psa: let mbedtls_ecc_group_from_psa() accept only exact bit lengths
Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
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dc33200b74
commit
0e608807e3
3 changed files with 17 additions and 24 deletions
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@ -126,16 +126,11 @@ psa_ecc_family_t mbedtls_ecc_group_to_psa(mbedtls_ecp_group_id grpid,
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* \param curve A PSA elliptic curve identifier
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* (`PSA_ECC_FAMILY_xxx`).
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* \param bits The bit-length of a private key on \p curve.
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* \param bits_is_sloppy If true, \p bits may be the bit-length rounded up
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* to the nearest multiple of 8. This allows the caller
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* to infer the exact curve from the length of a key
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* which is supplied as a byte string.
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*
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* \return The corresponding Mbed TLS elliptic curve identifier
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* (`MBEDTLS_ECP_DP_xxx`).
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* \return #MBEDTLS_ECP_DP_NONE if \c curve is not recognized.
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* \return #MBEDTLS_ECP_DP_NONE if \p bits is not
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* correct for \p curve.
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* \return #MBEDTLS_ECP_DP_NONE if the combination of \c curve
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* and \p bits is not recognized.
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*/
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mbedtls_ecp_group_id mbedtls_ecc_group_from_psa(psa_ecc_family_t curve,
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size_t bits);
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@ -32,13 +32,16 @@
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defined(MBEDTLS_PSA_BUILTIN_ALG_ECDSA) || \
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defined(MBEDTLS_PSA_BUILTIN_ALG_DETERMINISTIC_ECDSA) || \
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defined(MBEDTLS_PSA_BUILTIN_ALG_ECDH)
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/* Helper function to verify if the provided EC's family and key bit size are
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* valid. */
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static int check_ecc_parameters(psa_ecc_family_t family, size_t bits, int allow_bit_size_roundup)
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/* Helper function to verify if the provided EC's family and key bit size are valid.
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*
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* Note: "bits" parameter is used both as input and output and it might be updated
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* in case provided input value is not multiple of 8 ("sloppy" bits).
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*/
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static int check_ecc_parameters(psa_ecc_family_t family, size_t *bits)
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{
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switch (family) {
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case PSA_ECC_FAMILY_SECP_R1:
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switch (bits) {
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switch (*bits) {
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case 192:
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case 224:
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case 256:
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@ -46,14 +49,13 @@ static int check_ecc_parameters(psa_ecc_family_t family, size_t bits, int allow_
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case 521:
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return PSA_SUCCESS;
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case 528:
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if (allow_bit_size_roundup) {
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*bits = 521;
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return PSA_SUCCESS;
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}
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}
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break;
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case PSA_ECC_FAMILY_BRAINPOOL_P_R1:
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switch (bits) {
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switch (*bits) {
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case 256:
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case 384:
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case 512:
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@ -62,19 +64,18 @@ static int check_ecc_parameters(psa_ecc_family_t family, size_t bits, int allow_
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break;
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case PSA_ECC_FAMILY_MONTGOMERY:
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switch (bits) {
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switch (*bits) {
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case 448:
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case 255:
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return PSA_SUCCESS;
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case 256:
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if (allow_bit_size_roundup) {
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*bits = 255;
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return PSA_SUCCESS;
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}
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}
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break;
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case PSA_ECC_FAMILY_SECP_K1:
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switch (bits) {
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switch (*bits) {
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case 192:
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case 224:
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case 256:
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@ -136,8 +137,7 @@ psa_status_t mbedtls_psa_ecp_load_representation(
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}
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mbedtls_ecp_keypair_init(ecp);
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status = check_ecc_parameters(PSA_KEY_TYPE_ECC_GET_FAMILY(type), curve_bits,
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!explicit_bits);
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status = check_ecc_parameters(PSA_KEY_TYPE_ECC_GET_FAMILY(type), &curve_bits);
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if (status != PSA_SUCCESS) {
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goto exit;
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}
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@ -276,7 +276,6 @@ mbedtls_ecp_group_id mbedtls_ecc_group_from_psa(psa_ecc_family_t curve,
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#endif
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#if defined(PSA_WANT_ECC_SECP_R1_521)
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case 521:
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case 528:
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return MBEDTLS_ECP_DP_SECP521R1;
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#endif
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}
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@ -303,7 +302,6 @@ mbedtls_ecp_group_id mbedtls_ecc_group_from_psa(psa_ecc_family_t curve,
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switch (bits) {
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#if defined(PSA_WANT_ECC_MONTGOMERY_255)
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case 255:
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case 256:
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return MBEDTLS_ECP_DP_CURVE25519;
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#endif
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#if defined(PSA_WANT_ECC_MONTGOMERY_448)
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