diff options
Diffstat (limited to 'src/libstrongswan/plugins/gmp/gmp_diffie_hellman.c')
| -rw-r--r-- | src/libstrongswan/plugins/gmp/gmp_diffie_hellman.c | 68 |
1 files changed, 36 insertions, 32 deletions
diff --git a/src/libstrongswan/plugins/gmp/gmp_diffie_hellman.c b/src/libstrongswan/plugins/gmp/gmp_diffie_hellman.c index 40e83fc4c..294fb722f 100644 --- a/src/libstrongswan/plugins/gmp/gmp_diffie_hellman.c +++ b/src/libstrongswan/plugins/gmp/gmp_diffie_hellman.c @@ -15,7 +15,7 @@ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * for more details. * - * $Id: gmp_diffie_hellman.c 4346 2008-09-17 09:02:30Z martin $ + * $Id: gmp_diffie_hellman.c 4566 2008-11-04 13:12:11Z martin $ */ #include <gmp.h> @@ -304,23 +304,28 @@ struct modulus_entry_t { size_t modulus_len; /* + * Optimum length of exponent in bytes. + */ + size_t opt_exponent_len; + + /* * Generator value. */ u_int16_t generator; }; /** - * All supported modulus values. + * All supported modulus values - optimum exponent size according to RFC 3526. */ static modulus_entry_t modulus_entries[] = { - {MODP_768_BIT, group1_modulus, sizeof(group1_modulus), 2}, - {MODP_1024_BIT, group2_modulus, sizeof(group2_modulus), 2}, - {MODP_1536_BIT, group5_modulus, sizeof(group5_modulus), 2}, - {MODP_2048_BIT, group14_modulus, sizeof(group14_modulus), 2}, - {MODP_3072_BIT, group15_modulus, sizeof(group15_modulus), 2}, - {MODP_4096_BIT, group16_modulus, sizeof(group16_modulus), 2}, - {MODP_6144_BIT, group17_modulus, sizeof(group17_modulus), 2}, - {MODP_8192_BIT, group18_modulus, sizeof(group18_modulus), 2}, + {MODP_768_BIT, group1_modulus, sizeof(group1_modulus), 32, 2}, + {MODP_1024_BIT, group2_modulus, sizeof(group2_modulus), 32, 2}, + {MODP_1536_BIT, group5_modulus, sizeof(group5_modulus), 32, 2}, + {MODP_2048_BIT, group14_modulus, sizeof(group14_modulus), 48, 2}, + {MODP_3072_BIT, group15_modulus, sizeof(group15_modulus), 48, 2}, + {MODP_4096_BIT, group16_modulus, sizeof(group16_modulus), 64, 2}, + {MODP_6144_BIT, group17_modulus, sizeof(group17_modulus), 64, 2}, + {MODP_8192_BIT, group18_modulus, sizeof(group18_modulus), 64, 2}, }; typedef struct private_gmp_diffie_hellman_t private_gmp_diffie_hellman_t; @@ -375,6 +380,11 @@ struct private_gmp_diffie_hellman_t { size_t p_len; /** + * Optimal exponent length. + */ + size_t opt_exponent_len; + + /** * True if shared secret is computed and stored in my_public_value. */ bool computed; @@ -430,25 +440,6 @@ static void set_other_public_value(private_gmp_diffie_hellman_t *this, chunk_t v } /** - * Implementation of gmp_diffie_hellman_t.get_other_public_value. - */ -static status_t get_other_public_value(private_gmp_diffie_hellman_t *this, - chunk_t *value) -{ - if (!this->computed) - { - return FAILED; - } - value->len = this->p_len; - value->ptr = mpz_export(NULL, NULL, 1, value->len, 1, 0, this->yb); - if (value->ptr == NULL) - { - return FAILED; - } - return SUCCESS; -} - -/** * Implementation of gmp_diffie_hellman_t.get_my_public_value. */ static void get_my_public_value(private_gmp_diffie_hellman_t *this,chunk_t *value) @@ -504,6 +495,7 @@ static status_t set_modulus(private_gmp_diffie_hellman_t *this) chunk.len = modulus_entries[i].modulus_len; mpz_import(this->p, chunk.len, 1, 1, 1, 0, chunk.ptr); this->p_len = chunk.len; + this->opt_exponent_len = modulus_entries[i].opt_exponent_len; mpz_set_ui(this->g, modulus_entries[i].generator); status = SUCCESS; break; @@ -534,11 +526,12 @@ gmp_diffie_hellman_t *gmp_diffie_hellman_create(diffie_hellman_group_t group) private_gmp_diffie_hellman_t *this = malloc_thing(private_gmp_diffie_hellman_t); rng_t *rng; chunk_t random; + bool ansi_x9_42; + size_t exponent_len; /* public functions */ this->public.dh.get_shared_secret = (status_t (*)(diffie_hellman_t *, chunk_t *)) get_shared_secret; this->public.dh.set_other_public_value = (void (*)(diffie_hellman_t *, chunk_t )) set_other_public_value; - this->public.dh.get_other_public_value = (status_t (*)(diffie_hellman_t *, chunk_t *)) get_other_public_value; this->public.dh.get_my_public_value = (void (*)(diffie_hellman_t *, chunk_t *)) get_my_public_value; this->public.dh.get_dh_group = (diffie_hellman_group_t (*)(diffie_hellman_t *)) get_dh_group; this->public.dh.destroy = (void (*)(diffie_hellman_t *)) destroy; @@ -567,11 +560,22 @@ gmp_diffie_hellman_t *gmp_diffie_hellman_create(diffie_hellman_group_t group) destroy(this); return NULL; } - rng->allocate_bytes(rng, this->p_len, &random); + + ansi_x9_42 = lib->settings->get_int(lib->settings, + "charon.dh_exponent_ansi_x9_42", TRUE); + exponent_len = (ansi_x9_42) ? this->p_len : this->opt_exponent_len; + rng->allocate_bytes(rng, exponent_len, &random); rng->destroy(rng); + + if (ansi_x9_42) + { + /* achieve bitsof(p)-1 by setting MSB to 0 */ + *random.ptr &= 0x7F; + } mpz_import(this->xa, random.len, 1, 1, 1, 0, random.ptr); chunk_free(&random); - + DBG2("size of DH secret exponent: %u bits", mpz_sizeinbase(this->xa, 2)); + mpz_powm(this->ya, this->g, this->xa, this->p); return &this->public; |