Make use of gcry_kdf_derive.

Factoring common code out is always a Good Thing.  Also added a
configure test to print an error if gcry_kdf_derive is missing in
Libgcrypt.
This commit is contained in:
Werner Koch 2011-03-10 18:39:34 +01:00
parent 35c731d889
commit b9bcc77d6c
5 changed files with 59 additions and 140 deletions

View File

@ -1,3 +1,7 @@
2011-03-10 Werner Koch <wk@g10code.com>
* protect.c (hash_passphrase): Use the new gcry_kdf_derive.
2011-03-08 Werner Koch <wk@g10code.com>
* cvt-openpgp.c (GCRY_PK_ECDH) [!HAVE_GCRY_PK_ECDH]: Remove.

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@ -1023,70 +1023,13 @@ hash_passphrase (const char *passphrase, int hashalgo,
unsigned long s2kcount,
unsigned char *key, size_t keylen)
{
int rc;
gcry_md_hd_t md;
int pass, i;
int used = 0;
int pwlen = strlen (passphrase);
if ( (s2kmode != 0 && s2kmode != 1 && s2kmode != 3)
|| !hashalgo || !keylen || !key || !passphrase)
return gpg_error (GPG_ERR_INV_VALUE);
if ((s2kmode == 1 ||s2kmode == 3) && !s2ksalt)
return gpg_error (GPG_ERR_INV_VALUE);
rc = gcry_md_open (&md, hashalgo, GCRY_MD_FLAG_SECURE);
if (rc)
return rc;
for (pass=0; used < keylen; pass++)
{
if (pass)
{
gcry_md_reset (md);
for (i=0; i < pass; i++) /* preset the hash context */
gcry_md_putc (md, 0);
}
if (s2kmode == 1 || s2kmode == 3)
{
int len2 = pwlen + 8;
unsigned long count = len2;
if (s2kmode == 3)
{
count = s2kcount;
if (count < len2)
count = len2;
}
while (count > len2)
{
gcry_md_write (md, s2ksalt, 8);
gcry_md_write (md, passphrase, pwlen);
count -= len2;
}
if (count < 8)
gcry_md_write (md, s2ksalt, count);
else
{
gcry_md_write (md, s2ksalt, 8);
count -= 8;
gcry_md_write (md, passphrase, count);
}
}
else
gcry_md_write (md, passphrase, pwlen);
gcry_md_final (md);
i = gcry_md_get_algo_dlen (hashalgo);
if (i > keylen - used)
i = keylen - used;
memcpy (key+used, gcry_md_read (md, hashalgo), i);
used += i;
}
gcry_md_close(md);
return 0;
return gcry_kdf_derive (passphrase, strlen (passphrase),
s2kmode == 3? GCRY_KDF_ITERSALTED_S2K :
s2kmode == 1? GCRY_KDF_SALTED_S2K :
s2kmode == 0? GCRY_KDF_SIMPLE_S2K : GCRY_KDF_NONE,
hashalgo, s2ksalt, 8, s2kcount,
keylen, key);
}

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@ -742,6 +742,22 @@ AM_PATH_GPG_ERROR("$NEED_GPG_ERROR_VERSION",
AM_PATH_LIBGCRYPT("$NEED_LIBGCRYPT_API:$NEED_LIBGCRYPT_VERSION",
have_libgcrypt=yes,have_libgcrypt=no)
# FIxme: Remove this test after libgcrypt 1.5.0 has been released.
AC_CACHE_CHECK([whether Libgcrypt has gcry_kdf_derive],
gnupg_cv_gcry_kdf_derive,
[ _gnupg_gcry_save_cflags=$CFLAGS
_gnupg_gcry_save_libs=$LIBS
CFLAGS="$CFLAGS $LIBGCRYPT_CFLAGS"
LIBS="$LIBS $LIBGCRYPT_LIBS"
AC_TRY_LINK(
[#include <gcrypt.h>],
[ return gcry_kdf_derive (NULL,0,0,0,NULL,0,0,0,NULL); ],
gnupg_cv_gcry_kdf_derive=yes,
gnupg_cv_gcry_kdf_derive=no)
LIBS=$_gnupg_gcry_save_libs
CFLAGS=$_gnupg_gcry_save_cflags])
#
# libassuan is used for IPC
#
@ -1605,6 +1621,15 @@ if test "$have_libgcrypt" = "no"; then
*** ftp://ftp.gnupg.org/gcrypt/alpha/libgcrypt/
*** (at least version $NEED_LIBGCRYPT_VERSION using API $NEED_LIBGCRYPT_API is required.)
***]])
elif test "$gnupg_cv_gcry_kdf_derive" = no; then
die=yes
AC_MSG_NOTICE([[
***
*** Libgcrypt 1.5.0 has not yet been released and thus the API
*** is a bit in a flux. Your version misses the function
*** gcry_kdf_derive
*** You need to install a newer Libgcrypt version.
***]])
fi
if test "$have_libassuan" = "no"; then
die=yes

