Signatures example

Change-Id: If4c3edfc890769cd2df8c639fa9a95ca344aa494

diff --git a/examples/sign.c b/examples/sign.c
new file mode 100644 (file)
index 0000000..ca2282f
--- /dev/null
+++ b/examples/sign.c
@@ -0,0 +1,238 @@
+/*
+ *  Copyright (c) 2016 Samsung Electronics Co., Ltd All Rights Reserved
+ *
+ *  Contact:
+ *
+ *  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
+ */
+
+/**
+ * @file sign.c
+ * @brief
+ */
+
+#include <stdio.h>
+#include <crypto/crypto.h>
+#include <crypto/sign.h>
+#include <crypto/key.h>
+#include "misc.h"
+
+size_t IDX = 0;
+size_t MAX_IDX = 2345;
+const size_t SIZE = 666;
+
+void reset()
+{
+       IDX = 0;
+}
+
+size_t read_data(char* buffer, size_t size)
+{
+       size_t i = 0;
+
+       for(; i<size && IDX < MAX_IDX; i++,IDX++)
+               buffer[i] = IDX%0xff;
+
+       return i;
+}
+
+int sign(crypto_ctx_h ctx, char** signature, size_t* signature_len)
+{
+       char buffer[SIZE];
+
+       reset();
+       for(;;) {
+               size_t read = read_data(buffer, SIZE);
+               if(read == 0)
+                       break;
+
+               if(crypto_sign_update(ctx, buffer, read))
+                       return -1;
+       }
+
+       // TODO: is it a size in bytes or length in characters?
+       *signature_len = crypto_get_digest_length(ctx);
+       *signature = (char*)crypto_alloc(*signature_len);
+
+       // TODO: crypto_get_digest_length() returns int but crypto_sign_final accepts size_t. Use common type.
+       if(crypto_sign_final(ctx, *signature, signature_len))
+               return -1;
+
+       dump_hex(*signature, *signature_len, "Message signature: ");
+       return 0;
+}
+
+int verify(crypto_ctx_h ctx, const char* signature, size_t signature_len)
+{
+       char buffer[SIZE];
+
+       reset();
+       for(;;) {
+               size_t read = read_data(buffer, SIZE);
+               if(read == 0)
+                       break;
+
+               if(crypto_verify_update(ctx, buffer, read))
+                       return -1;
+       }
+
+       // TODO: use int or size_t for output sizes
+       if(crypto_verify_final(ctx, signature, (size_t)signature_len))
+               return -1;
+
+       printf("Verification succeeded\n");
+       return 0;
+}
+
+// Signature creation and verification using advanced API
+void sign_verify_rsa(void)
+{
+       char* signature = NULL;
+       size_t signature_len;
+
+       crypto_ctx_h ctx = NULL;
+       crypto_key_h prv = NULL, pub = NULL;
+       crypto_padding_e padding = CRYPTO_PADDING_PKCS1;
+
+
+       // GENERATE
+
+       if(crypto_key_gen_pair(&prv, &pub, CRYPTO_KEY_4096BIT, CRYPTO_KEY_TYPE_PAIR_RSA))
+               return;
+
+
+       // SIGN
+
+       if(crypto_sign_init(&ctx, CRYPTO_DIGEST_SHA512, prv))
+               goto finish;
+
+       // TODO: crypto_ctx_set_param should take void* not char*
+       if(crypto_ctx_set_param(ctx, CRYPTO_PARAM_PADDING, (char*)(&padding), sizeof(padding)))
+               goto finish;
+
+       if(sign(ctx, &signature, &signature_len))
+               goto finish;
+
+       // TODO: is this necessary or will next ctx init handle it?
+       crypto_ctx_free(ctx);
+       ctx = NULL;
+
+
+       // VERIFY
+
+       if(crypto_verify_init(&ctx, CRYPTO_DIGEST_SHA512, pub))
+               goto finish;
+
+       if(crypto_ctx_set_param(ctx, CRYPTO_PARAM_PADDING, (char*)(&padding), sizeof(padding)))
+               goto finish;
+
+       if(verify(ctx, signature, signature_len))
+               goto finish;
+
+finish:
+       crypto_free(signature);
+       crypto_key_free(prv);
+       crypto_key_free(pub);
+       crypto_ctx_free(ctx);
+}
+
+void sign_verify_hmac(void)
+{
+       char* signature = NULL;
+       size_t signature_len;
+
+       crypto_ctx_h ctx = NULL;
+       crypto_key_h key = NULL;
+
+
+       // GENERATE
+
+       if(crypto_key_gen(&key, CRYPTO_KEY_256BIT, CRYPTO_KEY_TYPE_SYMMETRIC))
+               return;
+
+       // SIGN
+
+       if(crypto_sign_init(&ctx, CRYPTO_DIGEST_SHA512, key))
+               goto finish;
+
+       if(sign(ctx, &signature, &signature_len))
+               goto finish;
+
+
+       // VERIFY
+
+       if(crypto_verify_init(&ctx, CRYPTO_DIGEST_SHA512, key))
+               goto finish;
+
+       if(verify(ctx, signature, signature_len))
+               goto finish;
+
+finish:
+       crypto_free(signature);
+       crypto_key_free(key);
+       crypto_ctx_free(ctx);
+}
+
+void sign_verify_cmac(void)
+{
+       char* signature = NULL;
+       size_t signature_len;
+
+       crypto_ctx_h ctx = NULL;
+       crypto_key_h key = NULL;
+
+
+       // GENERATE
+
+       if(crypto_key_gen(&key, CRYPTO_KEY_256BIT, CRYPTO_KEY_TYPE_SYMMETRIC))
+               return;
+
+       // SIGN
+       // TODO: CMAC must extract the key length to select the proper evp (EVP_aes_XXX_cbc()) it should be documented
+       if(crypto_sign_init(&ctx, CRYPTO_DIGEST_CMAC, key))
+               goto finish;
+
+       if(sign(ctx, &signature, &signature_len))
+               goto finish;
+
+
+       // VERIFY
+
+       if(crypto_verify_init(&ctx, CRYPTO_DIGEST_CMAC, key))
+               goto finish;
+
+       if(verify(ctx, signature, signature_len))
+               goto finish;
+
+finish:
+       crypto_free(signature);
+       crypto_key_free(key);
+       crypto_ctx_free(ctx);
+}
+
+
+int main()
+{
+       int ret = 0;
+       if ((ret = crypto_init()))
+               return ret;
+
+       // TODO simple?
+
+       sign_verify_rsa();
+       sign_verify_hmac();
+       sign_verify_cmac();
+
+       crypto_exit(); // TODO: what about handing of return value from exit??
+       return ret;
+}