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Java PBKDF2 with Bouncy Castle vs. .NET Rfc2898DeriveBytes?

I have a C # code that generates a key using PBKDF2.

//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);

It works great. I am trying to implement the same in Java with Bouncy Castle. It is impossible to get it working (the fact that Java has no unsigned types makes it even more annoying).

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;
}

The resulting bcKey bytes are different. What am I doing wrong? Am I going to process the conversion from unsigned to the correct subscription or will it not work the way I expect?

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1 answer

/ . , ( ) .

0-255 intsToBytes , .

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;
}
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