openssl3.2 - 官方demo学习 - cipher - aeskeywrap.c

openssl3.2 - 官方demo学习 - cipher - aeskeywrap.c

概述

AES-256-WRAP
经过实验 EVP_CIPHER_CTX_set_flags(ctx, EVP_CIPHER_CTX_FLAG_WRAP_ALLOW); 不是必须的.

笔记

/*! \file aeskeywrap.c */

/*
 * Copyright 2022-2023 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 wrap encryption demonstration program.
  */

#include 
#include 
#include 
#include 
#include 
#include 

#include "my_openSSL_lib.h"

  /* aes key */
static const unsigned char wrap_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 wrap_iv[] = {
	0x99, 0xaa, 0x3e, 0x68, 0xed, 0x81, 0x73, 0xa0, 0xee, 0xd0, 0x66, 0x84,
	0x99, 0xaa, 0x3e, 0x68,
};

/* Example plaintext to encrypt */
static const unsigned char wrap_pt[] = {
	0xad, 0x4f, 0xc9, 0xfc, 0x77, 0x69, 0xc9, 0xea, 0xfc, 0xdf, 0x00, 0xac,
	0x34, 0xec, 0x40, 0xbc, 0x28, 0x3f, 0xa4, 0x5e, 0xd8, 0x99, 0xe4, 0x5d,
	0x5e, 0x7a, 0xc4, 0xe6, 0xca, 0x7b, 0xa5, 0xb7,
};

/* Expected ciphertext value */
static const unsigned char wrap_ct[] = {
	0x97, 0x99, 0x55, 0xca, 0xf6, 0x3e, 0x95, 0x54, 0x39, 0xd6, 0xaf, 0x63, 0xff, 0x2c, 0xe3, 0x96,
	0xf7, 0x0d, 0x2c, 0x9c, 0xc7, 0x43, 0xc0, 0xb6, 0x31, 0x43, 0xb9, 0x20, 0xac, 0x6b, 0xd3, 0x67,
	0xad, 0x01, 0xaf, 0xa7, 0x32, 0x74, 0x26, 0x92,
};

/*
 * 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_wrap_encrypt(void)
{
	int ret = 0;
	EVP_CIPHER_CTX* ctx;
	EVP_CIPHER* cipher = NULL;
	int outlen, tmplen;
	unsigned char outbuf[1024];

	printf("aes wrap Encrypt:\n");
	printf("Plaintext:\n");
	BIO_dump_fp(stdout, wrap_pt, sizeof(wrap_pt));

	/* Create a context for the encrypt operation */
	if ((ctx = EVP_CIPHER_CTX_new()) == NULL)
		goto err;

	/*!
	* 调用 EVP_CIPHER_fetch()之前, 如果要调用 EVP_CIPHER_CTX_set_flags(param), 那么param该填什么值呢?
	 什么算法才需要在EVP_CIPHER_fetch()之前, 来调用 EVP_CIPHER_CTX_set_flags()?
	 如果不调用EVP_CIPHER_CTX_set_flags(), 会不正常么?
	*/

	EVP_CIPHER_CTX_set_flags(ctx, EVP_CIPHER_CTX_FLAG_WRAP_ALLOW);
	/*!
	* 实验过了, 在加密时, 不调用EVP_CIPHER_CTX_set_flags(), 加密也是ok的
	* 解密也是ok的, 好像调用EVP_CIPHER_CTX_set_flags()没啥效果.
	* 去看看EVP_CIPHER_CTX_set_flags()干了啥.
	* void EVP_CIPHER_CTX_set_flags(EVP_CIPHER_CTX *ctx, int flags)
{
	int oldflags = ctx->flags; // 0

	ctx->flags |= flags; // 1
	if (((oldflags ^ ctx->flags) & EVP_CIPH_FLAG_LENGTH_BITS) != 0)
		evp_cipher_ctx_enable_use_bits(ctx, 1); // 没执行到这里, 应该是, 如果没执行到这里, 那么EVP_CIPHER_CTX_set_flags()就没效果
}
	
