[thirdparty/glibc.git] / md5-crypt / md5-crypt.c

/* One way encryption based on MD5 sum.
   Copyright (C) 1996, 1997 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <sys/param.h>

#include "md5.h"


/* Define our magic string to mark salt for MD5 "encryption"
   replacement.  This is meant to be the same as for other MD5 based
   encryption implementations.  */
static const char md5_salt_prefix[] = "$1$";

/* Table with characters for base64 transformation.  */
static const char b64t[64] =
"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";


/* Prototypes for local functions.  */
extern char *md5_crypt_r __P ((const char *key, const char *salt, char *buffer,
			       int buflen));
extern char *md5_crypt __P ((const char *key, const char *salt));


/* This entry point is equivalent to the `crypt' function in Unix
   libcs.  */
char *
md5_crypt_r (key, salt, buffer, buflen)
     const char *key;
     const char *salt;
     char *buffer;
     int buflen;
{
  unsigned char alt_result[16];
  struct md5_ctx ctx;
  struct md5_ctx alt_ctx;
  size_t salt_len;
  size_t key_len;
  size_t cnt;
  char *cp;

  /* Find beginning of salt string.  The prefix should normally always
     be present.  Just in case it is not.  */
  if (strncmp (md5_salt_prefix, salt, sizeof (md5_salt_prefix) - 1) == 0)
    /* Skip salt prefix.  */
    salt += sizeof (md5_salt_prefix) - 1;

  salt_len = MIN (strcspn (salt, "$"), 8);
  key_len = strlen (key);

  /* Prepare for the real work.  */
  md5_init_ctx (&ctx);

  /* Add the key string.  */
  md5_process_bytes (key, key_len, &ctx);

  /* Because the SALT argument need not always have the salt prefix we
     add it separately.  */
  md5_process_bytes (md5_salt_prefix, sizeof (md5_salt_prefix) - 1, &ctx);

  /* The last part is the salt string.  This must be at most 8
     characters and it ends at the first `$' character (for
     compatibility which existing solutions).  */
  md5_process_bytes (salt, salt_len, &ctx);


  /* Compute alternate MD5 sum with input KEY, SALT, and KEY.  The
     final result will be added to the first context.  */
  md5_init_ctx (&alt_ctx);

  /* Add key.  */
  md5_process_bytes (key, key_len, &alt_ctx);

  /* Add salt.  */
  md5_process_bytes (salt, salt_len, &alt_ctx);

  /* Add key again.  */
  md5_process_bytes (key, key_len, &alt_ctx);

  /* Now get result of this (16 bytes) and add it to the other
     context.  */
  md5_finish_ctx (&alt_ctx, alt_result);

  /* Add for any character in the key one byte of the alternate sum.  */
  for (cnt = key_len; cnt > 16; cnt -= 16)
    md5_process_bytes (alt_result, 16, &ctx);
  md5_process_bytes (alt_result, cnt, &ctx);

  /* For the following code we need a NUL byte.  */
  *alt_result = '\0';

  /* The original implementation now does something weird: for every 1
     bit in the key the first 0 is added to the buffer, for every 0
     bit the first character of the key.  This does not seem to be
     what was intended but we have to follow this to be compatible.  */
  for (cnt = key_len; cnt > 0; cnt >>= 1)
    md5_process_bytes ((cnt & 1) != 0 ? (const char *) alt_result : key, 1,
		       &ctx);

  /* Create intermediate result.  */
  md5_finish_ctx (&ctx, alt_result);

  /* Now comes another weirdness.  In fear of password crackers here
     comes a quite long loop which just processes the output of the
     previous round again.  We cannot ignore this here.  */
  for (cnt = 0; cnt < 1000; ++cnt)
    {
      /* New context.  */
      md5_init_ctx (&ctx);

      /* Add key or last result.  */
      if ((cnt & 1) != 0)
	md5_process_bytes (key, key_len, &ctx);
      else
	md5_process_bytes (alt_result, 16, &ctx);

      /* Add salt for numbers not divisible by 3.  */
      if (cnt % 3 != 0)
	md5_process_bytes (salt, salt_len, &ctx);

      /* Add key for numbers not divisible by 7.  */
      if (cnt % 7 != 0)
	md5_process_bytes (key, key_len, &ctx);

      /* Add key or last result.  */
      if ((cnt & 1) != 0)
	md5_process_bytes (alt_result, 16, &ctx);
      else
	md5_process_bytes (key, key_len, &ctx);

      /* Create intermediate result.  */
      md5_finish_ctx (&ctx, alt_result);
    }

