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PORfc2898DeriveBytes for .NET and Java generate different values
 

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  1. PORfc2898DeriveBytes for .NET and Java generate different values
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    <p>I'm trying to use Rfc2898DeriveBytes for Android Java and .NET C# framework to generate key for encryption and decryption process. </p> <p>The problem is in spite of that the input values are same, I'm getting different keys in .NET and Java. </p> <p>.NET code:</p> <pre><code>private void btnRfc2898DeriveBytes_Click(object sender, EventArgs e) { byte[] salt = new byte[] { 19, 3, 24, 18, 14, 42, 57, 23 }; Rfc2898DeriveBytes keyGenerator = null; keyGenerator = new Rfc2898DeriveBytes("somestring", salt, 1000); txtRfc2898DeriveBytes.Text = System.Text.Encoding.UTF8.GetString(keyGenerator.GetBytes(16)); } </code></pre> <p>Java Code (used in an android application):</p> <pre><code>byte[] salt = new byte[] { 19, 3, 24, 18, 14, 42, 57, 23 }; Rfc2898DeriveBytes keyGenerator = null; try { keyGenerator = new Rfc2898DeriveBytes("somestring", salt, 1000); } catch (InvalidKeyException e1) { e1.printStackTrace(); } catch (NoSuchAlgorithmException e1) { e1.printStackTrace(); } catch (UnsupportedEncodingException e1) { // TODO Auto-generated catch block e1.printStackTrace(); } Log.i("key = ", decodeUTF8(keyGenerator.getBytes(16))); </code></pre> <p>Java Decode Method:</p> <pre><code>String decodeUTF8(byte[] bytes) { private final Charset UTF8_CHARSET = Charset.forName("UTF-8"); return new String(bytes, UTF8_CHARSET); } </code></pre> <p>Rfc2898DeriveBytes java class:</p> <pre><code>import java.io.UnsupportedEncodingException; import java.security.InvalidKeyException; import java.security.NoSuchAlgorithmException; import javax.crypto.Mac; import javax.crypto.spec.SecretKeySpec; /** * RFC 2898 password derivation compatible with .NET Rfc2898DeriveBytes class. */ public class Rfc2898DeriveBytes { private Mac _hmacSha1; private byte[] _salt; private int _iterationCount; private byte[] _buffer = new byte[20]; private int _bufferStartIndex = 0; private int _bufferEndIndex = 0; private int _block = 1; /** * Creates new instance. * @param password The password used to derive the key. * @param salt The key salt used to derive the key. * @param iterations The number of iterations for the operation. * @throws NoSuchAlgorithmException HmacSHA1 algorithm cannot be found. * @throws InvalidKeyException Salt must be 8 bytes or more. -or- Password cannot be null. */ public Rfc2898DeriveBytes(byte[] password, byte[] salt, int iterations) throws NoSuchAlgorithmException, InvalidKeyException { if ((salt == null) || (salt.length &lt; 8)) { throw new InvalidKeyException("Salt must be 8 bytes or more."); } if (password == null) { throw new InvalidKeyException("Password cannot be null."); } this._salt = salt; this._iterationCount = iterations; this._hmacSha1 = Mac.getInstance("HmacSHA1"); this._hmacSha1.init(new SecretKeySpec(password, "HmacSHA1")); } /** * Creates new instance. * @param password The password used to derive the key. * @param salt The key salt used to derive the key. * @param iterations The number of iterations for the operation. * @throws NoSuchAlgorithmException HmacSHA1 algorithm cannot be found. * @throws InvalidKeyException Salt must be 8 bytes or more. -or- Password cannot be null. * @throws UnsupportedEncodingException UTF-8 encoding is not supported. */ public Rfc2898DeriveBytes(String password, byte[] salt, int iterations) throws InvalidKeyException, NoSuchAlgorithmException, UnsupportedEncodingException { this(password.getBytes("UTF8"), salt, iterations); } /** * Creates new instance. * @param password The password used to derive the key. * @param salt The key salt used to derive the key. * @throws NoSuchAlgorithmException HmacSHA1 algorithm cannot be found. * @throws InvalidKeyException Salt must be 8 bytes or more. -or- Password cannot be null. * @throws UnsupportedEncodingException UTF-8 encoding is not supported. */ public Rfc2898DeriveBytes(String password, byte[] salt) throws NoSuchAlgorithmException, InvalidKeyException, UnsupportedEncodingException { this(password, salt, 0x3e8); } /** * Returns a pseudo-random key from a password, salt and iteration count. * @param count Number of bytes to return. * @return Byte array. */ public byte[] getBytes(int count) { byte[] result = new byte[count]; int resultOffset = 0; int bufferCount = this._bufferEndIndex - this._bufferStartIndex; if (bufferCount &gt; 0) { //if there is some data in buffer if (count &lt; bufferCount) { //if there is enough data in buffer System.arraycopy(this._buffer, this._bufferStartIndex, result, 0, count); this._bufferStartIndex += count; return result; } System.arraycopy(this._buffer, this._bufferStartIndex, result, 0, bufferCount); this._bufferStartIndex = this._bufferEndIndex = 0; resultOffset += bufferCount; } while (resultOffset &lt; count) { int needCount = count - resultOffset; this._buffer = this.func(); if (needCount &gt; 20) { //we one (or more) additional passes System.arraycopy(this._buffer, 0, result, resultOffset, 20); resultOffset += 20; } else { System.arraycopy(this._buffer, 0, result, resultOffset, needCount); this._bufferStartIndex = needCount; this._bufferEndIndex = 20; return result; } } return result; } private byte[] func() { this._hmacSha1.update(this._salt, 0, this._salt.length); byte[] tempHash = this._hmacSha1.doFinal(getBytesFromInt(this._block)); this._hmacSha1.reset(); byte[] finalHash = tempHash; for (int i = 2; i &lt;= this._iterationCount; i++) { tempHash = this._hmacSha1.doFinal(tempHash); for (int j = 0; j &lt; 20; j++) { finalHash[j] = (byte)(finalHash[j] ^ tempHash[j]); } } if (this._block == 2147483647) { this._block = -2147483648; } else { this._block += 1; } return finalHash; } private static byte[] getBytesFromInt(int i) { return new byte[] { (byte)(i &gt;&gt;&gt; 24), (byte)(i &gt;&gt;&gt; 16), (byte)(i &gt;&gt;&gt; 8), (byte)i }; } } </code></pre> <p>Edit:</p> <p>I also convert it to Hex, but getting different values also. </p> <p>C# function:</p> <pre><code>public static String encode(byte[] data) { char[] lookup = new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' }; int i = 0, p = 2, l = data.Length; char[] c = new char[l * 2 + 2]; byte d; c[0] = '0'; c[1] = 'x'; while (i &lt; l) { d = data[i++]; c[p++] = lookup[d / 0x10]; c[p++] = lookup[d % 0x10]; } return new string(c, 0, c.Length); } </code></pre> <p>Java method:</p> <pre><code>final protected static char[] hexArray = "0123456789ABCDEF".toCharArray(); public static String bytesToHex(byte[] bytes) { char[] hexChars = new char[bytes.length * 2]; int v; for ( int j = 0; j &lt; bytes.length; j++ ) { v = bytes[j] &amp; 0xFF; hexChars[j * 2] = hexArray[v &gt;&gt;&gt; 4]; hexChars[j * 2 + 1] = hexArray[v &amp; 0x0F]; } return new String(hexChars); } </code></pre> <p>What I'm doing wrong :( ?</p>
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