path: root/modules/pam_unix/md5.c

/*
 * This code implements the MD5 message-digest algorithm.
 * The algorithm is due to Ron Rivest.	This code was
 * written by Colin Plumb in 1993, no copyright is claimed.
 * This code is in the public domain; do with it what you wish.
 *
 * Equivalent code is available from RSA Data Security, Inc.
 * This code has been tested against that, and is equivalent,
 * except that you don't need to include two pages of legalese
 * with every copy.
 *
 * To compute the message digest of a chunk of bytes, declare an
 * MD5Context structure, pass it to MD5Init, call MD5Update as
 * needed on buffers full of bytes, and then call MD5Final, which
 * will fill a supplied 16-byte array with the digest.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include "md5.h"

#define PUT_64BIT_LE(cp, value) do {					\
	(cp)[7] = (value) >> 56;					\
	(cp)[6] = (value) >> 48;					\
	(cp)[5] = (value) >> 40;					\
	(cp)[4] = (value) >> 32;					\
	(cp)[3] = (value) >> 24;					\
	(cp)[2] = (value) >> 16;					\
	(cp)[1] = (value) >> 8;						\
	(cp)[0] = (value); } while (0)

#define PUT_32BIT_LE(cp, value) do {					\
	(cp)[3] = (value) >> 24;					\
	(cp)[2] = (value) >> 16;					\
	(cp)[1] = (value) >> 8;						\
	(cp)[0] = (value); } while (0)


static void to64(char* , long , int );


static u_int8_t PADDING[MD5_BLOCK_LENGTH] = {
	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
};

/*
 * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
 * initialization constants.
 */
void
MD5Init(MD5_CTX *ctx)
{
	ctx->count = 0;
	ctx->state[0] = 0x67452301;
	ctx->state[1] = 0xefcdab89;
	ctx->state[2] = 0x98badcfe;
	ctx->state[3] = 0x10325476;
}

/*
 * Update context to reflect the concatenation of another buffer full
 * of bytes.
 */
void
MD5Update(MD5_CTX *ctx, const unsigned char *input, size_t len)
{
	size_t have, need;

	/* Check how many bytes we already have and how many more we need. */
	have = (size_t)((ctx->count >> 3) & (MD5_BLOCK_LENGTH - 1));
	need = MD5_BLOCK_LENGTH - have;

	/* Update bitcount */
	ctx->count += (u_int64_t)len << 3;

	if (len >= need) {
		if (have != 0) {
			memcpy(ctx->buffer + have, input, need);
			MD5Transform(ctx->state, ctx->buffer);
			input += need;
			len -= need;
			have = 0;
		}

		/* Process data in MD5_BLOCK_LENGTH-byte chunks. */
		while (len >= MD5_BLOCK_LENGTH) {
			MD5Transform(ctx->state, input);
			input += MD5_BLOCK_LENGTH;
			len -= MD5_BLOCK_LENGTH;
		}
	}

	/* Handle any remaining bytes of data. */
	if (len != 0)
		memcpy(ctx->buffer + have, input, len);
}

/*
 * Pad pad to 64-byte boundary with the bit pattern
 * 1 0* (64-bit count of bits processed, MSB-first)
 */
void
MD5Pad(MD5_CTX *ctx)
{
	u_int8_t count[8];
	size_t padlen;

	/* Convert count to 8 bytes in little endian order. */
	PUT_64BIT_LE(count, ctx->count);

	/* Pad out to 56 mod 64. */
	padlen = MD5_BLOCK_LENGTH -
	    ((ctx->count >> 3) & (MD5_BLOCK_LENGTH - 1));
	if (padlen < 1 + 8)
		padlen += MD5_BLOCK_LENGTH;
	MD5Update(ctx, PADDING, padlen - 8);		/* padlen - 8 <= 64 */
	MD5Update(ctx, count, 8);
}

