[英]AES CCM Encryption and Decryption in Libgcrypt
I have a problem encrypting/decrypting a simple 16 byte message in Libgcrypt while using CCM mode of operation and AES algorithm. 在使用CCM操作模式和AES算法时,我在Libgcrypt中加密/解密一个简单的16字节消息时遇到问题。 In the documentation of Libgcrypt I cannot find which parameters to set for CCM (should I set IV or counter?). 在Libgcrypt的文档中,我无法找到为CCM设置的参数(我应该设置IV还是计数器?)。
I am stuck with the following code: 我坚持使用以下代码:
gcry_error_t err;
gcry_cipher_hd_t hd;
char * key = "1234567890123456";
char * plainText = "VNiJkPzAWPFm1234";
size_t messageSize = strlen(plainText);
char * cipherText = malloc(messageSize);
char * recoveredText = malloc(messageSize);
err = gcry_cipher_open(
&hd,
GCRY_CIPHER_AES128,
GCRY_CIPHER_MODE_CCM,
0);
err = gcry_cipher_setkey(hd, key, 16);
/* What to do here? */
err = gcry_cipher_encrypt(
hd,
cipherText,
messageSize,
plainText,
messageSize);
err = gcry_cipher_decrypt(
hd,
recoveredText,
messageSize,
cipherText,
messageSize);
How do I perform simple encryption/decryption using AES128 and CCM in Libgcrypt? 如何在Libgcrypt中使用AES128和CCM执行简单的加密/解密?
Example 例
The example is without additional non-encrypted data, therefore param[1] of gcry_cipher_ctl setting the GCRYCTL_SET_CCM_LENGTHS is 0. But it could be easily adjusted if required. 该示例没有附加的非加密数据,因此设置GCRYCTL_SET_CCM_LENGTHS的gcry_cipher_ctl的参数[1]为0.但是如果需要,可以很容易地调整它。
The functionality is divided into three parts: 功能分为三个部分:
If you run it, it will output the following text to the console: 如果您运行它,它将输出以下文本到控制台:
decrypted result: 'VNiJkPzAWPFm1234'
Code 码
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <gcrypt.h>
void error(const char *what, gcry_error_t err) {
fprintf(stderr, "%s failed: %s\n", what, gcry_strerror(err));
exit(1);
}
typedef struct {
const void *key;
const void *nonce;
size_t messageSize;
int authTagLength;
} Config;
void prepare(Config config, gcry_cipher_hd_t *hd) {
gcry_error_t err = gcry_cipher_open(hd, GCRY_CIPHER_AES128, GCRY_CIPHER_MODE_CCM, 0);
if (err) { error("gcry_cipher_open", err); }
err = gcry_cipher_setkey(*hd, config.key, strlen(config.key));
if (err) { error("gcry_cipher_setkey", err); }
err = gcry_cipher_setiv(*hd, config.nonce, strlen(config.nonce));
if (err) { error("gcry_cipher_setiv", err); }
uint64_t params[3];
params[0] = config.messageSize;
params[1] = 0;
params[2] = config.authTagLength;
err = gcry_cipher_ctl(*hd, GCRYCTL_SET_CCM_LENGTHS, params, sizeof(params));
if (err) { error("gcry_cipher_ctl", err); }
}
void *encrypt(Config config, const void *plainText, void **tag) {
gcry_cipher_hd_t hdEncrypt;
prepare(config, &hdEncrypt);
void *cipherText = malloc(config.messageSize);
gcry_error_t err = gcry_cipher_encrypt(hdEncrypt, cipherText, config.messageSize, plainText, config.messageSize);
if (err) { error("gcry_cipher_encrypt", err); }
*tag = malloc(config.authTagLength);
err = gcry_cipher_gettag(hdEncrypt, *tag, config.authTagLength);
if (err) { error("gcry_cipher_encrypt", err); }
gcry_cipher_close(hdEncrypt);
return cipherText;
}
void *decrypt(Config config, void *cipherText, void *tag) {
gcry_cipher_hd_t hdDecrypt;
prepare(config, &hdDecrypt);
void *recoveredText = malloc(config.messageSize);
gcry_error_t err = gcry_cipher_decrypt(hdDecrypt, recoveredText, config.messageSize, cipherText, config.messageSize);
if (err) { error("gcry_cipher_decrypt", err); }
err = gcry_cipher_checktag(hdDecrypt, tag, config.authTagLength);
if (gpg_err_code (err) == GPG_ERR_CHECKSUM) {
error("Authentication", err);
}
gcry_cipher_close(hdDecrypt);
return recoveredText;
}
int main() {
const char *plainText = "VNiJkPzAWPFm1234";
Config config;
config.key = "1234567890123456";
config.nonce = "0123456789012";
config.messageSize = strlen(plainText) + 1;
config.authTagLength = 10;
void *tag;
void *cipherText = encrypt(config, plainText, &tag);
char *recoveredText = decrypt(config, cipherText, tag);
printf("decrypted result: '%s'\n", recoveredText);
free(tag);
free(cipherText);
free(recoveredText);
return 0;
}
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