Move hmac_non_psa out of psa/ directory

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/programs/hash/hmac_demo.c b/programs/hash/hmac_demo.c
new file mode 100644
index 0000000..cae6224
--- /dev/null
+++ b/programs/hash/hmac_demo.c
@@ -0,0 +1,144 @@
+/**
+ * MD API multi-part HMAC demonstration.
+ *
+ * This programs computes the HMAC of two messages using the multi-part API.
+ *
+ * This is a companion to psa/hmac_demo.c, doing the same operations with the
+ * legacy MD API. The goal is that comparing the two programs will help people
+ * migrating to the PSA Crypto API.
+ *
+ * When it 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 and its companion psa/hmac_demo.c illustrate this by doing the
+ * same sequence of multi-part HMAC computation with both APIs; looking at the
+ * two side by side should make the differences and similarities clear.
+ */
+
+/*
+ *  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.
+ */
+
+/* First include Mbed TLS headers to get the Mbed TLS configuration and
+ * platform definitions that we'll use in this program. Also include
+ * standard C headers for functions we'll use here. */
+#include "mbedtls/build_info.h"
+
+#include "mbedtls/md.h"
+
+#include "mbedtls/platform_util.h" // for mbedtls_platform_zeroize
+
+#include <stdlib.h>
+#include <stdio.h>
+
+/* If the build options we need are not enabled, compile a placeholder. */
+#if !defined(MBEDTLS_MD_C)
+int main( void )
+{
+    printf( "MBEDTLS_MD_C not defined\r\n" );
+    return( 0 );
+}
+#else
+
+/* The real program starts here. */
+
+/* Dummy inputs for HMAC */
+const unsigned char msg1_part1[] = { 0x01, 0x02 };
+const unsigned char msg1_part2[] = { 0x03, 0x04 };
+const unsigned char msg2_part1[] = { 0x05, 0x05 };
+const unsigned char msg2_part2[] = { 0x06, 0x06 };
+
+/* Dummy key material - never do this in production!
+ * This example program uses SHA-256, so a 32-byte key makes sense. */
+const unsigned char key_bytes[32] = { 0 };
+
+/* Print the contents of a buffer in hex */
+void print_buf( const char *title, unsigned char *buf, size_t len )
+{
+    printf( "%s:", title );
+    for( size_t i = 0; i < len; i++ )
+        printf( " %02x", buf[i] );
+    printf( "\n" );
+}
+
+/* Run an Mbed TLS function and bail out if it fails. */
+#define CHK( expr )                                             \
+    do                                                          \
+    {                                                           \
+        ret = ( expr );                                         \
+        if( ret != 0 )                                          \
+        {                                                       \
+            printf( "Error %d at line %d: %s\n",                \
+                    ret,                                        \
+                    __LINE__,                                   \
+                    #expr );                                    \
+            goto exit;                                          \
+        }                                                       \
+    } while( 0 )
+
+/*
+ * This function demonstrates computation of the HMAC of two messages using
+ * the multipart API.
+ */
+int hmac_demo(void)
+{
+    int ret;
+    const mbedtls_md_type_t alg = MBEDTLS_MD_SHA256;
+    unsigned char out[MBEDTLS_MD_MAX_SIZE]; // safe but not optimal
+
+    mbedtls_md_context_t ctx;
+
+    mbedtls_md_init( &ctx );
+
+    /* prepare context and load key */
+    // the last argument to setup is 1 to enable HMAC (not just hashing)
+    CHK( mbedtls_md_setup( &ctx, mbedtls_md_info_from_type( alg ), 1 ) );
+    CHK( mbedtls_md_hmac_starts( &ctx, key_bytes, sizeof( key_bytes ) ) );
+
+    /* compute HMAC(key, msg1_part1 | msg1_part2) */
+    CHK( mbedtls_md_hmac_update( &ctx, msg1_part1, sizeof( msg1_part1 ) ) );
+    CHK( mbedtls_md_hmac_update( &ctx, msg1_part2, sizeof( msg1_part2 ) ) );
+    CHK( mbedtls_md_hmac_finish( &ctx, out ) );
+    print_buf( "msg1", out, sizeof( out ) );
+
+    /* compute HMAC(key, msg2_part1 | msg2_part2) */
+    CHK( mbedtls_md_hmac_reset( &ctx ) ); // prepare for new operation
+    CHK( mbedtls_md_hmac_update( &ctx, msg2_part1, sizeof( msg2_part1 ) ) );
+    CHK( mbedtls_md_hmac_update( &ctx, msg2_part2, sizeof( msg2_part2 ) ) );
+    CHK( mbedtls_md_hmac_finish( &ctx, out ) );
+    print_buf( "msg2", out, sizeof( out ) );
+
+exit:
+    mbedtls_md_free( &ctx );
+    mbedtls_platform_zeroize( out, sizeof( out ) );
+
+    return( ret );
+}
+
+int main(void)
+{
+    int ret;
+
+    CHK( hmac_demo() );
+
+exit:
+    return( ret == 0 ? EXIT_SUCCESS : EXIT_FAILURE );
+}
+
+#endif