diff options
Diffstat (limited to 'grub-core/lib/libgcrypt/cipher/dsa.c')
| -rw-r--r-- | grub-core/lib/libgcrypt/cipher/dsa.c | 1193 |
1 files changed, 1193 insertions, 0 deletions
diff --git a/grub-core/lib/libgcrypt/cipher/dsa.c b/grub-core/lib/libgcrypt/cipher/dsa.c new file mode 100644 index 0000000..883a815 --- /dev/null +++ b/grub-core/lib/libgcrypt/cipher/dsa.c @@ -0,0 +1,1193 @@ +/* dsa.c - DSA signature algorithm + * Copyright (C) 1998, 2000, 2001, 2002, 2003, + * 2006, 2008 Free Software Foundation, Inc. + * + * This file is part of Libgcrypt. + * + * Libgcrypt is free software; you can redistribute it and/or modify + * it under the terms of the GNU Lesser General Public License as + * published by the Free Software Foundation; either version 2.1 of + * the License, or (at your option) any later version. + * + * Libgcrypt is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this program; if not, see <http://www.gnu.org/licenses/>. + */ + +#include <config.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include "g10lib.h" +#include "mpi.h" +#include "cipher.h" + +typedef struct +{ + gcry_mpi_t p; /* prime */ + gcry_mpi_t q; /* group order */ + gcry_mpi_t g; /* group generator */ + gcry_mpi_t y; /* g^x mod p */ +} DSA_public_key; + + +typedef struct +{ + gcry_mpi_t p; /* prime */ + gcry_mpi_t q; /* group order */ + gcry_mpi_t g; /* group generator */ + gcry_mpi_t y; /* g^x mod p */ + gcry_mpi_t x; /* secret exponent */ +} DSA_secret_key; + + +/* A structure used to hold domain parameters. */ +typedef struct +{ + gcry_mpi_t p; /* prime */ + gcry_mpi_t q; /* group order */ + gcry_mpi_t g; /* group generator */ +} dsa_domain_t; + + +/* A sample 1024 bit DSA key used for the selftests. */ +static const char sample_secret_key[] = +"(private-key" +" (dsa" +" (p #00AD7C0025BA1A15F775F3F2D673718391D00456978D347B33D7B49E7F32EDAB" +" 96273899DD8B2BB46CD6ECA263FAF04A28903503D59062A8865D2AE8ADFB5191" +" CF36FFB562D0E2F5809801A1F675DAE59698A9E01EFE8D7DCFCA084F4C6F5A44" +" 44D499A06FFAEA5E8EF5E01F2FD20A7B7EF3F6968AFBA1FB8D91F1559D52D8777B#)" +" (q #00EB7B5751D25EBBB7BD59D920315FD840E19AEBF9#)" +" (g #1574363387FDFD1DDF38F4FBE135BB20C7EE4772FB94C337AF86EA8E49666503" +" AE04B6BE81A2F8DD095311E0217ACA698A11E6C5D33CCDAE71498ED35D13991E" +" B02F09AB40BD8F4C5ED8C75DA779D0AE104BC34C960B002377068AB4B5A1F984" +" 3FBA91F537F1B7CAC4D8DD6D89B0D863AF7025D549F9C765D2FC07EE208F8D15#)" +" (y #64B11EF8871BE4AB572AA810D5D3CA11A6CDBC637A8014602C72960DB135BF46" +" A1816A724C34F87330FC9E187C5D66897A04535CC2AC9164A7150ABFA8179827" +" 6E45831AB811EEE848EBB24D9F5F2883B6E5DDC4C659DEF944DCFD80BF4D0A20" +" 42CAA7DC289F0C5A9D155F02D3D551DB741A81695B74D4C8F477F9C7838EB0FB#)" +" (x #11D54E4ADBD3034160F2CED4B7CD292A4EBF3EC0#)))"; +/* A sample 1024 bit DSA key used for the selftests (public only). */ +static const char sample_public_key[] = +"(public-key" +" (dsa" +" (p #00AD7C0025BA1A15F775F3F2D673718391D00456978D347B33D7B49E7F32EDAB" +" 96273899DD8B2BB46CD6ECA263FAF04A28903503D59062A8865D2AE8ADFB5191" +" CF36FFB562D0E2F5809801A1F675DAE59698A9E01EFE8D7DCFCA084F4C6F5A44" +" 44D499A06FFAEA5E8EF5E01F2FD20A7B7EF3F6968AFBA1FB8D91F1559D52D8777B#)" +" (q #00EB7B5751D25EBBB7BD59D920315FD840E19AEBF9#)" +" (g #1574363387FDFD1DDF38F4FBE135BB20C7EE4772FB94C337AF86EA8E49666503" +" AE04B6BE81A2F8DD095311E0217ACA698A11E6C5D33CCDAE71498ED35D13991E" +" B02F09AB40BD8F4C5ED8C75DA779D0AE104BC34C960B002377068AB4B5A1F984" +" 3FBA91F537F1B7CAC4D8DD6D89B0D863AF7025D549F9C765D2FC07EE208F8D15#)" +" (y #64B11EF8871BE4AB572AA810D5D3CA11A6CDBC637A8014602C72960DB135BF46" +" A1816A724C34F87330FC9E187C5D66897A04535CC2AC9164A7150ABFA8179827" +" 6E45831AB811EEE848EBB24D9F5F2883B6E5DDC4C659DEF944DCFD80BF4D0A20" +" 42CAA7DC289F0C5A9D155F02D3D551DB741A81695B74D4C8F477F9C7838EB0FB#)))"; + + + + +static