package org.bouncycastle.pqc.crypto.xmss;
import org.bouncycastle.crypto.Digest;
import org.bouncycastle.crypto.Xof;
/**
* Crypto functions for XMSS.
*
*/
public final class KeyedHashFunctions {
private final Digest digest;
private final int digestSize;
protected KeyedHashFunctions(Digest digest, int digestSize) {
super();
if (digest == null) {
throw new NullPointerException("digest == null");
}
this.digest = digest;
this.digestSize = digestSize;
}
private byte[] coreDigest(int fixedValue, byte[] key, byte[] index) {
byte[] buffer = new byte[digestSize + key.length + index.length];
byte[] in = XMSSUtil.toBytesBigEndian(fixedValue, digestSize);
/* fill first n byte of out buffer */
for (int i = 0; i < in.length; i++) {
buffer[i] = in[i];
}
/* add key */
for (int i = 0; i < key.length; i++) {
buffer[in.length + i] = key[i];
}
/* add index */
for (int i = 0; i < index.length; i++) {
buffer[in.length + key.length + i] = index[i];
}
digest.update(buffer, 0, buffer.length);
byte[] out = new byte[digestSize];
if (digest instanceof Xof) {
((Xof) digest).doFinal(out, 0, digestSize);
} else {
digest.doFinal(out, 0);
}
return out;
}
protected byte[] F(byte[] key, byte[] in) {
if (key.length != digestSize) {
throw new IllegalArgumentException("wrong key length");
}
if (in.length != digestSize) {
throw new IllegalArgumentException("wrong in length");
}
return coreDigest(0, key, in);
}
protected byte[] H(byte[] key, byte[] in) {
if (key.length != digestSize) {
throw new IllegalArgumentException("wrong key length");
}
if (in.length != (2 * digestSize)) {
throw new IllegalArgumentException("wrong in length");
}
return coreDigest(1, key, in);
}
protected byte[] HMsg(byte[] key, byte[] in) {
if (key.length != (3 * digestSize)) {
throw new IllegalArgumentException("wrong key length");
}
return coreDigest(2, key, in);
}
protected byte[] PRF(byte[] key, byte[] address) {
if (key.length != digestSize) {
throw new IllegalArgumentException("wrong key length");
}
if (address.length != 32) {
throw new IllegalArgumentException("wrong address length");
}
return coreDigest(3, key, address);
}
}