables; the algorithm can be coded quite compactly.
`
` The MD5 algorithm is an extension of the MD4 message-digest algorithm
` 1,2]. MD5 is slightly slower than MD4, but is more "conservative" in
` design. MD5 was designed because it was felt that MD4 was perhaps
` being adopted for use more quickly than justified by the existing
` critical review; because MD4 was designed to be exceptionally fast,
` it is "at the edge" in terms of risking successful cryptanalytic
` attack. MD5 backs off a bit, giving up a little in speed for a much
` greater likelihood of ultimate security. It incorporates some
` suggestions made by various reviewers, and contains additional
` optimizations. The MD5 algorithm is being placed in the public domain
` for review and possible adoption as a standard.
`
` For OSI-based applications, MD5’s object identifier is
`
` md5 OBJECT IDENTIFIER ::=
` iso(1) member-body(2) US(840) rsadsi(113549) digestAlgorithm(2) 5}
`
` In the X.509 type AlgorithmIdentifier [3], the parameters for MD5
` 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 <<< s denote the 32-bit value obtained by circularly
` shifting (rotating) X left by s bit positions. Let not(X) denote the
` bit-wise complement of X, and let X v Y denote the bit-wise OR of X
` and Y. Let X xor Y denote the bit-wise XOR of X and Y, and let XY
` denote the bit-wise AND of X and Y.
`
`Rivest [Page 2]
`
`

`

`
`RFC 1321 MD5 Message-Digest Algorithm April 1992
`
`3. MD5 Algorithm Description
`
` We begin by supposing that we have a b-bit message as input, and that
` we wish to find its message digest. Here b is an arbitrary
` nonnegative integer; b may be zero, it need not be a multiple of
` eight, and it may be arbitrarily large. We imagine the bits of the
` message written down as follows:
`
` m_0 m_1 ... m_{b-1}
`
` The following five steps are performed to compute the message digest
` of the message.
`
`3.1 Step 1. Append Padding Bits
`
` The message is "padded" (extended) so that its length (in bits) is
` congruent to 448, modulo 512. That is, the message is extended so
` that it is just 64 bits shy of being a multiple of 512 bits long.
` Padding is always performed, even if the length of the message is
` already congruent to 448, modulo 512.
`
` Padding is performed as follows: a single "1" bit is appended to the
` message, and then "0" bits are appended so that the length in bits of
` the padded message becomes congruent to 448, modulo 512. In all, at
` least one bit and at most 512 bits are appended.
`
`3.2 Step 2. Append Length
`
` A 64-bit representation of b (the length of the message before the
` padding bits were added) is appended to the result of the previous
` step. In the unlikely event that b is greater than 2^64, then only
` the low-order 64 bits of b are used. (These bits are appended as two
` 32-bit words and appended low-order word first in accordance with the
` previous conventions.)
`
` At this point the resulting message (after padding with bits and with
` b) has a length that is an exact multiple of 512 bits. Equivalently,
` this message has a length that is an exact multiple of 16 (32-bit)
` words. Let M[0 ... N-1] denote the words of the resulting message,
` where N is a multiple of 16.
`
`3.3 Step 3. Initialize MD Buffer
`
` A four-word buffer (A,B,C,D) is used to compute the message digest.
` Here each of A, B, C, D is a 32-bit register. These registers are
` initialized to the following values in hexadecimal, low-order bytes
` first):
`
`Rivest [Page 3]
`
`

