Viewing file:  bn_mpi.c (1.89 KB) -rw-r--r--
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/*
* Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <stdio.h>
#include "internal/cryptlib.h"
#include "bn_local.h"
int BN_bn2mpi(const BIGNUM *a, unsigned char *d)
{
int bits;
int num = 0;
int ext = 0;
long l;
bits = BN_num_bits(a);
num = (bits + 7) / 8;
if (bits > 0) {
ext = ((bits & 0x07) == 0);
}
if (d == NULL)
return (num + 4 + ext);
l = num + ext;
d[0] = (unsigned char)(l >> 24) & 0xff;
d[1] = (unsigned char)(l >> 16) & 0xff;
d[2] = (unsigned char)(l >> 8) & 0xff;
d[3] = (unsigned char)(l) & 0xff;
if (ext)
d[4] = 0;
num = BN_bn2bin(a, &(d[4 + ext]));
if (a->neg)
d[4] |= 0x80;
return (num + 4 + ext);
}
BIGNUM *BN_mpi2bn(const unsigned char *d, int n, BIGNUM *ain)
{
long len;
int neg = 0;
BIGNUM *a = NULL;
if (n < 4 || (d[0] & 0x80) != 0) {
ERR_raise(ERR_LIB_BN, BN_R_INVALID_LENGTH);
return NULL;
}
len = ((long)d[0] << 24) | ((long)d[1] << 16) | ((int)d[2] << 8) | (int)
d[3];
if ((len + 4) != n) {
ERR_raise(ERR_LIB_BN, BN_R_ENCODING_ERROR);
return NULL;
}
if (ain == NULL)
a = BN_new();
else
a = ain;
if (a == NULL)
return NULL;
if (len == 0) {
a->neg = 0;
a->top = 0;
return a;
}
d += 4;
if ((*d) & 0x80)
neg = 1;
if (BN_bin2bn(d, (int)len, a) == NULL) {
if (ain == NULL)
BN_free(a);
return NULL;
}
a->neg = neg;
if (neg) {
BN_clear_bit(a, BN_num_bits(a) - 1);
}
bn_check_top(a);
return a;
}
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