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package com.trilead.ssh2.crypto.dh;
import djb.Curve25519;
import java.io.IOException;
import java.math.BigInteger;
import java.security.SecureRandom;
/**
* Created by Kenny Root on 1/23/16.
*/
public class Curve25519Exchange extends GenericDhExchange {
public static final String NAME = "curve25519-sha256@libssh.org";
private final byte[] clientPublic = new byte[Curve25519.KEY_SIZE];
private final byte[] clientPrivate = new byte[Curve25519.KEY_SIZE];
private final byte[] serverPublic = new byte[Curve25519.KEY_SIZE];
public Curve25519Exchange() {
super();
}
/*
* Used to test known vectors.
*/
public Curve25519Exchange(byte[] secret) {
if (secret.length != Curve25519.KEY_SIZE) {
throw new AssertionError("secret must be key size");
}
System.arraycopy(secret, 0, clientPrivate, 0, secret.length);
Curve25519.keygen(clientPublic, null, clientPrivate);
}
@Override
public void init(String name) throws IOException {
if (!NAME.equals(name)) {
throw new IOException("Invalid name " + name);
}
SecureRandom sr = new SecureRandom();
sr.nextBytes(clientPrivate);
Curve25519.keygen(clientPublic, null, clientPrivate);
}
@Override
public byte[] getE() {
return clientPublic.clone();
}
@Override
protected byte[] getServerE() {
return serverPublic.clone();
}
@Override
public void setF(byte[] f) throws IOException {
if (f.length != serverPublic.length) {
throw new IOException("Server sent invalid key length " + f.length + " (expected " +
serverPublic.length + ")");
}
System.arraycopy(f, 0, serverPublic, 0, f.length);
byte[] sharedSecretBytes = new byte[Curve25519.KEY_SIZE];
Curve25519.curve(sharedSecretBytes, clientPrivate, serverPublic);
sharedSecret = new BigInteger(1, sharedSecretBytes);
}
@Override
public String getHashAlgo() {
return "SHA-256";
}
}
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