diff options
| -rw-r--r-- | src/libstrongswan/plugins/gmp/gmp_diffie_hellman.c | 46 | ||||
| -rw-r--r-- | src/libstrongswan/plugins/openssl/openssl_diffie_hellman.c | 38 | ||||
| -rw-r--r-- | src/libstrongswan/utils.h | 5 |
3 files changed, 62 insertions, 27 deletions
diff --git a/src/libstrongswan/plugins/gmp/gmp_diffie_hellman.c b/src/libstrongswan/plugins/gmp/gmp_diffie_hellman.c index b811026af..0f9031430 100644 --- a/src/libstrongswan/plugins/gmp/gmp_diffie_hellman.c +++ b/src/libstrongswan/plugins/gmp/gmp_diffie_hellman.c @@ -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; @@ -504,6 +514,7 @@ 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; @@ -534,6 +545,8 @@ 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; @@ -567,11 +580,22 @@ gmp_diffie_hellman_t *gmp_diffie_hellman_create(diffie_hellman_group_t group) destroy(this); return NULL; } - rng->allocate_bytes(rng, DH_EXPONENT_ENTROPY_SIZE / BITS_PER_BYTE, &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; diff --git a/src/libstrongswan/plugins/openssl/openssl_diffie_hellman.c b/src/libstrongswan/plugins/openssl/openssl_diffie_hellman.c index 217b1aa55..f309236e8 100644 --- a/src/libstrongswan/plugins/openssl/openssl_diffie_hellman.c +++ b/src/libstrongswan/plugins/openssl/openssl_diffie_hellman.c @@ -38,23 +38,28 @@ struct modulus_entry_t { BIGNUM *(*get_prime)(BIGNUM *bn); /* + * Optimum length of exponent in bits. + */ + long 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, get_rfc2409_prime_768, 2}, - {MODP_1024_BIT, get_rfc2409_prime_1024, 2}, - {MODP_1536_BIT, get_rfc3526_prime_1536, 2}, - {MODP_2048_BIT, get_rfc3526_prime_2048, 2}, - {MODP_3072_BIT, get_rfc3526_prime_3072, 2}, - {MODP_4096_BIT, get_rfc3526_prime_4096, 2}, - {MODP_6144_BIT, get_rfc3526_prime_6144, 2}, - {MODP_8192_BIT, get_rfc3526_prime_8192, 2}, + {MODP_768_BIT, get_rfc2409_prime_768, 256, 2}, + {MODP_1024_BIT, get_rfc2409_prime_1024, 256, 2}, + {MODP_1536_BIT, get_rfc3526_prime_1536, 256, 2}, + {MODP_2048_BIT, get_rfc3526_prime_2048, 384, 2}, + {MODP_3072_BIT, get_rfc3526_prime_3072, 384, 2}, + {MODP_4096_BIT, get_rfc3526_prime_4096, 512, 2}, + {MODP_6144_BIT, get_rfc3526_prime_6144, 512, 2}, + {MODP_8192_BIT, get_rfc3526_prime_8192, 512, 2}, }; typedef struct private_openssl_diffie_hellman_t private_openssl_diffie_hellman_t; @@ -83,6 +88,11 @@ struct private_openssl_diffie_hellman_t { */ BIGNUM *pub_key; + /* + * Optimum length of exponent in bits. + */ + long opt_exponent_len; + /** * Shared secret */ @@ -180,6 +190,7 @@ static status_t set_modulus(private_openssl_diffie_hellman_t *this) this->dh->p = modulus_entries[i].get_prime(NULL); this->dh->g = BN_new(); BN_set_word(this->dh->g, modulus_entries[i].generator); + this->opt_exponent_len = modulus_entries[i].opt_exponent_len; return SUCCESS; } } @@ -202,6 +213,7 @@ static void destroy(private_openssl_diffie_hellman_t *this) */ openssl_diffie_hellman_t *openssl_diffie_hellman_create(diffie_hellman_group_t group) { + bool ansi_x9_42; private_openssl_diffie_hellman_t *this = malloc_thing(private_openssl_diffie_hellman_t); this->public.dh.get_shared_secret = (status_t (*)(diffie_hellman_t *, chunk_t *)) get_shared_secret; @@ -217,8 +229,7 @@ openssl_diffie_hellman_t *openssl_diffie_hellman_create(diffie_hellman_group_t g free(this); return NULL; } - this->dh->length = DH_EXPONENT_ENTROPY_SIZE; - + this->group = group; this->computed = FALSE; @@ -232,12 +243,17 @@ openssl_diffie_hellman_t *openssl_diffie_hellman_create(diffie_hellman_group_t g return NULL; } + ansi_x9_42 = lib->settings->get_bool(lib->settings, + "charon.dh_exponent_ansi_x9_42", TRUE); + this->dh->length = (ansi_x9_42) ? 0 : this->opt_exponent_len; + /* generate my public and private values */ if (!DH_generate_key(this->dh)) { destroy(this); return NULL; } + DBG2("size of DH secret exponent: %d bits", BN_num_bits(this->dh->priv_key)); return &this->public; } diff --git a/src/libstrongswan/utils.h b/src/libstrongswan/utils.h index 326047644..4d05ce58b 100644 --- a/src/libstrongswan/utils.h +++ b/src/libstrongswan/utils.h @@ -41,11 +41,6 @@ #define BUF_LEN 512 /** - * Entropy in bits of secret Diffie-Hellman exponents - */ -#define DH_EXPONENT_ENTROPY_SIZE 512 - -/** * Macro compares two strings for equality */ #define streq(x,y) (strcmp(x, y) == 0) |