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Diffstat (limited to 'demos/cipher/aesgcm.c')
| -rw-r--r-- | demos/cipher/aesgcm.c | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/demos/cipher/aesgcm.c b/demos/cipher/aesgcm.c new file mode 100644 index 000000000000..aaf4000d574f --- /dev/null +++ b/demos/cipher/aesgcm.c @@ -0,0 +1,228 @@ +/* + * Copyright 2012-2021 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 + */ + +/* + * Simple AES GCM authenticated encryption with additional data (AEAD) + * demonstration program. + */ + +#include <stdio.h> +#include <openssl/err.h> +#include <openssl/bio.h> +#include <openssl/evp.h> +#include <openssl/core_names.h> + +/* AES-GCM test data obtained from NIST public test vectors */ + +/* AES key */ +static const unsigned char gcm_key[] = { + 0xee, 0xbc, 0x1f, 0x57, 0x48, 0x7f, 0x51, 0x92, 0x1c, 0x04, 0x65, 0x66, + 0x5f, 0x8a, 0xe6, 0xd1, 0x65, 0x8b, 0xb2, 0x6d, 0xe6, 0xf8, 0xa0, 0x69, + 0xa3, 0x52, 0x02, 0x93, 0xa5, 0x72, 0x07, 0x8f +}; + +/* Unique initialisation vector */ +static const unsigned char gcm_iv[] = { + 0x99, 0xaa, 0x3e, 0x68, 0xed, 0x81, 0x73, 0xa0, 0xee, 0xd0, 0x66, 0x84 +}; + +/* Example plaintext to encrypt */ +static const unsigned char gcm_pt[] = { + 0xf5, 0x6e, 0x87, 0x05, 0x5b, 0xc3, 0x2d, 0x0e, 0xeb, 0x31, 0xb2, 0xea, + 0xcc, 0x2b, 0xf2, 0xa5 +}; + +/* + * Example of Additional Authenticated Data (AAD), i.e. unencrypted data + * which can be authenticated using the generated Tag value. + */ +static const unsigned char gcm_aad[] = { + 0x4d, 0x23, 0xc3, 0xce, 0xc3, 0x34, 0xb4, 0x9b, 0xdb, 0x37, 0x0c, 0x43, + 0x7f, 0xec, 0x78, 0xde +}; + +/* Expected ciphertext value */ +static const unsigned char gcm_ct[] = { + 0xf7, 0x26, 0x44, 0x13, 0xa8, 0x4c, 0x0e, 0x7c, 0xd5, 0x36, 0x86, 0x7e, + 0xb9, 0xf2, 0x17, 0x36 +}; + +/* Expected AEAD Tag value */ +static const unsigned char gcm_tag[] = { + 0x67, 0xba, 0x05, 0x10, 0x26, 0x2a, 0xe4, 0x87, 0xd7, 0x37, 0xee, 0x62, + 0x98, 0xf7, 0x7e, 0x0c +}; + +/* + * A library context and property query can be used to select & filter + * algorithm implementations. If they are NULL then the default library + * context and properties are used. + */ +OSSL_LIB_CTX *libctx = NULL; +const char *propq = NULL; + +int aes_gcm_encrypt(void) +{ + int ret = 0; + EVP_CIPHER_CTX *ctx; + EVP_CIPHER *cipher = NULL; + int outlen, tmplen; + size_t gcm_ivlen = sizeof(gcm_iv); + unsigned char outbuf[1024]; + unsigned char outtag[16]; + OSSL_PARAM params[2] = { + OSSL_PARAM_END, OSSL_PARAM_END + }; + + printf("AES GCM Encrypt:\n"); + printf("Plaintext:\n"); + BIO_dump_fp(stdout, gcm_pt, sizeof(gcm_pt)); + + /* Create a context for the encrypt operation */ + if ((ctx = EVP_CIPHER_CTX_new()) == NULL) + goto err; + + /* Fetch the cipher implementation */ + if ((cipher = EVP_CIPHER_fetch(libctx, "AES-256-GCM", propq)) == NULL) + goto err; + + /* Set IV length if default 96 bits is not appropriate */ + params[0] = OSSL_PARAM_construct_size_t(OSSL_CIPHER_PARAM_AEAD_IVLEN, + &gcm_ivlen); + + /* + * Initialise an encrypt operation with the cipher/mode, key, IV and + * IV length parameter. + * For demonstration purposes the IV is being set here. In a compliant + * application the IV would be generated internally so the iv passed in + * would be NULL. + */ + if (!EVP_EncryptInit_ex2(ctx, cipher, gcm_key, gcm_iv, params)) + goto err; + + /* Zero or more calls to specify any AAD */ + if (!EVP_EncryptUpdate(ctx, NULL, &outlen, gcm_aad, sizeof(gcm_aad))) + goto err; + + /* Encrypt plaintext */ + if (!EVP_EncryptUpdate(ctx, outbuf, &outlen, gcm_pt, sizeof(gcm_pt))) + goto err; + + /* Output encrypted block */ + printf("Ciphertext:\n"); + BIO_dump_fp(stdout, outbuf, outlen); + + /* Finalise: note get no output for GCM */ + if (!EVP_EncryptFinal_ex(ctx, outbuf, &tmplen)) + goto err; + + /* Get tag */ + params[0] = OSSL_PARAM_construct_octet_string(OSSL_CIPHER_PARAM_AEAD_TAG, + outtag, 16); + + if (!EVP_CIPHER_CTX_get_params(ctx, params)) + goto err; + + /* Output tag */ + printf("Tag:\n"); + BIO_dump_fp(stdout, outtag, 16); + + ret = 1; +err: + if (!ret) + ERR_print_errors_fp(stderr); + + EVP_CIPHER_free(cipher); + EVP_CIPHER_CTX_free(ctx); + + return ret; +} + +int aes_gcm_decrypt(void) +{ + int ret = 0; + EVP_CIPHER_CTX *ctx; + EVP_CIPHER *cipher = NULL; + int outlen, rv; + size_t gcm_ivlen = sizeof(gcm_iv); + unsigned char outbuf[1024]; + OSSL_PARAM params[2] = { + OSSL_PARAM_END, OSSL_PARAM_END + }; + + printf("AES GCM Decrypt:\n"); + printf("Ciphertext:\n"); + BIO_dump_fp(stdout, gcm_ct, sizeof(gcm_ct)); + + if ((ctx = EVP_CIPHER_CTX_new()) == NULL) + goto err; + + /* Fetch the cipher implementation */ + if ((cipher = EVP_CIPHER_fetch(libctx, "AES-256-GCM", propq)) == NULL) + goto err; + + /* Set IV length if default 96 bits is not appropriate */ + params[0] = OSSL_PARAM_construct_size_t(OSSL_CIPHER_PARAM_AEAD_IVLEN, + &gcm_ivlen); + + /* + * Initialise an encrypt operation with the cipher/mode, key, IV and + * IV length parameter. + */ + if (!EVP_DecryptInit_ex2(ctx, cipher, gcm_key, gcm_iv, params)) + goto err; + + /* Zero or more calls to specify any AAD */ + if (!EVP_DecryptUpdate(ctx, NULL, &outlen, gcm_aad, sizeof(gcm_aad))) + goto err; + + /* Decrypt plaintext */ + if (!EVP_DecryptUpdate(ctx, outbuf, &outlen, gcm_ct, sizeof(gcm_ct))) + goto err; + + /* Output decrypted block */ + printf("Plaintext:\n"); + BIO_dump_fp(stdout, outbuf, outlen); + + /* Set expected tag value. */ + params[0] = OSSL_PARAM_construct_octet_string(OSSL_CIPHER_PARAM_AEAD_TAG, + (void*)gcm_tag, sizeof(gcm_tag)); + + if (!EVP_CIPHER_CTX_set_params(ctx, params)) + goto err; + + /* Finalise: note get no output for GCM */ + rv = EVP_DecryptFinal_ex(ctx, outbuf, &outlen); + /* + * Print out return value. If this is not successful authentication + * failed and plaintext is not trustworthy. + */ + printf("Tag Verify %s\n", rv > 0 ? "Successful!" : "Failed!"); + + ret = 1; +err: + if (!ret) + ERR_print_errors_fp(stderr); + + EVP_CIPHER_free(cipher); + EVP_CIPHER_CTX_free(ctx); + + return ret; +} + +int main(int argc, char **argv) +{ + if (!aes_gcm_encrypt()) + return 1; + + if (!aes_gcm_decrypt()) + return 1; + + return 0; +} |