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pull updated OpenBSD BCrypt PBKDF implementation 

Includes fix for 1 byte output overflow for large key length
requests (not reachable in OpenSSH).

Pointed out by Joshua Rogers
This commit is contained in:
Damien Miller 2014-12-29 18:10:18 +11:00
parent c528c1b4af
commit 01b6349880
1 changed files with 15 additions and 11 deletions
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26
openbsd-compat/bcrypt_pbkdf.c
View File

@ -1,4 +1,4 @@
/* $OpenBSD: bcrypt_pbkdf.c,v 1.4 2013/07/29 00:55:53 tedu Exp $ */
/* $OpenBSD: bcrypt_pbkdf.c,v 1.9 2014/07/13 21:21:25 tedu Exp $ */
/*
* Copyright (c) 2013 Ted Unangst <tedu@openbsd.org>
*
@ -51,8 +51,8 @@
*
* One modification from official pbkdf2. Instead of outputting key material
* linearly, we mix it. pbkdf2 has a known weakness where if one uses it to
* generate (i.e.) 512 bits of key material for use as two 256 bit keys, an
* attacker can merely run once through the outer loop below, but the user
* generate (e.g.) 512 bits of key material for use as two 256 bit keys, an
* attacker can merely run once through the outer loop, but the user
* always runs it twice. Shuffling output bytes requires computing the
* entirety of the key material to assemble any subkey. This is something a
* wise caller could do; we just do it for you.
@ -97,9 +97,9 @@ bcrypt_hash(u_int8_t *sha2pass, u_int8_t *sha2salt, u_int8_t *out)
}
/* zap */
memset(ciphertext, 0, sizeof(ciphertext));
memset(cdata, 0, sizeof(cdata));
memset(&state, 0, sizeof(state));
explicit_bzero(ciphertext, sizeof(ciphertext));
explicit_bzero(cdata, sizeof(cdata));
explicit_bzero(&state, sizeof(state));
}
int
@ -113,6 +113,7 @@ bcrypt_pbkdf(const char *pass, size_t passlen, const u_int8_t *salt, size_t salt
u_int8_t *countsalt;
size_t i, j, amt, stride;
uint32_t count;
size_t origkeylen = keylen;
/* nothing crazy */
if (rounds < 1)
@ -155,14 +156,17 @@ bcrypt_pbkdf(const char *pass, size_t passlen, const u_int8_t *salt, size_t salt
* pbkdf2 deviation: ouput the key material non-linearly.
*/
amt = MIN(amt, keylen);
for (i = 0; i < amt; i++)
key[i * stride + (count - 1)] = out[i];
keylen -= amt;
for (i = 0; i < amt; i++) {
size_t dest = i * stride + (count - 1);
if (dest >= origkeylen)
break;
key[dest] = out[i];
}
keylen -= i;
}
/* zap */
memset(out, 0, sizeof(out));
memset(countsalt, 0, saltlen + 4);
explicit_bzero(out, sizeof(out));
free(countsalt);
return 0;