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package org.bouncycastle.jce.provider;
import org.bouncycastle.crypto.DataLengthException;
import org.bouncycastle.crypto.DerivationFunction;
import org.bouncycastle.crypto.DerivationParameters;
import org.bouncycastle.crypto.Digest;
import org.bouncycastle.crypto.OutputLengthException;
import org.bouncycastle.crypto.params.KDFParameters;
/**
* Generator for PBE derived keys and ivs as defined by IEEE P1363a
*
* This implementation is based on draft 9 of IEEE P1363a. Note:
* as this is still a draft the output of this generator may change, don't
* use it for anything that might be subject to long term storage.
*/
public class BrokenKDF2BytesGenerator
implements DerivationFunction
{
private Digest digest;
private byte[] shared;
private byte[] iv;
/**
* Construct a KDF2 Parameters generator. Generates key material
* according to IEEE P1363a - if you want orthodox results you should
* use a digest specified in the standard.
*
* Note: IEEE P1363a standard is still a draft standard, if the standard
* changes this function, the output of this function will change as well.
* Don't use this routine for anything subject to long term storage.
*
* @param digest the digest to be used as the source of derived keys.
*/
public BrokenKDF2BytesGenerator(
Digest digest)
{
this.digest = digest;
}
public void init(
DerivationParameters param)
{
if (!(param instanceof KDFParameters))
{
throw new IllegalArgumentException("KDF parameters required for generator");
}
KDFParameters p = (KDFParameters)param;
shared = p.getSharedSecret();
iv = p.getIV();
}
/**
* return the underlying digest.
*/
public Digest getDigest()
{
return digest;
}
/**
* fill len bytes of the output buffer with bytes generated from
* the derivation function.
*
* @throws IllegalArgumentException if the size of the request will cause an overflow.
* @throws DataLengthException if the out buffer is too small.
*/
public int generateBytes(
byte[] out,
int outOff,
int len)
throws DataLengthException, IllegalArgumentException
{
if ((out.length - len) < outOff)
{
throw new OutputLengthException("output buffer too small");
}
long oBits = len * 8L;
//
// this is at odds with the standard implementation, the
// maximum value should be hBits * (2^32 - 1) where hBits
// is the digest output size in bits. We can't have an
// array with a long index at the moment...
//
if (oBits > (digest.getDigestSize() * 8L * (1L<<32 - 1)))
{
throw new IllegalArgumentException("Output length too large");
}
int cThreshold = (int)(oBits / digest.getDigestSize());
byte[] dig = null;
dig = new byte[digest.getDigestSize()];
for (int counter = 1; counter <= cThreshold; counter++)
{
digest.update(shared, 0, shared.length);
digest.update((byte)(counter & 0xff));
digest.update((byte)((counter >> 8) & 0xff));
digest.update((byte)((counter >> 16) & 0xff));
digest.update((byte)((counter >> 24) & 0xff));
digest.update(iv, 0, iv.length);
digest.doFinal(dig, 0);
if ((len - outOff) > dig.length)
{
System.arraycopy(dig, 0, out, outOff, dig.length);
outOff += dig.length;
}
else
{
System.arraycopy(dig, 0, out, outOff, len - outOff);
}
}
digest.reset();
return len;
}
}