content: /*
   * Copyright 2025 the original author or authors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      https://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.alibaba.cloud.ai.studio.core.utils.security;
  
  import org.apache.commons.lang3.StringUtils;
  
  import java.nio.charset.StandardCharsets;
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  
  /**
   * Utility class for cryptographic operations. Provides methods for string masking and
   * hashing.
   *
   * @since 1.0.0.3
   */
  public class CryptoUtils {
  
  	/**
  	 * Masks a string by showing only the first and last 4 characters. If input is blank
  	 * or shorter than 12 characters, returns 16 asterisks.
  	 * @param original The string to mask
  	 * @return Masked string
  	 */
  	public static String mask(String original) {
  		if (StringUtils.isBlank(original) || original.length() <= 12) {
  			return "*".repeat(16);
  		}
  
  		int prefix_length = 4;
  		String start = original.substring(0, prefix_length);
  		String end = original.substring(original.length() - prefix_length);
  		int middleLength = original.length() - prefix_length * 2;
  
  		return start + "*".repeat(middleLength) + end;
  	}
  
  	/**
  	 * Generates SHA-512 hash of the input string.
  	 * @param original The string to hash
  	 * @return Hexadecimal representation of the hash
  	 * @throws RuntimeException if SHA-512 algorithm is not available
  	 */
  	public static String hashWithSha512(String original) {
  		try {
  			MessageDigest digest = MessageDigest.getInstance("SHA-512");
  			byte[] encodedHash = digest.digest(original.getBytes(StandardCharsets.UTF_8));
  			return bytesToHex(encodedHash);
  		}
  		catch (NoSuchAlgorithmException e) {
  			throw new RuntimeException("failed to hash with sha-512", e);
  		}
  	}
  
  	/**
  	 * Converts byte array to hexadecimal string.
  	 * @param hash Byte array to convert
  	 * @return Hexadecimal string representation
  	 */
  	private static String bytesToHex(byte[] hash) {
  		StringBuilder hexString = new StringBuilder(2 * hash.length);
  		for (byte b : hash) {
  			String hex = Integer.toHexString(0xff & b);
  			if (hex.length() == 1) {
  				hexString.append('0');
  			}
  			hexString.append(hex);
  		}
  		return hexString.toString();
  	}
  
  }
  