/*

 *  PSA hashing layer on top of Mbed TLS software crypto

 */

/*

 *  Copyright The Mbed TLS Contributors

 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later

 */

#include "common.h"

/* This is needed for MBEDTLS_ERR_XXX macros */

#include <mbedtls/error.h>

#if defined(MBEDTLS_ASN1_WRITE_C)

#include <mbedtls/asn1write.h>

#include <psa/crypto_sizes.h>

#endif

#include "psa_util_internal.h"

#if defined(MBEDTLS_PSA_CRYPTO_CLIENT)

#include <psa/crypto.h>

#if defined(MBEDTLS_MD_LIGHT)

#include <mbedtls/md.h>

#endif

#if defined(MBEDTLS_LMS_C)

#include <mbedtls/lms.h>

#endif

#if defined(MBEDTLS_SSL_TLS_C) && \

    (defined(MBEDTLS_USE_PSA_CRYPTO) || defined(MBEDTLS_SSL_PROTO_TLS1_3))

#include <mbedtls/ssl.h>

#endif

#if defined(PSA_WANT_KEY_TYPE_RSA_PUBLIC_KEY) ||    \

    defined(PSA_WANT_KEY_TYPE_RSA_KEY_PAIR_BASIC)

#include <mbedtls/rsa.h>

#endif

#if defined(MBEDTLS_USE_PSA_CRYPTO) && \

    defined(PSA_WANT_KEY_TYPE_ECC_PUBLIC_KEY)

#include <mbedtls/ecp.h>

#endif

#if defined(MBEDTLS_PK_C)

#include <mbedtls/pk.h>

#endif

#if defined(MBEDTLS_BLOCK_CIPHER_SOME_PSA)

#include <mbedtls/cipher.h>

#endif

#include <mbedtls/entropy.h>

/* PSA_SUCCESS is kept at the top of each error table since

 * it's the most common status when everything functions properly. */

#if defined(MBEDTLS_MD_LIGHT)

const mbedtls_error_pair_t psa_to_md_errors[] =

{

    { PSA_SUCCESS,                     0 },

    { PSA_ERROR_NOT_SUPPORTED,         MBEDTLS_ERR_MD_FEATURE_UNAVAILABLE },

    { PSA_ERROR_INVALID_ARGUMENT,      MBEDTLS_ERR_MD_BAD_INPUT_DATA },

    { PSA_ERROR_INSUFFICIENT_MEMORY,   MBEDTLS_ERR_MD_ALLOC_FAILED }

};

#endif

#if defined(MBEDTLS_BLOCK_CIPHER_SOME_PSA)

const mbedtls_error_pair_t psa_to_cipher_errors[] =

{

    { PSA_SUCCESS,                     0 },

    { PSA_ERROR_NOT_SUPPORTED,         MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE },

    { PSA_ERROR_INVALID_ARGUMENT,      MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA },

    { PSA_ERROR_INSUFFICIENT_MEMORY,   MBEDTLS_ERR_CIPHER_ALLOC_FAILED }

};

#endif

#if defined(MBEDTLS_LMS_C)

const mbedtls_error_pair_t psa_to_lms_errors[] =

{

    { PSA_SUCCESS,                     0 },

    { PSA_ERROR_BUFFER_TOO_SMALL,      MBEDTLS_ERR_LMS_BUFFER_TOO_SMALL },

    { PSA_ERROR_INVALID_ARGUMENT,      MBEDTLS_ERR_LMS_BAD_INPUT_DATA }

};

#endif

#if defined(MBEDTLS_SSL_TLS_C) && \

    (defined(MBEDTLS_USE_PSA_CRYPTO) || defined(MBEDTLS_SSL_PROTO_TLS1_3))

const mbedtls_error_pair_t psa_to_ssl_errors[] =

{

    { PSA_SUCCESS,                     0 },

    { PSA_ERROR_INSUFFICIENT_MEMORY,   MBEDTLS_ERR_SSL_ALLOC_FAILED },

    { PSA_ERROR_NOT_SUPPORTED,         MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE },

    { PSA_ERROR_INVALID_SIGNATURE,     MBEDTLS_ERR_SSL_INVALID_MAC },

    { PSA_ERROR_INVALID_ARGUMENT,      MBEDTLS_ERR_SSL_BAD_INPUT_DATA },

    { PSA_ERROR_BAD_STATE,             MBEDTLS_ERR_SSL_INTERNAL_ERROR },

    { PSA_ERROR_BUFFER_TOO_SMALL,      MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL }

};

