Java 中的 PBKDF2 与 Bouncy Castle 对比 .NET Rfc2898DeriveBytes？

Question

我有一些使用 PBKDF2 生成密钥的 C# 代码。

//byte[] salt = new RNGCryptoServiceProvider().GetBytes(salt);
byte[] salt = new byte[] { 19, 3, 248, 189, 144, 42, 57, 23 }; // for testing

byte[] bcKey = new Rfc2898DeriveBytes("mypassword", salt, 8192).GetBytes(32);

这很好用。我正在尝试使用 Bouncy Castle 在 Java 中实现相同的功能。无法让它工作（Java 缺少无符号类型的事实使它更加烦人）。

SecureRandom random = new SecureRandom();
byte[] salt = u2s(new int[] { 19, 3, 248, 189, 144, 42, 57, 23 });
//random.nextBytes(salt);

PBEParametersGenerator generator = new PKCS5S2ParametersGenerator();
generator.init(PBEParametersGenerator.PKCS5PasswordToUTF8Bytes(("BLK" + password).toCharArray()), salt, keyTransformationRounds);
KeyParameter params = (KeyParameter)generator.generateDerivedParameters(keyLengthBits);
byte[] bcKey = params.getKey();
int[] bcKeyU = s2u(bcKey);
System.out.println(new String(Base64.encode(bcKey), "UTF-8"));

// Helper functions because Java has no unsigned types
//
// EDIT: THESE FUNCTIONS ARE INCORRECT.
// See my answer below for the correct versions.
//
static byte[] u2s(int[] unsignedArray) throws IOException
{
    byte[] signedArray = new byte[unsignedArray.length];
    for (int i = 0; i < signedArray.length; i++)
    {
        if (unsignedArray[i] < 0 || unsignedArray[i] > 255)
        {
            throw new IOException("unsignedArray at " + i + " was not within the range 0 to 255.");
        }

        signedArray[i] = (byte)(unsignedArray[i] - 128);
    }

    return signedArray;
}

static int[] s2u(byte[] signedArray)
{
    int[] unsignedArray = new int[signedArray.length];
    for (int i = 0; i < unsignedArray.length; i++)
    {
        unsignedArray[i] = (int)(signedArray[i] + 128);
    }

    return unsignedArray;
}

生成的 bcKey 字节数组不同。我究竟做错了什么？我是要正确处理从无符号到有符号的转换，还是不能按我预期的那样工作？

Answer 1

我没有正确处理有符号/无符号转换。下面是一些帮助函数，演示整数数组（表示无符号字节数组）和有符号字节数组之间的转换。

检查intsToBytes 中 0-255 范围之外的整数不是必需的，但可能有助于调试。

static byte[] intsToBytes(int[] ints)
{
    byte[] bytes = new byte[ints.length];
    for (int i = 0; i < ints.length; i++)
    {
        if (ints[i] < 0 || ints[i] > 255) System.out.println(String.format("WARNING: ints at index %1$d (%2$d) was not a valid byte value (0-255)", i, ints[i]));

        bytes[i] = (byte)ints[i];
    }

    return bytes;
}

static int[] bytesToInts(byte[] bytes)
{
    int[] ints = new int[bytes.length];
    for (int i = 0; i < bytes.length; i++)
    {
        ints[i] = bytes[i] & 0xff;
    }

    return ints;
}