/*
* %CopyrightBegin%
*
* Copyright Ericsson AB 2010-2018. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* %CopyrightEnd%
*/
#include "srp.h"
#include "bn.h"
ERL_NIF_TERM srp_value_B_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{/* (Multiplier, Verifier, Generator, Exponent, Prime) */
BIGNUM *bn_verifier = NULL;
BIGNUM *bn_exponent = NULL, *bn_generator = NULL, *bn_prime = NULL, *bn_multiplier = NULL, *bn_result;
BN_CTX *bn_ctx;
unsigned char* ptr;
unsigned dlen;
ERL_NIF_TERM ret;
CHECK_NO_FIPS_MODE();
if (!get_bn_from_bin(env, argv[0], &bn_multiplier)
|| !get_bn_from_bin(env, argv[1], &bn_verifier)
|| !get_bn_from_bin(env, argv[2], &bn_generator)
|| !get_bn_from_bin(env, argv[3], &bn_exponent)
|| !get_bn_from_bin(env, argv[4], &bn_prime)) {
if (bn_multiplier) BN_free(bn_multiplier);
if (bn_verifier) BN_free(bn_verifier);
if (bn_generator) BN_free(bn_generator);
if (bn_exponent) BN_free(bn_exponent);
if (bn_prime) BN_free(bn_prime);
return enif_make_badarg(env);
}
bn_result = BN_new();
bn_ctx = BN_CTX_new();
/* B = k*v + g^b % N */
/* k * v */
BN_mod_mul(bn_multiplier, bn_multiplier, bn_verifier, bn_prime, bn_ctx);
/* g^b % N */
BN_mod_exp(bn_result, bn_generator, bn_exponent, bn_prime, bn_ctx);
/* k*v + g^b % N */
BN_mod_add(bn_result, bn_result, bn_multiplier, bn_prime, bn_ctx);
/* check that B % N != 0, reuse bn_multiplier */
BN_nnmod(bn_multiplier, bn_result, bn_prime, bn_ctx);
if (BN_is_zero(bn_multiplier)) {
ret = atom_error;
} else {
dlen = BN_num_bytes(bn_result);
ptr = enif_make_new_binary(env, dlen, &ret);
BN_bn2bin(bn_result, ptr);
}
BN_free(bn_result);
BN_CTX_free(bn_ctx);
BN_free(bn_prime);
BN_free(bn_generator);
BN_free(bn_multiplier);
BN_free(bn_exponent);
BN_free(bn_verifier);
return ret;
}
ERL_NIF_TERM srp_user_secret_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{/* (a, u, B, Multiplier, Prime, Exponent, Generator) */
/*
<premaster secret> = (B - (k * g^x)) ^ (a + (u * x)) % N
*/
BIGNUM *bn_exponent = NULL, *bn_a = NULL;
BIGNUM *bn_u = NULL, *bn_multiplier = NULL, *bn_exp2,
*bn_base, *bn_prime = NULL, *bn_generator = NULL,
*bn_B = NULL, *bn_result;
BN_CTX *bn_ctx;
unsigned char* ptr;
unsigned dlen;
ERL_NIF_TERM ret;
CHECK_NO_FIPS_MODE();
if (!get_bn_from_bin(env, argv[0], &bn_a)
|| !get_bn_from_bin(env, argv[1], &bn_u)
|| !get_bn_from_bin(env, argv[2], &bn_B)
|| !get_bn_from_bin(env, argv[3], &bn_multiplier)
|| !get_bn_from_bin(env, argv[4], &bn_generator)
|| !get_bn_from_bin(env, argv[5], &bn_exponent)
|| !get_bn_from_bin(env, argv[6], &bn_prime))
{
if (bn_exponent) BN_free(bn_exponent);
if (bn_a) BN_free(bn_a);
if (bn_u) BN_free(bn_u);
if (bn_B) BN_free(bn_B);
if (bn_multiplier) BN_free(bn_multiplier);