#endif

#if defined(PSA_WANT_KEY_TYPE_RSA_PUBLIC_KEY) ||    \

    defined(PSA_WANT_KEY_TYPE_RSA_KEY_PAIR_BASIC)

const mbedtls_error_pair_t psa_to_pk_rsa_errors[] =

{

    { PSA_SUCCESS,                     0 },

    { PSA_ERROR_NOT_PERMITTED,         MBEDTLS_ERR_RSA_BAD_INPUT_DATA },

    { PSA_ERROR_INVALID_ARGUMENT,      MBEDTLS_ERR_RSA_BAD_INPUT_DATA },

    { PSA_ERROR_INVALID_HANDLE,        MBEDTLS_ERR_RSA_BAD_INPUT_DATA },

    { PSA_ERROR_BUFFER_TOO_SMALL,      MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE },

    { PSA_ERROR_INSUFFICIENT_ENTROPY,  MBEDTLS_ERR_RSA_RNG_FAILED },

    { PSA_ERROR_INVALID_SIGNATURE,     MBEDTLS_ERR_RSA_VERIFY_FAILED },

    { PSA_ERROR_INVALID_PADDING,       MBEDTLS_ERR_RSA_INVALID_PADDING }

};

#endif

#if defined(MBEDTLS_USE_PSA_CRYPTO) && \

    defined(PSA_WANT_KEY_TYPE_ECC_PUBLIC_KEY)

const mbedtls_error_pair_t psa_to_pk_ecdsa_errors[] =

{

    { PSA_SUCCESS,                     0 },

    { PSA_ERROR_NOT_PERMITTED,         MBEDTLS_ERR_ECP_BAD_INPUT_DATA },

    { PSA_ERROR_INVALID_ARGUMENT,      MBEDTLS_ERR_ECP_BAD_INPUT_DATA },

    { PSA_ERROR_INVALID_HANDLE,        MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE },

    { PSA_ERROR_BUFFER_TOO_SMALL,      MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL },

    { PSA_ERROR_INSUFFICIENT_ENTROPY,  MBEDTLS_ERR_ECP_RANDOM_FAILED },

    { PSA_ERROR_INVALID_SIGNATURE,     MBEDTLS_ERR_ECP_VERIFY_FAILED }

};

#endif

int psa_generic_status_to_mbedtls(psa_status_t status)

{

    switch (status) {

        case PSA_SUCCESS:

            return 0;

        case PSA_ERROR_NOT_SUPPORTED:

            return MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED;

        case PSA_ERROR_CORRUPTION_DETECTED:

            return MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

        case PSA_ERROR_COMMUNICATION_FAILURE:

        case PSA_ERROR_HARDWARE_FAILURE:

            return MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED;

        case PSA_ERROR_NOT_PERMITTED:

        default:

            return MBEDTLS_ERR_ERROR_GENERIC_ERROR;

    }

}

int psa_status_to_mbedtls(psa_status_t status,

                          const mbedtls_error_pair_t *local_translations,

                          size_t local_errors_num,

                          int (*fallback_f)(psa_status_t))

{

    for (size_t i = 0; i < local_errors_num; i++) {

        if (status == local_translations[i].psa_status) {

            return local_translations[i].mbedtls_error;

        }

    }

    return fallback_f(status);

}

#if defined(MBEDTLS_PK_C)

int psa_pk_status_to_mbedtls(psa_status_t status)

{

    switch (status) {

        case PSA_ERROR_INVALID_HANDLE:

            return MBEDTLS_ERR_PK_KEY_INVALID_FORMAT;

        case PSA_ERROR_BUFFER_TOO_SMALL:

            return MBEDTLS_ERR_PK_BUFFER_TOO_SMALL;

        case PSA_ERROR_NOT_SUPPORTED:

            return MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE;

        case PSA_ERROR_INVALID_ARGUMENT:

            return MBEDTLS_ERR_PK_INVALID_ALG;

        case PSA_ERROR_NOT_PERMITTED:

            return MBEDTLS_ERR_PK_TYPE_MISMATCH;

        case PSA_ERROR_INSUFFICIENT_MEMORY:

            return MBEDTLS_ERR_PK_ALLOC_FAILED;

        case PSA_ERROR_BAD_STATE:

            return MBEDTLS_ERR_PK_BAD_INPUT_DATA;

        case PSA_ERROR_DATA_CORRUPT:

        case PSA_ERROR_DATA_INVALID:

        case PSA_ERROR_STORAGE_FAILURE:

            return MBEDTLS_ERR_PK_FILE_IO_ERROR;

        default:

            return psa_generic_status_to_mbedtls(status);