gcry_mpi_t gen_k (gcry_mpi_t q); +static int test_keys (DSA_secret_key *sk, unsigned int qbits); +static int check_secret_key (DSA_secret_key *sk); +static gpg_err_code_t generate (DSA_secret_key *sk, + unsigned int nbits, + unsigned int qbits, + int transient_key, + dsa_domain_t *domain, + gcry_mpi_t **ret_factors); +static void sign (gcry_mpi_t r, gcry_mpi_t s, gcry_mpi_t input, + DSA_secret_key *skey); +static int verify (gcry_mpi_t r, gcry_mpi_t s, gcry_mpi_t input, + DSA_public_key *pkey); + +static void (*progress_cb) (void *,const char *, int, int, int ); +static void *progress_cb_data; + + +void +_gcry_register_pk_dsa_progress (void (*cb) (void *, const char *, + int, int, int), + void *cb_data) +{ + progress_cb = cb; + progress_cb_data = cb_data; +} + + +static void +progress (int c) +{ + if (progress_cb) + progress_cb (progress_cb_data, "pk_dsa", c, 0, 0); +} + + +/* + * Generate a random secret exponent k less than q. + */ +static gcry_mpi_t +gen_k( gcry_mpi_t q ) +{ + gcry_mpi_t k = mpi_alloc_secure( mpi_get_nlimbs(q) ); + unsigned int nbits = mpi_get_nbits(q); + unsigned int nbytes = (nbits+7)/8; + char *rndbuf = NULL; + + /* To learn why we don't use mpi_mod to get the requested bit size, + read the paper: "The Insecurity of the Digital Signature + Algorithm with Partially Known Nonces" by Nguyen and Shparlinski. + Journal of Cryptology, New York. Vol 15, nr 3 (2003) */ + + if ( DBG_CIPHER ) + log_debug("choosing a random k "); + for (;;) + { + if( DBG_CIPHER ) + progress('.'); + + if ( !rndbuf || nbits < 32 ) + { + gcry_free(rndbuf); + rndbuf = gcry_random_bytes_secure( (nbits+7)/8, GCRY_STRONG_RANDOM ); + } + else + { /* Change only some of the higher bits. We could improve + this by directly requesting more memory at the first call + to get_random_bytes() and use these extra bytes here. + However the required management code is more complex and + thus we better use this simple method. */ + char *pp = gcry_random_bytes_secure( 4, GCRY_STRONG_RANDOM ); + memcpy( rndbuf,pp, 4 ); + gcry_free(pp); + } + _gcry_mpi_set_buffer( k, rndbuf, nbytes, 0 ); + + /* Make sure we have the requested number of bits. This code + looks a bit funny but it is easy to understand if you + consider that mpi_set_highbit clears all higher bits. We + don't have a clear_highbit, thus we first set the high bit + and then clear it again. */ + if ( mpi_test_bit( k, nbits-1 ) ) + mpi_set_highbit( k, nbits-1 ); + else + { + mpi_set_highbit( k, nbits-1 ); + mpi_clear_bit( k, nbits-1 ); + } + + if( !(mpi_cmp( k, q ) < 0) ) /* check: k < q */ + { + if( DBG_CIPHER ) + progress('+'); + continue; /* no */ + } + if( !(mpi_cmp_ui( k, 0 ) > 0) ) /* check: k > 0 */ + { + if( DBG_CIPHER ) + progress('-'); + continue; /* no */ + } + break; /* okay */ + } + gcry_free(rndbuf); + if( DBG_CIPHER ) + progress('\n'); + + return k; +} + + +/* Check that a freshly generated key actually works. Returns 0 on success. */ +static int +test_keys (DSA_secret_key *sk, unsigned int qbits) +{ + int result = -1; /* Default to failure. */ + DSA_public_key pk; + gcry_mpi_t data = gcry_mpi_new (qbits); + gcry_mpi_t sig_a = gcry_mpi_new (qbits); + gcry_mpi_t sig_b = gcry_mpi_new (qbits); + + /* Put the relevant parameters into a public key structure. */ + pk.p = sk->p; + pk.q = sk->q; + pk.g = sk->g; + pk.y = sk->y; + + /* Create a random plaintext. */ + gcry_mpi_randomize (data, qbits, GCRY_WEAK_RANDOM); + + /* Sign DATA using the secret key. */ + sign (sig_a, sig_b, data, sk); + + /* Verify the signature using the public key. */ + if ( !verify (sig_a, sig_b, data, &pk) ) + goto leave; /* Signature does not match. */ + + /* Modify the data and check that the signing fails. */ + gcry_mpi_add_ui (data, data, 1); + if ( verify (sig_a, sig_b, data, &pk) ) + goto