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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)
{
BIGNUM *ret;
ErlNifBinary bin;
int sz;
if (!enif_inspect_binary(env, term, &bin))
goto err;
if (bin.size > INT_MAX - 4)
goto err;
if (bin.size < 4)
goto err;
sz = (int)bin.size - 4;
if (get_int32(bin.data) != sz)
goto err;
if ((ret = BN_bin2bn(bin.data+4, sz, NULL)) == NULL)
goto err;
*bnp = ret;
return 1;
err:
return 0;
}
int get_bn_from_bin(ErlNifEnv* env, ERL_NIF_TERM term, BIGNUM** bnp)
{
BIGNUM *ret;
ErlNifBinary bin;
if (!enif_inspect_binary(env, term, &bin))
goto err;
if (bin.size > INT_MAX)
goto err;
if ((ret = BN_bin2bn(bin.data, (int)bin.size, NULL)) == NULL)
goto err;
*bnp = ret;
return 1;
err:
return 0;
}
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. */
if ((bn_len = BN_num_bytes(bn)) < 0)
goto err;
if ((bin_ptr = enif_make_new_binary(env, (size_t)bn_len, &term)) == NULL)
goto err;
if (BN_bn2bin(bn, bin_ptr) < 0)
goto err;
return term;
err:
return atom_error;
}
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 = NULL;
BN_CTX *bn_ctx = NULL;
unsigned char* ptr;
int 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))
goto bad_arg;
if (!get_bn_from_bin(env, argv[1], &bn_exponent))
goto bad_arg;
if (!get_bn_from_bin(env, argv[2], &bn_modulo))
goto bad_arg;
if (!enif_get_uint(env, argv[3], &bin_hdr))
goto bad_arg;
if (bin_hdr != 0 && bin_hdr != 4)
goto bad_arg;
if ((bn_result = BN_new()) == NULL)
goto err;
if ((bn_ctx = BN_CTX_new()) == NULL)
goto err;
if (!BN_mod_exp(bn_result, bn_base, bn_exponent, bn_modulo, bn_ctx))
goto err;
dlen = BN_num_bytes(bn_result);
if (dlen < 0 || dlen > INT_MAX / 8)
goto bad_arg;
extra_byte = bin_hdr && BN_is_bit_set(bn_result, dlen * 8 - 1);
if ((ptr = enif_make_new_binary(env, bin_hdr + extra_byte + (unsigned int)dlen, &ret)) == NULL)
goto err;
if (bin_hdr) {
put_uint32(ptr, extra_byte + (unsigned int)dlen);
ptr[4] = 0; /* extra zeroed byte to ensure a positive mpint */
ptr += bin_hdr + extra_byte;
}
BN_bn2bin(bn_result, ptr);
goto done;
bad_arg:
err:
ret = enif_make_badarg(env);
done:
if (bn_base)
BN_free(bn_base);
if (bn_exponent)
BN_free(bn_exponent);
if (bn_modulo)
BN_free(bn_modulo);
if (bn_result)
BN_free(bn_result);
if (bn_ctx)
BN_CTX_free(bn_ctx);
return ret;
}
#ifdef HAVE_EC
ERL_NIF_TERM bn2term(ErlNifEnv* env, const BIGNUM *bn)
{
int dlen;
unsigned char* ptr;
ERL_NIF_TERM ret;
if (bn == NULL)
return atom_undefined;
dlen = BN_num_bytes(bn);
if (dlen < 0)
goto err;
if ((ptr = enif_make_new_binary(env, (size_t)dlen, &ret)) == NULL)
goto err;
BN_bn2bin(bn, ptr);
return ret;
err:
return enif_make_badarg(env);
}
#endif
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