	EVP_CIPHER_CTX_set_flags(ctx, EVP_CIPHER_CTX_FLAG_WRAP_ALLOW);后, 只是 ctx->flags 由0变成了1
	*/

	/* Fetch the cipher implementation */
	if ((cipher = EVP_CIPHER_fetch(libctx, "AES-256-WRAP", propq)) == NULL)
		goto err;

	/*
	 * Initialise an encrypt operation with the cipher/mode, key and IV.
	 * We are not setting any custom params so let params be just NULL.
	 */
	if (!EVP_EncryptInit_ex2(ctx, cipher, wrap_key, wrap_iv, /* params */ NULL))
		goto err;

	/* Encrypt plaintext */
	if (!EVP_EncryptUpdate(ctx, outbuf, &outlen, wrap_pt, sizeof(wrap_pt)))
		goto err;

	/* Finalise: there can be some additional output from padding */
	if (!EVP_EncryptFinal_ex(ctx, outbuf + outlen, &tmplen))
		goto err;
	outlen += tmplen;

	/* Output encrypted block */
	printf("Ciphertext (outlen:%d):\n", outlen);
	BIO_dump_fp(stdout, outbuf, outlen);

	if (sizeof(wrap_ct) == outlen && !CRYPTO_memcmp(outbuf, wrap_ct, outlen))
		printf("Final ciphertext matches expected ciphertext\n");
	else
		printf("Final ciphertext differs from expected ciphertext\n");

	ret = 1;
err:
	if (!ret)
		ERR_print_errors_fp(stderr);

	EVP_CIPHER_free(cipher);
	EVP_CIPHER_CTX_free(ctx);

	return ret;
}

int aes_wrap_decrypt(void)
{
	int ret = 0;
	EVP_CIPHER_CTX* ctx;
	EVP_CIPHER* cipher = NULL;
	int outlen, tmplen;
	unsigned char outbuf[1024];

	printf("aes wrap Decrypt:\n");
	printf("Ciphertext:\n");
	BIO_dump_fp(stdout, wrap_ct, sizeof(wrap_ct));

	if ((ctx = EVP_CIPHER_CTX_new()) == NULL)
		goto err;

	EVP_CIPHER_CTX_set_flags(ctx, EVP_CIPHER_CTX_FLAG_WRAP_ALLOW);

	/* Fetch the cipher implementation */
	if ((cipher = EVP_CIPHER_fetch(libctx, "aes-256-wrap", propq)) == NULL)
		goto err;

	/*
	 * Initialise an encrypt operation with the cipher/mode, key and IV.
	 * We are not setting any custom params so let params be just NULL.
	 */
	if (!EVP_DecryptInit_ex2(ctx, cipher, wrap_key, wrap_iv, /* params */ NULL))
		goto err;

	/* Decrypt plaintext */
	if (!EVP_DecryptUpdate(ctx, outbuf, &outlen, wrap_ct, sizeof(wrap_ct)))
		goto err;

	/* Finalise: there can be some additional output from padding */
	if (!EVP_DecryptFinal_ex(ctx, outbuf + outlen, &tmplen))
		goto err;
	outlen += tmplen;

	/* Output decrypted block */
	printf("Plaintext (outlen:%d):\n", outlen);
	BIO_dump_fp(stdout, outbuf, outlen);

	if (sizeof(wrap_pt) == outlen && !CRYPTO_memcmp(outbuf, wrap_pt, outlen))
		printf("Final plaintext matches original plaintext\n");
	else
		printf("Final plaintext differs from original plaintext\n");

	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_wrap_encrypt())
		return EXIT_FAILURE;

	if (!aes_wrap_decrypt())
		return EXIT_FAILURE;

	return EXIT_SUCCESS;
}

END