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Implement pk_sign() for opaque ECDSA keys

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This commit is contained in:
Manuel Pégourié-Gonnard 2018-10-31 16:22:49 +01:00
parent d97390e97d
commit 3686771dfa
3 changed files with 176 additions and 1 deletions
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113
library/pk_wrap.c
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@ -41,10 +41,18 @@
#include "mbedtls/ecdsa.h"
#endif
#if defined(MBEDTLS_USE_PSA_CRYPTO)
#include "mbedtls/asn1write.h"
#endif
#if defined(MBEDTLS_PK_RSA_ALT_SUPPORT)
#include "mbedtls/platform_util.h"
#endif
#if defined(MBEDTLS_USE_PSA_CRYPTO)
#include "mbedtls/psa_util.h"
#endif
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
@ -753,13 +761,116 @@ static int pk_psa_can_do( mbedtls_pk_type_t type )
type == MBEDTLS_PK_ECDSA );
}
/* Like mbedtls_asn1_write_mpi, but from a buffer */
static int asn1_write_mpibuf( unsigned char **p, unsigned char *start,
const unsigned char *src, size_t slen )
{
int ret;
size_t len = 0;
if( (size_t)( *p - start ) < slen )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
len = slen;
*p -= len;
memcpy( *p, src, len );
if( **p & 0x80 )
{
if( *p - start < 1 )
return( MBEDTLS_ERR_ASN1_BUF_TOO_SMALL );
*--(*p) = 0x00;
len += 1;
}
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( p, start, len ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( p, start, MBEDTLS_ASN1_INTEGER ) );
return( (int) len );
}
/* Transcode signature from PSA format to ASN.1 sequence.
* See ecdsa_signature_to_asn1 in ecdsa.c.
*
* [in] sig: the signature in PSA format
* [in/out] sig_len: signature length pre- and post-transcoding
* [out] dst: the signature in ASN.1 format
*/
static int pk_ecdsa_sig_asn1_from_psa( const unsigned char *sig, size_t *sig_len,
unsigned char *dst )
{
int ret;
unsigned char buf[MBEDTLS_ECDSA_MAX_LEN];
unsigned char *p = buf + sizeof( buf );
size_t len = 0;
const size_t mpi_len = *sig_len / 2;
MBEDTLS_ASN1_CHK_ADD( len, asn1_write_mpibuf( &p, buf, sig + mpi_len, mpi_len ) );
MBEDTLS_ASN1_CHK_ADD( len, asn1_write_mpibuf( &p, buf, sig, mpi_len ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_len( &p, buf, len ) );
MBEDTLS_ASN1_CHK_ADD( len, mbedtls_asn1_write_tag( &p, buf,
MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE ) );
memcpy( dst, p, len );
*sig_len = len;
return( 0 );
}
static int pk_psa_sign_wrap( void *ctx, mbedtls_md_type_t md_alg,
const unsigned char *hash, size_t hash_len,
unsigned char *sig, size_t *sig_len,
int (*f_rng)(void *, unsigned char *, size_t), void *p_rng )
{
const psa_key_slot_t *key = (const psa_key_slot_t *) ctx;
psa_status_t status;
psa_algorithm_t alg = PSA_ALG_ECDSA( mbedtls_psa_translate_md( md_alg ) );
/* PSA needs a buffer of know size */
unsigned char buf[2 * MBEDTLS_ECP_MAX_BYTES];
const size_t buf_len = sizeof( buf );
/* PSA has its own RNG */
(void) f_rng;
(void) p_rng;
status = psa_asymmetric_sign( *key, alg, hash, hash_len,
buf, buf_len, sig_len );
/* translate errors to best approximation */
switch( status )
{
case PSA_SUCCESS:
break; /* don't return now */
case PSA_ERROR_NOT_SUPPORTED:
return( MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE );
case PSA_ERROR_INSUFFICIENT_MEMORY:
return( MBEDTLS_ERR_PK_ALLOC_FAILED );
case PSA_ERROR_COMMUNICATION_FAILURE:
case PSA_ERROR_HARDWARE_FAILURE:
case PSA_ERROR_TAMPERING_DETECTED:
return( MBEDTLS_ERR_PK_HW_ACCEL_FAILED );
case PSA_ERROR_INSUFFICIENT_ENTROPY:
return( MBEDTLS_ERR_ECP_RANDOM_FAILED );
case PSA_ERROR_BAD_STATE:
return( MBEDTLS_ERR_PK_BAD_INPUT_DATA );
default: /* should never happen */
return( MBEDTLS_ERR_PK_HW_ACCEL_FAILED );
}
pk_ecdsa_sig_asn1_from_psa( buf, sig_len, sig );
return( 0 );
}
const mbedtls_pk_info_t mbedtls_pk_opaque_psa_info = {
MBEDTLS_PK_OPAQUE_PSA,
"Opaque (PSA)",
pk_psa_get_bitlen,
pk_psa_can_do,
NULL, /* verify - will be done later */
NULL, /* coming soon: sign */
pk_psa_sign_wrap,
#if defined(MBEDTLS_ECDSA_C) && defined(MBEDTLS_ECP_RESTARTABLE)
NULL, /* restartable verify - not relevant */
NULL, /* restartable sign - not relevant */