`

`
`RFC 1321 MD5 Message-Digest Algorithm April 1992
`
` word A: 01 23 45 67
` word B: 89 ab cd ef
` word C: fe dc ba 98
` word D: 76 54 32 10
`
`3.4 Step 4. Process Message in 16-Word Blocks
`
` We first define four auxiliary functions that each take as input
` three 32-bit words and produce as output one 32-bit word.
`
` F(X,Y,Z) = XY v not(X) Z
` G(X,Y,Z) = XZ v Y not(Z)
` H(X,Y,Z) = X xor Y xor Z
` I(X,Y,Z) = Y xor (X v not(Z))
`
` In each bit position F acts as a conditional: if X then Y else Z.
` The function F could have been defined using + instead of v since XY
` and not(X)Z will never have 1’s in the same bit position.) It is
` interesting to note that if the bits of X, Y, and Z are independent
` and unbiased, the each bit of F(X,Y,Z) will be independent and
` unbiased.
`
` The functions G, H, and I are similar to the function F, in that they
` act in "bitwise parallel" to produce their output from the bits of X,
` Y, and Z, in such a manner that if the corresponding bits of X, Y,
` and Z are independent and unbiased, then each bit of G(X,Y,Z),
` H(X,Y,Z), and I(X,Y,Z) will be independent and unbiased. Note that
` the function H is the bit-wise "xor" or "parity" function of its
` inputs.
`
` This step uses a 64-element table T[1 ... 64] constructed from the
` sine function. Let T[i] denote the i-th element of the table, which
` is equal to the integer part of 4294967296 times abs(sin(i)), where i
` is in radians. The elements of the table are given in the appendix.
`
` Do the following:
`
` /* Process each 16-word block. */
` For i = 0 to N/16-1 do
`
` /* Copy block i into X. */
` For j = 0 to 15 do
` Set X[j] to M[i*16+j].
` end /* of loop on j */
`
` /* Save A as AA, B as BB, C as CC, and D as DD. */
` AA = A
` BB = B
`
`Rivest [Page 4]
`
`

`

`
`RFC 1321 MD5 Message-Digest Algorithm April 1992
`
` CC = C
` DD = D
`
` /* Round 1. */
` /* Let [abcd k s i] denote the operation
` a = b + ((a + F(b,c,d) + X[k] + T[i]) <<< s). */
` /* Do the following 16 operations. */
` [ABCD 0 7 1] [DABC 1 12 2] [CDAB 2 17 3] [BCDA 3 22 4]
` [ABCD 4 7 5] [DABC 5 12 6] [CDAB 6 17 7] [BCDA 7 22 8]
` [ABCD 8 7 9] [DABC 9 12 10] [CDAB 10 17 11] [BCDA 11 22 12]
` [ABCD 12 7 13] [DABC 13 12 14] [CDAB 14 17 15] [BCDA 15 22 16]
`
` /* Round 2. */
` /* Let [abcd k s i] denote the operation
` a = b + ((a + G(b,c,d) + X[k] + T[i]) <<< s). */
` /* Do the following 16 operations. */
` [ABCD 1 5 17] [DABC 6 9 18] [CDAB 11 14 19] [BCDA 0 20 20]
` [ABCD 5 5 21] [DABC 10 9 22] [CDAB 15 14 23] [BCDA 4 20 24]
` [ABCD 9 5 25] [DABC 14 9 26] [CDAB 3 14 27] [BCDA 8 20 28]
` [ABCD 13 5 29] [DABC 2 9 30] [CDAB 7 14 31] [BCDA 12 20 32]
`
` /* Round 3. */
` /* Let [abcd k s t] denote the operation
` a = b + ((a + H(b,c,d) + X[k] + T[i]) <<< s). */
` /* Do the following 16 operations. */
` [ABCD 5 4 33] [DABC 8 11 34] [CDAB 11 16 35] [BCDA 14 23 36]
` [ABCD 1 4 37] [DABC 4 11 38] [CDAB 7 16 39] [BCDA 10 23 40]
` [ABCD 13 4 41] [DABC 0 11 42] [CDAB 3 16 43] [BCDA 6 23 44]
` [ABCD 9 4 45] [DABC 12 11 46] [CDAB 15 16 47] [BCDA 2 23 48]
`
` /* Round 4. */
` /* Let [abcd k s t] denote the operation
` a = b + ((a + I(b,c,d) + X[k] + T[i]) <<< s). */
` /* Do the following 16 operations. */
` [ABCD 0 6 49] [DABC 7 10 50] [CDAB 14 15 51] [BCDA 5 21 52]
` [ABCD 12 6 53] [DABC 3 10 54] [CDAB 10 15 55] [BCDA 1 21 56]
` [ABCD 8 6 57] [DABC 15 10 58] [CDAB 6 15 59] [BCDA 13 21 60]
` [ABCD 4 6 61] [DABC 11 10 62] [CDAB 2 15 63] [BCDA 9 21 64]
`
` /* Then perform the following additions. (That is increment each
` of the four registers by the value it had before this block
` was started.) */
` A = A + AA
` B = B + BB
` C = C + CC
` D = D + DD
`
` end /* of loop on i */
`
`Rivest [Page 5]
`
`

