Add example program psa/hmac_md_psa

This is meant to highlight similarities and differences in the
multi-part HMAC APIs.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>

programs/.gitignore

@@ -39,6 +39,7 @@ pkey/rsa_sign_pss
 pkey/rsa_verify
 pkey/rsa_verify_pss
 psa/crypto_examples
+psa/hmac_md_psa
 psa/key_ladder_demo
 psa/psa_constant_names
 random/gen_entropy

programs/Makefile

@@ -85,6 +85,7 @@ APPS = \
 	pkey/rsa_verify \
 	pkey/rsa_verify_pss \
 	psa/crypto_examples \
+	psa/hmac_md_psa \
 	psa/key_ladder_demo \
 	psa/psa_constant_names \
 	random/gen_entropy \
@@ -261,6 +262,14 @@ pkey/rsa_encrypt$(EXEXT): pkey/rsa_encrypt.c $(DEP)
 	echo "  CC    pkey/rsa_encrypt.c"
 	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) pkey/rsa_encrypt.c    $(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
 
+psa/crypto_examples$(EXEXT): psa/crypto_examples.c $(DEP)
+	echo "  CC    psa/crypto_examples.c"
+	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) psa/crypto_examples.c    $(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
+
+psa/hmac_md_psa$(EXEXT): psa/hmac_md_psa.c $(DEP)
+	echo "  CC    psa/hmac_md_psa.c"
+	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) psa/hmac_md_psa.c    $(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
+
 psa/key_ladder_demo$(EXEXT): psa/key_ladder_demo.c $(DEP)
 	echo "  CC    psa/key_ladder_demo.c"
 	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) psa/key_ladder_demo.c    $(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
@@ -396,10 +405,6 @@ x509/req_app$(EXEXT): x509/req_app.c $(DEP)
 	echo "  CC    x509/req_app.c"
 	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) x509/req_app.c    $(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
 
-psa/crypto_examples$(EXEXT): psa/crypto_examples.c $(DEP)
-	echo "  CC    psa/crypto_examples.c"
-	$(CC) $(LOCAL_CFLAGS) $(CFLAGS) psa/crypto_examples.c    $(LOCAL_LDFLAGS) $(LDFLAGS) -o $@
-
 clean:
 ifndef WINDOWS
 	rm -f $(EXES)

programs/psa/CMakeLists.txt

@@ -1,5 +1,6 @@
 set(executables
     crypto_examples
+    hmac_md_psa
     key_ladder_demo
     psa_constant_names
 )

