package com.mossle.security.util;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import org.springframework.security.crypto.codec.Hex;
import org.springframework.security.crypto.codec.Utf8;
import org.springframework.security.crypto.keygen.BytesKeyGenerator;
import org.springframework.security.crypto.keygen.KeyGenerators;
import org.springframework.security.crypto.password.PasswordEncoder;
import static org.springframework.security.crypto.util.EncodingUtils.concatenate;
import static org.springframework.security.crypto.util.EncodingUtils.subArray;
public class MessageDigestPasswordEncoder implements PasswordEncoder {
private final MessageDigest messageDigest;
private final byte[] secret;
private final BytesKeyGenerator saltGenerator;
public MessageDigestPasswordEncoder() {
this("");
}
public MessageDigestPasswordEncoder(CharSequence secret) {
this("SHA-256", secret);
}
public MessageDigestPasswordEncoder(String algorithm, CharSequence secret) {
try {
messageDigest = MessageDigest.getInstance(algorithm);
} catch (NoSuchAlgorithmException e) {
throw new IllegalStateException("No such hashing algorithm", e);
}
this.secret = Utf8.encode(secret);
this.saltGenerator = KeyGenerators.secureRandom();
}
public String encode(CharSequence rawPassword) {
return encode(rawPassword, saltGenerator.generateKey());
}
public boolean matches(CharSequence rawPassword, String encodedPassword) {
byte[] digested = decode(encodedPassword);
byte[] salt = subArray(digested, 0, saltGenerator.getKeyLength());
return matches(digested, digest(rawPassword, salt));
}
private String encode(CharSequence rawPassword, byte[] salt) {
byte[] digest = digest(rawPassword, salt);
return new String(Hex.encode(digest));
}
private byte[] digest(CharSequence rawPassword, byte[] salt) {
byte[] digest = messageDigest.digest(concatenate(salt, secret,
Utf8.encode(rawPassword)));
return concatenate(salt, digest);
}
private byte[] decode(CharSequence encodedPassword) {
return Hex.decode(encodedPassword);
}
private boolean matches(byte[] expected, byte[] actual) {
if (expected.length != actual.length) {
return false;
}
int result = 0;
for (int i = 0; i < expected.length; i++) {
result |= (expected[i] ^ actual[i]);
}
return result == 0;
}
}