`

`
`RFC 1321 MD5 Message-Digest Algorithm April 1992
`
`3.5 Step 5. Output
`
` The message digest produced as output is A, B, C, D. That is, we
` begin with the low-order byte of A, and end with the high-order byte
` of D.
`
` This completes the description of MD5. A reference implementation in
` C is given in the appendix.
`
`4. Summary
`
` The MD5 message-digest algorithm is simple to implement, and provides
` a "fingerprint" or message digest of a message of arbitrary length.
` It is conjectured that the difficulty of coming up with two messages
` having the same message digest is on the order of 2^64 operations,
` and that the difficulty of coming up with any message having a given
` message digest is on the order of 2^128 operations. The MD5 algorithm
` has been carefully scrutinized for weaknesses. It is, however, a
` relatively new algorithm and further security analysis is of course
` justified, as is the case with any new proposal of this sort.
`
`5. Differences Between MD4 and MD5
`
` The following are the differences between MD4 and MD5:
`
` 1. A fourth round has been added.
`
` 2. Each step now has a unique additive constant.
`
` 3. The function g in round 2 was changed from (XY v XZ v YZ) to
` (XZ v Y not(Z)) to make g less symmetric.
`
` 4. Each step now adds in the result of the previous step. This
` promotes a faster "avalanche effect".
`
` 5. The order in which input words are accessed in rounds 2 and
` 3 is changed, to make these patterns less like each other.
`
` 6. The shift amounts in each round have been approximately
` optimized, to yield a faster "avalanche effect." The shifts in
` different rounds are distinct.
`
`Rivest [Page 6]
`
`

`

`
`RFC 1321 MD5 Message-Digest Algorithm April 1992
`
`References
`
` [1] Rivest, R., "The MD4 Message Digest Algorithm", RFC 1320, MIT and
` RSA Data Security, Inc., April 1992.
`
` [2] Rivest, R., "The MD4 message digest algorithm", in A.J. Menezes
` and S.A. Vanstone, editors, Advances in Cryptology - CRYPTO ’90
` Proceedings, pages 303-311, Springer-Verlag, 1991.
`
` [3] CCITT Recommendation X.509 (1988), "The Directory -
` Authentication Framework."
`
`APPENDIX A - Reference Implementation
`
` This appendix contains the following files taken from RSAREF: A
` Cryptographic Toolkit for Privacy-Enhanced Mail:
`
` global.h -- global header file
`
` md5.h -- header file for MD5
`
` md5c.c -- source code for MD5
`
` For more information on RSAREF, send email to <rsaref@rsa.com>.
`
` The appendix also includes the following file:
`
` mddriver.c -- test driver for MD2, MD4 and MD5
`
` The driver compiles for MD5 by default but can compile for MD2 or MD4
` if the symbol MD is defined on the C compiler command line as 2 or 4.
`
` The implementation is portable and should work on many different
` plaforms. However, it is not difficult to optimize the implementation
` on particular platforms, an exercise left to the reader. For example,
` on "little-endian" platforms where the lowest-addressed byte in a 32-
` bit word is the least significant and there are no alignment
` restrictions, the call to Decode in MD5Transform can be replaced with
` a typecast.
`
`A.1 global.h
`
`/* GLOBAL.H - RSAREF types and constants
` */
`
`/* PROTOTYPES should be set to one if and only if the compiler supports
` function argument prototyping.
`The following makes PROTOTYPES default to 0 if it has not already
`
`Rivest [Page 7]
`
`

