package org.bouncycastle.crypto.generators;

import org.bouncycastle.crypto.CipherParameters;
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.

The document this implementation is based on can be found at RSA's PKCS5 Page

/** * 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 = new HMac(new SHA1Digest());
construct a PKCS5 Scheme 2 Parameters generator.
/** * construct a PKCS5 Scheme 2 Parameters generator. */
public PKCS5S2ParametersGenerator() { } private void F( byte[] P, byte[] S, int c, byte[] iBuf, byte[] out, int outOff) { byte[] state = new byte[hMac.getMacSize()]; CipherParameters param = new KeyParameter(P); hMac.init(param); 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); if (c == 0) { throw new IllegalArgumentException("iteration count must be at least 1."); } for (int count = 1; count < c; count++) { hMac.init(param); hMac.update(state, 0, state.length); hMac.doFinal(state, 0); for (int j = 0; j != state.length; j++) { out[outOff + j] ^= state[j]; } } } private void intToOctet( byte[] buf, int i) { buf[0] = (byte)(i >>> 24); buf[1] = (byte)(i >>> 16); buf[2] = (byte)(i >>> 8); buf[3] = (byte)i; } private byte[] generateDerivedKey( int dkLen) { int hLen = hMac.getMacSize(); int l = (dkLen + hLen - 1) / hLen; byte[] iBuf = new byte[4]; byte[] out = new byte[l * hLen]; for (int i = 1; i <= l; i++) { intToOctet(iBuf, i); F(password, salt, iterationCount, iBuf, out, (i - 1) * hLen); } return out; }
Generate a key parameter derived from the password, salt, and iteration count we are currently initialised with.
Params:
  • keySize – the size of the key we want (in bits)
Returns:a KeyParameter object.
/** * 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.
Params:
  • keySize – the size of the key we want (in bits)
  • ivSize – the size of the iv we want (in bits)
Returns:a ParametersWithIV object.
/** * 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.
Params:
  • keySize – the size of the key we want (in bits)
Returns:a KeyParameter object.
/** * 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); } }