leave; /* Signature matches but should not. */ + + result = 0; /* The test succeeded. */ + + leave: + gcry_mpi_release (sig_b); + gcry_mpi_release (sig_a); + gcry_mpi_release (data); + return result; +} + + + +/* + Generate a DSA key pair with a key of size NBITS. If transient_key + is true the key is generated using the standard RNG and not the + very secure one. + + Returns: 2 structures filled with all needed values + and an array with the n-1 factors of (p-1) + */ +static gpg_err_code_t +generate (DSA_secret_key *sk, unsigned int nbits, unsigned int qbits, + int transient_key, dsa_domain_t *domain, gcry_mpi_t **ret_factors ) +{ + gcry_mpi_t p; /* the prime */ + gcry_mpi_t q; /* the 160 bit prime factor */ + gcry_mpi_t g; /* the generator */ + gcry_mpi_t y; /* g^x mod p */ + gcry_mpi_t x; /* the secret exponent */ + gcry_mpi_t h, e; /* helper */ + unsigned char *rndbuf; + gcry_random_level_t random_level; + + if (qbits) + ; /* Caller supplied qbits. Use this value. */ + else if ( nbits >= 512 && nbits <= 1024 ) + qbits = 160; + else if ( nbits == 2048 ) + qbits = 224; + else if ( nbits == 3072 ) + qbits = 256; + else if ( nbits == 7680 ) + qbits = 384; + else if ( nbits == 15360 ) + qbits = 512; + else + return GPG_ERR_INV_VALUE; + + if (qbits < 160 || qbits > 512 || (qbits%8) ) + return GPG_ERR_INV_VALUE; + if (nbits < 2*qbits || nbits > 15360) + return GPG_ERR_INV_VALUE; + + if (fips_mode ()) + { + if (nbits < 1024) + return GPG_ERR_INV_VALUE; + if (transient_key) + return GPG_ERR_INV_VALUE; + } + + if (domain->p && domain->q && domain->g) + { + /* Domain parameters are given; use them. */ + p = mpi_copy (domain->p); + q = mpi_copy (domain->q); + g = mpi_copy (domain->g); + gcry_assert (mpi_get_nbits (p) == nbits); + gcry_assert (mpi_get_nbits (q) == qbits); + h = mpi_alloc (0); + e = NULL; + } + else + { + /* Generate new domain parameters. */ + p = _gcry_generate_elg_prime (1, nbits, qbits, NULL, ret_factors); + /* Get q out of factors. */ + q = mpi_copy ((*ret_factors)[0]); + gcry_assert (mpi_get_nbits (q) == qbits); + + /* Find a generator g (h and e are helpers). + e = (p-1)/q */ + e = mpi_alloc (mpi_get_nlimbs (p)); + mpi_sub_ui (e, p, 1); + mpi_fdiv_q (e, e, q); + g = mpi_alloc (mpi_get_nlimbs (p)); + h = mpi_alloc_set_ui (1); /* (We start with 2.) */ + do + { + mpi_add_ui (h, h, 1); + /* g = h^e mod p */ + gcry_mpi_powm (g, h, e, p); + } + while (!mpi_cmp_ui (g, 1)); /* Continue until g != 1. */ + } + + /* Select a random number X with the property: + * 0 < x < q-1 + * This must be a very good random number because this is the secret + * part. The random quality depends on the transient_key flag. */ + random_level = transient_key ? GCRY_STRONG_RANDOM : GCRY_VERY_STRONG_RANDOM; + if (DBG_CIPHER) + log_debug("choosing a random x%s", transient_key? " (transient-key)":""); + gcry_assert( qbits >= 160 ); + x = mpi_alloc_secure( mpi_get_nlimbs(q) ); + mpi_sub_ui( h, q, 1 ); /* put q-1 into h */ + rndbuf = NULL; + do + { + if( DBG_CIPHER ) + progress('.'); + if( !rndbuf ) + rndbuf = gcry_random_bytes_secure ((qbits+7)/8, random_level); + else + { /* Change only some of the higher bits (= 2 bytes)*/ + char *r = gcry_random_bytes_secure (2, random_level); + memcpy(rndbuf, r, 2 ); + gcry_free(r); + } + + _gcry_mpi_set_buffer( x, rndbuf, (qbits+7)/8, 0 ); + mpi_clear_highbit( x, qbits+1 ); + } + while ( !