AES-GCM

THIS CODE IS JUST FOR UNDERSTANDING AND STUDY.

The code has been tested with GCC 4.8.4 and Valgrind-3.11.0. The block cipher is AES-128.

Usage

Encryption

void * context = gcm_init();
if ( !context ) { return OPERATION_FAIL; }

operation_result flag = gcm_setkey(context, key, 128 );

if ( OPERATION_FAIL != flag ) {
    gcm_crypt_and_tag(context,
        iv, iv_len,
        add, add_len,
        input, length,
        output,
        tag, tag_len);
}

gcm_free( context);

Decryption

void * context = gcm_init();
if ( !context ) { return OPERATION_FAIL; }

operation_result flag = gcm_setkey(context, key, 128 );

if ( OPERATION_FAIL != flag ) {
    gcm_auth_decrypt( context,
        iv, iv_len,
        add, add_len,
        tag, tag_len,
        input, length,
        output);
}

gcm_free( context);

How to test

According to The Galois/Counter Mode of Operation (GCM), 6 test cases are given is main.c. You can just change the value of TEST_CASE(from 1 to 6) for different test vectors.

Compile

make

License

Copyright (c) 2017 LuoPeng

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.