java - 如何使用 BouncyCaSTLe 轻量级 API 使用 PBE AES 加密/解密文件？

Question

我正在尝试使用 AES 通过 PBE 加密/解密文件。我正在使用 Bouncy Casle 库(轻量级 API)，因为我需要忽略 key 长度的限制。我找到了函数并更改了其中的一些代码。

public void decryptLW(InputStream in, OutputStream out, String password, byte[] salt, final int iterationCount) throws Exception {

    PKCS12ParametersGenerator pGen = new PKCS12ParametersGenerator(new SHA256Digest());
    char[] passwordChars = password.toCharArray();
    final byte[] pkcs12PasswordBytes = PBEParametersGenerator.PKCS12PasswordToBytes(passwordChars);
    pGen.init(pkcs12PasswordBytes, salt, iterationCount);
    CBCBlockCipher aesCBC = new CBCBlockCipher(new AESEngine());
    ParametersWithIV aesCBCParams = (ParametersWithIV) pGen.generateDerivedParameters(256, 128);
    aesCBC.init(false, aesCBCParams);
    PaddedBufferedBlockCipher aesCipher = new PaddedBufferedBlockCipher(aesCBC, new PKCS7Padding());

    try {

        // Read in the decrypted bytes and write the cleartext to out
        int numRead = 0;
        while ((numRead = in.read(buf)) >= 0) {

            byte[] plainTemp = new byte[aesCipher.getOutputSize(buf.length)];
            int offset = aesCipher.processBytes(buf, 0, buf.length, plainTemp, 0);
            int last = aesCipher.doFinal(plainTemp, offset);
            final byte[] plain = new byte[offset + last];
            System.arraycopy(plainTemp, 0, plain, 0, plain.length);

            out.write(plain, 0, numRead);
        }
        out.close();
        in.close();
    } catch (java.io.IOException e) {
    }

}

我有一个错误:

org.bouncycastle.crypto.InvalidCipherTextException: pad block corrupted
at org.bouncycastle.crypto.paddings.PKCS7Padding.padCount(Unknown Source)
at org.bouncycastle.crypto.paddings.PaddedBufferedBlockCipher.doFinal(Unknown Source)

我可以做什么来消除这个错误？我必须在此函数中更改什么才能获得加密文件的能力。

Answer 1

最后，我发现了问题，我没有初始化aesCipher。当我添加方法 aesCipher.init(true, aesCBCParams); 时它开始工作了。

我还更改了一些代码:

int numRead = 0;
        while ((numRead = fin.read(buf)) >= 0) {
            if (numRead == 1024) {
                byte[] plainTemp = new byte[aesCipher.getUpdateOutputSize(numRead)];
                int offset = aesCipher.processBytes(buf, 0, numRead, plainTemp, 0);

                final byte[] plain = new byte[offset];
                System.arraycopy(plainTemp, 0, plain, 0, plain.length);
                fout.write(plain, 0, plain.length);
            } else {
                byte[] plainTemp = new byte[aesCipher.getOutputSize(numRead)];
                int offset = aesCipher.processBytes(buf, 0, numRead, plainTemp, 0);
                int last = aesCipher.doFinal(plainTemp, offset);
                final byte[] plain = new byte[offset + last];
                System.arraycopy(plainTemp, 0, plain, 0, plain.length);
                fout.write(plain, 0, plain.length);
            }
        }