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/*
* Copyright 2004-2019 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (https://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.security;
import java.security.GeneralSecurityException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import org.h2.util.Bits;
/**
* This class implements the cryptographic hash function SHA-256.
*/
public class SHA256 {
private SHA256() {
}
/**
* Calculate the hash code by using the given salt. The salt is appended
* after the data before the hash code is calculated. After generating the
* hash code, the data and all internal buffers are filled with zeros to
* avoid keeping insecure data in memory longer than required (and possibly
* swapped to disk).
*
* @param data the data to hash
* @param salt the salt to use
* @return the hash code
*/
public static byte[] getHashWithSalt(byte[] data, byte[] salt) {
byte[] buff = new byte[data.length + salt.length];
System.arraycopy(data, 0, buff, 0, data.length);
System.arraycopy(salt, 0, buff, data.length, salt.length);
return getHash(buff, true);
}
/**
* Calculate the hash of a password by prepending the user name and a '@'
* character. Both the user name and the password are encoded to a byte
* array using UTF-16. After generating the hash code, the password array
* and all internal buffers are filled with zeros to avoid keeping the plain
* text password in memory longer than required (and possibly swapped to
* disk).
*
* @param userName the user name
* @param password the password
* @return the hash code
*/
public static byte[] getKeyPasswordHash(String userName, char[] password) {
String user = userName + "@";
byte[] buff = new byte[2 * (user.length() + password.length)];
int n = 0;
for (int i = 0, length = user.length(); i < length; i++) {
char c = user.charAt(i);
buff[n++] = (byte) (c >> 8);
buff[n++] = (byte) c;
}
for (char c : password) {
buff[n++] = (byte) (c >> 8);
buff[n++] = (byte) c;
}
Arrays.fill(password, (char) 0);
return getHash(buff, true);
}
/**
* Calculate the hash-based message authentication code.
*
* @param key the key
* @param message the message
* @return the hash
*/
public static byte[] getHMAC(byte[] key, byte[] message) {
return initMac(key).doFinal(message);
}
private static Mac initMac(byte[] key) {
// Java forbids empty keys
if (key.length == 0) {
key = new byte[1];
}
try {
Mac mac = Mac.getInstance("HmacSHA256");
mac.init(new SecretKeySpec(key, "HmacSHA256"));
return mac;
} catch (GeneralSecurityException e) {
throw new RuntimeException(e);
}
}
/**
* Calculate the hash using the password-based key derivation function 2.
*
* @param password the password
* @param salt the salt
* @param iterations the number of iterations
* @param resultLen the number of bytes in the result
* @return the result
*/
public static byte[] getPBKDF2(byte[] password, byte[] salt,
int iterations, int resultLen) {
byte[] result = new byte[resultLen];
Mac mac = initMac(password);
int len = 64 + Math.max(32, salt.length + 4);
byte[] message = new byte[len];
byte[] macRes = null;
for (int k = 1, offset = 0; offset < resultLen; k++, offset += 32) {
for (int i = 0; i < iterations; i++) {
if (i == 0) {
System.arraycopy(salt, 0, message, 0, salt.length);
Bits.writeInt(message, salt.length, k);
len = salt.length + 4;
} else {
System.arraycopy(macRes, 0, message, 0, 32);
len = 32;
}
mac.update(message, 0, len);
macRes = mac.doFinal();
for (int j = 0; j < 32 && j + offset < resultLen; j++) {
result[j + offset] ^= macRes[j];
}
}
}
Arrays.fill(password, (byte) 0);
return result;
}
/**
* Calculate the hash code for the given data.
*
* @param data the data to hash
* @param nullData if the data should be filled with zeros after calculating
* the hash code
* @return the hash code
*/
public static byte[] getHash(byte[] data, boolean nullData) {
byte[] result;
try {
result = MessageDigest.getInstance("SHA-256").digest(data);
} catch (NoSuchAlgorithmException e) {
throw new RuntimeException(e);
}
if (nullData) {
Arrays.fill(data, (byte) 0);
}
return result;
}
}
