如何将十六进制字符串转换为相对于 md5、sha-1 和 sha-256 的实际字符串

Question

>我有一个类根据 md5，sha1 sha 256 命名的值将字符串转换为十六进制字符串。

如何根据这些安全算法将十六进制字符串转换为字符串。

MD5 哈希： 06c219e5bc8378f3a8a3f83b4b7e4649SHA-1 哈希： e9fe51f94eadabf54dbf2fbbd57188b9abee436eSHA-256 哈希： 652c7dc687d98c9889304ed2e408c74b611e86a40caa51c4b43f1dd5913c5cd0实际字符串：我的秘密

这是我的代码片段，如下所示。

public class HashGenerator {
    private HashGenerator() {
    }
    public static String generateMD5(String message) throws HashGenerationException {
        return hashString(message, "MD5");
    }
    public static String generateSHA1(String message) throws HashGenerationException {
        return hashString(message, "SHA-1");
    }
    public static String generateSHA256(String message) throws HashGenerationException {
        return hashString(message, "SHA-256");
    }
    public static String convertFromMD5(String message) throws HashGenerationException{
        return hexStringtoByteArray(message, "MD5");
    }
    public static String convertFromSHA1(String message) throws HashGenerationException{
        return hexStringtoByteArray(message, "SHA-1");
    }
    public static String convertFromSHA256(String message) throws HashGenerationException{
        return hexStringtoByteArray(message, "SHA-256");
    }
    private static String hashString(String message, String algorithm)
            throws HashGenerationException {
        try {
            MessageDigest digest = MessageDigest.getInstance(algorithm);
            byte[] hashedBytes = digest.digest(message.getBytes("UTF-8"));
            return convertByteArrayToHexString(hashedBytes);
        } catch (NoSuchAlgorithmException | UnsupportedEncodingException ex) {
            throw new HashGenerationException(
                    "Could not generate hash from String", ex);
        }
    }

    private static String convertByteArrayToHexString(byte[] arrayBytes) {
        StringBuffer stringBuffer = new StringBuffer();
        for (int i = 0; i < arrayBytes.length; i++) {
            stringBuffer.append(Integer.toString((arrayBytes[i] & 0xff) + 0x100, 16)
                    .substring(1));
        }
        return stringBuffer.toString();
    }
    public static String hexStringtoByteArray(String str, String algorithm)
    {
       byte[] bytes = new byte[str.length() / 2];
       for (int i = 0; i < bytes.length; i++)
       {
          bytes[i] = (byte) Integer
                .parseInt(str.substring(2 * i, 2 * i + 2), 16);
       }
       try {
           MessageDigest digest = MessageDigest.getInstance(algorithm);
           byte[] hashedBytes = digest.digest(bytes);
           return new String(hashedBytes);
       } catch (Exception ex) {
           throw new HashGenerationException(
                   "Could not generate hash from String", ex);
       }
    }
}

Answer 1

一旦你使用 hexStringtoByteArray 从十六进制字符串中获得了一个字节数组，你就可以使用 new String(bytes, "UTF-8") 创建一个字符串，其中字节是方法中的字节数组。通过在创建字符串时指定 UTF-8，您可以获得十六进制以外的字符。

因此，新方法将如下所示：

public String hexStringtoByteArray(String str) { 
    byte[] bytes = new byte[str.length() / 2]; 
    for (int i = 0; i < bytes.length; i++) { 
        bytes[i] = (byte) Integer.parseInt(str.substring(2 * i, 2 * i + 2), 16); 
    } 
    return new String(bytes, "UTF-8"); 
}