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@ -1,3 +1,8 @@
2011-03-10 Werner Koch <wk@g10code.com>
* passphrase.c (hash_passphrase): Remove.
(passphrase_to_dek_ext): Use gcry_kdf_derive.
2011-03-03 Werner Koch <wk@g10code.com>
* keylist.c (print_card_key_info): Re-implement using the agent.

View File

@ -1,6 +1,6 @@
/* passphrase.c - Get a passphrase
* Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004,
* 2005, 2006, 2007, 2009 Free Software Foundation, Inc.
* 2005, 2006, 2007, 2009, 2011 Free Software Foundation, Inc.
*
* This file is part of GnuPG.
*
@ -101,81 +101,6 @@ encode_s2k_iterations (int iterations)
}
/* Hash a passphrase using the supplied s2k.
Always needs: dek->algo, s2k->mode, s2k->hash_algo. */
static void
hash_passphrase ( DEK *dek, char *pw, STRING2KEY *s2k)
{
gcry_md_hd_t md;
int pass, i;
int used = 0;
int pwlen = strlen(pw);
assert ( s2k->hash_algo );
dek->keylen = openpgp_cipher_get_algo_keylen (dek->algo);
if ( !(dek->keylen > 0 && dek->keylen <= DIM(dek->key)) )
BUG();
if (gcry_md_open (&md, s2k->hash_algo, 1))
BUG ();
for (pass=0; used < dek->keylen ; pass++ )
{
if ( pass )
{
gcry_md_reset (md);
for (i=0; i < pass; i++ ) /* Preset the hash context. */
gcry_md_putc (md, 0 );
}
if ( s2k->mode == 1 || s2k->mode == 3 )
{
int len2 = pwlen + 8;
ulong count = len2;
if ( s2k->mode == 3 )
{
count = S2K_DECODE_COUNT(s2k->count);
if ( count < len2 )
count = len2;
}
/* Fixme: To avoid DoS attacks by sending an sym-encrypted
packet with a very high S2K count, we should either cap
the iteration count or CPU seconds based timeout. */
/* A little bit complicated because we need a ulong for count. */
while ( count > len2 ) /* maybe iterated+salted */
{
gcry_md_write ( md, s2k->salt, 8 );
gcry_md_write ( md, pw, pwlen );
count -= len2;
}
if ( count < 8 )
gcry_md_write ( md, s2k->salt, count );
else
{
gcry_md_write ( md, s2k->salt, 8 );
count -= 8;
gcry_md_write ( md, pw, count );
}
}
else
gcry_md_write ( md, pw, pwlen );
gcry_md_final( md );
i = gcry_md_get_algo_dlen ( s2k->hash_algo );
if ( i > dek->keylen - used )
i = dek->keylen - used;
memcpy (dek->key+used, gcry_md_read (md, s2k->hash_algo), i);
used += i;
}
gcry_md_close(md);
}
int
have_static_passphrase()
{
@ -655,7 +580,24 @@ passphrase_to_dek_ext (u32 *keyid, int pubkey_algo,
if ( (!pw || !*pw) && (mode == 2 || mode == 4))
dek->keylen = 0;
else
hash_passphrase (dek, pw, s2k);
{
dek->keylen = openpgp_cipher_get_algo_keylen (dek->algo);
if (!(dek->keylen > 0 && dek->keylen <= DIM(dek->key)))
BUG ();
if (gcry_kdf_derive (pw, strlen (pw),
s2k->mode == 3? GCRY_KDF_ITERSALTED_S2K :
s2k->mode == 1? GCRY_KDF_SALTED_S2K :
/* */ GCRY_KDF_SIMPLE_S2K,
s2k->hash_algo, s2k->salt, 8,
S2K_DECODE_COUNT(s2k->count),
dek->keylen, dek->key))
{
xfree (pw);
xfree (dek);
write_status( STATUS_MISSING_PASSPHRASE );
return NULL;
}
}
if (s2k_cacheid)
memcpy (dek->s2k_cacheid, s2k_cacheid, sizeof dek->s2k_cacheid);
xfree(last_pw);