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* sign.c (hash_for): Add code to detect if the sk lives on a smart

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card.  If it does, only allow 160-bit hashes, a la DSA.  This involves
passing the *sk in, so change all callers.  This is correct for today,
given the current 160-bit q in DSA, and the current SHA-1/RIPEMD160
support in the openpgp card.  It will almost certainly need changing
down the road.

* app-openpgp.c (do_sign): Give user error if hash algorithm is not
supported by the card.
This commit is contained in:
David Shaw 2006-01-01 17:48:54 +00:00
parent 74117cf4d3
commit cbc5c947d5
3 changed files with 44 additions and 19 deletions
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12
g10/ChangeLog
View File

@ -1,3 +1,15 @@
2006-01-01 David Shaw <dshaw@jabberwocky.com>
* sign.c (hash_for): Add code to detect if the sk lives on a smart
card. If it does, only allow 160-bit hashes, a la DSA. This
involves passing the *sk in, so change all callers. This is
correct for today, given the current 160-bit q in DSA, and the
current SHA-1/RIPEMD160 support in the openpgp card. It will
almost certainly need changing down the road.
* app-openpgp.c (do_sign): Give user error if hash algorithm is
not supported by the card.
2005-12-23 David Shaw <dshaw@jabberwocky.com> 2005-12-23 David Shaw <dshaw@jabberwocky.com>
* keyserver.c (keyserver_import_pka): New. Moved from * keyserver.c (keyserver_import_pka): New. Moved from

6
g10/app-openpgp.c
View File

@ -2083,7 +2083,11 @@ do_sign (app_t app, const char *keyidstr, int hashalgo,
&& !memcmp (indata, rmd160_prefix, 15)) && !memcmp (indata, rmd160_prefix, 15))
; ;
else else
return gpg_error (GPG_ERR_INV_VALUE); {
log_error(_("card does not support digest algorithm %s\n"),
digest_algo_to_string(hashalgo));
return gpg_error (GPG_ERR_INV_VALUE);
}
/* Check whether an OpenPGP card of any version has been requested. */ /* Check whether an OpenPGP card of any version has been requested. */
if (strlen (keyidstr) < 32 || strncmp (keyidstr, "D27600012401", 12)) if (strlen (keyidstr) < 32 || strncmp (keyidstr, "D27600012401", 12))

