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diff --git a/doc/rfc/rfc1321.txt b/doc/rfc/rfc1321.txt new file mode 100644 index 0000000..68af27d --- /dev/null +++ b/doc/rfc/rfc1321.txt @@ -0,0 +1,1179 @@ + + + + + + +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] + +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\ +1234567890123456789012345678901234567890"); +} + +/* Digests a file and prints the result. + + + +Rivest [Page 19] + +RFC 1321 MD5 Message-Digest Algorithm April 1992 + + + */ +static void MDFile (filename) +char *filename; +{ + FILE *file; + MD_CTX context; + int len; + unsigned char buffer[1024], digest[16]; + + if ((file = fopen (filename, "rb")) == NULL) + printf ("%s can't be opened\n", filename); + + else { + MDInit (&context); + while (len = fread (buffer, 1, 1024, file)) + MDUpdate (&context, buffer, len); + MDFinal (digest, &context); + + fclose (file); + + printf ("MD%d (%s) = ", MD, filename); + MDPrint (digest); + printf ("\n"); + } +} + +/* Digests the standard input and prints the result. + */ +static void MDFilter () +{ + MD_CTX context; + int len; + unsigned char buffer[16], digest[16]; + + MDInit (&context); + while (len = fread (buffer, 1, 16, stdin)) + MDUpdate (&context, buffer, len); + MDFinal (digest, &context); + + MDPrint (digest); + printf ("\n"); +} + +/* Prints a message digest in hexadecimal. + */ +static void MDPrint (digest) +unsigned char digest[16]; +{ + + + +Rivest [Page 20] + +RFC 1321 MD5 Message-Digest Algorithm April 1992 + + + unsigned int i; + + for (i = 0; i < 16; i++) + printf ("%02x", digest[i]); +} + +A.5 Test suite + + The MD5 test suite (driver option "-x") should print the following + results: + +MD5 test suite: +MD5 ("") = d41d8cd98f00b204e9800998ecf8427e +MD5 ("a") = 0cc175b9c0f1b6a831c399e269772661 +MD5 ("abc") = 900150983cd24fb0d6963f7d28e17f72 +MD5 ("message digest") = f96b697d7cb7938d525a2f31aaf161d0 +MD5 ("abcdefghijklmnopqrstuvwxyz") = c3fcd3d76192e4007dfb496cca67e13b +MD5 ("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789") = +d174ab98d277d9f5a5611c2c9f419d9f +MD5 ("123456789012345678901234567890123456789012345678901234567890123456 +78901234567890") = 57edf4a22be3c955ac49da2e2107b67a + +Security Considerations + + The level of security discussed in this memo is considered to be + sufficient for implementing very high security hybrid digital- + signature schemes based on MD5 and a public-key cryptosystem. + +Author's Address + + Ronald L. Rivest + Massachusetts Institute of Technology + Laboratory for Computer Science + NE43-324 + 545 Technology Square + Cambridge, MA 02139-1986 + + Phone: (617) 253-5880 + EMail: rivest@theory.lcs.mit.edu + + + + + + + + + + + + +Rivest [Page 21] +
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