if (bn_generator) BN_free(bn_generator);
if (bn_prime) BN_free(bn_prime);
return enif_make_badarg(env);
}
bn_ctx = BN_CTX_new();
bn_result = BN_new();
/* check that B % N != 0 */
BN_nnmod(bn_result, bn_B, bn_prime, bn_ctx);
if (BN_is_zero(bn_result)) {
BN_free(bn_exponent);
BN_free(bn_a);
BN_free(bn_generator);
BN_free(bn_prime);
BN_free(bn_u);
BN_free(bn_B);
BN_CTX_free(bn_ctx);
return atom_error;
}
/* (B - (k * g^x)) */
bn_base = BN_new();
BN_mod_exp(bn_result, bn_generator, bn_exponent, bn_prime, bn_ctx);
BN_mod_mul(bn_result, bn_multiplier, bn_result, bn_prime, bn_ctx);
BN_mod_sub(bn_base, bn_B, bn_result, bn_prime, bn_ctx);
/* a + (u * x) */
bn_exp2 = BN_new();
BN_mul(bn_result, bn_u, bn_exponent, bn_ctx);
BN_add(bn_exp2, bn_a, bn_result);
/* (B - (k * g^x)) ^ (a + (u * x)) % N */
BN_mod_exp(bn_result, bn_base, bn_exp2, bn_prime, bn_ctx);
dlen = BN_num_bytes(bn_result);
ptr = enif_make_new_binary(env, dlen, &ret);
BN_bn2bin(bn_result, ptr);
BN_free(bn_result);
BN_CTX_free(bn_ctx);
BN_free(bn_multiplier);
BN_free(bn_exp2);
BN_free(bn_u);
BN_free(bn_exponent);
BN_free(bn_a);
BN_free(bn_B);
BN_free(bn_base);
BN_free(bn_generator);
BN_free(bn_prime);
return ret;
}
ERL_NIF_TERM srp_host_secret_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{/* (Verifier, b, u, A, Prime) */
/*
<premaster secret> = (A * v^u) ^ b % N
*/
BIGNUM *bn_b = NULL, *bn_verifier = NULL;
BIGNUM *bn_prime = NULL, *bn_A = NULL, *bn_u = NULL, *bn_base, *bn_result;
BN_CTX *bn_ctx;
unsigned char* ptr;
unsigned dlen;
ERL_NIF_TERM ret;
CHECK_NO_FIPS_MODE();
if (!get_bn_from_bin(env, argv[0], &bn_verifier)
|| !get_bn_from_bin(env, argv[1], &bn_b)
|| !get_bn_from_bin(env, argv[2], &bn_u)
|| !get_bn_from_bin(env, argv[3], &bn_A)
|| !get_bn_from_bin(env, argv[4], &bn_prime))
{
if (bn_verifier) BN_free(bn_verifier);
if (bn_b) BN_free(bn_b);
if (bn_u) BN_free(bn_u);
if (bn_A) BN_free(bn_A);
if (bn_prime) BN_free(bn_prime);
return enif_make_badarg(env);
}
bn_ctx = BN_CTX_new();
bn_result = BN_new();
/* check that A % N != 0 */
BN_nnmod(bn_result, bn_A, bn_prime, bn_ctx);
if (BN_is_zero(bn_result)) {
BN_free(bn_b);
BN_free(bn_verifier);
BN_free(bn_prime);
BN_free(bn_A);
BN_CTX_free(bn_ctx);
return atom_error;
}
/* (A * v^u) */
bn_base = BN_new();
BN_mod_exp(bn_base, bn_verifier, bn_u, bn_prime, bn_ctx);
BN_mod_mul(bn_base, bn_A, bn_base, bn_prime, bn_ctx);
/* (A * v^u) ^ b % N */
BN_mod_exp(bn_result, bn_base, bn_b, bn_prime, bn_ctx);
dlen = BN_num_bytes(bn_result);
ptr = enif_make_new_binary(env, dlen, &ret);
BN_bn2bin(bn_result, ptr);
BN_free(bn_result);
BN_CTX_free(bn_ctx);
BN_free(bn_u);
BN_free(bn_base);
BN_free(bn_verifier);
BN_free(bn_prime);
BN_free(bn_A);
BN_free(bn_b);
return ret;
}