45
g10/sign.c
View File

@ -407,21 +407,20 @@ complete_sig( PKT_signature *sig, PKT_secret_key *sk, MD_HANDLE md )
*/ */
static int static int
hash_for(int pubkey_algo, int packet_version ) hash_for(PKT_secret_key *sk)
{ {
if( opt.def_digest_algo ) if( opt.def_digest_algo )
return opt.def_digest_algo; return opt.def_digest_algo;
else if( recipient_digest_algo ) else if( recipient_digest_algo )
return recipient_digest_algo; return recipient_digest_algo;
else if(PGP2 && pubkey_algo == PUBKEY_ALGO_RSA && packet_version < 4 ) else if(sk->pubkey_algo==PUBKEY_ALGO_DSA
|| (sk->is_protected && sk->protect.s2k.mode==1002))
{ {
/* Old-style PGP only understands MD5 */ /* The sk lives on a smartcard, or it's a DSA key. DSA requires
return DIGEST_ALGO_MD5; a 160-bit hash, and current smartcards only handle SHA-1 and
} RIPEMD/160 (i.e. 160-bit hashes). This is correct now, but
else if( pubkey_algo == PUBKEY_ALGO_DSA ) may need revision as the cards add algorithms and/or DSA is
{ expanded to use larger hashes. */
/* We need a 160-bit hash for DSA, so we can't just take the first
in the pref list */
if(opt.personal_digest_prefs) if(opt.personal_digest_prefs)
{ {
@ -434,6 +433,11 @@ hash_for(int pubkey_algo, int packet_version )
return DIGEST_ALGO_SHA1; return DIGEST_ALGO_SHA1;
} }
else if(PGP2 && sk->pubkey_algo == PUBKEY_ALGO_RSA && sk->version < 4 )
{
/* Old-style PGP only understands MD5 */
return DIGEST_ALGO_MD5;
}
else if( opt.personal_digest_prefs ) else if( opt.personal_digest_prefs )
{ {
/* It's not DSA, so we can use whatever the first hash algorithm /* It's not DSA, so we can use whatever the first hash algorithm
@ -511,7 +515,7 @@ write_onepass_sig_packets (SK_LIST sk_list, IOBUF out, int sigclass )
sk = sk_rover->sk; sk = sk_rover->sk;
ops = xmalloc_clear (sizeof *ops); ops = xmalloc_clear (sizeof *ops);
ops->sig_class = sigclass; ops->sig_class = sigclass;
ops->digest_algo = hash_for (sk->pubkey_algo, sk->version); ops->digest_algo = hash_for (sk);
ops->pubkey_algo = sk->pubkey_algo; ops->pubkey_algo = sk->pubkey_algo;
keyid_from_sk (sk, ops->keyid); keyid_from_sk (sk, ops->keyid);
ops->last = (skcount == 1); ops->last = (skcount == 1);
@ -651,7 +655,6 @@ write_signature_packets (SK_LIST sk_list, IOBUF out, MD_HANDLE hash,
else else
sig->version=sk->version; sig->version=sk->version;
keyid_from_sk (sk, sig->keyid); keyid_from_sk (sk, sig->keyid);
sig->digest_algo = hash_for (sk->pubkey_algo, sk->version);
sig->pubkey_algo = sk->pubkey_algo; sig->pubkey_algo = sk->pubkey_algo;
if(timestamp) if(timestamp)
sig->timestamp = timestamp; sig->timestamp = timestamp;
@ -670,7 +673,7 @@ write_signature_packets (SK_LIST sk_list, IOBUF out, MD_HANDLE hash,
hash_sigversion_to_magic (md, sig); hash_sigversion_to_magic (md, sig);
md_final (md); md_final (md);
rc = do_sign( sk, sig, md, hash_for (sig->pubkey_algo, sk->version) ); rc = do_sign( sk, sig, md, hash_for (sk) );
md_close (md); md_close (md);
if( !rc ) { /* and write it */ if( !rc ) { /* and write it */
@ -846,8 +849,14 @@ sign_file( STRLIST filenames, int detached, STRLIST locusr,
sk, but so long as there is only one signing algorithm sk, but so long as there is only one signing algorithm
with hash restrictions, this is ok. -dms */ with hash restrictions, this is ok. -dms */
/* Current smartcards only do 160-bit hashes as well.
Note that this may well have to change as the cards add
algorithms. */
for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next )
if(sk_rover->sk->pubkey_algo==PUBKEY_ALGO_DSA) if(sk_rover->sk->pubkey_algo==PUBKEY_ALGO_DSA
|| (sk_rover->sk->is_protected
&& sk_rover->sk->protect.s2k.mode==1002))
hashlen=20; hashlen=20;
if((algo= if((algo=
@ -859,7 +868,7 @@ sign_file( STRLIST filenames, int detached, STRLIST locusr,
for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) { for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) {
PKT_secret_key *sk = sk_rover->sk; PKT_secret_key *sk = sk_rover->sk;
md_enable(mfx.md, hash_for(sk->pubkey_algo, sk->version )); md_enable(mfx.md, hash_for(sk));
} }
if( !multifile ) if( !multifile )
@ -1077,7 +1086,7 @@ clearsign_file( const char *fname, STRLIST locusr, const char *outfile )
for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) { for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) {
PKT_secret_key *sk = sk_rover->sk; PKT_secret_key *sk = sk_rover->sk;
if( hash_for(sk->pubkey_algo, sk->version) == DIGEST_ALGO_MD5 ) if( hash_for(sk) == DIGEST_ALGO_MD5 )
only_md5 = 1; only_md5 = 1;
else { else {
only_md5 = 0; only_md5 = 0;
@ -1094,7 +1103,7 @@ clearsign_file( const char *fname, STRLIST locusr, const char *outfile )
iobuf_writestr(out, "Hash: " ); iobuf_writestr(out, "Hash: " );
for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) { for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) {
PKT_secret_key *sk = sk_rover->sk; PKT_secret_key *sk = sk_rover->sk;
int i = hash_for(sk->pubkey_algo, sk->version); int i = hash_for(sk);
if( !hashs_seen[ i & 0xff ] ) { if( !hashs_seen[ i & 0xff ] ) {
s = digest_algo_to_string( i ); s = digest_algo_to_string( i );
@ -1119,7 +1128,7 @@ clearsign_file( const char *fname, STRLIST locusr, const char *outfile )
textmd = md_open(0, 0); textmd = md_open(0, 0);
for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) { for( sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next ) {
PKT_secret_key *sk = sk_rover->sk; PKT_secret_key *sk = sk_rover->sk;
md_enable(textmd, hash_for(sk->pubkey_algo, sk->version)); md_enable(textmd, hash_for(sk));
} }
if ( DBG_HASHING ) if ( DBG_HASHING )
md_start_debug( textmd, "clearsign" ); md_start_debug( textmd, "clearsign" );
@ -1242,7 +1251,7 @@ sign_symencrypt_file (const char *fname, STRLIST locusr)
for (sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next) { for (sk_rover = sk_list; sk_rover; sk_rover = sk_rover->next) {
PKT_secret_key *sk = sk_rover->sk; PKT_secret_key *sk = sk_rover->sk;
md_enable (mfx.md, hash_for (sk->pubkey_algo, sk->version )); md_enable (mfx.md, hash_for (sk));
} }
iobuf_push_filter (inp, md_filter, &mfx); iobuf_push_filter (inp, md_filter, &mfx);