Java中的MbedTLS AES 128加密和解密

编程问答 2022-11-08

问题描述

我正在尝试使用mbedTLS在运行FreeRTOS的微处理器上加密一些文本。我正在将AES 128 CBC与PKCS7填充一起使用。如果我尝试在文本少于16个字符时使用mbedTLS进行加密并使用Java进行解密，则可以使用。我可以用Java解密它，并且文本匹配。如果更长，则不再起作用。我在做什么错了？

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,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,&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：填充块已损坏

谢谢

//编辑：

尝试了一种更新方法，但仍然没有运气，同样的异常：

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,16);
mbedtls_cipher_reset(&ctx);
mbedtls_cipher_update(&ctx,text,strlen((char*) text),&olen); // Olen is 48
mbedtls_cipher_finish(&ctx,&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获取64字节的数据，但仍会引发相同的异常。

Topaco，请您提供使用更新和完成功能的简短示例吗？谢谢

解决方法

由于它是用注释编写的，因此仍然无法使用。这是您的代码，其中包含@Topaco在注释中建议的更改：

#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,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,&olen);
    total_len += olen;
    for (int i = 0; i < total_len; i++)
        printf("%02X",output[i]);
    mbedtls_cipher_free(&ctx);
    return 0;
}

测试

我添加了两行：

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

这给出了输出：

2FE64A72125E30B15C376FD2142D36FA778142DC4FD4A1F36EECDBCDA19BFAA0

如果我稍微修改一下Java端并使用以下命令传输消息：

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

从以下答案中获取hexStringToByteArray：https://stackoverflow.com/a/140861/2331445

我在Java端获得以下代码：

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;
}

最终将以下输出输出到调试控制台：

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

那是原始消息-这样就可以工作。

,

您的代码中还有一个问题。 在设置填充模式之前，您需要设置密码信息。否则函数 mbedtls_cipher_set_padding_mode 将返回错误

bouncycastleccryptographyjavajavambedtls