1 files changed, 223 insertions, 0 deletions
diff --git a/crypt/md5-crypt.c b/crypt/md5-crypt.c
new file mode 100644
index 0000000000..126103503c
--- /dev/null
+++ b/crypt/md5-crypt.c
@@ -0,0 +1,223 @@
+/* One way encryption based on MD5 sum.
+   Copyright (C) 1996, 1997, 1999 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 (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);
+}