Question

I have a web service (Java) which requires a password for all cases. But the password must be come to me securely. Is there a standard way for all platforms -> java encryption/decryption. How can I decrypt a string which could come a random platform(php,.net,iPhone).

Answer 1

Usually passwords are encrypted using some algorithm say (MD5) and exchange with services… You don’t have to decrypt password… it’s like you create a MD5 hash string of password and the key is the actual password it self.

So on server, you would store MD5 hash of actual password and each client will create MD5 hash string of given password and finally you would validate both hash strings for password verification…

You would easily find java code online to create MD5 hash… one example is

public static String convertStringToMD5Hash(String string) {
    byte[] hash;

    try {
        hash = MessageDigest.getInstance("MD5").digest(string.getBytes("UTF-8"));
    } catch (NoSuchAlgorithmException e) {
        throw new RuntimeException("MD5 not supported?", e);
    } catch (UnsupportedEncodingException e) {
        throw new RuntimeException("UTF-8 not supported?", e);
    }

    StringBuilder hex = new StringBuilder(hash.length * 2);

    for (byte b : hash) {
        int i = (b & 0xFF);
        if (i < 0x10)
            hex.append('0');
        hex.append(Integer.toHexString(i));
    }

    return hex.toString();
}

Disclaimer: Code works on my machine and may need
improvement/optimization for production use