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psa_util: improve leading zeros check in convert_der_to_raw_single_int()

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Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
This commit is contained in:
Valerio Setti 2024-02-07 16:16:58 +01:00
parent ef07fa0fc3
commit 1910390b4a
2 changed files with 21 additions and 10 deletions
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15
library/psa_util.c
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@ -488,18 +488,21 @@ static int convert_der_to_raw_single_int(unsigned char *der, size_t der_len,
return ret;
}
/* It's invalid to have MSb set without a leading 0x00 (leading 0x00 is
* checked below). */
if ((*p & 0x80) != 0) {
/* It's invalid to have:
* - unpadded_len == 0.
* - MSb set without a leading 0x00 (leading 0x00 is checked below). */
if (((unpadded_len == 0) || (*p & 0x80) != 0)) {
return MBEDTLS_ERR_ASN1_INVALID_DATA;
}
/* Skip possible leading zero */
if ((unpadded_len > 0) && (*p == 0x00)) {
if (*p == 0x00) {
p++;
unpadded_len--;
/* Only 1 leading zero is allowed, otherwise that's an error. */
if (*p == 0x00) {
/* It is not allowed to have more than 1 leading zero.
* Ignore the case in which unpadded_len = 0 because that's a 0 encoded
* in ASN.1 format (i.e. 020100). */
if ((unpadded_len > 0) && (*p == 0x00)) {
return MBEDTLS_ERR_ASN1_INVALID_DATA;
}
}

16
tests/suites/test_suite_psa_crypto_util.data
View file

@ -110,13 +110,21 @@ ECDSA DER -> Raw, 256bit, Valid s only 1 zero byte
depends_on:PSA_VENDOR_ECC_MAX_CURVE_BITS >= 256
ecdsa_der_to_raw:256:"302502201111111111111111111111111111111111111111111111111111111111111111020100":"11111111111111111111111111111111111111111111111111111111111111110000000000000000000000000000000000000000000000000000000000000000":0
ECDSA DER -> Raw, 256bit, Valid 0-length r
ECDSA DER -> Raw, 256bit, Invalid 0-length r
depends_on:PSA_VENDOR_ECC_MAX_CURVE_BITS >= 256
ecdsa_der_to_raw:256:"3024020002202222222222222222222222222222222222222222222222222222222222222222":"00000000000000000000000000000000000000000000000000000000000000002222222222222222222222222222222222222222222222222222222222222222":0
ecdsa_der_to_raw:256:"3024020002202222222222222222222222222222222222222222222222222222222222222222":"00000000000000000000000000000000000000000000000000000000000000002222222222222222222222222222222222222222222222222222222222222222":MBEDTLS_ERR_ASN1_INVALID_DATA
ECDSA DER -> Raw, 256bit, Valid 0-length s
ECDSA DER -> Raw, 256bit, Invalid 0-length s
depends_on:PSA_VENDOR_ECC_MAX_CURVE_BITS >= 256
ecdsa_der_to_raw:256:"3024022011111111111111111111111111111111111111111111111111111111111111110200":"11111111111111111111111111111111111111111111111111111111111111110000000000000000000000000000000000000000000000000000000000000000":0
ecdsa_der_to_raw:256:"3024022011111111111111111111111111111111111111111111111111111111111111110200":"11111111111111111111111111111111111111111111111111111111111111110000000000000000000000000000000000000000000000000000000000000000":MBEDTLS_ERR_ASN1_INVALID_DATA
ECDSA DER -> Raw, 256bit, Invalid r 2 leading zeros
depends_on:PSA_VENDOR_ECC_MAX_CURVE_BITS >= 256
ecdsa_der_to_raw:256:"3027020300000102202222222222222222222222222222222222222222222222222222222222222222":"00000000000000000000000000000000000000000000000000000000000000002222222222222222222222222222222222222222222222222222222222222222":MBEDTLS_ERR_ASN1_INVALID_DATA
ECDSA DER -> Raw, 256bit, Invalid s 2 leading zeros
depends_on:PSA_VENDOR_ECC_MAX_CURVE_BITS >= 256
ecdsa_der_to_raw:256:"3027022011111111111111111111111111111111111111111111111111111111111111110203000001":"11111111111111111111111111111111111111111111111111111111111111110000000000000000000000000000000000000000000000000000000000000000":MBEDTLS_ERR_ASN1_INVALID_DATA
ECDSA DER -> Raw, 256bit, Invalid r: MSb set without leading zero
depends_on:PSA_VENDOR_ECC_MAX_CURVE_BITS >= 256