c-MbedTLS AES 128在Java中进行加密和解密

Question

我正在尝试用mbedTLS对运行FreeRTOS的微处理器上的一些文本进行加密。我使用的是带有PKCS7填充的AES 128 CBC。如果我尝试在mbedTLS中加密，并在文本短于16个字符时在Java中解密，它就可以工作了。我可以用Java解密它，并且文本匹配。如果它更长，那么它就不再工作。我做错了什么？

mbedTLS代码：

unsigned char key[17] = "asdfghjklqwertzu";
unsigned char iv[17] = "qwertzuiopasdfgh";
unsigned char output[1024];
size_t olen;
size_t total_len = 0;
mbedtls_cipher_context_t ctx;
mbedtls_cipher_init(&ctx);
mbedtls_cipher_set_padding_mode(&ctx, MBEDTLS_PADDING_PKCS7);
mbedtls_cipher_setup(&ctx,
mbedtls_cipher_info_from_values(MBEDTLS_CIPHER_ID_AES, 128,
MBEDTLS_MODE_CBC));
mbedtls_cipher_setkey(&ctx, key, 128, MBEDTLS_ENCRYPT);
mbedtls_cipher_set_iv(&ctx, iv, 16);
mbedtls_cipher_reset(&ctx);
char aa[] = "hello world! test long padd";
for( int offset = 0; offset < strlen(aa); offset += mbedtls_cipher_get_block_size( &ctx ) ) {
int ilen = ( (unsigned int) strlen(aa) - offset > mbedtls_cipher_get_block_size( &ctx ) ) ?
mbedtls_cipher_get_block_size( &ctx ) : (unsigned int) ( strlen(aa) - offset );
char sub[100];
strncpy ( sub, aa+offset, ilen );
unsigned char* sub2 = reinterpret_cast<unsigned char *>(sub);
mbedtls_cipher_update(&ctx, sub2, ilen, output, &olen);
total_len += olen;
}
// After the loop
mbedtls_cipher_finish(&ctx, output, &olen);
total_len += olen;
mbedtls_cipher_free(&ctx);

Java代码：

try {
IvParameterSpec ivParameterSpec = new IvParameterSpec(iv.getBytes());
SecretKeySpec skey = new SecretKeySpec(encryptionKey.getBytes(), "AES");
Cipher cipherDecrypt = Cipher.getInstance("AES/CBC/PKCS7Padding");
cipherDecrypt.init(Cipher.DECRYPT_MODE, skey, ivParameterSpec);
return Optional.ofNullable(ByteString.copyFrom(cipherDecrypt.doFinal(message.toByteArray())));
} catch (BadPaddingException | IllegalBlockSizeException | InvalidAlgorithmParameterException | InvalidKeyException | NoSuchAlgorithmException | NoSuchPaddingException e) {
log.error("Error during message decryption: ", e);
}

Java抛出javax.crypto.BadPaddingException：pad块损坏

感谢

//编辑：

尝试了一种更新方法，但仍然没有成功，同样的例外：

unsigned char key[17] = "asdfghjklqwertzu";
unsigned char iv[17] = "qwertzuiopasdfgh";
//unsigned char buffer[1024];
unsigned char output[1024];
size_t olen;
unsigned char text[] = "abc abc abc abc abc abc abc abc abc abc abc abc abc abc abc";
mbedtls_cipher_context_t ctx;
mbedtls_cipher_init(&ctx);
mbedtls_cipher_set_padding_mode(&ctx, MBEDTLS_PADDING_PKCS7);
mbedtls_cipher_setup(&ctx,
mbedtls_cipher_info_from_values(MBEDTLS_CIPHER_ID_AES, 128,
MBEDTLS_MODE_CBC));
mbedtls_cipher_setkey(&ctx, key, 128, MBEDTLS_ENCRYPT);
mbedtls_cipher_set_iv(&ctx, iv, 16);
mbedtls_cipher_reset(&ctx);
mbedtls_cipher_update(&ctx, text, strlen((char*) text), output, &olen); // Olen is 48
mbedtls_cipher_finish(&ctx, output, &olen); // Olen is 16
mbedtls_cipher_free(&ctx);
// 48 + 16 = 64 which is according to https://www.devglan.com/online-tools/aes-encryption-decryption correct