/*
 * Final wrapup--call MD5Pad, fill in digest and zero out ctx.
 */
void
MD5Final(unsigned char digest[MD5_DIGEST_LENGTH], MD5_CTX *ctx)
{
	int i;

	MD5Pad(ctx);
	if (digest != NULL) {
		for (i = 0; i < 4; i++)
			PUT_32BIT_LE(digest + i * 4, ctx->state[i]);
		memset(ctx, 0, sizeof(*ctx));
	}
}


/* The four core functions - F1 is optimized somewhat */

/* #define F1(x, y, z) (x & y | ~x & z) */
#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))

/* This is the central step in the MD5 algorithm. */
#define MD5STEP(f, w, x, y, z, data, s) \
	( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )

/*
 * The core of the MD5 algorithm, this alters an existing MD5 hash to
 * reflect the addition of 16 longwords of new data.  MD5Update blocks
 * the data and converts bytes into longwords for this routine.
 */
void
MD5Transform(u_int32_t state[4], const u_int8_t block[MD5_BLOCK_LENGTH])
{
	u_int32_t a, b, c, d, in[MD5_BLOCK_LENGTH / 4];

#if BYTE_ORDER == LITTLE_ENDIAN
	memcpy(in, block, sizeof(in));
#else
	for (a = 0; a < MD5_BLOCK_LENGTH / 4; a++) {
		in[a] = (u_int32_t)(
		    (u_int32_t)(block[a * 4 + 0]) |
		    (u_int32_t)(block[a * 4 + 1]) <<  8 |
		    (u_int32_t)(block[a * 4 + 2]) << 16 |
		    (u_int32_t)(block[a * 4 + 3]) << 24);
	}
#endif

	a = state[0];
	b = state[1];
	c = state[2];
	d = state[3];

	MD5STEP(F1, a, b, c, d, in[ 0] + 0xd76aa478,  7);
	MD5STEP(F1, d, a, b, c, in[ 1] + 0xe8c7b756, 12);
	MD5STEP(F1, c, d, a, b, in[ 2] + 0x242070db, 17);
	MD5STEP(F1, b, c, d, a, in[ 3] + 0xc1bdceee, 22);
	MD5STEP(F1, a, b, c, d, in[ 4] + 0xf57c0faf,  7);
	MD5STEP(F1, d, a, b, c, in[ 5] + 0x4787c62a, 12);
	MD5STEP(F1, c, d, a, b, in[ 6] + 0xa8304613, 17);
	MD5STEP(F1, b, c, d, a, in[ 7] + 0xfd469501, 22);
	MD5STEP(F1, a, b, c, d, in[ 8] + 0x698098d8,  7);
	MD5STEP(F1, d, a, b, c, in[ 9] + 0x8b44f7af, 12);
	MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
	MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
	MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122,  7);
	MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
	MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
	MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);

	MD5STEP(F2, a, b, c, d, in[ 1] + 0xf61e2562,  5);
	MD5STEP(F2, d, a, b, c, in[ 6] + 0xc040b340,  9);
	MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
	MD5STEP(F2, b, c, d, a, in[ 0] + 0xe9b6c7aa, 20);
	MD5STEP(F2, a, b, c, d, in[ 5] + 0xd62f105d,  5);
	MD5STEP(F2, d, a, b, c, in[10] + 0x02441453,  9);
	MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
	MD5STEP(F2, b, c, d, a, in[ 4] + 0xe7d3fbc8, 20);
	MD5STEP(F2, a, b, c, d, in[ 9] + 0x21e1cde6,  5);
	MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6,  9);
	MD5STEP(F2, c, d, a, b, in[ 3] + 0xf4d50d87, 14);
	MD5STEP(F2, b, c, d, a, in[ 8] + 0x455a14ed, 20);
	MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905,  5);
	MD5STEP(F2, d, a, b, c, in[ 2] + 0xfcefa3f8,  9);
	MD5STEP(F2, c, d, a, b, in[ 7] + 0x676f02d9, 14);
	MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);

