/*
* Compute and write signature
*/
int mbedtls_ecdsa_write_signature( mbedtls_ecdsa_context *ctx, mbedtls_md_type_t md_alg,
const unsigned char *hash, size_t hlen,
unsigned char *sig, size_t *slen,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng )
{
int ret;
mbedtls_mpi r, s;
mbedtls_mpi_init( &r );
mbedtls_mpi_init( &s );
#if defined(MBEDTLS_ECDSA_DETERMINISTIC)
(void) f_rng;
(void) p_rng;
MBEDTLS_MPI_CHK( mbedtls_ecdsa_sign_det( &ctx->grp, &r, &s, &ctx->d,
hash, hlen, md_alg ) );
#else
(void) md_alg;
MBEDTLS_MPI_CHK( mbedtls_ecdsa_sign( &ctx->grp, &r, &s, &ctx->d,
hash, hlen, f_rng, p_rng ) );
#endif
MBEDTLS_MPI_CHK( ecdsa_signature_to_asn1( &r, &s, sig, slen ) );
cleanup:
mbedtls_mpi_free( &r );
mbedtls_mpi_free( &s );
return( ret );
}
bool ECDSA_Sign(COSE * pSigner, int index, const cn_cbor * pKey, int cbitDigest, const byte * rgbToSign, size_t cbToSign, cose_errback * perr)
{
#if defined(MBEDTLS_ECDSA_DETERMINISTIC)
byte rgbDigest[MBEDTLS_MD_MAX_SIZE];
uint8_t * pbSig = NULL;
cn_cbor_errback cbor_error;
int cbR;
mbedtls_md_type_t mdType;
const mbedtls_md_info_t *pmdInfo;
mbedtls_ecp_keypair keypair;
mbedtls_mpi r;
mbedtls_mpi s;
#ifdef USE_CBOR_CONTEXT
cn_cbor_context * context = &pSigner->m_allocContext;
#endif
cn_cbor * p = NULL;
bool result = false;
mbedtls_ecp_keypair_init(&keypair);
mbedtls_mpi_init(&r);
mbedtls_mpi_init(&s);
if(!ECKey_From(pKey, &keypair, perr)) goto errorReturn;
CHECK_CONDITION(keypair.d.n != 0, COSE_ERR_INVALID_PARAMETER);
switch(cbitDigest)
{
case 256:
mdType = MBEDTLS_MD_SHA256;
break;
case 384:
mdType = MBEDTLS_MD_SHA384;
break;
case 512:
mdType = MBEDTLS_MD_SHA512;
break;
default:
FAIL_CONDITION(COSE_ERR_INVALID_PARAMETER);
}
pmdInfo = mbedtls_md_info_from_type(mdType);
CHECK_CONDITION(pmdInfo != NULL, COSE_ERR_INVALID_PARAMETER);
CHECK_CONDITION(mbedtls_md(pmdInfo, rgbToSign, cbToSign, rgbDigest) == 0, COSE_ERR_INVALID_PARAMETER);
CHECK_CONDITION(mbedtls_ecdsa_sign_det(&keypair.grp, &r, &s, &keypair.d, rgbDigest, mbedtls_md_get_size(pmdInfo), mdType) == 0, COSE_ERR_CRYPTO_FAIL);
cbR = (keypair.grp.nbits + 7) / 8;
pbSig = COSE_CALLOC(cbR, 2, context);
CHECK_CONDITION(pbSig != NULL, COSE_ERR_OUT_OF_MEMORY);
CHECK_CONDITION(mbedtls_mpi_write_binary(&r, pbSig, cbR) == 0, COSE_ERR_INTERNAL);
CHECK_CONDITION(mbedtls_mpi_write_binary(&s, pbSig + cbR, cbR) == 0, COSE_ERR_INTERNAL);
p = cn_cbor_data_create(pbSig, cbR*2, CBOR_CONTEXT_PARAM_COMMA &cbor_error);
CHECK_CONDITION_CBOR(p != NULL, cbor_error);
CHECK_CONDITION(_COSE_array_replace(pSigner, p, index, CBOR_CONTEXT_PARAM_COMMA NULL), COSE_ERR_CBOR);
p = NULL;
pbSig = NULL;
result = true;
errorReturn:
cn_cbor_free(p CBOR_CONTEXT_PARAM);
COSE_FREE(pbSig, context);
mbedtls_mpi_free(&r);
mbedtls_mpi_free(&s);
mbedtls_ecp_keypair_free(&keypair);
return result;
#else
return false;
#endif
}