programs/psa/hmac_md_psa.c

@@ -0,0 +1,174 @@
+/*
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+/*
+ * This is a simple example of multi-part HMAC computation using both the old
+ * MD API and the new PSA API; its goal is to help migration to PSA Crypto.
+ *
+ * When in comes to multi-part HMAC operations, the `mbedtls_md_context`
+ * serves a dual purpose (1) hold the key, and (2) save progress information
+ * for the current operation. With PSA those roles are held by two disinct
+ * objects: (1) a psa_key_id_t to hold the key, and (2) a psa_operation_t for
+ * multi-part progress.
+ *
+ * This program illustrates this by doing the same sequence of multi-part HMAC
+ * computation with both APIs; looking at the two function md() and mac() side
+ * by side should make the differences and similarities clear.
+ */
+
+#include <stdio.h>
+
+#include "mbedtls/build_info.h"
+
+#if !defined(MBEDTLS_PSA_CRYPTO_C) || !defined(MBEDTLS_MD_C)
+int main( void )
+{
+    printf( "MBEDTLS_PSA_CRYPTO_C and/or MBEDTLS_MD_C not defined.\r\n" );
+    return( 0 );
+}
+#else /* MBEDTLS_PSA_CRYPTO_C && MBEDTLS_MD_C */
+
+#include "mbedtls/md.h"
+#include "psa/crypto.h"
+
+/*
+ * Dummy inputs for HMAC
+ */
+const unsigned char part1[] = { 0x01, 0x02 };
+const unsigned char part2[] = { 0x03, 0x04 };
+const unsigned char part3[] = { 0x05, 0x05 };
+const unsigned char part4[] = { 0x06, 0x06 };
+
+const unsigned char key_bytes[32] = { 0 };
+
+unsigned char out[32];
+
+void print_out( const char *title )
+{
+    printf( "%s:", title );
+    for( size_t i = 0; i < sizeof( out ); i++ )
+        printf( " %02x", out[i] );
+    printf( "\n" );
+}
+
+#define CHK( code )     \
+    do {                \
+        ret = code;     \
+        if( ret != 0 )  \
+            goto exit;  \
+    } while( 0 )
+
+int md(void)
+{
+    int ret;
+    mbedtls_md_context_t ctx;
+
+    mbedtls_md_init( &ctx );
+
+    /* prepare context and load key */
+    CHK( mbedtls_md_setup( &ctx, mbedtls_md_info_from_type( MBEDTLS_MD_SHA256 ), 1 ) );
+    CHK( mbedtls_md_hmac_starts( &ctx, key_bytes, sizeof( key_bytes ) ) );
+
+    /* compute HMAC(key, part 1 | part 2) */
+    CHK( mbedtls_md_hmac_update( &ctx, part1, sizeof( part1 ) ) );
+    CHK( mbedtls_md_hmac_update( &ctx, part2, sizeof( part2 ) ) );
+    CHK( mbedtls_md_hmac_finish( &ctx, out ) );
+    print_out( "12" );
+
+    /* compute HMAC(key, part 3 | part 4) */
+    CHK( mbedtls_md_hmac_reset( &ctx ) ); // prepare for new operation
+    CHK( mbedtls_md_hmac_update( &ctx, part3, sizeof( part3 ) ) );
+    CHK( mbedtls_md_hmac_update( &ctx, part4, sizeof( part4 ) ) );
+    CHK( mbedtls_md_hmac_finish( &ctx, out ) );
+    print_out( "34" );
+
+exit:
+    mbedtls_md_free( &ctx );
+
+    return( ret );
+}
+
+#undef CHK
+
+#define CHK( code )     \
+    do {                \
+        status = code;     \
+        if( status != PSA_SUCCESS )  \
+            goto exit;  \
+    } while( 0 )
+
+psa_status_t mac(void)
+{
+    psa_status_t status;
+    psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
+    psa_key_id_t key = 0;
+    psa_algorithm_t alg = PSA_ALG_HMAC(PSA_ALG_SHA_256);
+
+    /* prepare key */
+    psa_set_key_usage_flags( &attributes, PSA_KEY_USAGE_SIGN_MESSAGE );
+    psa_set_key_algorithm( &attributes, alg );
+    psa_set_key_type( &attributes, PSA_KEY_TYPE_HMAC );
+    psa_set_key_bits( &attributes, 8 * sizeof( key_bytes ) );
+
+    status = psa_import_key( &attributes, key_bytes, sizeof( key_bytes ), &key );
+    if( status != PSA_SUCCESS )
+        return( status );
+
+    /* prepare operation */
+    psa_mac_operation_t op = PSA_MAC_OPERATION_INIT;
+    size_t out_len = 0;
+
+    /* compute HMAC(key, part 1 | part 2) */
+    CHK( psa_mac_sign_setup( &op, key, alg ) );
+    CHK( psa_mac_update( &op, part1, sizeof( part1 ) ) );
+    CHK( psa_mac_update( &op, part2, sizeof( part2 ) ) );
+    CHK( psa_mac_sign_finish( &op, out, sizeof( out ), &out_len ) );
+    print_out( "12" );
+
+    /* compute HMAC(key, part 3 | part 4) */
+    CHK( psa_mac_sign_setup( &op, key, alg ) );
+    CHK( psa_mac_update( &op, part3, sizeof( part3 ) ) );
+    CHK( psa_mac_update( &op, part4, sizeof( part4 ) ) );
+    CHK( psa_mac_sign_finish( &op, out, sizeof( out ), &out_len ) );
+    print_out( "34" );
+
+exit:
+    psa_mac_abort( &op );
+
+    return( status );
+}
+
+#undef CHK
+
+int main(void)
+{
+    printf( "MD\n" );
+    int ret = md();
+    if( ret != 0 )
+        printf( "ret = %d (-0x%04x)\n", ret, -ret );
+
+    psa_status_t status = psa_crypto_init();
+    if( status != PSA_SUCCESS )
+        printf( "psa init: %d\n", status );
+
+    printf( "\nPSA\n" );
+    status = mac();
+    if( status != PSA_SUCCESS )
+        printf( "psa mac: %d\n", status );
+}
+
+#endif /* MBEDTLS_PSA_CRYPTO_C && MBEDTLS_MD_C */