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package org.bouncycastle.crypto.generators;
import org.bouncycastle.crypto.CipherParameters;
import org.bouncycastle.crypto.Digest;
import org.bouncycastle.crypto.Mac;
import org.bouncycastle.crypto.PBEParametersGenerator;
import org.bouncycastle.crypto.digests.SHA1Digest;
import org.bouncycastle.crypto.macs.HMac;
import org.bouncycastle.crypto.params.KeyParameter;
import org.bouncycastle.crypto.params.ParametersWithIV;
/**
* Generator for PBE derived keys and ivs as defined by PKCS 5 V2.0 Scheme 2.
* This generator uses a SHA-1 HMac as the calculation function.
* <p>
* The document this implementation is based on can be found at
* <a href=http://www.rsasecurity.com/rsalabs/pkcs/pkcs-5/index.html>
* RSA's PKCS5 Page</a>
*/
public class PKCS5S2ParametersGenerator
extends PBEParametersGenerator
{
private Mac hMac;
private byte[] state;
/**
* construct a PKCS5 Scheme 2 Parameters generator.
*/
public PKCS5S2ParametersGenerator()
{
this(new SHA1Digest());
}
public PKCS5S2ParametersGenerator(Digest digest)
{
hMac = new HMac(digest);
state = new byte[hMac.getMacSize()];
}
private void F(
byte[] S,
int c,
byte[] iBuf,
byte[] out,
int outOff)
{
if (c == 0)
{
throw new IllegalArgumentException("iteration count must be at least 1.");
}
if (S != null)
{
hMac.update(S, 0, S.length);
}
hMac.update(iBuf, 0, iBuf.length);
hMac.doFinal(state, 0);
System.arraycopy(state, 0, out, outOff, state.length);
for (int count = 1; count < c; count++)
{
hMac.update(state, 0, state.length);
hMac.doFinal(state, 0);
for (int j = 0; j != state.length; j++)
{
out[outOff + j] ^= state[j];
}
}
}
private byte[] generateDerivedKey(
int dkLen)
{
int hLen = hMac.getMacSize();
int l = (dkLen + hLen - 1) / hLen;
byte[] iBuf = new byte[4];
byte[] outBytes = new byte[l * hLen];
int outPos = 0;
CipherParameters param = new KeyParameter(password);
hMac.init(param);
for (int i = 1; i <= l; i++)
{
// Increment the value in 'iBuf'
int pos = 3;
while (++iBuf[pos] == 0)
{
--pos;
}
F(salt, iterationCount, iBuf, outBytes, outPos);
outPos += hLen;
}
return outBytes;
}
/**
* Generate a key parameter derived from the password, salt, and iteration
* count we are currently initialised with.
*
* @param keySize the size of the key we want (in bits)
* @return a KeyParameter object.
*/
public CipherParameters generateDerivedParameters(
int keySize)
{
keySize = keySize / 8;
byte[] dKey = generateDerivedKey(keySize);
return new KeyParameter(dKey, 0, keySize);
}
/**
* Generate a key with initialisation vector parameter derived from
* the password, salt, and iteration count we are currently initialised
* with.
*
* @param keySize the size of the key we want (in bits)
* @param ivSize the size of the iv we want (in bits)
* @return a ParametersWithIV object.
*/
public CipherParameters generateDerivedParameters(
int keySize,
int ivSize)
{
keySize = keySize / 8;
ivSize = ivSize / 8;
byte[] dKey = generateDerivedKey(keySize + ivSize);
return new ParametersWithIV(new KeyParameter(dKey, 0, keySize), dKey, keySize, ivSize);
}
/**
* Generate a key parameter for use with a MAC derived from the password,
* salt, and iteration count we are currently initialised with.
*
* @param keySize the size of the key we want (in bits)
* @return a KeyParameter object.
*/
public CipherParameters generateDerivedMacParameters(
int keySize)
{
return generateDerivedParameters(keySize);
}
}
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