  /* Now we can construct the result string.  It consists of three
     parts.  */
  cp = stpncpy (buffer, md5_salt_prefix, MAX (0, buflen));
  buflen -= sizeof (md5_salt_prefix);

  cp = stpncpy (cp, salt, MIN ((size_t) buflen, salt_len));
  buflen -= MIN ((size_t) buflen, salt_len);

  if (buflen > 0)
    {
      *cp++ = '$';
      --buflen;
    }

#define b64_from_24bit(B2, B1, B0, N)					      \
  do {									      \
    unsigned int w = ((B2) << 16) | ((B1) << 8) | (B0);			      \
    int n = (N);							      \
    while (n-- > 0 && buflen > 0)					      \
      {									      \
	*cp++ = b64t[w & 0x3f];						      \
	--buflen;							      \
	w >>= 6;							      \
      }									      \
  } while (0)


  b64_from_24bit (alt_result[0], alt_result[6], alt_result[12], 4);
  b64_from_24bit (alt_result[1], alt_result[7], alt_result[13], 4);
  b64_from_24bit (alt_result[2], alt_result[8], alt_result[14], 4);
  b64_from_24bit (alt_result[3], alt_result[9], alt_result[15], 4);
  b64_from_24bit (alt_result[4], alt_result[10], alt_result[5], 4);
  b64_from_24bit (0, 0, alt_result[11], 2);
  if (buflen <= 0)
    {
      __set_errno (ERANGE);
      buffer = NULL;
    }
  else
    *cp = '\0';		/* Terminate the string.  */

  /* Clear the buffer for the intermediate result so that people
     attaching to processes or reading core dumps cannot get any
     information.  */
  memset (alt_result, '\0', sizeof (alt_result));

  return buffer;
}


char *
md5_crypt (key, salt)
     const char *key;
     const char *salt;
{
  /* We don't want to have an arbitrary limit in the size of the
     password.  We can compute the size of the result in advance and
     so we can prepare the buffer we pass to `md5_crypt_r'.  */
  static char *buffer = NULL;
  static int buflen = 0;
  int needed = 3 + strlen (salt) + 1 + 26 + 1;

  if (buflen < needed)
    {
      buflen = needed;
      if ((buffer = realloc (buffer, buflen)) == NULL)
	return NULL;
    }