`

`
`RFC 1321 MD5 Message-Digest Algorithm April 1992
`
` been defined with C compiler flags.
` */
`#ifndef PROTOTYPES
`#define PROTOTYPES 0
`#endif
`
`/* POINTER defines a generic pointer type */
`typedef unsigned char *POINTER;
`
`/* UINT2 defines a two byte word */
`typedef unsigned short int UINT2;
`
`/* UINT4 defines a four byte word */
`typedef unsigned long int UINT4;
`
`/* PROTO_LIST is defined depending on how PROTOTYPES is defined above.
`If using PROTOTYPES, then PROTO_LIST returns the list, otherwise it
` returns an empty list.
` */
`#if PROTOTYPES
`#define PROTO_LIST(list) list
`#else
`#define PROTO_LIST(list) ()
`#endif
`
`A.2 md5.h
`
`/* MD5.H - header file for MD5C.C
` */
`
`/* Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
`rights reserved.
`
`License to copy and use this software is granted provided that it
`is identified as the "RSA Data Security, Inc. MD5 Message-Digest
`Algorithm" in all material mentioning or referencing this software
`or this function.
`
`License is also granted to make and use derivative works provided
`that such works are identified as "derived from the RSA Data
`Security, Inc. MD5 Message-Digest Algorithm" in all material
`mentioning or referencing the derived work.
`
`RSA Data Security, Inc. makes no representations concerning either
`the merchantability of this software or the suitability of this
`software for any particular purpose. It is provided "as is"
`without express or implied warranty of any kind.
`
`Rivest [Page 8]
`
`

`

`
`RFC 1321 MD5 Message-Digest Algorithm April 1992
`
`These notices must be retained in any copies of any part of this
`documentation and/or software.
` */
`
`/* MD5 context. */
`typedef struct {
` UINT4 state[4]; /* state (ABCD) */
` UINT4 count[2]; /* number of bits, modulo 2^64 (lsb first) */
` unsigned char buffer[64]; /* input buffer */
`} MD5_CTX;
`
`void MD5Init PROTO_LIST ((MD5_CTX *));
`void MD5Update PROTO_LIST
` ((MD5_CTX *, unsigned char *, unsigned int));
`void MD5Final PROTO_LIST ((unsigned char [16], MD5_CTX *));
`
`A.3 md5c.c
`
`/* MD5C.C - RSA Data Security, Inc., MD5 message-digest algorithm
` */
`
`/* Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
`rights reserved.
`
`License to copy and use this software is granted provided that it
`is identified as the "RSA Data Security, Inc. MD5 Message-Digest
`Algorithm" in all material mentioning or referencing this software
`or this function.
`
`License is also granted to make and use derivative works provided
`that such works are identified as "derived from the RSA Data
`Security, Inc. MD5 Message-Digest Algorithm" in all material
`mentioning or referencing the derived work.
`
`RSA Data Security, Inc. makes no representations concerning either
`the merchantability of this software or the suitability of this
`software for any particular purpose. It is provided "as is"
`without express or implied warranty of any kind.
`
`These notices must be retained in any copies of any part of this
`documentation and/or software.
` */
`
`#include "global.h"
`#include "md5.h"
`
`/* Constants for MD5Transform routine.
` */
`
`Rivest [Page 9]
`
`

`

`
`RFC 1321 MD5 Message-Digest Algorithm April 1992
`
`#define S11 7
`#define S12 12
`#define S13 17
`#define S14 22
`#define S21 5
`#define S22 9
`#define S23 14
`#define S24 20
`#define S31 4
`#define S32 11
`#define S33 16
`#define S34 23
`#define S41 6
`#define S42 10
`#define S43 15
`#define S44 21
`
`static void MD5Transform PROTO_LIST ((UINT4 [4], unsigned char [64]));
`static void Encode PROTO_LIST
` ((unsigned char *, UINT4 *, unsigned int));
`static void Decode PROTO_LIST
` ((UINT4 *, unsigned char *, unsigned int));
`static void MD5_memcpy PROTO_LIST ((POINTER, POINTER, unsigned int));
`static void MD5_memset PROTO_LIST ((POINTER, int, unsigned int));
`
`static unsigned char PADDING[64] = {
` 0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
` 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
` 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
`};
`
`/* F, G, H and I are basic MD5 functions.
` */
`#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
`#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
`#define H(x, y, z) ((x) ^ (y) ^ (z))
`#define I(x, y, z) ((y) ^ ((x) | (~z)))
`
`/* ROTATE_LEFT rotates x left n bits.
` */
`#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))
`
`/* FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
`Rotation is separate from addition to prevent recomputation.
` */
`#define FF(a, b, c, d, x, s, ac) { \
` (a) += F ((b), (c), (d)) + (x) + (UINT4)(ac); \
` (a) = ROTATE_LEFT ((a), (s)); \
`
`Rivest [Page 10]
`
`

