Add an EVP demo for HMAC

Fixes openssl#14109

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18752)

(cherry picked from commit e269d8af79de7b0dcc1b72687eed340cc3822a9e)

2 files changed, 169 insertions, 2 deletions

diff --git a/demos/mac/Makefile b/demos/mac/Makefile
index 86fb323291..500efd4127 100644
--- a/demos/mac/Makefile
+++ b/demos/mac/Makefile
@@ -14,10 +14,11 @@ LDFLAGS = $(OPENSSL_LIBS_LOCATION) -lssl -lcrypto
 all: gmac poly1305
 
 gmac: gmac.o
+hmac-sha512: hmac-sha512.o
 poly1305: poly1305.o
 
-gmac poly1305:
+gmac hmac-sha512 poly1305:
 	$(CC) $(CFLAGS) -o $@ $< $(LDFLAGS)
 
 clean:
-	$(RM) gmac poly1305 *.o
+	$(RM) gmac hmac-sha512 poly1305 *.o
diff --git a/demos/mac/hmac-sha512.c b/demos/mac/hmac-sha512.c
new file mode 100644
index 0000000000..c258b90ee3
--- /dev/null
+++ b/demos/mac/hmac-sha512.c
@@ -0,0 +1,166 @@
+/*-
+ * Copyright 2022 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+/*
+ * Example of using EVP_MAC_ methods to calculate
+ * a HMAC of static buffers
+ */
+
+#include <string.h>
+#include <stdio.h>
+#include <openssl/crypto.h>
+#include <openssl/core_names.h>
+#include <openssl/err.h>
+#include <openssl/evp.h>
+#include <openssl/hmac.h>
+#include <openssl/params.h>
+
+/*
+ * Hard coding the key into an application is very bad.
+ * It is done here solely for educational purposes.
+ */
+static unsigned char key[] = {
+    0x25, 0xfd, 0x12, 0x99, 0xdf, 0xad, 0x1a, 0x03,
+    0x0a, 0x81, 0x3c, 0x2d, 0xcc, 0x05, 0xd1, 0x5c,
+    0x17, 0x7a, 0x36, 0x73, 0x17, 0xef, 0x41, 0x75,
+    0x71, 0x18, 0xe0, 0x1a, 0xda, 0x99, 0xc3, 0x61,
+    0x38, 0xb5, 0xb1, 0xe0, 0x82, 0x2c, 0x70, 0xa4,
+    0xc0, 0x8e, 0x5e, 0xf9, 0x93, 0x9f, 0xcf, 0xf7,
+    0x32, 0x4d, 0x0c, 0xbd, 0x31, 0x12, 0x0f, 0x9a,
+    0x15, 0xee, 0x82, 0xdb, 0x8d, 0x29, 0x54, 0x14,
+};
+
+static const unsigned char data[] =
+    "To be, or not to be, that is the question,\n"
+    "Whether tis nobler in the minde to suffer\n"
+    "The ſlings and arrowes of outragious fortune,\n"
+    "Or to take Armes again in a sea of troubles,\n"
+    "And by opposing, end them, to die to sleep;\n"
+    "No more, and by a sleep, to say we end\n"
+    "The heart-ache, and the thousand natural shocks\n"
+    "That flesh is heir to? tis a consumation\n"
+    "Devoutly to be wished. To die to sleep,\n"
+    "To sleepe, perchance to dreame, Aye, there's the rub,\n"
+    "For in that sleep of death what dreams may come\n"
+    "When we haue shuffled off this mortal coil\n"
+    "Must give us pause. There's the respect\n"
+    "That makes calamity of so long life:\n"
+    "For who would bear the Ships and Scorns of time,\n"
+    "The oppressor's wrong, the proud man's Contumely,\n"
+    "The pangs of dispised love, the Law's delay,\n"
+;
+
+/* The known value of the HMAC/SHA3-512 MAC of the above soliloqy */
+static const unsigned char expected_output[] = {
+    0x3b, 0x77, 0x5f, 0xf1, 0x4f, 0x9e, 0xb9, 0x23,
+    0x8f, 0xdc, 0xa0, 0x68, 0x15, 0x7b, 0x8a, 0xf1,
+    0x96, 0x23, 0xaa, 0x3c, 0x1f, 0xe9, 0xdc, 0x89,
+    0x11, 0x7d, 0x58, 0x07, 0xe7, 0x96, 0x17, 0xe3,
+    0x44, 0x8b, 0x03, 0x37, 0x91, 0xc0, 0x6e, 0x06,