    }

}

#endif /* MBEDTLS_PK_C */

/****************************************************************/

/* Key management */

/****************************************************************/

#if defined(PSA_WANT_KEY_TYPE_ECC_PUBLIC_KEY)

psa_ecc_family_t mbedtls_ecc_group_to_psa(mbedtls_ecp_group_id grpid,

                                          size_t *bits)

{

    switch (grpid) {

#if defined(MBEDTLS_ECP_HAVE_SECP192R1)

        case MBEDTLS_ECP_DP_SECP192R1:

            *bits = 192;

            return PSA_ECC_FAMILY_SECP_R1;

#endif

#if defined(MBEDTLS_ECP_HAVE_SECP224R1)

        case MBEDTLS_ECP_DP_SECP224R1:

            *bits = 224;

            return PSA_ECC_FAMILY_SECP_R1;

#endif

#if defined(MBEDTLS_ECP_HAVE_SECP256R1)

        case MBEDTLS_ECP_DP_SECP256R1:

            *bits = 256;

            return PSA_ECC_FAMILY_SECP_R1;

#endif

#if defined(MBEDTLS_ECP_HAVE_SECP384R1)

        case MBEDTLS_ECP_DP_SECP384R1:

            *bits = 384;

            return PSA_ECC_FAMILY_SECP_R1;

#endif

#if defined(MBEDTLS_ECP_HAVE_SECP521R1)

        case MBEDTLS_ECP_DP_SECP521R1:

            *bits = 521;

            return PSA_ECC_FAMILY_SECP_R1;

#endif

#if defined(MBEDTLS_ECP_HAVE_BP256R1)

        case MBEDTLS_ECP_DP_BP256R1:

            *bits = 256;

            return PSA_ECC_FAMILY_BRAINPOOL_P_R1;

#endif

#if defined(MBEDTLS_ECP_HAVE_BP384R1)

        case MBEDTLS_ECP_DP_BP384R1:

            *bits = 384;

            return PSA_ECC_FAMILY_BRAINPOOL_P_R1;

#endif

#if defined(MBEDTLS_ECP_HAVE_BP512R1)

        case MBEDTLS_ECP_DP_BP512R1:

            *bits = 512;

            return PSA_ECC_FAMILY_BRAINPOOL_P_R1;

#endif

#if defined(MBEDTLS_ECP_HAVE_CURVE25519)

        case MBEDTLS_ECP_DP_CURVE25519:

            *bits = 255;

            return PSA_ECC_FAMILY_MONTGOMERY;

#endif

#if defined(MBEDTLS_ECP_HAVE_SECP192K1)

        case MBEDTLS_ECP_DP_SECP192K1:

            *bits = 192;

            return PSA_ECC_FAMILY_SECP_K1;

#endif

#if defined(MBEDTLS_ECP_HAVE_SECP224K1)

    /* secp224k1 is not and will not be supported in PSA (#3541). */

#endif

#if defined(MBEDTLS_ECP_HAVE_SECP256K1)

        case MBEDTLS_ECP_DP_SECP256K1:

            *bits = 256;

            return PSA_ECC_FAMILY_SECP_K1;

#endif

#if defined(MBEDTLS_ECP_HAVE_CURVE448)

        case MBEDTLS_ECP_DP_CURVE448:

            *bits = 448;

            return PSA_ECC_FAMILY_MONTGOMERY;

#endif

        default:

            *bits = 0;

            return 0;

    }

}

mbedtls_ecp_group_id mbedtls_ecc_group_from_psa(psa_ecc_family_t family,

                                                size_t bits)

{

    switch (family) {

        case PSA_ECC_FAMILY_SECP_R1:

            switch (bits) {

#if defined(PSA_WANT_ECC_SECP_R1_192)

                case 192:

                    return MBEDTLS_ECP_DP_SECP192R1;

#endif

#if defined(PSA_WANT_ECC_SECP_R1_224)

                case 224:

                    return MBEDTLS_ECP_DP_SECP224R1;

#endif

#if defined(PSA_WANT_ECC_SECP_R1_256)

                case 256:

                    return MBEDTLS_ECP_DP_SECP256R1;

#endif

#if defined(PSA_WANT_ECC_SECP_R1_384)

                case 384:

                    return MBEDTLS_ECP_DP_SECP384R1;

#endif

#if defined(PSA_WANT_ECC_SECP_R1_521)

                case 521:

                    return MBEDTLS_ECP_DP_SECP521R1;