`

`
`RFC 1321 MD5 Message-Digest Algorithm April 1992
`
` (a) += (b); \
` }
`#define GG(a, b, c, d, x, s, ac) { \
` (a) += G ((b), (c), (d)) + (x) + (UINT4)(ac); \
` (a) = ROTATE_LEFT ((a), (s)); \
` (a) += (b); \
` }
`#define HH(a, b, c, d, x, s, ac) { \
` (a) += H ((b), (c), (d)) + (x) + (UINT4)(ac); \
` (a) = ROTATE_LEFT ((a), (s)); \
` (a) += (b); \
` }
`#define II(a, b, c, d, x, s, ac) { \
` (a) += I ((b), (c), (d)) + (x) + (UINT4)(ac); \
` (a) = ROTATE_LEFT ((a), (s)); \
` (a) += (b); \
` }
`
`/* MD5 initialization. Begins an MD5 operation, writing a new context.
` */
`void MD5Init (context)
`MD5_CTX *context; /* context */
`
`{
`
` context->count[0] = context->count[1] = 0;
` /* Load magic initialization constants.
`*/
` context->state[0] = 0x67452301;
` context->state[1] = 0xefcdab89;
` context->state[2] = 0x98badcfe;
` context->state[3] = 0x10325476;
`
`} /
`
`* MD5 block update operation. Continues an MD5 message-digest
` operation, processing another message block, and updating the
` context.
` */
`void MD5Update (context, input, inputLen)
`MD5_CTX *context; /* context */
`unsigned char *input; /* input block */
`unsigned int inputLen; /* length of input block */
`
`{
`
` unsigned int i, index, partLen;
`
` /* Compute number of bytes mod 64 */
` index = (unsigned int)((context->count[0] >> 3) & 0x3F);
`
` /* Update number of bits */
` if ((context->count[0] += ((UINT4)inputLen << 3))
`
`Rivest [Page 11]
`
`

`

`
`RFC 1321 MD5 Message-Digest Algorithm April 1992
`
` < ((UINT4)inputLen << 3))
` context->count[1]++;
` context->count[1] += ((UINT4)inputLen >> 29);
`
` partLen = 64 - index;
`
` /* Transform as many times as possible.
`*/
` if (inputLen >= partLen) {
` MD5_memcpy
` ((POINTER)&context->buffer[index], (POINTER)input, partLen);
` MD5Transform (context->state, context->buffer);
`
` for (i = partLen; i + 63 < inputLen; i += 64)
` MD5Transform (context->state, &input[i]);
`
` index = 0;
` }
` else
` i = 0;
`
` /* Buffer remaining input */
` MD5_memcpy
` ((POINTER)&context->buffer[index], (POINTER)&input[i],
` inputLen-i);
`
`} /
`
`* MD5 finalization. Ends an MD5 message-digest operation, writing the
` the message digest and zeroizing the context.
` */
`void MD5Final (digest, context)
`unsigned char digest[16]; /* message digest */
`MD5_CTX *context; /* context */
`
`{
`
` unsigned char bits[8];
` unsigned int index, padLen;
`
` /* Save number of bits */
` Encode (bits, context->count, 8);
`
` /* Pad out to 56 mod 64.
`*/
` index = (unsigned int)((context->count[0] >> 3) & 0x3f);
` padLen = (index < 56) ? (56 - index) : (120 - index);
` MD5Update (context, PADDING, padLen);
`
` /* Append length (before padding) */
` MD5Update (context, bits, 8);
`
`Rivest [Page 12]
`
`