Java获得64字节的数据，但仍然抛出相同的异常。

Topaco，你能提供更新和完成功能的使用的简短例子吗？谢谢

Answer 1

由于它是在注释中编写的，所以它仍然不起作用。以下是您的代码和@Topaco在评论中建议的更改：

#include <stdio.h>
#include <string.h>
#include <mbedtls/cipher.h>
int main() {
unsigned char key[17] = "asdfghjklqwertzu";
unsigned char iv[17] = "qwertzuiopasdfgh";
unsigned char output[1024];
size_t olen;
size_t total_len = 0;
mbedtls_cipher_context_t ctx;
mbedtls_cipher_init(&ctx);
mbedtls_cipher_set_padding_mode(&ctx, MBEDTLS_PADDING_PKCS7);
mbedtls_cipher_setup(&ctx,
mbedtls_cipher_info_from_values(MBEDTLS_CIPHER_ID_AES, 128,
MBEDTLS_MODE_CBC));
mbedtls_cipher_setkey(&ctx, key, 128, MBEDTLS_ENCRYPT);
mbedtls_cipher_set_iv(&ctx, iv, 16);
mbedtls_cipher_reset(&ctx);
char aa[] = "hello world! test long padd";
for (int offset = 0; offset < strlen(aa); offset += mbedtls_cipher_get_block_size(&ctx)) {
int ilen = ((unsigned int) strlen(aa) - offset > mbedtls_cipher_get_block_size(&ctx)) ?
mbedtls_cipher_get_block_size(&ctx) : (unsigned int) (strlen(aa) - offset);
char sub[100];
strncpy (sub, aa + offset, ilen);
unsigned char *sub2 = (unsigned char *) (sub);
mbedtls_cipher_update(&ctx, sub2, ilen, output + total_len, &olen);
total_len += olen;
}
mbedtls_cipher_finish(&ctx, output + total_len, &olen);
total_len += olen;
for (int i = 0; i < total_len; i++)
printf("%02X", output[i]);
mbedtls_cipher_free(&ctx);
return 0;
}

测试

我增加了两行：

for (int i = 0; i < total_len; i++)
printf("%02X", output[i]);

这给出了输出：

2FE64A72125E30B15C376FD2142D36FA778142DC4FD4A1F36EECDBCDA19BFAA0

如果我修改Java端一点，并用传输消息

byte[] message = hexStringToByteArray("2FE64A72125E30B15C376FD2142D36FA778142DC4FD4A1F36EECDBCDA19BFAA0");

其中hexStringToByteArray取自此答案：https://stackoverflow.com/a/140861/2331445

我在Java方面得到了以下代码：

public Optional<ByteString> test() {
String encryptionKey = "asdfghjklqwertzu";
String iv = "qwertzuiopasdfgh";
byte[] message = hexStringToByteArray("2FE64A72125E30B15C376FD2142D36FA778142DC4FD4A1F36EECDBCDA19BFAA0");
Security.addProvider(new BouncyCastleProvider());
try {
IvParameterSpec ivParameterSpec = new IvParameterSpec(iv.getBytes());
SecretKeySpec skey = new SecretKeySpec(encryptionKey.getBytes(), "AES");
Cipher cipherDecrypt = Cipher.getInstance("AES/CBC/PKCS7Padding");
cipherDecrypt.init(Cipher.DECRYPT_MODE, skey, ivParameterSpec);
return Optional.ofNullable(ByteString.copyFrom(cipherDecrypt.doFinal(message)));
} catch (BadPaddingException | IllegalBlockSizeException | InvalidAlgorithmParameterException | InvalidKeyException | NoSuchAlgorithmException | NoSuchPaddingException e) {
System.out.println("Error during message decryption: " + e);
}
return null;
}

它最终在调试控制台上给出以下输出：

Optional[<ByteString@1e127982 size=27 contents="hello world! test long padd">]

这是最初的信息——所以它是这样工作的。

Answer 2

您的代码中仍然存在一个问题。在设置填充模式之前，您需要设置密码信息。否则功能mbedtls_cipher_set_padding_mode将返回错误