mirror of https://github.com/openssl/openssl
229 lines
6.4 KiB
C
229 lines
6.4 KiB
C
/*
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* Copyright 2012-2023 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the Apache License 2.0 (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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/*
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* Simple AES GCM authenticated encryption with additional data (AEAD)
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* demonstration program.
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*/
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#include <stdio.h>
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#include <openssl/err.h>
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#include <openssl/bio.h>
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#include <openssl/evp.h>
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#include <openssl/core_names.h>
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/* AES-GCM test data obtained from NIST public test vectors */
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/* AES key */
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static const unsigned char gcm_key[] = {
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0xee, 0xbc, 0x1f, 0x57, 0x48, 0x7f, 0x51, 0x92, 0x1c, 0x04, 0x65, 0x66,
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0x5f, 0x8a, 0xe6, 0xd1, 0x65, 0x8b, 0xb2, 0x6d, 0xe6, 0xf8, 0xa0, 0x69,
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0xa3, 0x52, 0x02, 0x93, 0xa5, 0x72, 0x07, 0x8f
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};
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/* Unique initialisation vector */
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static const unsigned char gcm_iv[] = {
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0x99, 0xaa, 0x3e, 0x68, 0xed, 0x81, 0x73, 0xa0, 0xee, 0xd0, 0x66, 0x84
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};
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/* Example plaintext to encrypt */
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static const unsigned char gcm_pt[] = {
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0xf5, 0x6e, 0x87, 0x05, 0x5b, 0xc3, 0x2d, 0x0e, 0xeb, 0x31, 0xb2, 0xea,
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0xcc, 0x2b, 0xf2, 0xa5
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};
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/*
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* Example of Additional Authenticated Data (AAD), i.e. unencrypted data
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* which can be authenticated using the generated Tag value.
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*/
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static const unsigned char gcm_aad[] = {
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0x4d, 0x23, 0xc3, 0xce, 0xc3, 0x34, 0xb4, 0x9b, 0xdb, 0x37, 0x0c, 0x43,
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0x7f, 0xec, 0x78, 0xde
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};
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/* Expected ciphertext value */
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static const unsigned char gcm_ct[] = {
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0xf7, 0x26, 0x44, 0x13, 0xa8, 0x4c, 0x0e, 0x7c, 0xd5, 0x36, 0x86, 0x7e,
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0xb9, 0xf2, 0x17, 0x36
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};
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/* Expected AEAD Tag value */
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static const unsigned char gcm_tag[] = {
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0x67, 0xba, 0x05, 0x10, 0x26, 0x2a, 0xe4, 0x87, 0xd7, 0x37, 0xee, 0x62,
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0x98, 0xf7, 0x7e, 0x0c
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};
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/*
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* A library context and property query can be used to select & filter
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* algorithm implementations. If they are NULL then the default library
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* context and properties are used.
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*/
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OSSL_LIB_CTX *libctx = NULL;
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const char *propq = NULL;
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static int aes_gcm_encrypt(void)
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{
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int ret = 0;
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EVP_CIPHER_CTX *ctx;
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EVP_CIPHER *cipher = NULL;
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int outlen, tmplen;
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size_t gcm_ivlen = sizeof(gcm_iv);
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unsigned char outbuf[1024];
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unsigned char outtag[16];
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OSSL_PARAM params[2] = {
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OSSL_PARAM_END, OSSL_PARAM_END
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};
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printf("AES GCM Encrypt:\n");
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printf("Plaintext:\n");
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BIO_dump_fp(stdout, gcm_pt, sizeof(gcm_pt));
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/* Create a context for the encrypt operation */
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if ((ctx = EVP_CIPHER_CTX_new()) == NULL)
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goto err;
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/* Fetch the cipher implementation */
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if ((cipher = EVP_CIPHER_fetch(libctx, "AES-256-GCM", propq)) == NULL)
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goto err;
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/* Set IV length if default 96 bits is not appropriate */
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params[0] = OSSL_PARAM_construct_size_t(OSSL_CIPHER_PARAM_AEAD_IVLEN,
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&gcm_ivlen);
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/*
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* Initialise an encrypt operation with the cipher/mode, key, IV and
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* IV length parameter.
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* For demonstration purposes the IV is being set here. In a compliant
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* application the IV would be generated internally so the iv passed in
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* would be NULL.
