1 files changed, 134 insertions, 0 deletions
diff --git a/demos/digest/EVP_MD_stdin.c b/demos/digest/EVP_MD_stdin.c
new file mode 100644
index 000000000000..71a3d325a364
--- /dev/null
+++ b/demos/digest/EVP_MD_stdin.c
@@ -0,0 +1,134 @@
+/*-
+ * Copyright 2019-2021 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_MD_fetch and EVP_Digest* methods to calculate
+ * a digest of static buffers
+ * You can find SHA3 test vectors from NIST here:
+ * https://csrc.nist.gov/CSRC/media/Projects/Cryptographic-Algorithm-Validation-Program/documents/sha3/sha-3bytetestvectors.zip
+ * For example, contains these lines:
+    Len = 80
+    Msg = 1ca984dcc913344370cf
+    MD = 6915ea0eeffb99b9b246a0e34daf3947852684c3d618260119a22835659e4f23d4eb66a15d0affb8e93771578f5e8f25b7a5f2a55f511fb8b96325ba2cd14816
+ * use xxd convert the hex message string to binary input for EVP_MD_stdin:
+ * echo "1ca984dcc913344370cf" | xxd -r -p | ./EVP_MD_stdin
+ * and then verify the output matches MD above.
+ */
+
+#include <string.h>
+#include <stdio.h>
+#include <openssl/err.h>
+#include <openssl/evp.h>
+
+/*-
+ * This demonstration will show how to digest data using
+ * a BIO created to read from stdin
+ */
+
+int demonstrate_digest(BIO *input)
+{
+    OSSL_LIB_CTX *library_context = NULL;
+    int result = 0;
+    const char * option_properties = NULL;
+    EVP_MD *message_digest = NULL;
+    EVP_MD_CTX *digest_context = NULL;
+    unsigned int digest_length;
+    unsigned char *digest_value = NULL;
+    unsigned char buffer[512];
+    int ii;
+
+    library_context = OSSL_LIB_CTX_new();
+    if (library_context == NULL) {
+        fprintf(stderr, "OSSL_LIB_CTX_new() returned NULL\n");
+        goto cleanup;
+    }
+
+    /*
+     * Fetch a message digest by name
+     * The algorithm name is case insensitive. 
+     * See providers(7) for details about algorithm fetching
+     */
+    message_digest = EVP_MD_fetch(library_context,
+                                  "SHA3-512", option_properties);
+    if (message_digest == NULL) {
+        fprintf(stderr, "EVP_MD_fetch could not find SHA3-512.");
+        ERR_print_errors_fp(stderr);
+        OSSL_LIB_CTX_free(library_context);
+        return 0;
+    }
+    /* Determine the length of the fetched digest type */
+    digest_length = EVP_MD_get_size(message_digest);
+    if (digest_length <= 0) {
+        fprintf(stderr, "EVP_MD_get_size returned invalid size.\n");
+        goto cleanup;
+    }
+
+    digest_value = OPENSSL_malloc(digest_length);
+    if (digest_value == NULL) {
+        fprintf(stderr, "No memory.\n");
+        goto cleanup;
+    }
+    /*
+     * Make a message digest context to hold temporary state
+     * during digest creation
+     */
+    digest_context = EVP_MD_CTX_new();
+    if (digest_context == NULL) {
+        fprintf(stderr, "EVP_MD_CTX_new failed.\n");
+        ERR_print_errors_fp(stderr);
+        goto cleanup;
+    }
+    /*
+     * Initialize the message digest context to use the fetched 
+     * digest provider
+     */
+    if (EVP_DigestInit(digest_context, message_digest) != 1) {
+        fprintf(stderr, "EVP_DigestInit failed.\n");
+        ERR_print_errors_fp(stderr);
+        goto cleanup;
+    }
+    while ((ii = BIO_read(input, buffer, sizeof(buffer))) > 0) {
+        if (EVP_DigestUpdate(digest_context, buffer, ii) != 1) {
+            fprintf(stderr, "EVP_DigestUpdate() failed.\n");
+            goto cleanup;
+        }
+    }
+    if (EVP_DigestFinal(digest_context, digest_value, &digest_length) != 1) {
+        fprintf(stderr, "EVP_DigestFinal() failed.\n");
+        goto cleanup;
+    }
+    result = 1;
+    for (ii=0; ii<digest_length; ii++) {
+        fprintf(stdout, "%02x", digest_value[ii]);
+    }
+    fprintf(stdout, "\n");
+
+cleanup:
+    if (result != 1)
+        ERR_print_errors_fp(stderr);
+    /* OpenSSL free functions will ignore NULL arguments */
+    EVP_MD_CTX_free(digest_context);
+    OPENSSL_free(digest_value);
+    EVP_MD_free(message_digest);
+
+    OSSL_LIB_CTX_free(library_context);
+    return result;
+}
+
+int main(void)
+{
+    int result = 1;
+    BIO *input = BIO_new_fd( fileno(stdin), 1 );
+
+    if (input != NULL) {
+        result = demonstrate_digest(input);
+        BIO_free(input);
+    }
+    return result;
+}