com.sshtools.common.ssh.components.DiffieHellmanGroups Maven / Gradle / Ivy
/**
* (c) 2002-2021 JADAPTIVE Limited. All Rights Reserved.
*
* This file is part of the Maverick Synergy Java SSH API.
*
* Maverick Synergy is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Maverick Synergy is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with Maverick Synergy. If not, see safePrimes = new ArrayList();
static List customPrimes = new ArrayList();
static {
safePrimes.add(group1);
safePrimes.add(group5);
safePrimes.add(group14);
safePrimes.add(group15);
safePrimes.add(group16);
safePrimes.add(group17);
safePrimes.add(group18);
}
public static class DHGroup {
BigInteger g;
BigInteger p;
Integer size;
private DHGroup(Integer size, BigInteger g, BigInteger p) {
this.size = size;
this.g= g;
this.p = p;
}
public BigInteger getG() {
return g;
}
public BigInteger getP() {
return p;
}
public Integer getSize() {
return size;
}
}
public static final int TYPE_SAFE = 2;
public static final int TESTS_COMPOSITE = 0x01;
public static void loadGroups(URI url) throws IOException {
BufferedReader reader = new BufferedReader(new InputStreamReader(url.toURL().openStream()));
String line;
while((line = reader.readLine())!=null) {
line = line.trim();
if(line.startsWith("#")) {
continue;
}
String[] parts = line.split("\\s+");
if(parts.length != 7) {
continue;
}
Integer t = Integer.parseInt(parts[1]);
if(t != 2) {
continue;
}
t = Integer.parseInt(parts[2]);
if((t & TESTS_COMPOSITE) != 0 || (t & ~TESTS_COMPOSITE) == 0) {
continue;
}
if(Integer.parseInt(parts[3]) == 0) {
continue;
}
customPrimes.add(new DHGroup(Integer.parseInt(parts[4]) + 1,
new BigInteger(parts[5], 16),
new BigInteger(parts[6], 16)));
}
Collections.sort(customPrimes, new Comparator() {
@Override
public int compare(DHGroup o1, DHGroup o2) {
return o1.size.compareTo(o2.getSize());
}
});
}
public static boolean verifyParameters(BigInteger shared, BigInteger p) {
if(shared.compareTo(BigInteger.ONE) <= 0
|| shared.compareTo(p.subtract(BigInteger.ONE)) >= 0) {
Log.error("Invalid DH shared value (1 < y < p-1) {}", shared.toString(16));
return false;
}
return true;
}
/**
* get the biggest safe prime from the list that is <= maximumSize
* @param maximumSize
* @return BigInteger
*/
public static DHGroup getSafePrime(UnsignedInteger32 maximumSize) {
if(Log.isDebugEnabled()) {
Log.debug("Looking for diffie hellman group with maximum size of " + maximumSize.intValue() + " bits");
}
List selectedGroups = new ArrayList();
int largedSize = 0;
for(DHGroup group : customPrimes) {
if(group.getSize() > maximumSize.intValue()) {
break;
}
if(largedSize < group.getSize()) {
largedSize = group.getSize();
selectedGroups.clear();
}
selectedGroups.add(group);
}
if(!selectedGroups.isEmpty()) {
return selectedGroups.get(new Random().nextInt(selectedGroups.size()));
}
BigInteger prime = group1;
for(Iterator it = safePrimes.iterator(); it.hasNext(); ) {
BigInteger p = it.next();
int len = p.bitLength();
if(len > maximumSize.intValue()) {
break;
}
prime = p;
}
if(Log.isDebugEnabled()) {
Log.debug("Found diffie hellman group with " + prime.bitLength() + " bits");
}
return new DHGroup(prime.bitLength(), TWO, prime);
}
public static Collection allDefaultGroups() {
return Collections.unmodifiableList(safePrimes);
}
}