+    0x7c, 0x54, 0xe4, 0xa4, 0xcc, 0xd5, 0x16, 0xbb,
+    0x5e, 0x4d, 0x64, 0x7d, 0x88, 0x23, 0xc9, 0xb7,
+    0x25, 0xda, 0xbe, 0x4b, 0xe4, 0xd5, 0x34, 0x30,
+};
+
+/*
+ * A property query used for selecting the MAC implementation.
+ */
+static const char *propq = NULL;
+
+int main(void)
+{
+    int rv = EXIT_FAILURE;
+    OSSL_LIB_CTX *library_context = NULL;
+    EVP_MAC *mac = NULL;
+    EVP_MAC_CTX *mctx = NULL;
+    EVP_MD_CTX *digest_context = NULL;
+    unsigned char *out = NULL;
+    size_t out_len = 0;
+    OSSL_PARAM params[4], *p = params;
+    char digest_name[] = "SHA3-512";
+
+    library_context = OSSL_LIB_CTX_new();
+    if (library_context == NULL) {
+        fprintf(stderr, "OSSL_LIB_CTX_new() returned NULL\n");
+        goto end;
+    }
+
+    /* Fetch the HMAC implementation */
+    mac = EVP_MAC_fetch(library_context, "HMAC", propq);
+    if (mac == NULL) {
+        fprintf(stderr, "EVP_MAC_fetch() returned NULL\n");
+        goto end;
+    }
+
+    /* Create a context for the HMAC operation */
+    mctx = EVP_MAC_CTX_new(mac);
+    if (mctx == NULL) {
+        fprintf(stderr, "EVP_MAC_CTX_new() returned NULL\n");
+        goto end;
+    }
+
+    /* The underlying digest to be used */
+    *p++ = OSSL_PARAM_construct_utf8_string(OSSL_MAC_PARAM_DIGEST, digest_name,
+                                            sizeof(digest_name));
+    *p = OSSL_PARAM_construct_end();
+
+    /* Initialise the HMAC operation */
+    if (!EVP_MAC_init(mctx, key, sizeof(key), params)) {
+        fprintf(stderr, "EVP_MAC_init() failed\n");
+        goto end;
+    }
+
+    /* Make one or more calls to process the data to be authenticated */
+    if (!EVP_MAC_update(mctx, data, sizeof(data))) {
+        fprintf(stderr, "EVP_MAC_update() failed\n");
+        goto end;
+    }
+
+    /* Make a call to the final with a NULL buffer to get the length of the MAC */
+    if (!EVP_MAC_final(mctx, NULL, &out_len, 0)) {
+        fprintf(stderr, "EVP_MAC_final() failed\n");
+        goto end;
+    }
+    out = OPENSSL_malloc(out_len);
+    if (out == NULL) {
+        fprintf(stderr, "malloc failed\n");
+        goto end;
+    }
+    /* Make one call to the final to get the MAC */
+    if (!EVP_MAC_final(mctx, out, &out_len, out_len)) {
+        fprintf(stderr, "EVP_MAC_final() failed\n");
+        goto end;
+    }
+
+    printf("Generated MAC:\n");
+    BIO_dump_indent_fp(stdout, out, out_len, 2);
+    putchar('\n');
+
+    if (out_len != sizeof(expected_output)) {
+        fprintf(stderr, "Generated MAC has an unexpected length\n");
+        goto end;
+    }
+
+    if (CRYPTO_memcmp(expected_output, out, sizeof(expected_output)) != 0) {
+        fprintf(stderr, "Generated MAC does not match expected value\n");
+        goto end;
+    }
+
+    rv = EXIT_SUCCESS;
+end:
+    if (rv != EXIT_SUCCESS)
+        ERR_print_errors_fp(stderr);
+    /* OpenSSL free functions will ignore NULL arguments */
+    OPENSSL_free(out);
+    EVP_MD_CTX_free(digest_context);
+    EVP_MAC_CTX_free(mctx);
+    EVP_MAC_free(mac);
+    OSSL_LIB_CTX_free(library_context);
+    return rv;
+}