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*/
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if (!EVP_EncryptInit_ex2(ctx, cipher, gcm_key, gcm_iv, params))
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goto err;
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/* Zero or more calls to specify any AAD */
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if (!EVP_EncryptUpdate(ctx, NULL, &outlen, gcm_aad, sizeof(gcm_aad)))
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goto err;
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/* Encrypt plaintext */
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if (!EVP_EncryptUpdate(ctx, outbuf, &outlen, gcm_pt, sizeof(gcm_pt)))
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goto err;
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/* Output encrypted block */
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printf("Ciphertext:\n");
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BIO_dump_fp(stdout, outbuf, outlen);
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/* Finalise: note get no output for GCM */
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if (!EVP_EncryptFinal_ex(ctx, outbuf, &tmplen))
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goto err;
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/* Get tag */
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params[0] = OSSL_PARAM_construct_octet_string(OSSL_CIPHER_PARAM_AEAD_TAG,
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outtag, 16);
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if (!EVP_CIPHER_CTX_get_params(ctx, params))
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goto err;
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/* Output tag */
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printf("Tag:\n");
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BIO_dump_fp(stdout, outtag, 16);
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ret = 1;
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err:
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if (!ret)
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ERR_print_errors_fp(stderr);
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EVP_CIPHER_free(cipher);
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EVP_CIPHER_CTX_free(ctx);
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return ret;
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}
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static int aes_gcm_decrypt(void)
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{
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int ret = 0;
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EVP_CIPHER_CTX *ctx;
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EVP_CIPHER *cipher = NULL;
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int outlen, rv;
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size_t gcm_ivlen = sizeof(gcm_iv);
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unsigned char outbuf[1024];
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OSSL_PARAM params[2] = {
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OSSL_PARAM_END, OSSL_PARAM_END
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};
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printf("AES GCM Decrypt:\n");
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printf("Ciphertext:\n");
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BIO_dump_fp(stdout, gcm_ct, sizeof(gcm_ct));
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if ((ctx = EVP_CIPHER_CTX_new()) == NULL)
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goto err;
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/* Fetch the cipher implementation */
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if ((cipher = EVP_CIPHER_fetch(libctx, "AES-256-GCM", propq)) == NULL)
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goto err;
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/* Set IV length if default 96 bits is not appropriate */
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params[0] = OSSL_PARAM_construct_size_t(OSSL_CIPHER_PARAM_AEAD_IVLEN,
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&gcm_ivlen);
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/*
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* Initialise an encrypt operation with the cipher/mode, key, IV and
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* IV length parameter.
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*/
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if (!EVP_DecryptInit_ex2(ctx, cipher, gcm_key, gcm_iv, params))
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goto err;
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/* Zero or more calls to specify any AAD */
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if (!EVP_DecryptUpdate(ctx, NULL, &outlen, gcm_aad, sizeof(gcm_aad)))
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goto err;
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/* Decrypt plaintext */
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if (!EVP_DecryptUpdate(ctx, outbuf, &outlen, gcm_ct, sizeof(gcm_ct)))
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goto err;
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/* Output decrypted block */
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printf("Plaintext:\n");
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BIO_dump_fp(stdout, outbuf, outlen);
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/* Set expected tag value. */
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params[0] = OSSL_PARAM_construct_octet_string(OSSL_CIPHER_PARAM_AEAD_TAG,
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(void*)gcm_tag, sizeof(gcm_tag));
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if (!EVP_CIPHER_CTX_set_params(ctx, params))
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goto err;
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/* Finalise: note get no output for GCM */
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rv = EVP_DecryptFinal_ex(ctx, outbuf, &outlen);
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/*
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* Print out return value. If this is not successful authentication
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* failed and plaintext is not trustworthy.
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*/
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printf("Tag Verify %s\n", rv > 0 ? "Successful!" : "Failed!");
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ret = 1;
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err:
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if (!ret)
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ERR_print_errors_fp(stderr);
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EVP_CIPHER_free(cipher);
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EVP_CIPHER_CTX_free(ctx);
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return ret;
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}
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int main(int argc, char **argv)
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{
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if (!aes_gcm_encrypt())
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return EXIT_FAILURE;
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if (!aes_gcm_decrypt())
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return EXIT_FAILURE;
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return EXIT_SUCCESS;
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}
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