Question

我从使用 AES 128位标准：FIPS 179 加密的流中获取了一些数据包。他们只给了我一个16字符串作为密码。在Android方法中有一个IV参数。我在此SO thread中使用了示例代码。但数据不会解密。

public class AESCrypt {

private final Cipher cipher;
private final SecretKeySpec key;
private AlgorithmParameterSpec spec;


public AESCrypt(String password) throws Exception
{
    // hash password with SHA-256 and crop the output to 128-bit for key
    MessageDigest digest = MessageDigest.getInstance("SHA-256");
    digest.update(password.getBytes("UTF-8"));
    byte[] keyBytes = new byte[32];
    System.arraycopy(digest.digest(), 0, keyBytes, 0, keyBytes.length);

    cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
    key = new SecretKeySpec(keyBytes, "AES");
    spec = getIV();
}       

public AlgorithmParameterSpec getIV()
{
    byte[] iv = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, };
    IvParameterSpec ivParameterSpec;
    ivParameterSpec = new IvParameterSpec(iv);

    return ivParameterSpec;
}

public String encrypt(String plainText) throws Exception
{
    cipher.init(Cipher.ENCRYPT_MODE, key, spec);
    byte[] encrypted = cipher.doFinal(plainText.getBytes("UTF-8"));
    String encryptedText = new String(Base64.encode(encrypted, Base64.DEFAULT), "UTF-8");

    return encryptedText;
}

public String decrypt(String cryptedText) throws Exception
{
    cipher.init(Cipher.DECRYPT_MODE, key, spec);
    byte[] bytes = Base64.decode(cryptedText, Base64.DEFAULT);
    byte[] decrypted = cipher.doFinal(bytes);
    String decryptedText = new String(decrypted, "UTF-8");

    return decryptedText;
}

}

Answer 1

要解密数据，您需要使用用于加密数据的相同初始化向量。如果（并且希望）IV不总是相同的，它必须以某种方式从流中获得。如果它已修复，则需要在代码中添加相同的字节。

如何为fips创建IV 197标准AES 128位加密（Android）

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