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package org.spongycastle.crypto.generators;
import org.spongycastle.crypto.CipherParameters;
import org.spongycastle.crypto.Digest;
import org.spongycastle.crypto.ExtendedDigest;
import org.spongycastle.crypto.PBEParametersGenerator;
import org.spongycastle.crypto.params.KeyParameter;
import org.spongycastle.crypto.params.ParametersWithIV;
/**
* Generator for PBE derived keys and ivs as defined by PKCS 12 V1.0.
* <p>
* The document this implementation is based on can be found at
* <a href=http://www.rsasecurity.com/rsalabs/pkcs/pkcs-12/index.html>
* RSA's PKCS12 Page</a>
*/
public class PKCS12ParametersGenerator
extends PBEParametersGenerator
{
public static final int KEY_MATERIAL = 1;
public static final int IV_MATERIAL = 2;
public static final int MAC_MATERIAL = 3;
private Digest digest;
private int u;
private int v;
/**
* Construct a PKCS 12 Parameters generator. This constructor will
* accept any digest which also implements ExtendedDigest.
*
* @param digest the digest to be used as the source of derived keys.
* @exception IllegalArgumentException if an unknown digest is passed in.
*/
public PKCS12ParametersGenerator(
Digest digest)
{
this.digest = digest;
if (digest instanceof ExtendedDigest)
{
u = digest.getDigestSize();
v = ((ExtendedDigest)digest).getByteLength();
}
else
{
throw new IllegalArgumentException("Digest " + digest.getAlgorithmName() + " unsupported");
}
}
/**
* add a + b + 1, returning the result in a. The a value is treated
* as a BigInteger of length (b.length * 8) bits. The result is
* modulo 2^b.length in case of overflow.
*/
private void adjust(
byte[] a,
int aOff,
byte[] b)
{
int x = (b[b.length - 1] & 0xff) + (a[aOff + b.length - 1] & 0xff) + 1;
a[aOff + b.length - 1] = (byte)x;
x >>>= 8;
for (int i = b.length - 2; i >= 0; i--)
{
x += (b[i] & 0xff) + (a[aOff + i] & 0xff);
a[aOff + i] = (byte)x;
x >>>= 8;
}
}
/**
* generation of a derived key ala PKCS12 V1.0.
*/
private byte[] generateDerivedKey(
int idByte,
int n)
{
byte[] D = new byte[v];
byte[] dKey = new byte[n];
for (int i = 0; i != D.length; i++)
{
D[i] = (byte)idByte;
}
byte[] S;
if ((salt != null) && (salt.length != 0))
{
S = new byte[v * ((salt.length + v - 1) / v)];
for (int i = 0; i != S.length; i++)
{
S[i] = salt[i % salt.length];
}
}
else
{
S = new byte[0];
}
byte[] P;
if ((password != null) && (password.length != 0))
{
P = new byte[v * ((password.length + v - 1) / v)];
for (int i = 0; i != P.length; i++)
{
P[i] = password[i % password.length];
}
}
else
{
P = new byte[0];
}
byte[] I = new byte[S.length + P.length];
System.arraycopy(S, 0, I, 0, S.length);
System.arraycopy(P, 0, I, S.length, P.length);
byte[] B = new byte[v];
int c = (n + u - 1) / u;
byte[] A = new byte[u];
for (int i = 1; i <= c; i++)
{
digest.update(D, 0, D.length);
digest.update(I, 0, I.length);
digest.doFinal(A, 0);
for (int j = 1; j < iterationCount; j++)
{
digest.update(A, 0, A.length);
digest.doFinal(A, 0);
}
for (int j = 0; j != B.length; j++)
{
B[j] = A[j % A.length];
}
for (int j = 0; j != I.length / v; j++)
{
adjust(I, j * v, B);
}
if (i == c)
{
System.arraycopy(A, 0, dKey, (i - 1) * u, dKey.length - ((i - 1) * u));
}
else
{
System.arraycopy(A, 0, dKey, (i - 1) * u, A.length);
}
}
return dKey;
}
/**
* 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(KEY_MATERIAL, 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(KEY_MATERIAL, keySize);
byte[] iv = generateDerivedKey(IV_MATERIAL, ivSize);
return new ParametersWithIV(new KeyParameter(dKey, 0, keySize), iv, 0, 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)
{
keySize = keySize / 8;
byte[] dKey = generateDerivedKey(MAC_MATERIAL, keySize);
return new KeyParameter(dKey, 0, keySize);
}
}
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