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https://github.com/Mbed-TLS/mbedtls.git
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psa_util: add raw<->DER ECDSA conversion functions
Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
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Valerio Setti
parent
aa3fa98bc4
commit
75501f5ede
@ -176,6 +176,42 @@ static inline mbedtls_md_type_t mbedtls_md_type_from_psa_alg(psa_algorithm_t psa
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return (mbedtls_md_type_t) (psa_alg & PSA_ALG_HASH_MASK);
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}
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#if defined(MBEDTLS_ASN1_WRITE_C)
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/** Convert an ECDSA signature from raw format to DER ASN.1 one.
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*
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* \param raw Buffer that contains the signature in raw format.
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* \param raw_len Length of raw buffer in bytes
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* \param[out] der Buffer that will be filled with the converted DER
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* output. It can overlap with raw buffer.
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* \param der_size Size of the output der buffer in bytes.
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* \param[out] der_len On success it contains the amount of valid data
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* (in bytes) written to der buffer. It's undefined
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* in case of failure.
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* \param bits Size of each raw coordinate in bits.
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*/
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int mbedtls_ecdsa_raw_to_der(const unsigned char *raw, size_t raw_len,
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unsigned char *der, size_t der_size, size_t *der_len,
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size_t bits);
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#endif /* MBEDTLS_ASN1_WRITE_C */
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#if defined(MBEDTLS_ASN1_PARSE_C)
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/** Convert an ECDSA signature from DER ASN.1 format to raw.
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*
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* \param der Buffer that contains the signature in DER format.
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* \param der_len Size of the der buffer in bytes.
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* \param[out] raw Buffer that will be filled with the converted raw
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* signature. It can overlap with der buffer.
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* \param raw_size Size of the raw buffer in bytes.
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* \param[out] raw_len On success it is updated with the amount of valid
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* data (in bytes) written to raw buffer. It's undefined
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* in case of failure.
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* \param bits Size of each raw coordinate in bits.
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*/
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int mbedtls_ecdsa_der_to_raw(const unsigned char *der, size_t der_len,
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unsigned char *raw, size_t raw_size, size_t *raw_len,
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size_t bits);
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#endif /* MBEDTLS_ASN1_PARSE_C */
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/**@}*/
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#endif /* MBEDTLS_PSA_CRYPTO_C */
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@ -40,6 +40,10 @@
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#if defined(MBEDTLS_BLOCK_CIPHER_SOME_PSA)
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#include <mbedtls/cipher.h>
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#endif
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#if defined(MBEDTLS_ASN1_WRITE_C)
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#include <mbedtls/asn1write.h>
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#include <psa/crypto_sizes.h>
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#endif
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/* PSA_SUCCESS is kept at the top of each error table since
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* it's the most common status when everything functions properly. */
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@ -330,4 +334,205 @@ mbedtls_ecp_group_id mbedtls_ecc_group_from_psa(psa_ecc_family_t family,
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}
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#endif /* PSA_WANT_KEY_TYPE_ECC_PUBLIC_KEY */
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#if defined(MBEDTLS_ASN1_WRITE_C)
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/*
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* Convert a single raw coordinate to DER ASN.1 format.
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* Note: this function is similar to mbedtls_asn1_write_mpi(), but it doesn't
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* depend on BIGNUM_C.
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* Note: this function fills der_buf backward.
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*/
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static int convert_raw_to_der_single_int(const unsigned char *raw_buf, size_t raw_len,
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unsigned char *der_buf_start,
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unsigned char *der_buf_end)
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{
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unsigned char *p = der_buf_end;
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int len = raw_len;
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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/* Copy the raw coordinate to the end of der_buf. */
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if ((p - der_buf_start) < len) {
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return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
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}
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p -= len;
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memcpy(p, raw_buf, len);
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/* ASN.1 DER encoding requires minimal length, so skip leading 0s.
