openssh-portable/md5crypt.c

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/*
* ----------------------------------------------------------------------------
* "THE BEER-WARE LICENSE" (Revision 42):
* <phk@login.dknet.dk> wrote this file. As long as you retain this
* notice you can do whatever you want with this stuff. If we meet some
* day, and you think this stuff is worth it, you can buy me a beer in
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* return. Poul-Henning Kamp
* ----------------------------------------------------------------------------
*/
#include "includes.h"
#if defined(HAVE_MD5_PASSWORDS) && !defined(HAVE_MD5_CRYPT)
#include <sys/types.h>
#include <string.h>
#include <openssl/md5.h>
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/* 0 ... 63 => ascii - 64 */
static unsigned char itoa64[] =
"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
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static char *magic = "$1$";
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static char *
to64(unsigned long v, int n)
{
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static char buf[5];
char *s = buf;
if (n > 4)
return (NULL);
memset(buf, '\0', sizeof(buf));
while (--n >= 0) {
*s++ = itoa64[v&0x3f];
v >>= 6;
}
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return (buf);
}
int
is_md5_salt(const char *salt)
{
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return (strncmp(salt, magic, strlen(magic)) == 0);
}
char *
md5_crypt(const char *pw, const char *salt)
{
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static char passwd[120], salt_copy[9];
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static const char *sp, *ep;
unsigned char final[16];
int sl, pl, i, j;
MD5_CTX ctx, ctx1;
unsigned long l;
/* Refine the Salt first */
sp = salt;
/* If it starts with the magic string, then skip that */
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if(strncmp(sp, magic, strlen(magic)) == 0)
sp += strlen(magic);
/* It stops at the first '$', max 8 chars */
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for (ep = sp; *ep != '$'; ep++) {
if (*ep == '\0' || ep >= (sp + 8))
return (NULL);
}
/* get the length of the true salt */
sl = ep - sp;
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/* Stash the salt */
memcpy(salt_copy, sp, sl);
salt_copy[sl] = '\0';
MD5_Init(&ctx);
/* The password first, since that is what is most unknown */
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MD5_Update(&ctx, pw, strlen(pw));
/* Then our magic string */
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MD5_Update(&ctx, magic, strlen(magic));
/* Then the raw salt */
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MD5_Update(&ctx, sp, sl);
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/* Then just as many characters of the MD5(pw, salt, pw) */
MD5_Init(&ctx1);
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MD5_Update(&ctx1, pw, strlen(pw));
MD5_Update(&ctx1, sp, sl);
MD5_Update(&ctx1, pw, strlen(pw));
MD5_Final(final, &ctx1);
for(pl = strlen(pw); pl > 0; pl -= 16)
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MD5_Update(&ctx, final, pl > 16 ? 16 : pl);
/* Don't leave anything around in vm they could use. */
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memset(final, '\0', sizeof final);
/* Then something really weird... */
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for (j = 0, i = strlen(pw); i != 0; i >>= 1)
if (i & 1)
MD5_Update(&ctx, final + j, 1);
else
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MD5_Update(&ctx, pw + j, 1);
/* Now make the output string */
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snprintf(passwd, sizeof(passwd), "%s%s$", magic, salt_copy);
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MD5_Final(final, &ctx);
/*
* and now, just to make sure things don't run too fast
* On a 60 Mhz Pentium this takes 34 msec, so you would
* need 30 seconds to build a 1000 entry dictionary...
*/
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for(i = 0; i < 1000; i++) {
MD5_Init(&ctx1);
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if (i & 1)
MD5_Update(&ctx1, pw, strlen(pw));
else
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MD5_Update(&ctx1, final, 16);
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if (i % 3)
MD5_Update(&ctx1, sp, sl);
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if (i % 7)
MD5_Update(&ctx1, pw, strlen(pw));
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if (i & 1)
MD5_Update(&ctx1, final, 16);
else
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MD5_Update(&ctx1, pw, strlen(pw));
MD5_Final(final, &ctx1);
}
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l = (final[ 0]<<16) | (final[ 6]<<8) | final[12];
strlcat(passwd, to64(l, 4), sizeof(passwd));
l = (final[ 1]<<16) | (final[ 7]<<8) | final[13];
strlcat(passwd, to64(l, 4), sizeof(passwd));
l = (final[ 2]<<16) | (final[ 8]<<8) | final[14];
strlcat(passwd, to64(l, 4), sizeof(passwd));
l = (final[ 3]<<16) | (final[ 9]<<8) | final[15];
strlcat(passwd, to64(l, 4), sizeof(passwd));
l = (final[ 4]<<16) | (final[10]<<8) | final[ 5];
strlcat(passwd, to64(l, 4), sizeof(passwd));
l = final[11] ;
strlcat(passwd, to64(l, 2), sizeof(passwd));
/* Don't leave anything around in vm they could use. */
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memset(final, 0, sizeof(final));
memset(salt_copy, 0, sizeof(salt_copy));
memset(&ctx, 0, sizeof(ctx));
memset(&ctx1, 0, sizeof(ctx1));
(void)to64(0, 4);
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return (passwd);
}
#endif /* defined(HAVE_MD5_PASSWORDS) && !defined(HAVE_MD5_CRYPT) */