	MD5STEP(F3, a, b, c, d, in[ 5] + 0xfffa3942,  4);
	MD5STEP(F3, d, a, b, c, in[ 8] + 0x8771f681, 11);
	MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
	MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
	MD5STEP(F3, a, b, c, d, in[ 1] + 0xa4beea44,  4);
	MD5STEP(F3, d, a, b, c, in[ 4] + 0x4bdecfa9, 11);
	MD5STEP(F3, c, d, a, b, in[ 7] + 0xf6bb4b60, 16);
	MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
	MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6,  4);
	MD5STEP(F3, d, a, b, c, in[ 0] + 0xeaa127fa, 11);
	MD5STEP(F3, c, d, a, b, in[ 3] + 0xd4ef3085, 16);
	MD5STEP(F3, b, c, d, a, in[ 6] + 0x04881d05, 23);
	MD5STEP(F3, a, b, c, d, in[ 9] + 0xd9d4d039,  4);
	MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
	MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
	MD5STEP(F3, b, c, d, a, in[2 ] + 0xc4ac5665, 23);

	MD5STEP(F4, a, b, c, d, in[ 0] + 0xf4292244,  6);
	MD5STEP(F4, d, a, b, c, in[7 ] + 0x432aff97, 10);
	MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
	MD5STEP(F4, b, c, d, a, in[5 ] + 0xfc93a039, 21);
	MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3,  6);
	MD5STEP(F4, d, a, b, c, in[3 ] + 0x8f0ccc92, 10);
	MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
	MD5STEP(F4, b, c, d, a, in[1 ] + 0x85845dd1, 21);
	MD5STEP(F4, a, b, c, d, in[8 ] + 0x6fa87e4f,  6);
	MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
	MD5STEP(F4, c, d, a, b, in[6 ] + 0xa3014314, 15);
	MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
	MD5STEP(F4, a, b, c, d, in[4 ] + 0xf7537e82,  6);
	MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
	MD5STEP(F4, c, d, a, b, in[2 ] + 0x2ad7d2bb, 15);
	MD5STEP(F4, b, c, d, a, in[9 ] + 0xeb86d391, 21);

	state[0] += a;
	state[1] += b;
	state[2] += c;
	state[3] += d;
}


/*
 * MD5String: takes a string as an argument and returns the 
 * digest for this string.
 */

char * MD5Hash(const char * string, const char * salt) { 

	int i,j,passl,saltl,pl;
	unsigned long l;
	MD5_CTX mdContext, mdContext2;
	unsigned char digest[16];
	const char *magic = "$1$";
	const char *sp , *tsp; /*sp: salt pointer / tsp : true salt pointer*/
	char * md5hash, *passwd;

	md5hash = (char *) malloc (sizeof(char)*120);
	passwd = md5hash; 
	sp = salt;

	/* skip magic string if it's in salt -- 
	 * this can't happen here, since we create the 
	 * salt without a magic string but someone may use
	 * this for something else one day */
        if (!strncmp(sp, magic, strlen(magic)))
		sp += strlen(magic);

	/* stop salt at '$' or after 8 chars */
	for (tsp = sp; *tsp && *tsp != '$' && tsp < (sp + 8); tsp++)
		continue;
	/* Define salt and pass length */
	saltl = tsp - sp ;
	passl = strlen(string);

	/* Init the condext */
	MD5Init(&mdContext);
	/* Update with the password first */
	MD5Update(&mdContext, (unsigned const char *)string, passl);
	/* Then use the magic string */
	MD5Update(&mdContext, (unsigned const char *)magic, strlen(magic));
	/* Then use the salt */
	MD5Update(&mdContext, (unsigned const char *)salt, saltl);
	
