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This library implements a secure and upgradeable password hashing mechanism.
/*
* The MIT License (MIT)
*
* Copyright (c) 2015 QAware GmbH
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
package de.qaware.heimdall;
import de.qaware.heimdall.algorithm.AlgorithmException;
import de.qaware.heimdall.algorithm.HashAlgorithm;
import de.qaware.heimdall.algorithm.HashAlgorithmRegistry;
import de.qaware.heimdall.config.ConfigCoder;
import de.qaware.heimdall.config.HashAlgorithmConfig;
import de.qaware.heimdall.salt.SaltProvider;
import de.qaware.heimdall.util.Base64;
import de.qaware.heimdall.util.Preconditions;
import java.util.Arrays;
/**
* Default implementation for {@link Password}.
*/
public class PasswordImpl implements Password {
/**
* Radix for hex.
*/
private static final int RADIX_HEX = 16;
/**
* Delimiter for the parts of the hash.
*/
private static final String HASH_DELIMITER = ":";
/**
* Hash version 1.
*/
private static final int VERSION_1 = 1;
/**
* Current hash version.
*/
private static final int CURRENT_VERSION = VERSION_1;
private static final String CLEARTEXT_PARAM = "cleartext";
/**
* The salt provider.
*/
private final SaltProvider saltProvider;
/**
* The decoder/encoder for configs.
*/
private final ConfigCoder configCoder;
/**
* Default hash algorithm.
*/
private final HashAlgorithm defaultHashAlgorithm;
/**
* Hash alhgorithm registry.
*/
private final HashAlgorithmRegistry hashAlgorithmRegistry;
/**
* Constructor.
*
* @param saltProvider The salt provider.
* @param configCoder The config coder.
* @param hashAlgorithmRegistry The hash algorithm registry.
*/
public PasswordImpl(SaltProvider saltProvider, ConfigCoder configCoder, HashAlgorithmRegistry hashAlgorithmRegistry, HashAlgorithm defaultHashAlgorithm) {
this.saltProvider = Preconditions.checkNotNull(saltProvider, "saltProvider");
this.configCoder = Preconditions.checkNotNull(configCoder, "configCoder");
this.hashAlgorithmRegistry = Preconditions.checkNotNull(hashAlgorithmRegistry, "hashAlgorithmRegistry");
this.defaultHashAlgorithm = Preconditions.checkNotNull(defaultHashAlgorithm, "defaultHashAlgorithm");
}
@Override
public String hash(String cleartext) throws PasswordException {
Preconditions.checkNotNull(cleartext, CLEARTEXT_PARAM);
char[] cleartextAsChars = cleartext.toCharArray();
try {
return hash(cleartextAsChars);
} finally {
purgeArray(cleartextAsChars);
}
}
@Override
public String hash(SecureCharArray cleartext) throws PasswordException {
return hash(cleartext.getChars());
}
@Override
public String hash(char[] cleartext) throws PasswordException {
Preconditions.checkNotNull(cleartext, CLEARTEXT_PARAM);
return hash(cleartext, defaultHashAlgorithm, defaultHashAlgorithm.getDefaultConfig());
}
@Override
public String hash(String cleartext, HashAlgorithm hashAlgorithm, HashAlgorithmConfig config) throws PasswordException {
Preconditions.checkNotNull(cleartext, CLEARTEXT_PARAM);
Preconditions.checkNotNull(hashAlgorithm, "hashAlgorithm");
Preconditions.checkNotNull(config, "config");
char[] cleartextAsChars = cleartext.toCharArray();
try {
return hash(cleartextAsChars, hashAlgorithm, config);
} finally {
purgeArray(cleartextAsChars);
}
}
@Override
public String hash(SecureCharArray cleartext, HashAlgorithm hashAlgorithm, HashAlgorithmConfig config) throws PasswordException {
return hash(cleartext.getChars(), hashAlgorithm, config);
}
@Override
public String hash(char[] cleartext, HashAlgorithm hashAlgorithm, HashAlgorithmConfig config) throws PasswordException {
Preconditions.checkNotNull(cleartext, CLEARTEXT_PARAM);
Preconditions.checkNotNull(hashAlgorithm, "hashAlgorithm");
Preconditions.checkNotNull(config, "config");
int saltSizeInBits = hashAlgorithm.getOutputSizeInBits();
int id = hashAlgorithm.getId();
byte[] salt = saltProvider.create(saltSizeInBits);
byte[] hash;
try {
hash = hashAlgorithm.hash(cleartext, salt, config);
} catch (AlgorithmException e) {
throw new PasswordException(e);
}
return concatenate(id, salt, config, hash);
}
@Override
public boolean verify(SecureCharArray cleartext, String hash) throws PasswordException {
return verify(cleartext.getChars(), hash);
}
@Override
public boolean verify(String cleartext, String hash) throws PasswordException {
Preconditions.checkNotNull(cleartext, CLEARTEXT_PARAM);
Preconditions.checkNotNull(hash, "hash");
char[] cleartextAsChars = cleartext.toCharArray();
try {
return verify(cleartextAsChars, hash);
} finally {
purgeArray(cleartextAsChars);
}
}
@Override
public boolean verify(char[] cleartext, String hash) throws PasswordException {
Preconditions.checkNotNull(cleartext, CLEARTEXT_PARAM);
Preconditions.checkNotNull(hash, "hash");
String[] parts = hash.split(HASH_DELIMITER);
int version = Integer.parseInt(parts[0], RADIX_HEX);
switch (version) {
case VERSION_1:
return verifyVersion1(cleartext, hash);
default:
throw new PasswordException("Unsupported hash version: " + version);
}
}
/**
* Verifies that the cleartext matches the hash generated by the version 1 of the software.
