使用自定义密钥的 BouncyCastle J2ME RSA

Question

我想在我的 Blackberry 应用程序中使用 BouncyCastle J2ME/RIM Crypto。

我遇到的问题是我想从 C#.NET 程序生成用于加密的公钥，该程序将密钥发送到 BlackBerry。

是否可以使用原始字符串加密消息？另外，我是否需要知道其他常见变量，例如模数等？抱歉，但我对密码算法完全陌生。

我需要 BouncyCastle 还是可以使用 RIM Crypto 完成以上操作？

谢谢， 康纳

Answer 1

我是使用 bouncycastle 完成的，但与 RIM Crypto 类似。 根据例子。如您所见，键是字符串...：

    public CypherDecypherExample()
   {        
    String plain    ="a plain string";
    String cipher   = null;
    String decipher = null;
    byte [] byte_cipher = null;
    byte [] byte_plain  = null;

    // key           |-- 128 bit -->|-- 256 bit --->|
    String key    = "aaaaaaaaaaaaaaaacccccccccccccccc";
    String iv     = "bbbbbbbbbbbbbbbb";

System.out.println("bouncycastle.plain: " + plain);

    try {
        byte_cipher = encrypt(plain.getBytes(), key.getBytes(), iv.getBytes());
        cipher = new String(byte_cipher);
        System.out.println("bouncycastle.cipher: " + cipher);

    } catch (Exception e) {
        e.printStackTrace();
    }


    try {
        byte_plain = decrypt(byte_cipher, key.getBytes(), iv.getBytes());
        decipher = new String(byte_plain);
        System.out.println("bouncycastle.decipher: " + decipher);
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

} 

private static byte[] cipherData(PaddedBufferedBlockCipher cipher, byte[] data)
throws Exception
{
    String plain = new String(data);
    System.out.println("bouncycastle.cipherData: " + plain);

    int minSize = cipher.getOutputSize(data.length);
    byte[] outBuf = new byte[minSize];
    int length1 = cipher.processBytes(data, 0, data.length, outBuf, 0);
    int length2 = cipher.doFinal(outBuf, length1);
    int actualLength = length1 + length2;
    byte[] result = new byte[actualLength];
    System.arraycopy(outBuf, 0, result, 0, result.length);

System.out.println("bouncycastle.cipherData returning");

    return result;
}

private static byte[] decrypt(byte[] cipher, byte[] key, byte[] iv) throws Exception
{
    PaddedBufferedBlockCipher aes = new PaddedBufferedBlockCipher((BlockCipher) new CBCBlockCipher(
            new AESEngine()));
    CipherParameters ivAndKey = new ParametersWithIV(new KeyParameter(key), iv);
    aes.init(false, ivAndKey);
    return cipherData(aes, cipher);
}

private static byte[] encrypt(byte[] plain, byte[] key, byte[] iv) throws Exception
{       
    PaddedBufferedBlockCipher aes = new PaddedBufferedBlockCipher(new CBCBlockCipher(
            new AESEngine()));

    CipherParameters ivAndKey = new ParametersWithIV(new KeyParameter(key), iv);

    aes.init(true, ivAndKey);

    return cipherData(aes, plain);
}

Answer 2

一个 RSA 公钥由两部分组成，而不是像我想象的那样。

有Exponent 和Modulus。这些都是数字，但我将它们作为 Base64 字符串从 .NET 客户端传递给 Blackberry，并在 RIM Crypto 函数使用它们时将它们解码为字节数组，因为它们将字节数组作为参数。

byte[] exponent = Base64InputStream.decode("exponent base64 string");
byte[] modulus = Base64InputStream.decode("modulus base64 string");

NoCopyByteArrayOutputStream cipherUserData = new NoCopyByteArrayOutputStream();             
RSACryptoSystem cryptoSystem = new RSACryptoSystem(1024);

// Create Public key using your variables from before
RSAPublicKey publicKey = new RSAPublicKey( cryptoSystem, exponent, modulus);

// Encryption engine objects
RSAEncryptorEngine eEngine = new RSAEncryptorEngine(publicKey);
PKCS1FormatterEngine fEngine = new PKCS1FormatterEngine(eEngine);
BlockEncryptor cryptoStream = new BlockEncryptor(fEngine, cipherUserData);  


// Read the user data and encrypt while doing so. Remember, cryptoStream writes its data to
// cipherUserData so this is where the encrypted version of userData will end up.
cryptoStream.write( userData, 0, userData.length );

cryptoStream.close();
cipherUserData.close();

String encryptedUserData = new String(cipherUserData.toByteArray());

伙计们，这几乎就是所有内容了，这很简单，但我花了很长时间才从 API 文档中得到它 :)

重要提示 RSA 仅限于加密目的，因为您只能加密

我在上面写的东西花了好几天的时间修修补补和阅读。我希望它可以帮助某人更快地实现他们的目标。 :)