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package eu.siacs.conversations.utils;
import java.security.SecureRandom;
import java.text.Normalizer;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import eu.siacs.conversations.Config;
public final class CryptoHelper {
public static final String FILETRANSFER = "?FILETRANSFERv1:";
private final static char[] hexArray = "0123456789abcdef".toCharArray();
private final static char[] vowels = "aeiou".toCharArray();
private final static char[] consonants = "bcdfghjklmnpqrstvwxyz".toCharArray();
final public static byte[] ONE = new byte[] { 0, 0, 0, 1 };
public static String bytesToHex(byte[] bytes) {
char[] hexChars = new char[bytes.length * 2];
for (int j = 0; j < bytes.length; j++) {
int v = bytes[j] & 0xFF;
hexChars[j * 2] = hexArray[v >>> 4];
hexChars[j * 2 + 1] = hexArray[v & 0x0F];
}
return new String(hexChars);
}
public static byte[] hexToBytes(String hexString) {
int len = hexString.length();
byte[] array = new byte[len / 2];
for (int i = 0; i < len; i += 2) {
array[i / 2] = (byte) ((Character.digit(hexString.charAt(i), 16) << 4) + Character
.digit(hexString.charAt(i + 1), 16));
}
return array;
}
public static String hexToString(final String hexString) {
return new String(hexToBytes(hexString));
}
public static byte[] concatenateByteArrays(byte[] a, byte[] b) {
byte[] result = new byte[a.length + b.length];
System.arraycopy(a, 0, result, 0, a.length);
System.arraycopy(b, 0, result, a.length, b.length);
return result;
}
public static String randomMucName(SecureRandom random) {
return randomWord(3, random) + "." + randomWord(7, random);
}
private static String randomWord(int lenght, SecureRandom random) {
StringBuilder builder = new StringBuilder(lenght);
for (int i = 0; i < lenght; ++i) {
if (i % 2 == 0) {
builder.append(consonants[random.nextInt(consonants.length)]);
} else {
builder.append(vowels[random.nextInt(vowels.length)]);
}
}
return builder.toString();
}
/**
* Escapes usernames or passwords for SASL.
*/
public static String saslEscape(final String s) {
final StringBuilder sb = new StringBuilder((int) (s.length() * 1.1));
for (int i = 0; i < s.length(); i++) {
char c = s.charAt(i);
switch (c) {
case ',':
sb.append("=2C");
break;
case '=':
sb.append("=3D");
break;
default:
sb.append(c);
break;
}
}
return sb.toString();
}
public static String saslPrep(final String s) {
return Normalizer.normalize(s, Normalizer.Form.NFKC);
}
public static String prettifyFingerprint(String fingerprint) {
if (fingerprint.length() < 40) {
return fingerprint;
}
StringBuilder builder = new StringBuilder(fingerprint);
builder.insert(8, " ");
builder.insert(17, " ");
builder.insert(26, " ");
builder.insert(35, " ");
return builder.toString();
}
public static String[] getOrderedCipherSuites(final String[] platformSupportedCipherSuites) {
final Collection<String> cipherSuites = new LinkedHashSet<>(Arrays.asList(Config.ENABLED_CIPHERS));
final List<String> platformCiphers = Arrays.asList(platformSupportedCipherSuites);
cipherSuites.retainAll(platformCiphers);
cipherSuites.addAll(platformCiphers);
filterWeakCipherSuites(cipherSuites);
return cipherSuites.toArray(new String[cipherSuites.size()]);
}
private static void filterWeakCipherSuites(final Collection<String> cipherSuites) {
final Iterator<String> it = cipherSuites.iterator();
while (it.hasNext()) {
String cipherName = it.next();
// remove all ciphers with no or very weak encryption or no authentication
for (String weakCipherPattern : Config.WEAK_CIPHER_PATTERNS) {
if (cipherName.contains(weakCipherPattern)) {
it.remove();
break;
}
}
}
}
}
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