Java中的PBKDF2与Bouncy Castle vs .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); 

这工作正常。我试图用Bouncy Castle在Java中实现它。无法实现它（Java缺少无符号类型使得它更加恼人）。

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？我是否正在处理从无符号到正确签名的转换，还是不能按我的预期工作？

Answer 1

我没有正确处理签名/未签名的转换。这里有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。

在intsToBytes范围以外的整数在0-255范围内的检查是不必要的，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; 
}