#endif

            }

            break;

        case PSA_ECC_FAMILY_BRAINPOOL_P_R1:

            switch (bits) {

#if defined(PSA_WANT_ECC_BRAINPOOL_P_R1_256)

                case 256:

                    return MBEDTLS_ECP_DP_BP256R1;

#endif

#if defined(PSA_WANT_ECC_BRAINPOOL_P_R1_384)

                case 384:

                    return MBEDTLS_ECP_DP_BP384R1;

#endif

#if defined(PSA_WANT_ECC_BRAINPOOL_P_R1_512)

                case 512:

                    return MBEDTLS_ECP_DP_BP512R1;

#endif

            }

            break;

        case PSA_ECC_FAMILY_MONTGOMERY:

            switch (bits) {

#if defined(PSA_WANT_ECC_MONTGOMERY_255)

                case 255:

                    return MBEDTLS_ECP_DP_CURVE25519;

#endif

#if defined(PSA_WANT_ECC_MONTGOMERY_448)

                case 448:

                    return MBEDTLS_ECP_DP_CURVE448;

#endif

            }

            break;

        case PSA_ECC_FAMILY_SECP_K1:

            switch (bits) {

#if defined(PSA_WANT_ECC_SECP_K1_192)

                case 192:

                    return MBEDTLS_ECP_DP_SECP192K1;

#endif

#if defined(PSA_WANT_ECC_SECP_K1_224)

            /* secp224k1 is not and will not be supported in PSA (#3541). */

#endif

#if defined(PSA_WANT_ECC_SECP_K1_256)

                case 256:

                    return MBEDTLS_ECP_DP_SECP256K1;

#endif

            }

            break;

    }

    return MBEDTLS_ECP_DP_NONE;

}

#endif /* PSA_WANT_KEY_TYPE_ECC_PUBLIC_KEY */

/* Wrapper function allowing the classic API to use the PSA RNG.

 *

 * `mbedtls_psa_get_random(MBEDTLS_PSA_RANDOM_STATE, ...)` calls

 * `psa_generate_random(...)`. The state parameter is ignored since the

 * PSA API doesn't support passing an explicit state.

 */

int mbedtls_psa_get_random(void *p_rng,

                           unsigned char *output,

                           size_t output_size)

{

    /* This function takes a pointer to the RNG state because that's what

     * classic mbedtls functions using an RNG expect. The PSA RNG manages

     * its own state internally and doesn't let the caller access that state.

     * So we just ignore the state parameter, and in practice we'll pass

     * NULL. */

    (void) p_rng;

    psa_status_t status = psa_generate_random(output, output_size);

    if (status == PSA_SUCCESS) {

        return 0;

    } else {

        return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;

    }

}

#endif /* MBEDTLS_PSA_CRYPTO_CLIENT */

#if defined(MBEDTLS_PSA_UTIL_HAVE_ECDSA)

/**

 * \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. This must be > 0.

 * \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,

                                         unsigned char *der_buf_end)

{

    unsigned char *p = der_buf_end;

    int len;

    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    /* ASN.1 DER encoding requires minimal length, so skip leading 0s.

     * Provided input MPIs should not be 0, but as a failsafe measure, still

     * detect that and return error in case. */

    while (*raw_buf == 0x00) {

        ++raw_buf;

        --raw_len;

        if (raw_len == 0) {

            return MBEDTLS_ERR_ASN1_INVALID_DATA;

        }

    }

    len = (int) raw_len;

    /* Copy the raw coordinate to the end of der_buf. */

    if ((p - der_buf_start) < len) {

        return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;

    }

    p -= len;

    memcpy(p, raw_buf, len);

    /* If MSb is 1, ASN.1 requires that we prepend a 0. */

    if (*p & 0x80) {

        if ((p - der_buf_start) < 1) {

            return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;

        }

        --p;

        *p = 0x00;

        ++len;

    }

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&p, der_buf_start, len));

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&p, der_buf_start, MBEDTLS_ASN1_INTEGER));

    return len;

}

int mbedtls_ecdsa_raw_to_der(size_t bits, const unsigned char *raw, size_t raw_len,

                             unsigned char *der, size_t der_size, size_t *der_len)

{

    unsigned char r[PSA_BITS_TO_BYTES(PSA_VENDOR_ECC_MAX_CURVE_BITS)];

    unsigned char s[PSA_BITS_TO_BYTES(PSA_VENDOR_ECC_MAX_CURVE_BITS)];

    const size_t coordinate_len = PSA_BITS_TO_BYTES(bits);

    size_t len = 0;

    unsigned char *p = der + der_size;

