File Coverage

src/rsa/rsa_ssl_decrypt.c

Criterion	Covered	Total	%
statement	0	11	0.0
branch	0	6	0.0
condition			n/a
subroutine			n/a
pod			n/a
total	0	17	0.0

/*
 * Copyright (c) 2016 Thomas Pornin
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include "inner.h"

/* see bearssl_rsa.h */
uint32_t
br_rsa_ssl_decrypt(br_rsa_private core, const br_rsa_private_key *sk,
	unsigned char *data, size_t len)
{
	uint32_t x;
	size_t u;

	/*
	 * A first check on length. Since this test works only on the
	 * buffer length, it needs not (and cannot) be constant-time.
	 */
	if (len < 59 || len != (sk->n_bitlen + 7) >> 3) {
		return 0;
	}
	x = core(data, sk);

	x &= EQ(data[0], 0x00);
	x &= EQ(data[1], 0x02);
	for (u = 2; u < (len - 49); u ++) {
		x &= NEQ(data[u], 0);
	}
	x &= EQ(data[len - 49], 0x00);
	memmove(data, data + len - 48, 48);
	return x;
}