SHA512Crypt.java

package games.strategy.util;

import java.math.BigInteger;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * Replacement for MD5Crypt
 * using SHA512 instead.
 *
 * <p>
 * Do not use for Passwords!
 * Use the BCrypt library instead!
 * </p>
 */
public class SHA512Crypt {

  public static final String SHA_512 = "SHA-512";

  /**
   * Returns the SHA256-Hash of the given String.
   */
  public static String crypt(final String text) {
    return crypt(text, "");
  }

  /**
   * Returns the SHA256-Hash of the given String using the specified Salt.
   */
  public static String crypt(final String text, final String salt) {
    try {
      final MessageDigest md = MessageDigest.getInstance(SHA_512);

      md.update(salt.getBytes(StandardCharsets.UTF_8));
      final byte[] digest = md.digest(text.getBytes(StandardCharsets.UTF_8));

      return String.format("%064x", new BigInteger(1, digest));
    } catch (final NoSuchAlgorithmException e) {
      // This Code shouldn't be executed under any circumstances
      throw new IllegalStateException("The SHA512Crypt class uses an invalid algorithm", e);
    }
  }

  /**
   * Same as {@link SHA512Crypt#crypt(text, salt)}, but passing the salt as well.
   */
  public static String cryptPassSalt(final String text, final String salt) {
    return "$" + salt + crypt(text, salt);
  }
}