Implement pk_sign() for opaque ECDSA keys
diff --git a/library/pk_wrap.c b/library/pk_wrap.c
index d01694c..47f39d7 100644
--- a/library/pk_wrap.c
+++ b/library/pk_wrap.c
@@ -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 @@
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 */
diff --git a/tests/suites/test_suite_pk.data b/tests/suites/test_suite_pk.data
index 417670d..011b1f5 100644
--- a/tests/suites/test_suite_pk.data
+++ b/tests/suites/test_suite_pk.data
@@ -188,3 +188,6 @@
ECDSA restartable sign/verify: ECKEY, max_ops=250
depends_on:MBEDTLS_ECP_DP_SECP256R1_ENABLED:MBEDTLS_SHA256_C
pk_sign_verify_restart:MBEDTLS_PK_ECKEY:MBEDTLS_ECP_DP_SECP256R1:"C9AFA9D845BA75166B5C215767B1D6934E50C3DB36E89B127B8A622B120F6721":"60FED4BA255A9D31C961EB74C6356D68C049B8923B61FA6CE669622E60F29FB6":"7903FE1008B8BC99A41AE9E95628BC64F2F1B20C2D7E9F5177A3C294D4462299":MBEDTLS_MD_SHA256:"test":"3045022100f1abb023518351cd71d881567b1ea663ed3efcf6c5132b354f28d3b0b7d383670220019f4113742a2b14bd25926b49c649155f267e60d3814b4c0cc84250e46f0083":250:2:64
+
+PSA wrapped sign
+pk_psa_sign:
diff --git a/tests/suites/test_suite_pk.function b/tests/suites/test_suite_pk.function
index 1edc04e..563fa44 100644
--- a/tests/suites/test_suite_pk.function
+++ b/tests/suites/test_suite_pk.function
@@ -72,6 +72,7 @@
/*
* Generate a key in a free key slot and return this key slot,
* or PK_PSA_INVALID_SLOT if no slot was available.
+ * The key uses NIST P-256 and is usable for signing with SHA-256.
*/
psa_key_slot_t pk_psa_genkey( void )
{
@@ -80,10 +81,20 @@
const int curve = PSA_ECC_CURVE_SECP256R1;
const psa_key_type_t type = PSA_KEY_TYPE_ECC_KEYPAIR(curve);
const size_t bits = 256;
+ psa_key_policy_t policy;
+ /* find a free key slot */
if( PSA_SUCCESS != mbedtls_psa_get_free_key_slot( &key ) )
return( PK_PSA_INVALID_SLOT );
+ /* set up policy on key slot */
+ psa_key_policy_init( &policy );
+ psa_key_policy_set_usage( &policy, PSA_KEY_USAGE_SIGN,
+ PSA_ALG_ECDSA(PSA_ALG_SHA_256) );
+ if( PSA_SUCCESS != psa_set_key_policy( key, &policy ) )
+ return( PK_PSA_INVALID_SLOT );
+
+ /* generate key */
if( PSA_SUCCESS != psa_generate_key( key, type, bits, NULL, 0 ) )
return( PK_PSA_INVALID_SLOT );
@@ -760,3 +771,53 @@
mbedtls_pk_free( &rsa ); mbedtls_pk_free( &alt );
}
/* END_CASE */
+
+/* BEGIN_CASE depends_on:MBEDTLS_SHA256_C:MBEDTLS_USE_PSA_CRYPTO:MBEDTLS_ECDSA_C:MBEDTLS_ECP_DP_SECP256R1_ENABLED */
+void pk_psa_sign( )
+{
+ mbedtls_pk_context pk;
+ psa_key_slot_t key;
+ unsigned char hash[50], sig[100], pkey[100];
+ size_t sig_len, klen = 0;
+
+ /*
+ * This tests making signatures with a wrapped PSA key:
+ * - generate a fresh PSA key
+ * - wrap it in a PK context and make a signature this way
+ * - extract the public key
+ * - parse it to a PK context and verify the signature this way
+ */
+
+ mbedtls_pk_init( &pk );
+
+ memset( hash, 0x2a, sizeof hash );
+ memset( sig, 0, sizeof sig );
+ memset( pkey, 0, sizeof pkey );
+
+ key = pk_psa_genkey();
+ TEST_ASSERT( key != 0 );
+
+ TEST_ASSERT( mbedtls_pk_setup_psa( &pk, key ) == 0 );
+
+ TEST_ASSERT( mbedtls_pk_sign( &pk, MBEDTLS_MD_SHA256,
+ hash, sizeof hash, sig, &sig_len,
+ NULL, NULL ) == 0 );
+
+ mbedtls_pk_free( &pk );
+
+ TEST_ASSERT( PSA_SUCCESS == psa_export_public_key(
+ key, pkey, sizeof( pkey ), &klen ) );
+ TEST_ASSERT( PSA_SUCCESS == psa_destroy_key( key ) );
+
+ mbedtls_pk_init( &pk );
+
+ TEST_ASSERT( mbedtls_pk_parse_public_key( &pk, pkey, klen ) == 0 );
+
+
+ TEST_ASSERT( mbedtls_pk_verify( &pk, MBEDTLS_MD_SHA256,
+ hash, sizeof hash, sig, sig_len ) == 0 );
+
+exit:
+ mbedtls_pk_free( &pk );
+}
+/* END_CASE */