bool ECDSA_Verify(COSE * pSigner, int index, const cn_cbor * pKey, int cbitDigest, const byte * rgbToSign, size_t cbToSign, cose_errback * perr)
{
mbedtls_ecp_keypair keypair;
mbedtls_mpi r;
mbedtls_mpi s;
mbedtls_md_type_t mdType;
const mbedtls_md_info_t *pmdInfo;
byte rgbDigest[MBEDTLS_MD_MAX_SIZE];
cn_cbor * pSig;
bool result = false;
mbedtls_ecp_keypair_init(&keypair);
mbedtls_mpi_init(&r);
mbedtls_mpi_init(&s);
if(!ECKey_From(pKey, &keypair, perr)) goto errorReturn;
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);
pSig = _COSE_arrayget_int(pSigner, index);
CHECK_CONDITION((pSig != NULL) && (pSig->type == CN_CBOR_BYTES), COSE_ERR_INVALID_PARAMETER);
CHECK_CONDITION(mbedtls_mpi_read_binary( &r, pSig->v.bytes, pSig->length / 2 ) == 0, COSE_ERR_OUT_OF_MEMORY);
CHECK_CONDITION(mbedtls_mpi_read_binary( &s, pSig->v.bytes + pSig->length / 2, pSig->length / 2 ) == 0, COSE_ERR_OUT_OF_MEMORY);
CHECK_CONDITION(mbedtls_ecdsa_verify(&keypair.grp, rgbDigest, mbedtls_md_get_size(pmdInfo), &keypair.Q, &r, &s) == 0, COSE_ERR_CRYPTO_FAIL);
result = true;
errorReturn:
mbedtls_mpi_free(&r);
mbedtls_mpi_free(&s);
mbedtls_ecp_keypair_free(&keypair);
return result;
}
/*
* Parse a SEC1 encoded private EC key
*/
static int pk_parse_key_sec1_der( mbedtls_ecp_keypair *eck,
const unsigned char *key,
size_t keylen )
{
int ret;
int version, pubkey_done;
size_t len;
mbedtls_asn1_buf params;
unsigned char *p = (unsigned char *) key;
unsigned char *end = p + keylen;
unsigned char *end2;
/*
* RFC 5915, or SEC1 Appendix C.4
*
* ECPrivateKey ::= SEQUENCE {
* version INTEGER { ecPrivkeyVer1(1) } (ecPrivkeyVer1),
* privateKey OCTET STRING,
* parameters [0] ECParameters {{ NamedCurve }} OPTIONAL,
* publicKey [1] BIT STRING OPTIONAL
* }
*/
if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) ) != 0 )
{
return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
}
end = p + len;
if( ( ret = mbedtls_asn1_get_int( &p, end, &version ) ) != 0 )
return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
if( version != 1 )
return( MBEDTLS_ERR_PK_KEY_INVALID_VERSION );
if( ( ret = mbedtls_asn1_get_tag( &p, end, &len, MBEDTLS_ASN1_OCTET_STRING ) ) != 0 )
return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
if( ( ret = mbedtls_mpi_read_binary( &eck->d, p, len ) ) != 0 )
{
mbedtls_ecp_keypair_free( eck );
return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
}
p += len;
pubkey_done = 0;
if( p != end )
{
/*
* Is 'parameters' present?
*/
if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
MBEDTLS_ASN1_CONTEXT_SPECIFIC | MBEDTLS_ASN1_CONSTRUCTED | 0 ) ) == 0 )
{
if( ( ret = pk_get_ecparams( &p, p + len, ¶ms) ) != 0 ||
( ret = pk_use_ecparams( ¶ms, &eck->grp ) ) != 0 )
{
mbedtls_ecp_keypair_free( eck );
return( ret );
}
}
else if( ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
{
mbedtls_ecp_keypair_free( eck );
return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
}
/*
* Is 'publickey' present? If not, or if we can't read it (eg because it
* is compressed), create it from the private key.
*/
if( ( ret = mbedtls_asn1_get_tag( &p, end, &len,
MBEDTLS_ASN1_CONTEXT_SPECIFIC | MBEDTLS_ASN1_CONSTRUCTED | 1 ) ) == 0 )
{
end2 = p + len;
if( ( ret = mbedtls_asn1_get_bitstring_null( &p, end2, &len ) ) != 0 )
return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
if( p + len != end2 )
return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT +
MBEDTLS_ERR_ASN1_LENGTH_MISMATCH );
if( ( ret = pk_get_ecpubkey( &p, end2, eck ) ) == 0 )
pubkey_done = 1;
else
{
/*
* The only acceptable failure mode of pk_get_ecpubkey() above
* is if the point format is not recognized.
*/
if( ret != MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE )
return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT );
}
}
else if( ret != MBEDTLS_ERR_ASN1_UNEXPECTED_TAG )
{
mbedtls_ecp_keypair_free( eck );
return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
}
}
if( ! pubkey_done &&
( ret = mbedtls_ecp_mul( &eck->grp, &eck->Q, &eck->d, &eck->grp.G,
NULL, NULL ) ) != 0 )
{
mbedtls_ecp_keypair_free( eck );
return( MBEDTLS_ERR_PK_KEY_INVALID_FORMAT + ret );
}
if( ( ret = mbedtls_ecp_check_privkey( &eck->grp, &eck->d ) ) != 0 )
{
mbedtls_ecp_keypair_free( eck );
return( ret );
}
return( 0 );
}
static void eckey_free_wrap( void *ctx )
{
mbedtls_ecp_keypair_free( (mbedtls_ecp_keypair *) ctx );
mbedtls_free( ctx );
}
/*
* Free context
*/
void mbedtls_ecdsa_free( mbedtls_ecdsa_context *ctx )
{
mbedtls_ecp_keypair_free( ctx );
}
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
}