	/* Update original using characters from MD5Hash of pwd,salt,pwd */
	MD5Init(&mdContext2);
	MD5Update(&mdContext2, (unsigned const char *)string, passl);
	MD5Update(&mdContext2, (unsigned const char *)salt, saltl);
	MD5Update(&mdContext2, (unsigned const char *)string, passl);
	MD5Final (digest, &mdContext2);
	
	/* Cool, huh? */
	for (pl = passl; pl > 0; pl -= 16)
	                MD5Update(&mdContext,(unsigned const char *)digest,pl>16 ? 16 : pl);
	
	/* Don't leave behind sensitive data */
	memset(digest, 0, sizeof digest);

	/* Weird stuff... */
	for (j = 0, i = passl; i; i >>= 1) {
		if (i & 1)
			MD5Update(&mdContext,(unsigned const char *)digest+j,1);
		else
			MD5Update(&mdContext,(unsigned const char *)string+j,1);
	}

	/* Update hash with magic + salt + $ */
	strcpy(passwd, magic);
	strncat(passwd, salt, saltl);
	strcat(passwd,"$");
	passwd += strlen(md5hash);

	MD5Final(digest,&mdContext);

	/* Ensure that it can't go too fast (not sure why we need this) */
        for (i = 0; i < 1000; i++) {
		MD5Init(&mdContext2);
		if (i & 1)
			MD5Update(&mdContext2,(unsigned const char *)string,passl);
		else
			MD5Update(&mdContext2,(unsigned const char *)digest,16);
		if (i % 3)
			MD5Update(&mdContext2,(unsigned const char *)salt,saltl);
	
		if (i % 7)
			MD5Update(&mdContext2,(unsigned const char *)string,passl);
	
		if (i & 1)
			MD5Update(&mdContext2,(unsigned const char *)digest,16);
		else
			MD5Update(&mdContext2,(unsigned const char *)string,passl);
		
		MD5Final(digest,&mdContext2);

	}
	
	/* Do some binary permutations */
	l = (digest[0] << 16) | (digest[6] << 8) | digest[12];
        to64(passwd, l, 4);
	passwd += 4;
	l = (digest[1] << 16) | (digest[7] << 8) | digest[13];
	to64(passwd, l, 4);
	passwd += 4;
	l = (digest[2] << 16) | (digest[8] << 8) | digest[14];
	to64(passwd, l, 4);
	passwd += 4;
	l = (digest[3] << 16) | (digest[9] << 8) | digest[15];
	to64(passwd, l, 4);
	passwd += 4;
	l = (digest[4] << 16) | (digest[10] << 8) | digest[5];
	to64(passwd, l, 4);
	passwd += 4;
	l = digest[11];
	to64(passwd, l, 2);
	passwd += 2;
	*passwd = '\0';
	
	/* Don't leave behind sensitive data */
	memset(digest, 0, sizeof digest);
	puts(md5hash);
	return (md5hash);
}



/* 
 * Mostly stolen from freebsd-lib's pam_unix module which was mostly 
 * stolen from passwd(1)'s local_passwd.c
 *
 * Good ideas are meant to be reused ;)
 */

static unsigned char itoa64[] =         /* 0 ... 63 => ascii - 64 */
        "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";

static void to64(char *s, long v, int n) {
	        while (--n >= 0) {
			*s++ = itoa64[v&0x3f];
			v >>= 6;
		}
}

/* Salt suitable for traditional DES and MD5 */
void makesalt(char salt[SALTSIZE]) {
	        int i,fd;
		unsigned char tmp;
		/* These are not really random numbers, they are just
		 * numbers that change to thwart construction of a
		 * dictionary. This is exposed to the public.
		 */
		fd = open("/dev/urandom", O_RDONLY);
		for (i = 0; i < SALTSIZE; i += 1) {
			read (fd, &tmp, sizeof(char) );
			to64(&salt[i], tmp, 1);
		}
		close(fd);

		salt[SALTSIZE] = '\0';
}