A portable, fast, and free implementation of the MD5 Message-Digest Algorithm (RFC 1321)

This is an OpenSSL-compatible implementation of the RSA Data Security, Inc. MD5 Message-Digest Algorithm (RFC 1321).

Written by Solar Designer <solar at openwall.com> in 2001 and placed in the public domain. There's absolutely no warranty.

This differs from Colin Plumb's older public domain implementation in that no exactly 32-bit integer data type is required (any 32-bit or wider unsigned integer data type will do), there's no compile-time endianness configuration, and the function prototypes match OpenSSL's. No code from Colin Plumb's implementation has been reused; this comment merely compares the properties of the two independent implementations.

The primary goals of this implementation are portability and ease of use. It is meant to be fast, but not as fast as possible. Some known optimizations are not included to reduce source code size and avoid compile-time configuration.

Download md5.c and md5.h (both are also shown below). Revision history for them happens to be maintained in the popa3d CVS tree.

This code is used in Openwall's popa3d and blists, as well as in PHP 5.3.0+, ClamAV, Dovecot, Eggdrop, FreeType, masqmail, Staden Package io_lib, and more.

Back to other source code snippets and frameworks placed in the public domain.

/*
 * This is an OpenSSL-compatible implementation of the RSA Data Security, Inc.
 * MD5 Message-Digest Algorithm (RFC 1321).
 *
 * Homepage:
 * http://openwall.info/wiki/people/solar/software/public-domain-source-code/md5
 *
 * Author:
 * Alexander Peslyak, better known as Solar Designer <solar at openwall.com>
 *
 * This software was written by Alexander Peslyak in 2001.  No copyright is
 * claimed, and the software is hereby placed in the public domain.
 * In case this attempt to disclaim copyright and place the software in the
 * public domain is deemed null and void, then the software is
 * Copyright (c) 2001 Alexander Peslyak and it is hereby released to the
 * general public under the following terms:
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted.
 *
 * There's ABSOLUTELY NO WARRANTY, express or implied.
 *
 * (This is a heavily cut-down "BSD license".)
 *
 * This differs from Colin Plumb's older public domain implementation in that
 * no exactly 32-bit integer data type is required (any 32-bit or wider
 * unsigned integer data type will do), there's no compile-time endianness
 * configuration, and the function prototypes match OpenSSL's.  No code from
 * Colin Plumb's implementation has been reused; this comment merely compares
 * the properties of the two independent implementations.
 *
 * The primary goals of this implementation are portability and ease of use.
 * It is meant to be fast, but not as fast as possible.  Some known
 * optimizations are not included to reduce source code size and avoid
 * compile-time configuration.
 */
 
#ifndef HAVE_OPENSSL
 
#include <string.h>
 
#include "md5.h"
 
/*
 * The basic MD5 functions.
 *
 * F and G are optimized compared to their RFC 1321 definitions for
 * architectures that lack an AND-NOT instruction, just like in Colin Plumb's
 * implementation.
 */
#define F(x, y, z)			((z) ^ ((x) & ((y) ^ (z))))
#define G(x, y, z)			((y) ^ ((z) & ((x) ^ (y))))
#define H(x, y, z)			(((x) ^ (y)) ^ (z))
#define H2(x, y, z)			((x) ^ ((y) ^ (z)))
#define I(x, y, z)			((y) ^ ((x) | ~(z)))
 
/*
 * The MD5 transformation for all four rounds.
 */
#define STEP(f, a, b, c, d, x, t, s) \
	(a) += f((b), (c), (d)) + (x) + (t); \
	(a) = (((a) << (s)) | (((a) & 0xffffffff) >> (32 - (s)))); \
	(a) += (b);
 
/*
 * SET reads 4 input bytes in little-endian byte order and stores them in a
 * properly aligned word in host byte order.
 *
 * The check for little-endian architectures that tolerate unaligned memory
 * accesses is just an optimization.  Nothing will break if it fails to detect
 * a suitable architecture.
 *
 * Unfortunately, this optimization may be a C strict aliasing rules violation
 * if the caller's data buffer has effective type that cannot be aliased by
 * MD5_u32plus.  In practice, this problem may occur if these MD5 routines are
 * inlined into a calling function, or with future and dangerously advanced
 * link-time optimizations.  For the time being, keeping these MD5 routines in
 * their own translation unit avoids the problem.
 */
#if defined(__i386__) || defined(__x86_64__) || defined(__vax__)
#define SET(n) \
	(*(MD5_u32plus *)&ptr[(n) * 4])
#define GET(n) \
	SET(n)
#else
#define SET(n) \
	(ctx->block[(n)] = \
	(MD5_u32plus)ptr[(n) * 4] | \
	((MD5_u32plus)ptr[(n) * 4 + 1] << 8) | \
	((MD5_u32plus)ptr[(n) * 4 + 2] << 16) | \
	((MD5_u32plus)ptr[(n) * 4 + 3] << 24))
#define GET(n) \
	(ctx->block[(n)])
#endif
 
