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 < 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 > 0) { // if there is some data in buffer
if (count < 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 < count) {
int needCount = count - resultOffset;
this._buffer = this.func();
if (needCount > 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 <= this._iterationCount; i++) {
tempHash = this._hmacSha1.doFinal(tempHash);
for (int j = 0; j < 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 >>> 24), (byte) (i >>> 16), (byte) (i >>> 8), (byte) i };
}
}