digest.c

#include <ctype.h>
#include <string.h>

#include "digest.h"
#include "utils.h"

int verify_digest(const unsigned char *digest, const unsigned char *data,
		size_t data_size)
{
	unsigned char tmp_digest[SHA_DIGEST_LENGTH];
	SHA1(data, data_size, tmp_digest);
	return !memcmp(tmp_digest, digest, SHA_DIGEST_LENGTH);
}

static const char hex_digit[] = "0123456789abcdef";

const char *__digest_string(const unsigned char *digest, char *strbuf)
{
	char *ptr;
	int i;

	for (i = 0, ptr = strbuf; i < SHA_DIGEST_LENGTH; i ++) {
		*ptr++ = hex_digit[digest[i] & 0xf];
		*ptr++ = hex_digit[(digest[i] >> 4) & 0xf];
	}
	*ptr = 0;

	return strbuf;
}


unsigned char *__string_digest(const char *str, unsigned char *digest)
{
	const char *d0, *d1;
	int i;

	if (!digest)
		return ERR_PTR(ENOMEM);

	for (i = 0; i < SHA_DIGEST_LENGTH; i ++) {
		if (!*str)
			return ERR_PTR(EINVAL);
		d0 = strchr(hex_digit, tolower(*str++));
		if (!d0 || !*str)
			return ERR_PTR(EINVAL);
		d1 = strchr(hex_digit, tolower(*str++));
		if (!d1)
			return ERR_PTR(EINVAL);
		digest[i] = (d0 - hex_digit) | ((d1 - hex_digit) << 4);
	}

	return digest;
}

int digest_distance(const unsigned char *a, const unsigned char *b)
{
	const unsigned *ia = (void *)a;
	const unsigned *ib = (void *)b;
	int i;

	for (i = 0; i < SHA_DIGEST_INTS; i ++) {
		unsigned bit = ffs(ia[i] ^ ib[i]);
		if (bit)
			return SHA_DIGEST_BITS - (bit + i * 32);
	}

	return -1;
}