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/*
* %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 "bn.h"
int get_bn_from_mpint(ErlNifEnv* env, ERL_NIF_TERM term, BIGNUM** bnp)
{
ErlNifBinary bin;
int sz;
if (!enif_inspect_binary(env,term,&bin)) {
return 0;
}
ERL_VALGRIND_ASSERT_MEM_DEFINED(bin.data, bin.size);
sz = bin.size - 4;
if (sz < 0 || get_int32(bin.data) != sz) {
return 0;
}
*bnp = BN_bin2bn(bin.data+4, sz, NULL);
return 1;
}
int get_bn_from_bin(ErlNifEnv* env, ERL_NIF_TERM term, BIGNUM** bnp)
{
ErlNifBinary bin;
if (!enif_inspect_binary(env,term,&bin)) {
return 0;
}
ERL_VALGRIND_ASSERT_MEM_DEFINED(bin.data, bin.size);
*bnp = BN_bin2bn(bin.data, bin.size, NULL);
return 1;
}
ERL_NIF_TERM bin_from_bn(ErlNifEnv* env, const BIGNUM *bn)
{
int bn_len;
unsigned char *bin_ptr;
ERL_NIF_TERM term;
/* Copy the bignum into an erlang binary. */
bn_len = BN_num_bytes(bn);
bin_ptr = enif_make_new_binary(env, bn_len, &term);
BN_bn2bin(bn, bin_ptr);
return term;
}
ERL_NIF_TERM mod_exp_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{/* (Base,Exponent,Modulo,bin_hdr) */
BIGNUM *bn_base=NULL, *bn_exponent=NULL, *bn_modulo=NULL, *bn_result;
BN_CTX *bn_ctx;
unsigned char* ptr;
unsigned dlen;
unsigned bin_hdr; /* return type: 0=plain binary, 4: mpint */
unsigned extra_byte;
ERL_NIF_TERM ret;
if (!get_bn_from_bin(env, argv[0], &bn_base)
|| !get_bn_from_bin(env, argv[1], &bn_exponent)
|| !get_bn_from_bin(env, argv[2], &bn_modulo)
|| !enif_get_uint(env,argv[3],&bin_hdr) || (bin_hdr & ~4)) {
if (bn_base) BN_free(bn_base);
if (bn_exponent) BN_free(bn_exponent);
if (bn_modulo) BN_free(bn_modulo);
return enif_make_badarg(env);
}
bn_result = BN_new();
bn_ctx = BN_CTX_new();
BN_mod_exp(bn_result, bn_base, bn_exponent, bn_modulo, bn_ctx);
dlen = BN_num_bytes(bn_result);
extra_byte = bin_hdr && BN_is_bit_set(bn_result, dlen*8-1);
ptr = enif_make_new_binary(env, bin_hdr+extra_byte+dlen, &ret);
if (bin_hdr) {
put_int32(ptr, extra_byte+dlen);
ptr[4] = 0; /* extra zeroed byte to ensure a positive mpint */
ptr += bin_hdr + extra_byte;
}
BN_bn2bin(bn_result, ptr);
BN_free(bn_result);
BN_CTX_free(bn_ctx);
BN_free(bn_modulo);
BN_free(bn_exponent);
BN_free(bn_base);
return ret;
}
#ifdef HAVE_EC
ERL_NIF_TERM bn2term(ErlNifEnv* env, const BIGNUM *bn)
{
unsigned dlen;
unsigned char* ptr;
ERL_NIF_TERM ret;
if (!bn)
return atom_undefined;
dlen = BN_num_bytes(bn);
ptr = enif_make_new_binary(env, dlen, &ret);
BN_bn2bin(bn, ptr);
ERL_VALGRIND_MAKE_MEM_DEFINED(ptr, dlen);
return ret;
}
#endif
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