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Make padlen check const-time

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Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
This commit is contained in:
Dave Rodgman 2023-09-19 17:09:13 +01:00
parent c2630fac52
commit 51c15309f2
1 changed files with 3 additions and 4 deletions
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7
library/nist_kw.c
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@ -421,10 +421,9 @@ int mbedtls_nist_kw_unwrap(mbedtls_nist_kw_context *ctx,
* larger than 8, because of the type wrap around.
*/
padlen = in_len - KW_SEMIBLOCK_LENGTH - Plen;
if (padlen > 7) {
padlen &= 7;
ret = MBEDTLS_ERR_CIPHER_AUTH_FAILED;
}
ret = -((int) mbedtls_ct_uint_if_else_0(mbedtls_ct_uint_gt(padlen, 7),
-MBEDTLS_ERR_CIPHER_AUTH_FAILED));
padlen &= 7;
/* Check padding in "constant-time" */
const uint8_t zero[KW_SEMIBLOCK_LENGTH] = { 0 };