*
* @param cleartext The cleartext.
* @param hash The hash.
* @return True if the given cleartext password matches the given hash, false otherwise.
* @throws PasswordException If verifying the hash failed.
*/
private boolean verifyVersion1(char[] cleartext, String hash) throws PasswordException {
String[] parts = split(hash);
int id = Integer.parseInt(parts[1], RADIX_HEX);
byte[] salt = Base64.decode(parts[2]);
HashAlgorithmConfig config = configCoder.decode(parts[3]);
byte[] hashBytes = Base64.decode(parts[4]);
HashAlgorithm hashAlgorithm;
try {
hashAlgorithm = hashAlgorithmRegistry.getAlgorithm(id);
} catch (AlgorithmException e) {
throw new PasswordException(e);
}
byte[] hashedCleartext;
try {
hashedCleartext = hashAlgorithm.hash(cleartext, salt, config);
} catch (AlgorithmException e) {
throw new PasswordException(e);
}
return slowEquals(hashedCleartext, hashBytes);
}
@Override
public boolean needsRehash(String hash) throws PasswordException {
Preconditions.checkNotNull(hash, "hash");
String[] parts = split(hash);
int version = Integer.parseInt(parts[0], RADIX_HEX);
if (CURRENT_VERSION > version) {
return true;
}
int id = Integer.parseInt(parts[1], RADIX_HEX);
HashAlgorithmConfig config = configCoder.decode(parts[3]);
HashAlgorithm algorithm;
try {
algorithm = hashAlgorithmRegistry.getAlgorithm(id);
} catch (AlgorithmException e) {
throw new PasswordException(e);
}
// If algorithm or config is deprecated, a rehash is needed
try {
return algorithm.isAlgorithmDeprecated() || algorithm.isConfigDeprecated(config);
} catch (AlgorithmException e) {
throw new PasswordException(e);
}
}
/**
* Purges the content of the given char array.
*
* @param array Char array to purge.
*/
private void purgeArray(char[] array) {
Arrays.fill(array, '0');
}
/**
* Concatenates the hash parts.
*
* @param id Id of the hash algorithm.
* @param salt Salt.
* @param config Hash algorithm config.
* @param hash Hash.
* @return Concatenated hash parts.
*/
private String concatenate(int id, byte[] salt, HashAlgorithmConfig config, byte[] hash) {
assert salt != null;
assert config != null;
assert hash != null;
String versionAsString = Integer.toHexString(CURRENT_VERSION);
String idAsString = Integer.toHexString(id);
String saltAsString = Base64.encode(salt);
String configAsString = configCoder.encode(config);
String hashAsString = Base64.encode(hash);
return versionAsString + HASH_DELIMITER + idAsString + HASH_DELIMITER + saltAsString + HASH_DELIMITER + configAsString + HASH_DELIMITER + hashAsString;
}
/**
* Splits a hash in parts.
*
* @param hash Hash to split.
* @return Hash parts.
* @throws PasswordException If there is a incorrect number of parts.
*/
private String[] split(String hash) throws PasswordException {
assert hash != null;
String[] parts = hash.split(HASH_DELIMITER);
if (parts.length != 5) {
throw new PasswordException("Expected a length of 5, but got " + parts.length);
}
return parts;
}
/**
* Compares two byte arrays in a way which isn't subject to timing attacks.
*
* @param hash1 Hash 1.
* @param hash2 Hash 2.
* @return True if both hashes are equal, false otherwise.
*/
private static boolean slowEquals(byte[] hash1, byte[] hash2) {
assert hash1 != null;
assert hash2 != null;
int diff = hash1.length ^ hash2.length;
for (int i = 0; i < hash1.length && i < hash2.length; i++) {
diff |= hash1[i] ^ hash2[i];
}
return diff == 0;
}
}