    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    if (bits == 0) {

        return MBEDTLS_ERR_ASN1_INVALID_DATA;

    }

    if (raw_len != (2 * coordinate_len)) {

        return MBEDTLS_ERR_ASN1_INVALID_DATA;

    }

    if (coordinate_len > sizeof(r)) {

        return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;

    }

    /* Since raw and der buffers might overlap, dump r and s before starting

     * the conversion. */

    memcpy(r, raw, coordinate_len);

    memcpy(s, raw + coordinate_len, coordinate_len);

    /* der buffer will initially be written starting from its end so we pick s

     * first and then r. */

    ret = convert_raw_to_der_single_int(s, coordinate_len, der, p);

    if (ret < 0) {

        return ret;

    }

    p -= ret;

    len += ret;

    ret = convert_raw_to_der_single_int(r, coordinate_len, der, p);

    if (ret < 0) {

        return ret;

    }

    p -= ret;

    len += ret;

    /* Add ASN.1 header (len + tag). */

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_len(&p, der, len));

    MBEDTLS_ASN1_CHK_ADD(len, mbedtls_asn1_write_tag(&p, der,

                                                     MBEDTLS_ASN1_CONSTRUCTED |

                                                     MBEDTLS_ASN1_SEQUENCE));

    /* memmove the content of der buffer to its beginnig. */

    memmove(der, p, len);

    *der_len = len;

    return 0;

}

/**

 * \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 and it must be zeroed before

 *                          calling this function.

 * \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 coordinate_size)

{

    unsigned char *p = der;

    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;

    size_t unpadded_len, padding_len = 0;

    /* Get the length of ASN.1 element (i.e. the integer we need to parse). */

    ret = mbedtls_asn1_get_tag(&p, p + der_len, &unpadded_len,

                               MBEDTLS_ASN1_INTEGER);

    if (ret != 0) {

        return ret;

    }

    /* 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 (*p == 0x00) {

        p++;

        unpadded_len--;

        /* 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;

        }

    }

    if (unpadded_len > coordinate_size) {

        /* Parsed number is longer than the maximum expected value. */

        return MBEDTLS_ERR_ASN1_INVALID_DATA;

    }

    padding_len = coordinate_size - unpadded_len;

    /* raw buffer was already zeroed by the calling function so zero-padding

     * operation is skipped here. */

    memcpy(raw + padding_len, p, unpadded_len);

    p += unpadded_len;

    return (int) (p - der);

}

int mbedtls_ecdsa_der_to_raw(size_t bits, const unsigned char *der, size_t der_len,

                             unsigned char *raw, size_t raw_size, size_t *raw_len)

{

    unsigned char raw_tmp[PSA_VENDOR_ECDSA_SIGNATURE_MAX_SIZE];

    unsigned char *p = (unsigned char *) der;

    size_t data_len;

    size_t coordinate_size = PSA_BITS_TO_BYTES(bits);

    int ret;

    if (bits == 0) {

        return MBEDTLS_ERR_ASN1_INVALID_DATA;

    }

    /* The output raw buffer should be at least twice the size of a raw

     * coordinate in order to store r and s. */

    if (raw_size < coordinate_size * 2) {

        return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;

    }

    if (2 * coordinate_size > sizeof(raw_tmp)) {

        return MBEDTLS_ERR_ASN1_BUF_TOO_SMALL;

    }

    /* Check that the provided input DER buffer has the right header. */

    ret = mbedtls_asn1_get_tag(&p, der + der_len, &data_len,

                               MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE);

    if (ret != 0) {

        return ret;

    }

    memset(raw_tmp, 0, 2 * coordinate_size);

    /* Extract r */

    ret = convert_der_to_raw_single_int(p, data_len, raw_tmp, coordinate_size);

    if (ret < 0) {

        return ret;

    }

    p += ret;

    data_len -= ret;

    /* Extract s */

    ret = convert_der_to_raw_single_int(p, data_len, raw_tmp + coordinate_size,

                                        coordinate_size);

    if (ret < 0) {

        return ret;

    }

    p += ret;

    data_len -= ret;

    /* Check that we consumed all the input der data. */

    if ((size_t) (p - der) != der_len) {

        return MBEDTLS_ERR_ASN1_LENGTH_MISMATCH;

    }

    memcpy(raw, raw_tmp, 2 * coordinate_size);

    *raw_len = 2 * coordinate_size;

    return 0;

}

#endif /* MBEDTLS_PSA_UTIL_HAVE_ECDSA */