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// SPDX-License-Identifier: GPL-2.0+
/* Copyright (C) 2020 Steffen Jaeckel <jaeckel-floss@eyet-services.de> */
#include <crypt.h>
#include "crypt-port.h"
typedef int (*crypt_fn)(const char *, size_t, const char *, size_t, uint8_t *,
size_t, void *, size_t);
const unsigned char ascii64[65] =
"./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
static void equals_constant_time(const void *a_, const void *b_, size_t len,
int *equal)
{
u8 ret = 0;
const u8 *a = a_, *b = b_;
int i;
for (i = 0; i < len; i++)
ret |= a[i] ^ b[i];
ret |= ret >> 4;
ret |= ret >> 2;
ret |= ret >> 1;
ret &= 1;
*equal = ret ^ 1;
}
int crypt_compare(const char *should, const char *passphrase, int *equal)
{
u8 output[CRYPT_OUTPUT_SIZE], scratch[ALG_SPECIFIC_SIZE];
size_t n;
int err;
struct {
const char *prefix;
crypt_fn crypt;
} crypt_algos[] = {
#if defined(CONFIG_CRYPT_PW_SHA256)
{ "$5$", crypt_sha256crypt_rn_wrapped },
#endif
#if defined(CONFIG_CRYPT_PW_SHA512)
{ "$6$", crypt_sha512crypt_rn_wrapped },
#endif
{ NULL, NULL }
};
*equal = 0;
for (n = 0; n < ARRAY_SIZE(crypt_algos); ++n) {
if (!crypt_algos[n].prefix)
continue;
if (strncmp(should, crypt_algos[n].prefix, 3) == 0)
break;
}
if (n >= ARRAY_SIZE(crypt_algos))
return -EINVAL;
err = crypt_algos[n].crypt(passphrase, strlen(passphrase), should, 0,
output, sizeof(output), scratch,
sizeof(scratch));
/* early return on error, nothing really happened inside the crypt() function */
if (err)
return err;
equals_constant_time(should, output, strlen((const char *)output),
equal);
memset(scratch, 0, sizeof(scratch));
memset(output, 0, sizeof(output));
return 0;
}
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