( mpi_cmp_ui( x, 0 )>0 && mpi_cmp( x, h )<0 ) ); + gcry_free(rndbuf); + mpi_free( e ); + mpi_free( h ); + + /* y = g^x mod p */ + y = mpi_alloc( mpi_get_nlimbs(p) ); + gcry_mpi_powm( y, g, x, p ); + + if( DBG_CIPHER ) + { + progress('\n'); + log_mpidump("dsa p", p ); + log_mpidump("dsa q", q ); + log_mpidump("dsa g", g ); + log_mpidump("dsa y", y ); + log_mpidump("dsa x", x ); + } + + /* Copy the stuff to the key structures. */ + sk->p = p; + sk->q = q; + sk->g = g; + sk->y = y; + sk->x = x; + + /* Now we can test our keys (this should never fail!). */ + if ( test_keys (sk, qbits) ) + { + gcry_mpi_release (sk->p); sk->p = NULL; + gcry_mpi_release (sk->q); sk->q = NULL; + gcry_mpi_release (sk->g); sk->g = NULL; + gcry_mpi_release (sk->y); sk->y = NULL; + gcry_mpi_release (sk->x); sk->x = NULL; + fips_signal_error ("self-test after key generation failed"); + return GPG_ERR_SELFTEST_FAILED; + } + return 0; +} + + +/* Generate a DSA key pair with a key of size NBITS using the + algorithm given in FIPS-186-3. If USE_FIPS186_2 is true, + FIPS-186-2 is used and thus the length is restricted to 1024/160. + If DERIVEPARMS is not NULL it may contain a seed value. If domain + parameters are specified in DOMAIN, DERIVEPARMS may not be given + and NBITS and QBITS must match the specified domain parameters. */ +static gpg_err_code_t +generate_fips186 (DSA_secret_key *sk, unsigned int nbits, unsigned int qbits, + gcry_sexp_t deriveparms, int use_fips186_2, + dsa_domain_t *domain, + int *r_counter, void **r_seed, size_t *r_seedlen, + gcry_mpi_t *r_h) +{ + gpg_err_code_t ec; + struct { + gcry_sexp_t sexp; + const void *seed; + size_t seedlen; + } initial_seed = { NULL, NULL, 0 }; + gcry_mpi_t prime_q = NULL; + gcry_mpi_t prime_p = NULL; + gcry_mpi_t value_g = NULL; /* The generator. */ + gcry_mpi_t value_y = NULL; /* g^x mod p */ + gcry_mpi_t value_x = NULL; /* The secret exponent. */ + gcry_mpi_t value_h = NULL; /* Helper. */ + gcry_mpi_t value_e = NULL; /* Helper. */ + + /* Preset return values. */ + *r_counter = 0; + *r_seed = NULL; + *r_seedlen = 0; + *r_h = NULL; + + /* Derive QBITS from NBITS if requested */ + if (!qbits) + { + if (nbits == 1024) + qbits = 160; + else if (nbits == 2048) + qbits = 224; + else if (nbits == 3072) + qbits = 256; + } + + /* Check that QBITS and NBITS match the standard. Note that FIPS + 186-3 uses N for QBITS and L for NBITS. */ + if (nbits == 1024 && qbits == 160) + ; + else if (nbits == 2048 && qbits == 224) + ; + else if (nbits == 2048 && qbits == 256) + ; + else if (nbits == 3072 && qbits == 256) + ; + else + return GPG_ERR_INV_VALUE; + + if (domain->p && domain->q && domain->g) + { + /* Domain parameters are given; use them. */ + prime_p = mpi_copy (domain->p); + prime_q = mpi_copy (domain->q); + value_g = mpi_copy (domain->g); + gcry_assert (mpi_get_nbits (prime_p) == nbits); + gcry_assert (mpi_get_nbits (prime_q) == qbits); + gcry_assert (!deriveparms); + ec = 0; + } + else + { + /* Generate new domain parameters. */ + + /* Get an initial seed value. */ + if (deriveparms) + { + initial_seed.sexp = gcry_sexp_find_token (deriveparms, "seed", 0); + if (initial_seed.sexp) + initial_seed.seed = gcry_sexp_nth_data (initial_seed.sexp, 1, + &initial_seed.seedlen); + } + + /* Fixme: Enable 186-3 after it has been approved and after fixing + the generation function. */ + /* if (use_fips186_2) */ + (void)use_fips186_2; + ec = _gcry_generate_fips186_2_prime (nbits, qbits, + initial_seed.seed, + initial_seed.seedlen, + &prime_q, &prime_p, + r_counter, + r_seed, r_seedlen); + /* else */ + /* ec = _gcry_generate_fips186_3_prime (nbits, qbits, NULL, 0, */ + /* &prime_q, &prime_p, */ + /* r_counter, */ + /* r_seed, r_seedlen, NULL); */ + gcry_sexp_release (initial_seed.sexp); + if (ec) + goto leave; + + /* Find a generator g (h and e are helpers). + e = (p-1)/q */ + value_e = mpi_alloc_like (prime_p); + mpi_sub_ui (value_e, prime_p, 1); + mpi_fdiv_q (value_e, value_e, prime_q ); + value_g = mpi_alloc_like (prime_p); + value_h = mpi_alloc_set_ui (1); + do + { + mpi_add_ui (value_h, value_h, 1); + /* g = h^e mod p */ + mpi_powm (value_g, value_h, value_e, prime_p); + } + while (!mpi_cmp_ui (value_g, 1)); /* Continue until g != 1. */ + } + + + /* Select a random number x with: 0 < x < q */ + value_x = gcry_mpi_snew (qbits); + do + { + if( DBG_CIPHER ) + progress('.'); + gcry_mpi_randomize (value_x, qbits, GCRY_VERY_STRONG_RANDOM); + mpi_clear_highbit (value_x, qbits+1); + } + while (!