`

`
`RFC 1321 MD5 Message-Digest Algorithm April 1992
`
` /* Store state in digest */
` Encode (digest, context->state, 16);
`
` /* Zeroize sensitive information.
`*/
` MD5_memset ((POINTER)context, 0, sizeof (*context));
`
`} /
`
`* MD5 basic transformation. Transforms state based on block.
` */
`static void MD5Transform (state, block)
`UINT4 state[4];
`unsigned char block[64];
`
`{
`
` UINT4 a = state[0], b = state[1], c = state[2], d = state[3], x[16];
`
` Decode (x, block, 64);
`
` /* Round 1 */
` FF (a, b, c, d, x[ 0], S11, 0xd76aa478); /* 1 */
` FF (d, a, b, c, x[ 1], S12, 0xe8c7b756); /* 2 */
` FF (c, d, a, b, x[ 2], S13, 0x242070db); /* 3 */
` FF (b, c, d, a, x[ 3], S14, 0xc1bdceee); /* 4 */
` FF (a, b, c, d, x[ 4], S11, 0xf57c0faf); /* 5 */
` FF (d, a, b, c, x[ 5], S12, 0x4787c62a); /* 6 */
` FF (c, d, a, b, x[ 6], S13, 0xa8304613); /* 7 */
` FF (b, c, d, a, x[ 7], S14, 0xfd469501); /* 8 */
` FF (a, b, c, d, x[ 8], S11, 0x698098d8); /* 9 */
` FF (d, a, b, c, x[ 9], S12, 0x8b44f7af); /* 10 */
` FF (c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
` FF (b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
` FF (a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
` FF (d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
` FF (c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
` FF (b, c, d, a, x[15], S14, 0x49b40821); /* 16 */
`
` /* Round 2 */
` GG (a, b, c, d, x[ 1], S21, 0xf61e2562); /* 17 */
` GG (d, a, b, c, x[ 6], S22, 0xc040b340); /* 18 */
` GG (c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
` GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa); /* 20 */
` GG (a, b, c, d, x[ 5], S21, 0xd62f105d); /* 21 */
` GG (d, a, b, c, x[10], S22, 0x2441453); /* 22 */
` GG (c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
` GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8); /* 24 */
` GG (a, b, c, d, x[ 9], S21, 0x21e1cde6); /* 25 */
` GG (d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
` GG (c, d, a, b, x[ 3], S23, 0xf4d50d87); /* 27 */
`
`Rivest [Page 13]
`
`

`

`
`RFC 1321 MD5 Message-Digest Algorithm April 1992
`
` GG (b, c, d, a, x[ 8], S24, 0x455a14ed); /* 28 */
` GG (a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
` GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8); /* 30 */
` GG (c, d, a, b, x[ 7], S23, 0x676f02d9); /* 31 */
` GG (b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */
`
` /* Round 3 */
` HH (a, b, c, d, x[ 5], S31, 0xfffa3942); /* 33 */
` HH (d, a, b, c, x[ 8], S32, 0x8771f681); /* 34 */
` HH (c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
` HH (b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
` HH (a, b, c, d, x[ 1], S31, 0xa4beea44); /* 37 */
` HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9); /* 38 */
` HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60); /* 39 */
` HH (b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
` HH (a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
` HH (d, a, b, c, x[ 0], S32, 0xeaa127fa); /* 42 */
` HH (c, d, a, b, x[ 3], S33, 0xd4ef3085); /* 43 */
` HH (b, c, d, a, x[ 6], S34, 0x4881d05); /* 44 */
` HH (a, b, c, d, x[ 9], S31, 0xd9d4d039); /* 45 */
` HH (d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
` HH (c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
` HH (b, c, d, a, x[ 2], S34, 0xc4ac5665); /* 48 */
`
` /* Round 4 */
` II (a, b, c, d, x[ 0], S41, 0xf4292244); /* 49 */
` II (d, a, b, c, x[ 7], S42, 0x432aff97); /* 50 */
` II (c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
` II (b, c, d, a, x[ 5], S44, 0xfc93a039); /* 52 */
` II (a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
` II (d, a, b, c, x[ 3], S42, 0x8f0ccc92); /* 54 */
` II (c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
` II (b, c, d, a, x[ 1], S44, 0x85845dd1); /* 56 */
` II (a, b, c, d, x[ 8], S41, 0x6fa87e4f); /* 57 */
` II (d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
` II (c, d, a, b, x[ 6], S43, 0xa3014314); /* 59 */
` II (b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
` II (a, b, c, d, x[ 4], S41, 0xf7537e82); /* 61 */
` II (d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
` II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); /* 63 */
` II (b, c, d, a, x[ 9], S44, 0xeb86d391); /* 64 */
`
` state[0] += a;
` state[1] += b;
` state[2] += c;
` state[3] += d;
`
` /* Zeroize sensitive information.
`
`Rivest [Page 14]
`
`

