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psa_util: improve description for ECDSA conversion functions

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Signed-off-by: Valerio Setti <valerio.setti@nordicsemi.no>
This commit is contained in:
Valerio Setti 2024-01-09 14:20:23 +01:00
parent aed21640bd
commit 84890c9be2
2 changed files with 46 additions and 11 deletions
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6
include/mbedtls/psa_util.h
View file

@ -177,7 +177,8 @@ static inline mbedtls_md_type_t mbedtls_md_type_from_psa_alg(psa_algorithm_t psa
}
#if defined(MBEDTLS_ASN1_WRITE_C)
/** Convert an ECDSA signature from raw format to DER ASN.1 one.
/** Convert an ECDSA signature from raw format (used by PSA APIs) to DER ASN.1
* format (used by legacy crypto APIs).
*
* \param raw Buffer that contains the signature in raw format.
* \param raw_len Length of raw buffer in bytes
@ -195,7 +196,8 @@ int mbedtls_ecdsa_raw_to_der(const unsigned char *raw, size_t raw_len,
#endif /* MBEDTLS_ASN1_WRITE_C */
#if defined(MBEDTLS_ASN1_PARSE_C)
/** Convert an ECDSA signature from DER ASN.1 format to raw.
/** Convert an ECDSA signature from DER ASN.1 format (used by legacy crypto
* APIs) to raw format (used by PSA APIs).
*
* \param der Buffer that contains the signature in DER format.
* \param der_len Size of the der buffer in bytes.

51
library/psa_util.c
View file

@ -335,11 +335,25 @@ mbedtls_ecp_group_id mbedtls_ecc_group_from_psa(psa_ecc_family_t family,
#endif /* PSA_WANT_KEY_TYPE_ECC_PUBLIC_KEY */
#if defined(MBEDTLS_ASN1_WRITE_C)
/*
* Convert a single raw coordinate to DER ASN.1 format.
* Note: this function is similar to mbedtls_asn1_write_mpi(), but it doesn't
* depend on BIGNUM_C.
* Note: this function fills der_buf backward.
/**
* \brief Convert a single raw coordinate to DER ASN.1 format. The output der
* buffer is filled backward (i.e. starting from its end).
*
* \param raw_buf Buffer containing the raw coordinate to be
* converted.
* \param raw_len Length of raw_buf in bytes.
* \param der_buf_start Pointer to the beginning of the buffer which
* will be filled with the DER converted data.
* \param der_buf_end End of the buffer used to store the DER output.
*
* \return On success, the amount of data (in bytes) written to
* the DER buffer.
* \return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL if the provided der
* buffer is too small to contain all the converted data.
* \return MBEDTLS_ERR_ASN1_INVALID_DATA if the input raw
* coordinate is null (i.e. all zeros).
*
* \warning Raw and der buffer must not be overlapping.
*/
static int convert_raw_to_der_single_int(const unsigned char *raw_buf, size_t raw_len,
unsigned char *der_buf_start,
@ -436,9 +450,28 @@ int mbedtls_ecdsa_raw_to_der(const unsigned char *raw, size_t raw_len,
#endif /* MBEDTLS_ASN1_WRITE_C */
#if defined(MBEDTLS_ASN1_PARSE_C)
/*
* Convert a single integer from ASN.1 DER format to raw.
* Note: der and raw buffers are not overlapping here.
/**
* \brief Convert a single integer from ASN.1 DER format to raw.
*
* \param der Buffer containing the DER integer value to be
* converted.
* \param der_len Length of the der buffer in bytes.
* \param raw Output buffer that will be filled with the
* converted data. This should be at least
* coordinate_size bytes.
* \param raw_len Size (in bytes) of the output raw buffer.
* \param coordinate_size Size (in bytes) of a single coordinate in raw
* format.
*
* \return On success, the amount of DER data parsed from the
* provided der buffer.
* \return MBEDTLS_ERR_ASN1_UNEXPECTED_TAG if the integer tag
* is missing in the der buffer.
* \return MBEDTLS_ERR_ASN1_LENGTH_MISMATCH if the integer
* is null (i.e. all zeros) or if the output raw buffer
* is too small to contain the converted raw value.
*
* \warning Der and raw buffers must not be overlapping.
*/
static int convert_der_to_raw_single_int(unsigned char *der, size_t der_len,
unsigned char *raw, size_t raw_len,
@ -466,7 +499,7 @@ static int convert_der_to_raw_single_int(unsigned char *der, size_t der_len,
}
if (raw_len < coordinate_size) {
return MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;
return ERR_ASN1_BUF_TOO_SMALL;
}
if (unpadded_len < coordinate_size) {