/*
 * This processes one or more 64-byte data blocks, but does NOT update the bit
 * counters.  There are no alignment requirements.
 */
static const void *body(MD5_CTX *ctx, const void *data, unsigned long size)
{
	const unsigned char *ptr;
	MD5_u32plus a, b, c, d;
	MD5_u32plus saved_a, saved_b, saved_c, saved_d;
 
	ptr = (const unsigned char *)data;
 
	a = ctx->a;
	b = ctx->b;
	c = ctx->c;
	d = ctx->d;
 
	do {
		saved_a = a;
		saved_b = b;
		saved_c = c;
		saved_d = d;
 
/* Round 1 */
		STEP(F, a, b, c, d, SET(0), 0xd76aa478, 7)
		STEP(F, d, a, b, c, SET(1), 0xe8c7b756, 12)
		STEP(F, c, d, a, b, SET(2), 0x242070db, 17)
		STEP(F, b, c, d, a, SET(3), 0xc1bdceee, 22)
		STEP(F, a, b, c, d, SET(4), 0xf57c0faf, 7)
		STEP(F, d, a, b, c, SET(5), 0x4787c62a, 12)
		STEP(F, c, d, a, b, SET(6), 0xa8304613, 17)
		STEP(F, b, c, d, a, SET(7), 0xfd469501, 22)
		STEP(F, a, b, c, d, SET(8), 0x698098d8, 7)
		STEP(F, d, a, b, c, SET(9), 0x8b44f7af, 12)
		STEP(F, c, d, a, b, SET(10), 0xffff5bb1, 17)
		STEP(F, b, c, d, a, SET(11), 0x895cd7be, 22)
		STEP(F, a, b, c, d, SET(12), 0x6b901122, 7)
		STEP(F, d, a, b, c, SET(13), 0xfd987193, 12)
		STEP(F, c, d, a, b, SET(14), 0xa679438e, 17)
		STEP(F, b, c, d, a, SET(15), 0x49b40821, 22)
 
/* Round 2 */
		STEP(G, a, b, c, d, GET(1), 0xf61e2562, 5)
		STEP(G, d, a, b, c, GET(6), 0xc040b340, 9)
		STEP(G, c, d, a, b, GET(11), 0x265e5a51, 14)
		STEP(G, b, c, d, a, GET(0), 0xe9b6c7aa, 20)
		STEP(G, a, b, c, d, GET(5), 0xd62f105d, 5)
		STEP(G, d, a, b, c, GET(10), 0x02441453, 9)
		STEP(G, c, d, a, b, GET(15), 0xd8a1e681, 14)
		STEP(G, b, c, d, a, GET(4), 0xe7d3fbc8, 20)
		STEP(G, a, b, c, d, GET(9), 0x21e1cde6, 5)
		STEP(G, d, a, b, c, GET(14), 0xc33707d6, 9)
		STEP(G, c, d, a, b, GET(3), 0xf4d50d87, 14)
		STEP(G, b, c, d, a, GET(8), 0x455a14ed, 20)
		STEP(G, a, b, c, d, GET(13), 0xa9e3e905, 5)
		STEP(G, d, a, b, c, GET(2), 0xfcefa3f8, 9)
		STEP(G, c, d, a, b, GET(7), 0x676f02d9, 14)
		STEP(G, b, c, d, a, GET(12), 0x8d2a4c8a, 20)
 
/* Round 3 */
		STEP(H, a, b, c, d, GET(5), 0xfffa3942, 4)
		STEP(H2, d, a, b, c, GET(8), 0x8771f681, 11)
		STEP(H, c, d, a, b, GET(11), 0x6d9d6122, 16)
		STEP(H2, b, c, d, a, GET(14), 0xfde5380c, 23)
		STEP(H, a, b, c, d, GET(1), 0xa4beea44, 4)
		STEP(H2, d, a, b, c, GET(4), 0x4bdecfa9, 11)
		STEP(H, c, d, a, b, GET(7), 0xf6bb4b60, 16)
		STEP(H2, b, c, d, a, GET(10), 0xbebfbc70, 23)
		STEP(H, a, b, c, d, GET(13), 0x289b7ec6, 4)
		STEP(H2, d, a, b, c, GET(0), 0xeaa127fa, 11)
		STEP(H, c, d, a, b, GET(3), 0xd4ef3085, 16)
		STEP(H2, b, c, d, a, GET(6), 0x04881d05, 23)
		STEP(H, a, b, c, d, GET(9), 0xd9d4d039, 4)
		STEP(H2, d, a, b, c, GET(12), 0xe6db99e5, 11)
		STEP(H, c, d, a, b, GET(15), 0x1fa27cf8, 16)
		STEP(H2, b, c, d, a, GET(2), 0xc4ac5665, 23)
 