`

`
`RFC 1321 MD5 Message-Digest Algorithm April 1992
`
`*/
` MD5_memset ((POINTER)x, 0, sizeof (x));
`
`} /
`
`* Encodes input (UINT4) into output (unsigned char). Assumes len is
` a multiple of 4.
` */
`static void Encode (output, input, len)
`unsigned char *output;
`UINT4 *input;
`unsigned int len;
`
`{
`
` unsigned int i, j;
`
` for (i = 0, j = 0; j < len; i++, j += 4) {
` output[j] = (unsigned char)(input[i] & 0xff);
` output[j+1] = (unsigned char)((input[i] >> 8) & 0xff);
` output[j+2] = (unsigned char)((input[i] >> 16) & 0xff);
` output[j+3] = (unsigned char)((input[i] >> 24) & 0xff);
` }
`
`} /
`
`* Decodes input (unsigned char) into output (UINT4). Assumes len is
` a multiple of 4.
` */
`static void Decode (output, input, len)
`UINT4 *output;
`unsigned char *input;
`unsigned int len;
`
`{
`
` unsigned int i, j;
`
` for (i = 0, j = 0; j < len; i++, j += 4)
` output[i] = ((UINT4)input[j]) | (((UINT4)input[j+1]) << 8) |
` (((UINT4)input[j+2]) << 16) | (((UINT4)input[j+3]) << 24);
`
`} /
`
`* Note: Replace "for loop" with standard memcpy if possible.
` */
`
`static void MD5_memcpy (output, input, len)
`POINTER output;
`POINTER input;
`unsigned int len;
`
`{
`
` unsigned int i;
`
` for (i = 0; i < len; i++)
`
`Rivest [Page 15]
`
`

`

`
`RFC 1321 MD5 Message-Digest Algorithm April 1992
`
` output[i] = input[i];
`
`} /
`
`* Note: Replace "for loop" with standard memset if possible.
` */
`static void MD5_memset (output, value, len)
`POINTER output;
`int value;
`unsigned int len;
`
`{
`
` unsigned int i;
`
` for (i = 0; i < len; i++)
` ((char *)output)[i] = (char)value;
`
`} A
`
`.4 mddriver.c
`
`/* MDDRIVER.C - test driver for MD2, MD4 and MD5
` */
`
`/* Copyright (C) 1990-2, RSA Data Security, Inc. Created 1990. All
`rights reserved.
`
`RSA Data Security, Inc. makes no representations concerning either
`the merchantability of this software or the suitability of this
`software for any particular purpose. It is provided "as is"
`without express or implied warranty of any kind.
`
`These notices must be retained in any copies of any part of this
`documentation and/or software.
` */
`
`/* The following makes MD default to MD5 if it has not already been
` defined with C compiler flags.
` */
`#ifndef MD
`#define MD MD5
`#endif
`
`#include <stdio.h>
`#include <time.h>
`#include <string.h>
`#include "global.h"
`#if MD == 2
`#include "md2.h"
`#endif
`#if MD == 4
`
`Rivest [Page 16]
`
`

