| /* 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); |
| } |