/* One way encryption based on MD5 sum. Copyright (C) 1996, 1997, 1999, 2000 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper , 1996. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ /* warmenhoven took this file and made it work with the md5.[ch] we * already had. isn't that lovely. people should just use linux or * freebsd, crypt works properly on those systems. i hate solaris */ #if HAVE_CONFIG_H # include #endif #if HAVE_STRING_H # include #elif HAVE_STRINGS_H # include #endif #include #include "crypt.h" #include "md5.h" /* for MIN and MAX */ #include "libyahoo.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"; char *yahoo_crypt(const char *key, const char *salt) { char *buffer = NULL; int buflen = 0; int needed = 3 + strlen (salt) + 1 + 26 + 1; md5_byte_t alt_result[16]; md5_state_t ctx; md5_state_t alt_ctx; size_t salt_len; size_t key_len; size_t cnt; char *cp; if (buflen < needed) { buflen = needed; if ((buffer = realloc(buffer, buflen)) == NULL) return NULL; } /* 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, "$"), 8); key_len = strlen (key); /* Prepare for the real work. */ md5_init(&ctx); /* Add the key string. */ md5_append(&ctx, (md5_byte_t *)key, key_len); /* Because the SALT argument need not always have the salt prefix we add it separately. */ md5_append(&ctx, (md5_byte_t *)md5_salt_prefix, sizeof (md5_salt_prefix) - 1); /* The last part is the salt string. This must be at most 8 characters and it ends at the first `$' character (for compatibility which existing solutions). */ md5_append(&ctx, (md5_byte_t *)salt, salt_len); /* Compute alternate MD5 sum with input KEY, SALT, and KEY. The final result will be added to the first context. */ md5_init(&alt_ctx); /* Add key. */ md5_append(&alt_ctx, (md5_byte_t *)key, key_len); /* Add salt. */ md5_append(&alt_ctx, (md5_byte_t *)salt, salt_len); /* Add key again. */ md5_append(&alt_ctx, (md5_byte_t *)key, key_len); /* Now get result of this (16 bytes) and add it to the other context. */ md5_finish(&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_append(&ctx, alt_result, 16); md5_append(&ctx, alt_result, cnt); /* For the following code we need a NUL byte. */ alt_result[0] = '\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_append(&ctx, (cnt & 1) != 0 ? alt_result : (md5_byte_t *)key, 1); /* Create intermediate result. */ md5_finish(&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); /* Add key or last result. */ if ((cnt & 1) != 0) md5_append(&ctx, (md5_byte_t *)key, key_len); else md5_append(&ctx, alt_result, 16); /* Add salt for numbers not divisible by 3. */ if (cnt % 3 != 0) md5_append(&ctx, (md5_byte_t *)salt, salt_len); /* Add key for numbers not divisible by 7. */ if (cnt % 7 != 0) md5_append(&ctx, (md5_byte_t *)key, key_len); /* Add key or last result. */ if ((cnt & 1) != 0) md5_append(&ctx, alt_result, 16); else md5_append(&ctx, (md5_byte_t *)key, key_len); /* Create intermediate result. */ md5_finish(&ctx, alt_result); } /* Now we can construct the result string. It consists of three parts. */ strncpy(buffer, md5_salt_prefix, MAX (0, buflen)); cp = buffer + strlen(buffer); buflen -= sizeof (md5_salt_prefix); strncpy(cp, salt, MIN ((size_t) buflen, salt_len)); cp = cp + strlen(cp); 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) { FREE(buffer); } 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. We do it in this way to clear correct_words[] inside the MD5 implementation as well. */ md5_init(&ctx); md5_finish(&ctx, alt_result); memset (&ctx, '\0', sizeof (ctx)); memset (&alt_ctx, '\0', sizeof (alt_ctx)); return buffer; }