`

`
`RFC 1321 MD5 Message-Digest Algorithm April 1992
`
`#include "md4.h"
`#endif
`#if MD == 5
`#include "md5.h"
`#endif
`
`/* Length of test block, number of test blocks.
` */
`#define TEST_BLOCK_LEN 1000
`#define TEST_BLOCK_COUNT 1000
`
`static void MDString PROTO_LIST ((char *));
`static void MDTimeTrial PROTO_LIST ((void));
`static void MDTestSuite PROTO_LIST ((void));
`static void MDFile PROTO_LIST ((char *));
`static void MDFilter PROTO_LIST ((void));
`static void MDPrint PROTO_LIST ((unsigned char [16]));
`
`#if MD == 2
`#define MD_CTX MD2_CTX
`#define MDInit MD2Init
`#define MDUpdate MD2Update
`#define MDFinal MD2Final
`#endif
`#if MD == 4
`#define MD_CTX MD4_CTX
`#define MDInit MD4Init
`#define MDUpdate MD4Update
`#define MDFinal MD4Final
`#endif
`#if MD == 5
`#define MD_CTX MD5_CTX
`#define MDInit MD5Init
`#define MDUpdate MD5Update
`#define MDFinal MD5Final
`#endif
`
`/* Main driver.
`
`Arguments (may be any combination):
` -sstring - digests string
` -t - runs time trial
` -x - runs test script
` filename - digests file
` (none) - digests standard input
` */
`int main (argc, argv)
`int argc;
`
`Rivest [Page 17]
`
`

`

`
`RFC 1321 MD5 Message-Digest Algorithm April 1992
`
`char *argv[];
`
`{
`
` int i;
`
` if (argc > 1)
` for (i = 1; i < argc; i++)
` if (argv[i][0] == ’-’ && argv[i][1] == ’s’)
` MDString (argv[i] + 2);
` else if (strcmp (argv[i], "-t") == 0)
` MDTimeTrial ();
` else if (strcmp (argv[i], "-x") == 0)
` MDTestSuite ();
` else
` MDFile (argv[i]);
` else
` MDFilter ();
`
` return (0);
`
`} /
`
`* Digests a string and prints the result.
` */
`static void MDString (string)
`char *string;
`
`{
`
` MD_CTX context;
` unsigned char digest[16];
` unsigned int len = strlen (string);
`
` MDInit (&context);
` MDUpdate (&context, string, len);
` MDFinal (digest, &context);
`
` printf ("MD%d (\"%s\") = ", MD, string);
` MDPrint (digest);
` printf ("\n");
`
`} /
`
`* Measures the time to digest TEST_BLOCK_COUNT TEST_BLOCK_LEN-byte
` blocks.
` */
`static void MDTimeTrial ()
`
`{
`
` MD_CTX context;
` time_t endTime, startTime;
` unsigned char block[TEST_BLOCK_LEN], digest[16];
` unsigned int i;
`
`Rivest [Page 18]
`
`

`

`
`RFC 1321 MD5 Message-Digest Algorithm April 1992
`
` printf
` ("MD%d time trial. Digesting %d %d-byte blocks ...", MD,
` TEST_BLOCK_LEN, TEST_BLOCK_COUNT);
`
` /* Initialize block */
` for (i = 0; i < TEST_BLOCK_LEN; i++)
` block[i] = (unsigned char)(i & 0xff);
`
` /* Start timer */
` time (&startTime);
`
` /* Digest blocks */
` MDInit (&context);
` for (i = 0; i < TEST_BLOCK_COUNT; i++)
` MDUpdate (&context, block, TEST_BLOCK_LEN);
` MDFinal (digest, &context);
`
` /* Stop timer */
` time (&endTime);
`
` printf (" done\n");
` printf ("Digest = ");
` MDPrint (digest);
` printf ("\nTime = %ld seconds\n", (long)(endTime-startTime));
` printf
` ("Speed = %ld bytes/second\n",
` (long)TEST_BLOCK_LEN * (long)TEST_BLOCK_COUNT/(endTime-startTime));
`
`} /
`
`* Digests a reference suite of strings and prints the results.
` */
`static void MDTestSuite ()
`
`{
`
` printf ("MD%d test suite:\n", MD);
`
` MDString ("");
` MDString ("a");
` MDString ("abc");
` MDString ("message digest");
` MDString ("abcdefghijklmnopqrstuvwxyz");
` MDString
` ("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789");
` MDString
` ("1234567890123456789012345678901234567890