  return md5_crypt_r (key, salt, buffer, buflen);
}
Commit	Line	Data
c84142e8 UD	1	/* One way encryption based on MD5 sum.
	2	Copyright (C) 1996, 1997 Free Software Foundation, Inc.
	3	This file is part of the GNU C Library.
	4	Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.
	5
	6	The GNU C Library is free software; you can redistribute it and/or
	7	modify it under the terms of the GNU Library General Public License as
	8	published by the Free Software Foundation; either version 2 of the
	9	License, or (at your option) any later version.
	10
	11	The GNU C Library is distributed in the hope that it will be useful,
	12	but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	14	Library General Public License for more details.
	15
	16	You should have received a copy of the GNU Library General Public
	17	License along with the GNU C Library; see the file COPYING.LIB. If not,
	18	write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
	19	Boston, MA 02111-1307, USA. */
68dbb3a6 UD	20
	21	#include <errno.h>
	22	#include <stdlib.h>
	23	#include <string.h>
	24	#include <sys/param.h>
	25
	26	#include "md5.h"
	27
	28
	29	/* Define our magic string to mark salt for MD5 "encryption"
	30	replacement. This is meant to be the same as for other MD5 based
	31	encryption implementations. */
	32	static const char md5_salt_prefix[] = "$1$";
	33
	34	/* Table with characters for base64 transformation. */
	35	static const char b64t[64] =
	36	"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
	37
	38
	39	/* Prototypes for local functions. */
	40	extern char md5_crypt_r __P ((const char key, const char salt, char buffer,
	41	int buflen));
	42	extern char md5_crypt __P ((const char key, const char *salt));
	43
	44
	45
	46	/* This entry point is equivalent to the `crypt' function in Unix
	47	libcs. */
	48	char *
	49	md5_crypt_r (key, salt, buffer, buflen)
	50	const char *key;
	51	const char *salt;
	52	char *buffer;
	53	int buflen;
	54	{
	55	unsigned char alt_result[16];
	56	struct md5_ctx ctx;
	57	struct md5_ctx alt_ctx;
	58	size_t salt_len;
	59	size_t key_len;
	60	size_t cnt;
	61	char *cp;
	62
	63	/* Find beginning of salt string. The prefix should normally always
	64	be present. Just in case it is not. */
	65	if (strncmp (md5_salt_prefix, salt, sizeof (md5_salt_prefix) - 1) == 0)
	66	/* Skip salt prefix. */
	67	salt += sizeof (md5_salt_prefix) - 1;
	68
	69	salt_len = MIN (strcspn (salt, "$"), 8);
	70	key_len = strlen (key);
	71
	72	/* Prepare for the real work. */
	73	md5_init_ctx (&ctx);
	74
	75	/* Add the key string. */
	76	md5_process_bytes (key, key_len, &ctx);
	77
	78	/* Because the SALT argument need not always have the salt prefix we
	79	add it separately. */
	80	md5_process_bytes (md5_salt_prefix, sizeof (md5_salt_prefix) - 1, &ctx);
	81
	82	/* The last part is the salt string. This must be at most 8
	83	characters and it ends at the first `$' character (for
84	compatibility which existing solutions). */
85	md5_process_bytes (salt, salt_len, &ctx);
86
87
88	/* Compute alternate MD5 sum with input KEY, SALT, and KEY. The
89	final result will be added to the first context. */
90	md5_init_ctx (&alt_ctx);
91
92	/* Add key. */
93	md5_process_bytes (key, key_len, &alt_ctx);
94
95	/* Add salt. */
96	md5_process_bytes (salt, salt_len, &alt_ctx);
97
98	/* Add key again. */
99	md5_process_bytes (key, key_len, &alt_ctx);
100
101	/* Now get result of this (16 bytes) and add it to the other
102	context. */
103	md5_finish_ctx (&alt_ctx, alt_result);
104
105	/* Add for any character in the key one byte of the alternate sum. */
106	for (cnt = key_len; cnt > 16; cnt -= 16)
107	md5_process_bytes (alt_result, 16, &ctx);
108	md5_process_bytes (alt_result, cnt, &ctx);
109
110	/* For the following code we need a NUL byte. */
111	*alt_result = '\0';
112
113	/* The original implementation now does something weird: for every 1
114	bit in the key the first 0 is added to the buffer, for every 0
115	bit the first character of the key. This does not seem to be
116	what was intended but we have to follow this to be compatible. */
117	for (cnt = key_len; cnt > 0; cnt >>= 1)
118	md5_process_bytes ((cnt & 1) != 0 ? (const char *) alt_result : key, 1,
119	&ctx);
120
121	/* Create intermediate result. */
122	md5_finish_ctx (&ctx, alt_result);
123
124	/* Now comes another weirdness. In fear of password crackers here
125	comes a quite long loop which just processes the output of the
126	previous round again. We cannot ignore this here. */
127	for (cnt = 0; cnt < 1000; ++cnt)
128	{
129	/* New context. */
130	md5_init_ctx (&ctx);
131
132	/* Add key or last result. */
133	if ((cnt & 1) != 0)
134	md5_process_bytes (key, key_len, &ctx);
135	else
136	md5_process_bytes (alt_result, 16, &ctx);
137
138	/* Add salt for numbers not divisible by 3. */
139	if (cnt % 3 != 0)
140	md5_process_bytes (salt, salt_len, &ctx);
141
142	/* Add key for numbers not divisible by 7. */
143	if (cnt % 7 != 0)
144	md5_process_bytes (key, key_len, &ctx);
145
146	/* Add key or last result. */
147	if ((cnt & 1) != 0)
148	md5_process_bytes (alt_result, 16, &ctx);
149	else
150	md5_process_bytes (key, key_len, &ctx);
151
152	/* Create intermediate result. */
153	md5_finish_ctx (&ctx, alt_result);
154	}
155
156	/* Now we can construct the result string. It consists of three
157	parts. */
158	cp = stpncpy (buffer, md5_salt_prefix, MAX (0, buflen));
159	buflen -= sizeof (md5_salt_prefix);
160
161	cp = stpncpy (cp, salt, MIN ((size_t) buflen, salt_len));
162	buflen -= MIN ((size_t) buflen, salt_len);
163
164	if (buflen > 0)
165	{
166	*cp++ = '$';
167	--buflen;
168	}
169
170	#define b64_from_24bit(B2, B1, B0, N) \
171	do { \
172	unsigned int w = ((B2) << 16) \| ((B1) << 8) \| (B0); \
173	int n = (N); \
174	while (n-- > 0 && buflen > 0) \
175	{ \
176	*cp++ = b64t[w & 0x3f]; \
177	--buflen; \
178	w >>= 6; \
179	} \
180	} while (0)
181
182
183	b64_from_24bit (alt_result[0], alt_result[6], alt_result[12], 4);
184	b64_from_24bit (alt_result[1], alt_result[7], alt_result[13], 4);
185	b64_from_24bit (alt_result[2], alt_result[8], alt_result[14], 4);
186	b64_from_24bit (alt_result[3], alt_result[9], alt_result[15], 4);
187	b64_from_24bit (alt_result[4], alt_result[10], alt_result[5], 4);
188	b64_from_24bit (0, 0, alt_result[11], 2);
189	if (buflen <= 0)
190	{
191	__set_errno (ERANGE);
192	buffer = NULL;
193	}
194	else
195	cp = '\0'; / Terminate the string. */
196
197	/* Clear the buffer for the intermediate result so that people
198	attaching to processes or reading core dumps cannot get any
199	information. */
200	memset (alt_result, '\0', sizeof (alt_result));
201
202	return buffer;
203	}
204
205
206	char *
207	md5_crypt (key, salt)
208	const char *key;
209	const char *salt;
210	{
211	/* We don't want to have an arbitrary limit in the size of the
212	password. We can compute the size of the result in advance and
213	so we can prepare the buffer we pass to `md5_crypt_r'. */
214	static char *buffer = NULL;
215	static int buflen = 0;
216	int needed = 3 + strlen (salt) + 1 + 26 + 1;
217
218	if (buflen < needed)
219	{
220	buflen = needed;
221	if ((buffer = realloc (buffer, buflen)) == NULL)
222	return NULL;
223	}
224
225	return md5_crypt_r (key, salt, buffer, buflen);
226	}