/* Round 4 */
		STEP(I, a, b, c, d, GET(0), 0xf4292244, 6)
		STEP(I, d, a, b, c, GET(7), 0x432aff97, 10)
		STEP(I, c, d, a, b, GET(14), 0xab9423a7, 15)
		STEP(I, b, c, d, a, GET(5), 0xfc93a039, 21)
		STEP(I, a, b, c, d, GET(12), 0x655b59c3, 6)
		STEP(I, d, a, b, c, GET(3), 0x8f0ccc92, 10)
		STEP(I, c, d, a, b, GET(10), 0xffeff47d, 15)
		STEP(I, b, c, d, a, GET(1), 0x85845dd1, 21)
		STEP(I, a, b, c, d, GET(8), 0x6fa87e4f, 6)
		STEP(I, d, a, b, c, GET(15), 0xfe2ce6e0, 10)
		STEP(I, c, d, a, b, GET(6), 0xa3014314, 15)
		STEP(I, b, c, d, a, GET(13), 0x4e0811a1, 21)
		STEP(I, a, b, c, d, GET(4), 0xf7537e82, 6)
		STEP(I, d, a, b, c, GET(11), 0xbd3af235, 10)
		STEP(I, c, d, a, b, GET(2), 0x2ad7d2bb, 15)
		STEP(I, b, c, d, a, GET(9), 0xeb86d391, 21)
 
		a += saved_a;
		b += saved_b;
		c += saved_c;
		d += saved_d;
 
		ptr += 64;
	} while (size -= 64);
 
	ctx->a = a;
	ctx->b = b;
	ctx->c = c;
	ctx->d = d;
 
	return ptr;
}
 
void MD5_Init(MD5_CTX *ctx)
{
	ctx->a = 0x67452301;
	ctx->b = 0xefcdab89;
	ctx->c = 0x98badcfe;
	ctx->d = 0x10325476;
 
	ctx->lo = 0;
	ctx->hi = 0;
}
 
void MD5_Update(MD5_CTX *ctx, const void *data, unsigned long size)
{
	MD5_u32plus saved_lo;
	unsigned long used, available;
 
	saved_lo = ctx->lo;
	if ((ctx->lo = (saved_lo + size) & 0x1fffffff) < saved_lo)
		ctx->hi++;
	ctx->hi += size >> 29;
 
	used = saved_lo & 0x3f;
 
	if (used) {
		available = 64 - used;
 
		if (size < available) {
			memcpy(&ctx->buffer[used], data, size);
			return;
		}
 
		memcpy(&ctx->buffer[used], data, available);
		data = (const unsigned char *)data + available;
		size -= available;
		body(ctx, ctx->buffer, 64);
	}
 
	if (size >= 64) {
		data = body(ctx, data, size & ~(unsigned long)0x3f);
		size &= 0x3f;
	}
 
	memcpy(ctx->buffer, data, size);
}
 
#define OUT(dst, src) \
	(dst)[0] = (unsigned char)(src); \
	(dst)[1] = (unsigned char)((src) >> 8); \
	(dst)[2] = (unsigned char)((src) >> 16); \
	(dst)[3] = (unsigned char)((src) >> 24);
 
void MD5_Final(unsigned char *result, MD5_CTX *ctx)
{
	unsigned long used, available;
 
	used = ctx->lo & 0x3f;
 
	ctx->buffer[used++] = 0x80;
 
	available = 64 - used;
 
	if (available < 8) {
		memset(&ctx->buffer[used], 0, available);
		body(ctx, ctx->buffer, 64);
		used = 0;
		available = 64;
	}
 
	memset(&ctx->buffer[used], 0, available - 8);
 
	ctx->lo <<= 3;
	OUT(&ctx->buffer[56], ctx->lo)
	OUT(&ctx->buffer[60], ctx->hi)
 
	body(ctx, ctx->buffer, 64);
 
	OUT(&result[0], ctx->a)
	OUT(&result[4], ctx->b)
	OUT(&result[8], ctx->c)
	OUT(&result[12], ctx->d)
 
	memset(ctx, 0, sizeof(*ctx));
}
 
#endif

/*
 * This is an OpenSSL-compatible implementation of the RSA Data Security, Inc.
 * MD5 Message-Digest Algorithm (RFC 1321).
 *
 * Homepage:
 * http://openwall.info/wiki/people/solar/software/public-domain-source-code/md5
 *
 * Author:
 * Alexander Peslyak, better known as Solar Designer <solar at openwall.com>
 *
 * This software was written by Alexander Peslyak in 2001.  No copyright is
 * claimed, and the software is hereby placed in the public domain.
 * In case this attempt to disclaim copyright and place the software in the
 * public domain is deemed null and void, then the software is
 * Copyright (c) 2001 Alexander Peslyak and it is hereby released to the
 * general public under the following terms:
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted.
 *
 * There's ABSOLUTELY NO WARRANTY, express or implied.
 *
 * See md5.c for more information.
 */
 
#ifdef HAVE_OPENSSL
#include <openssl/md5.h>
#elif !defined(_MD5_H)
#define _MD5_H
 
/* Any 32-bit or wider unsigned integer data type will do */
typedef unsigned int MD5_u32plus;
 
typedef struct {
	MD5_u32plus lo, hi;
	MD5_u32plus a, b, c, d;
	unsigned char buffer[64];
	MD5_u32plus block[16];
} MD5_CTX;
 
extern void MD5_Init(MD5_CTX *ctx);
extern void MD5_Update(MD5_CTX *ctx, const void *data, unsigned long size);
extern void MD5_Final(unsigned char *result, MD5_CTX *ctx);
 
#endif

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