(mpi_cmp_ui (value_x, 0) > 0 && mpi_cmp (value_x, prime_q) < 0)); + + /* y = g^x mod p */ + value_y = mpi_alloc_like (prime_p); + gcry_mpi_powm (value_y, value_g, value_x, prime_p); + + if (DBG_CIPHER) + { + progress('\n'); + log_mpidump("dsa p", prime_p ); + log_mpidump("dsa q", prime_q ); + log_mpidump("dsa g", value_g ); + log_mpidump("dsa y", value_y ); + log_mpidump("dsa x", value_x ); + log_mpidump("dsa h", value_h ); + } + + /* Copy the stuff to the key structures. */ + sk->p = prime_p; prime_p = NULL; + sk->q = prime_q; prime_q = NULL; + sk->g = value_g; value_g = NULL; + sk->y = value_y; value_y = NULL; + sk->x = value_x; value_x = NULL; + *r_h = value_h; value_h = NULL; + + leave: + gcry_mpi_release (prime_p); + gcry_mpi_release (prime_q); + gcry_mpi_release (value_g); + gcry_mpi_release (value_y); + gcry_mpi_release (value_x); + gcry_mpi_release (value_h); + gcry_mpi_release (value_e); + + /* As a last step test this keys (this should never fail of course). */ + if (!ec && test_keys (sk, qbits) ) + { + gcry_mpi_release (sk->p); sk->p = NULL; + gcry_mpi_release (sk->q); sk->q = NULL; + gcry_mpi_release (sk->g); sk->g = NULL; + gcry_mpi_release (sk->y); sk->y = NULL; + gcry_mpi_release (sk->x); sk->x = NULL; + fips_signal_error ("self-test after key generation failed"); + ec = GPG_ERR_SELFTEST_FAILED; + } + + if (ec) + { + *r_counter = 0; + gcry_free (*r_seed); *r_seed = NULL; + *r_seedlen = 0; + gcry_mpi_release (*r_h); *r_h = NULL; + } + + return ec; +} + + + +/* + Test whether the secret key is valid. + Returns: if this is a valid key. + */ +static int +check_secret_key( DSA_secret_key *sk ) +{ + int rc; + gcry_mpi_t y = mpi_alloc( mpi_get_nlimbs(sk->y) ); + + gcry_mpi_powm( y, sk->g, sk->x, sk->p ); + rc = !mpi_cmp( y, sk->y ); + mpi_free( y ); + return rc; +} + + + +/* + Make a DSA signature from HASH and put it into r and s. + */ +static void +sign(gcry_mpi_t r, gcry_mpi_t s, gcry_mpi_t hash, DSA_secret_key *skey ) +{ + gcry_mpi_t k; + gcry_mpi_t kinv; + gcry_mpi_t tmp; + + /* Select a random k with 0 < k < q */ + k = gen_k( skey->q ); + + /* r = (a^k mod p) mod q */ + gcry_mpi_powm( r, skey->g, k, skey->p ); + mpi_fdiv_r( r, r, skey->q ); + + /* kinv = k^(-1) mod q */ + kinv = mpi_alloc( mpi_get_nlimbs(k) ); + mpi_invm(kinv, k, skey->q ); + + /* s = (kinv * ( hash + x * r)) mod q */ + tmp = mpi_alloc( mpi_get_nlimbs(skey->p) ); + mpi_mul( tmp, skey->x, r ); + mpi_add( tmp, tmp, hash ); + mpi_mulm( s , kinv, tmp, skey->q ); + + mpi_free(k); + mpi_free(kinv); + mpi_free(tmp); +} + + +/* + Returns true if the signature composed from R and S is valid. + */ +static int +verify (gcry_mpi_t r, gcry_mpi_t s, gcry_mpi_t hash, DSA_public_key *pkey ) +{ + int rc; + gcry_mpi_t w, u1, u2, v; + gcry_mpi_t base[3]; + gcry_mpi_t ex[3]; + + if( !(mpi_cmp_ui( r, 0 ) > 0 && mpi_cmp( r, pkey->q ) < 0) ) + return 0; /* assertion 0 < r < q failed */ + if( !(mpi_cmp_ui( s, 0 ) > 0 && mpi_cmp( s, pkey->q ) < 0) ) + return 0; /* assertion 0 < s < q failed */ + + w = mpi_alloc( mpi_get_nlimbs(pkey->q) ); + u1 = mpi_alloc( mpi_get_nlimbs(pkey->q) ); + u2 = mpi_alloc( mpi_get_nlimbs(pkey->q) ); + v = mpi_alloc( mpi_get_nlimbs(pkey->p) ); + + /* w = s^(-1) mod q */ + mpi_invm( w, s, pkey->q ); + + /* u1 = (hash * w) mod q */ + mpi_mulm( u1, hash, w, pkey->q ); + + /* u2 = r * w mod q */ + mpi_mulm( u2, r, w, pkey->q ); + + /* v = g^u1 * y^u2 mod p mod q */ + base[0] = pkey->g; ex[0] = u1; + base[1] = pkey->y; ex[1] = u2; + base[2] = NULL; ex[2] = NULL; + mpi_mulpowm( v, base, ex, pkey->p ); + mpi_fdiv_r( v, v, pkey->q ); + + rc = !mpi_cmp( v, r ); + + mpi_free(w); + mpi_free(u1); + mpi_free(u2); + mpi_free(v); + + return rc; +} + + +/********************************************* + ************** interface ****************** + *********************************************/ + +static gcry_err_code_t +dsa_generate_ext (int algo, unsigned int nbits, unsigned long evalue, + const gcry_sexp_t genparms, + gcry_mpi_t *skey, gcry_mpi_t **retfactors, + gcry_sexp_t *r_extrainfo) +{ + gpg_err_code_t ec; + DSA_secret_key sk; + gcry_sexp_t l1; + unsigned int qbits = 0; + gcry_sexp_t deriveparms = NULL; + gcry_sexp_t seedinfo = NULL; + int transient_key = 0; + int use_fips186_2 = 0; + int use_fips186 = 0; + dsa_domain_t domain; + + (void)algo; /* No need to check it. */ + (void)evalue; /* Not required for DSA. */ + + memset (&domain, 0, sizeof domain); + + if (genparms) + { + gcry_sexp_t domainsexp; + + /* Parse the optional qbits element. */ + l1 = gcry_sexp_find_token (genparms, "qbits", 0); + if (l1) + { + char buf[50]; + const char *s; + size_t n; + + s = gcry_sexp_nth_data (l1, 1, &n); + if (!s || n >= DIM (buf) - 1 ) + { + gcry_sexp_release (l1); + return GPG_ERR_INV_OBJ; /* No value or value too large. */ + } + memcpy (buf, s, n); + buf[n] = 0; + qbits = (unsigned int)strtoul (buf, NULL, 0); + gcry_sexp_release (l1); + } + + /* Parse the optional transient-key flag. */ + l1 = gcry_sexp_find_token (genparms, "transient-key", 0); + if (l1) + { + transient_key = 1; + gcry_sexp_release (l1); + } + + /* Get the optional derive parameters. */ + deriveparms = gcry_sexp_find_token (genparms, "derive-parms", 0); + + /* Parse the optional "use-fips186" flags. */ + l1 = gcry_sexp_find_token (genparms, "use-fips186", 0); + if (l1) + { + use_fips186 = 1; + gcry_sexp_release (l1); + } + l1 = gcry_sexp_find_token (genparms, "use-fips186-2", 0); + if (l1) + { + use_fips186_2 = 1; + gcry_sexp_release (l1); + } + + /* Check whether domain parameters are given. */ + domainsexp = gcry_sexp_find_token (genparms, "domain", 0); + if (domainsexp) + { + /* DERIVEPARMS can't be used together with domain + parameters. NBITS abnd QBITS may not be specified + because there values are derived from the domain + parameters. */ + if (deriveparms || qbits || nbits) + { + gcry_sexp_release (domainsexp); + gcry_sexp_release (deriveparms); + return GPG_ERR_INV_VALUE; + } + + /* Put all domain parameters into the domain object. */ + l1 = gcry_sexp_find_token (domainsexp, "p", 0); + domain.p = gcry_sexp_nth_mpi (l1, 1, GCRYMPI_FMT_USG); + gcry_sexp_release (l1); + l1 = gcry_sexp_find_token (domainsexp, "q", 0); + domain.q = gcry_sexp_nth_mpi (l1, 1, GCRYMPI_FMT_USG); + gcry_sexp_release (l1); + l1 = gcry_sexp_find_token (domainsexp, "g", 0); + domain.g = gcry_sexp_nth_mpi (l1, 1, GCRYMPI_FMT_USG); + gcry_sexp_release (l1); + gcry_sexp_release (domainsexp); + + /* Check that all domain parameters are available. */ + if (!domain.p || !domain.q || !domain.g) + { + gcry_mpi_release (domain.p); + gcry_mpi_release (domain.q); + gcry_mpi_release (domain.g); + gcry_sexp_release (deriveparms); + return GPG_ERR_MISSING_VALUE; + } + + /* Get NBITS and QBITS from the domain parameters. */ + nbits = mpi_get_nbits (domain.p); + qbits = mpi_get_nbits (domain.q); + } + } + + if (deriveparms || use_fips186 || use_fips186_2 || fips_mode ()) + { + int counter; + void *seed; + size_t seedlen; + gcry_mpi_t h_value; + + ec = generate_fips186 (&sk, nbits, qbits, deriveparms, use_fips186_2, + &domain, + &counter, &seed, &seedlen, &h_value); + gcry_sexp_release (deriveparms); + if (!ec && h_value) + { + /* Format the seed-values unless domain parameters are used + for which a H_VALUE of NULL is an indication. */ + ec = gpg_err_code (gcry_sexp_build + (&seedinfo, NULL, + "(seed-values(counter %d)(seed %b)(h %m))", + counter, (int)seedlen, seed, h_value)); + if (ec) + { + gcry_mpi_release (sk.p); sk.p = NULL; + gcry_mpi_release (sk.q); sk.q = NULL; + gcry_mpi_release (sk.g); sk.g = NULL; + gcry_mpi_release (sk.y); sk.y = NULL; + gcry_mpi_release (sk.x); sk.x = NULL; + } + gcry_free (seed); + gcry_mpi_release (h_value); + } + } + else + { + ec = generate (&sk, nbits, qbits, transient_key, &domain, retfactors); + } + + gcry_mpi_release (domain.p); + gcry_mpi_release (domain.q); + gcry_mpi_release (domain.g); + + if (!ec) + { + skey[0] = sk.p; + skey[1] = sk.q; + skey[2] = sk.g; + skey[3] = sk.y; + skey[4] = sk.x; + + if (!r_extrainfo) + { + /* Old style interface - return the factors - if any - at + retfactors. */ + } + else if (!*retfactors && !seedinfo) + { + /* No factors and no seedinfo, thus there is nothing to return. */ + *r_extrainfo = NULL; + } + else + { + /* Put the factors into extrainfo and set retfactors to NULL + to make use of the new interface. Note that the factors + are not confidential thus we can store them in standard + memory. */ + int nfactors, i, j; + char *p; + char *format = NULL; + void **arg_list = NULL; + + for (nfactors=0; *retfactors && (*retfactors)[nfactors]; nfactors++) + ; + /* Allocate space for the format string: + "(misc-key-info%S(pm1-factors%m))" + with one "%m" for each factor and construct it. */ + format = gcry_malloc (50 + 2*nfactors); + if (!format) + ec = gpg_err_code_from_syserror (); + else + { + p = stpcpy (format, "(misc-key-info"); + if (seedinfo) + p = stpcpy (p, "%S"); + if (nfactors) + { + p = stpcpy (p, "(pm1-factors"); + for (i=0; i < nfactors; i++) + p = stpcpy (p, "%m"); + p = stpcpy (p, ")"); + } + p = stpcpy (p, ")"); + + /* Allocate space for the list of factors plus one for + an S-expression plus an extra NULL entry for safety + and fill it with the factors. */ + arg_list = gcry_calloc (nfactors+1+1, sizeof *arg_list); + if (!arg_list) + ec = gpg_err_code_from_syserror (); + else + { + i = 0; + if (seedinfo) + arg_list[i++] = &seedinfo; + for (j=0; j < nfactors; j++) + arg_list[i++] = (*retfactors) + j; + arg_list[i] = NULL; + + ec = gpg_err_code (gcry_sexp_build_array + (r_extrainfo, NULL, format, arg_list)); + } + } + + gcry_free (arg_list); + gcry_free (format); + for (i=0; i < nfactors; i++) + { + gcry_mpi_release ((*retfactors)[i]); + (*retfactors)[i] = NULL; + } + gcry_free (*retfactors); + *retfactors = NULL; + if (ec) + { + for (i=0; i < 5; i++) + { + gcry_mpi_release (skey[i]); + skey[i] = NULL; + } + } + } + } + + gcry_sexp_release (seedinfo); + return ec; +} + + +static gcry_err_code_t +dsa_generate (int algo, unsigned int nbits, unsigned long evalue, + gcry_mpi_t *skey, gcry_mpi_t **retfactors) +{ + (void)evalue; + return dsa_generate_ext (algo, nbits, 0, NULL, skey, retfactors, NULL); +} + + + +static gcry_err_code_t +dsa_check_secret_key (int algo, gcry_mpi_t *skey) +{ + gcry_err_code_t err = GPG_ERR_NO_ERROR; + DSA_secret_key sk; + + (void)algo; + + if ((! skey[0]) || (! skey[1]) || (! skey[2]) || (! skey[3]) || (! skey[4])) + err = GPG_ERR_BAD_MPI; + else + { + sk.p = skey[0]; + sk.q = skey[1]; + sk.g = skey[2]; + sk.y = skey[3]; + sk.x = skey[4]; + if (! check_secret_key (&sk)) + err = GPG_ERR_BAD_SECKEY; + } + + return err; +} + + +static gcry_err_code_t +dsa_sign (int algo, gcry_mpi_t *resarr, gcry_mpi_t data, gcry_mpi_t *skey) +{ + gcry_err_code_t err = GPG_ERR_NO_ERROR; + DSA_secret_key sk; + + (void)algo; + + if ((! data) + || (! skey[0]) || (! skey[1]) || (! skey[2]) + || (! skey[3]) || (! skey[4])) + err = GPG_ERR_BAD_MPI; + else + { + sk.p = skey[0]; + sk.q = skey[1]; + sk.g = skey[2]; + sk.y = skey[3]; + sk.x = skey[4]; + resarr[0] = mpi_alloc (mpi_get_nlimbs (sk.p)); + resarr[1] = mpi_alloc (mpi_get_nlimbs (sk.p)); + sign (resarr[0], resarr[1], data, &sk); + } + return err; +} + +static gcry_err_code_t +dsa_verify (int algo, gcry_mpi_t hash, gcry_mpi_t *data, gcry_mpi_t *pkey, + int (*cmp) (void *, gcry_mpi_t), void *opaquev) +{ + gcry_err_code_t err = GPG_ERR_NO_ERROR; + DSA_public_key pk; + + (void)algo; + (void)cmp; + (void)opaquev; + + if ((! data[0]) || (! data[1]) || (! hash) + || (! pkey[0]) || (! pkey[1]) || (! pkey[2]) || (! pkey[3])) + err = GPG_ERR_BAD_MPI; + else + { + pk.p = pkey[0]; + pk.q = pkey[1]; + pk.g = pkey[2]; + pk.y = pkey[3]; + if (! verify (data[0], data[1], hash, &pk)) + err = GPG_ERR_BAD_SIGNATURE; + } + return err; +} + + +static unsigned int +dsa_get_nbits (int algo, gcry_mpi_t *pkey) +{ + (void)algo; + + return mpi_get_nbits (pkey[0]); +} + + + +/* + Self-test section. + */ + +static const char * +selftest_sign_1024 (gcry_sexp_t pkey, gcry_sexp_t skey) +{ + static const char sample_data[] = + "(data (flags raw)" + " (value #a0b1c2d3e4f500102030405060708090a1b2c3d4#))"; + static const char sample_data_bad[] = + "(data (flags raw)" + " (value #a0b1c2d3e4f510102030405060708090a1b2c3d4#))"; + + const char *errtxt = NULL; + gcry_error_t err; + gcry_sexp_t data = NULL; + gcry_sexp_t data_bad = NULL; + gcry_sexp_t sig = NULL; + + err = gcry_sexp_sscan (&data, NULL, + sample_data, strlen (sample_data)); + if (!err) + err = gcry_sexp_sscan (&data_bad, NULL, + sample_data_bad, strlen (sample_data_bad)); + if (err) + { + errtxt = "converting data failed"; + goto leave; + } + + err = gcry_pk_sign (&sig, data, skey); + if (err) + { + errtxt = "signing failed"; + goto leave; + } + err = gcry_pk_verify (sig, data, pkey); + if (err) + { + errtxt = "verify failed"; + goto leave; + } + err = gcry_pk_verify (sig, data_bad, pkey); + if (gcry_err_code (err) != GPG_ERR_BAD_SIGNATURE) + { + errtxt = "bad signature not detected"; + goto leave; + } + + + leave: + gcry_sexp_release (sig); + gcry_sexp_release (data_bad); + gcry_sexp_release (data); + return errtxt; +} + + +static gpg_err_code_t +selftests_dsa (selftest_report_func_t report) +{ + const char *what; + const char *errtxt; + gcry_error_t err; + gcry_sexp_t skey = NULL; + gcry_sexp_t pkey = NULL; + + /* Convert the S-expressions into the internal representation. */ + what = "convert"; + err = gcry_sexp_sscan (&skey, NULL, + sample_secret_key, strlen (sample_secret_key)); + if (!err) + err = gcry_sexp_sscan (&pkey, NULL, + sample_public_key, strlen (sample_public_key)); + if (err) + { + errtxt = gcry_strerror (err); + goto failed; + } + + what = "key consistency"; + err = gcry_pk_testkey (skey); + if (err) + { + errtxt = gcry_strerror (err); + goto failed; + } + + what = "sign"; + errtxt = selftest_sign_1024 (pkey, skey); + if (errtxt) + goto failed; + + gcry_sexp_release (pkey); + gcry_sexp_release (skey); + return 0; /* Succeeded. */ + + failed: + gcry_sexp_release (pkey); + gcry_sexp_release (skey); + if (report) + report ("pubkey", GCRY_PK_DSA, what, errtxt); + return GPG_ERR_SELFTEST_FAILED; +} + + +/* Run a full self-test for ALGO and return 0 on success. */ +static gpg_err_code_t +run_selftests (int algo, int extended, selftest_report_func_t report) +{ + gpg_err_code_t ec; + + (void)extended; + + switch (algo) + { + case GCRY_PK_DSA: + ec = selftests_dsa (report); + break; + default: + ec = GPG_ERR_PUBKEY_ALGO; + break; + + } + return ec; +} + + + + +static const char *dsa_names[] = + { + "dsa", + "openpgp-dsa", + NULL, + }; + +gcry_pk_spec_t _gcry_pubkey_spec_dsa = + { + "DSA", dsa_names, + "pqgy", "pqgyx", "", "rs", "pqgy", + GCRY_PK_USAGE_SIGN, + dsa_generate, + dsa_check_secret_key, + NULL, + NULL, + dsa_sign, + dsa_verify, + dsa_get_nbits + }; +pk_extra_spec_t _gcry_pubkey_extraspec_dsa = + { + run_selftests, + dsa_generate_ext + }; |