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* Provided input MPIs should not be 0, but as a failsafe measure, still
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* detect that and return error in case. */
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while (*p == 0x00) {
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++p;
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--len;
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if (len == 0) {
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return MBEDTLS_ERR_ASN1_INVALID_DATA;
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}
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}
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/* If MSb is 1, ASN.1 requires that we prepend a 0. */
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if (*p & 0x80) {
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if ((p - der_buf_start) < 1) {
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return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
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}
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--p;
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*p = 0x00;
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++len;
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}
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&p, der_buf_start, len));
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&p, der_buf_start, MBEDTLS_ASN1_INTEGER));
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return len;
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}
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int mbedtls_ecdsa_raw_to_der(const unsigned char *raw, size_t raw_len,
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unsigned char *der, size_t der_size, size_t *der_len,
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size_t bits)
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{
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unsigned char r[PSA_BITS_TO_BYTES(PSA_VENDOR_ECC_MAX_CURVE_BITS)];
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unsigned char s[PSA_BITS_TO_BYTES(PSA_VENDOR_ECC_MAX_CURVE_BITS)];
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const size_t coordinate_len = PSA_BITS_TO_BYTES(bits);
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size_t len = 0;
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unsigned char *p = der + der_size;
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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if (raw_len < 2 * coordinate_len) {
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return MBEDTLS_ERR_ASN1_INVALID_DATA;
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}
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/* Since raw and der buffers might overlap, dump r and s before starting
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* the conversion. */
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memset(r, 0, sizeof(r));
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memcpy(r, raw, coordinate_len);
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memset(s, 0, sizeof(s));
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memcpy(s, raw + coordinate_len, coordinate_len);
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/* der buffer will initially be written starting from its end so we pick s
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* first and then r. */
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ret = convert_raw_to_der_single_int(s, coordinate_len, der, p);
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if (ret < 0) {
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return ret;
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}
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p -= ret;
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len += ret;
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ret = convert_raw_to_der_single_int(r, coordinate_len, der, p);
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if (ret < 0) {
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return ret;
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}
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p -= ret;
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len += ret;
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/* Add ASN.1 header (len + tag). */
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&p, der, len));
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MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&p, der,
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MBEDTLS_ASN1_CONSTRUCTED |
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MBEDTLS_ASN1_SEQUENCE));
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/* memmove the content of der buffer to its beginnig. */
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memmove(der, p, len);
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*der_len = len;
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return 0;
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}
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#endif /* MBEDTLS_ASN1_WRITE_C */
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#if defined(MBEDTLS_ASN1_PARSE_C)
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/*
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* Convert a single integer from ASN.1 DER format to raw.
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* Note: der and raw buffers are not overlapping here.
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*/
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static int convert_der_to_raw_single_int(unsigned char *der, size_t der_len,
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unsigned char *raw, size_t raw_len,
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size_t coordinate_size)
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{
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unsigned char *p = der;
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int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
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size_t unpadded_len, padding_len = 0;
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/* Get the length of ASN.1 element (i.e. the integer we need to parse). */
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ret = mbedtls_asn1_get_tag(&p, p + der_len, &unpadded_len,
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MBEDTLS_ASN1_INTEGER);
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if (ret != 0) {
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return ret;
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}
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/* Skip leading zeros */
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while (*p == 0x00) {
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p++;
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unpadded_len--;
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/* It should never happen that the input number is all zeros. */
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if (unpadded_len == 0) {
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return MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
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}
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}
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if (raw_len < coordinate_size) {
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return MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
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}
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if (unpadded_len < coordinate_size) {
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padding_len = coordinate_size - unpadded_len;
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memset(raw, 0x00, padding_len);
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}
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memcpy(raw + padding_len, p, unpadded_len);
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p += unpadded_len;
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return (int) (p - der);
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}
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int mbedtls_ecdsa_der_to_raw(const unsigned char *der, size_t der_len,
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unsigned char *raw, size_t raw_size, size_t *raw_len,
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size_t bits)
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{
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unsigned char raw_tmp[PSA_VENDOR_ECDSA_SIGNATURE_MAX_SIZE];
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unsigned char *p = (unsigned char *) der;
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size_t data_len;
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size_t coordinate_size = PSA_BITS_TO_BYTES(bits);
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int ret;
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/* The output raw buffer should be at least twice the size of a raw
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* coordinate in order to store r and s. */
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if (raw_size < coordinate_size * 2) {
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return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;
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}
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/* Check that the provided input DER buffer has the right header. */
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ret = mbedtls_asn1_get_tag(&p, der + der_len, &data_len,
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MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE);
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if (ret != 0) {
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return ret;
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}
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memset(raw_tmp, 0, sizeof(raw_tmp));
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/* Extract r */
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ret = convert_der_to_raw_single_int(p, data_len, raw_tmp, sizeof(raw_tmp),
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coordinate_size);
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if (ret < 0) {
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return ret;
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}
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p += ret;
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data_len -= ret;
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/* Extract s */
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ret = convert_der_to_raw_single_int(p, data_len, raw_tmp + coordinate_size,
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sizeof(raw_tmp) - coordinate_size,
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coordinate_size);
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if (ret < 0) {
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return ret;
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}
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p += ret;
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data_len -= ret;
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/* Check that we consumed all the input der data. */
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if ((p - der) != (int) der_len) {
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return MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
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}
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memcpy(raw, raw_tmp, 2 * coordinate_size);
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*raw_len = 2 * coordinate_size;
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return 0;
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}
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#endif /* MBEDTLS_ASN1_PARSE_C */
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#endif /* MBEDTLS_PSA_CRYPTO_C */
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