What is a one-way hash in Java?

A one-way hash is a mathematical function that converts input data into a unique, fixed-length string that cannot be reversed, making it ideal for data verification.

Is hashing the same as encryption?

No. Encryption is reversible using a key, while hashing is a one-way process that cannot be reversed.

What are hash collisions?

A hash collision occurs when two different inputs produce the same hash output. Good hash algorithms minimize the likelihood of collisions.

Why are hashes used for passwords?

Hashes are used for passwords because they allow systems to verify correctness without storing or exposing the original password.

Why use BigInteger for hashing?

Java BigInteger is used in hashing to handle extremely large numbers without losing precision, which is common in cryptographic recurrence formulas.

Is custom hashing secure for passwords?

Custom hashing is excellent for educational purposes and digital signatures; however, for sensitive passwords, it is recommended to use industry-standard algorithms like Argon2 or bcrypt alongside salting.

Java Hashing Algorithms & One-Way Encryption Guide

Understanding Hashes in Java

In modern web development, ensuring data authenticity and integrity is critical. While many developers rely on standard libraries, understanding the mechanics of a custom JS hash function allows for specialized applications like digital signatures and secure message authentication.

This guide explores a unique approach to mathematical hashing in Java, utilizing recurrence series and large-scale integer manipulation.

What is a One-Way Hash? | Explanation for Java Kids

A one-way hash is a cryptographic function that transforms an input into a unique string of characters. It is designed to be non-revertible encryption; you can easily generate a hash from a message, but it is computationally impossible to reconstruct the original message from the hash. This makes it ideal for verifying data without exposing the raw information.

The Mathematical Foundation for the Java Hash Algorithm

The core of this algorithm is based on a specific mathematical recurrence series. By applying a formula to the character codes of a string, we create a high-entropy output.

The Recurrence Equation | Maths Explanation for Java Kids

The algorithm utilizes the following series to generate the hash weight:

$$ T_n = (n-2)t_1 + 2^n $$

Where:

$n$ represents the position of the character.
$t_1$ is the initial seed or value derived from the character code.

Implementing the Custom Hash in Java

To ensure precision during complex calculations, we utilize a Java BigInteger approach. This prevents rounding errors often found in standard floating-point arithmetic when dealing with large numbers.

Key Features of the Java Hash Implementation:

Character Code Processing: Using `charCodeAt`, the algorithm iterates through each string element to gather raw data.
Bitwise Rotation: To increase security, the output undergoes a bitwise rotation based on the modulo of the recurrence result, ensuring that small changes in input (avalanche effect) result in vastly different hashes.
Digital Signatures: The resulting hash can be used as a signature to verify that a file or message has not been altered.

Create a new Java class file;
Call it Hashes.
Type out the adjoining Java Hashing Algorithm.

Important: BigInteger is inbuilt in Java.
You only need to import the java.math.BigInteger library.

Why Use Custom Mathematical Hashing? | Explanation for Java Kids

Implementing tertiary level Java math in your security protocols offers several benefits:

No Dependencies: Perform secure checks without bloating your project with external libraries.
Educational Insight: Gain a deeper understanding of how cryptographic authenticity is calculated at a low level.
Performance: Tailored algorithms can be optimized for specific data types, providing faster verification for niche applications.

Hashing vs Encryption | Explanation for Java Kids

Although hashing and encryption are sometimes confused, they serve different purposes.

Encryption is reversible. Encrypted data can be decrypted using a key.
Hashing is non-reversible. Once data is hashed, it cannot be restored to its original form.

This distinction makes hashing particularly suitable for sensitive data such as passwords, where systems only need to verify correctness rather than retrieve the original value.

Properties of a Good Hash Algorithm | Explanation for Java Kids

Deterministic: The same input always produces the same output.
Collision Resistant: Different inputs should not produce the same hash.
Non-Reversible: Hashes cannot be converted back to the original input.
Efficient: Quick to compute even for large inputs.

Applications of Hashing in Java

Java hashing is commonly used in a variety of real-world scenarios:

Password verification: Systems store hashed passwords instead of plaintext values
Data integrity checks: Hashes ensure data has not been altered
Authentication mechanisms: Hashes help verify user credentials securely
Digital signatures: Hash values confirm message authenticity

In each case, hashing allows systems to confirm data validity without exposing sensitive information.

Hash Collisions and Their Implications

A hash collision occurs when two different inputs produce the same hash output. While collisions are theoretically unavoidable, good hash algorithms make them extremely rare.

In practice, collision resistance is essential for maintaining trust in systems that rely on hashes for security and verification.

Summary: Java Hashing Algorithm

Hashes in Java provide a secure and efficient way to represent data using one-way hash functions. By producing fixed-length, non-reversible outputs, hash algorithms play a critical role in data security, authentication, and integrity verification.

Understanding how Java hash functions work - and when to use them - is essential for building reliable and secure web applications.

Java Code for Hashes - Class File

package miscellaneous;

import java.math.BigInteger;

public class Hashes {

    public Hashes() {
    }

    public String hashWord(char[] msg) {
        // encoding eqn { Tn = (n-2)t1 + 2^n } - please use your own eqn
        String hash = "";
        BigInteger n;
        BigInteger t1;
        BigInteger x;
        for (int i = 0; i < msg.length; i++) {
            // get unicode of this character as n
            n = BigInteger.valueOf((int) msg[i]);
            t1 = BigInteger.valueOf(i + 1);
            // use recurrence series equation to hash
            x = n.subtract(BigInteger.valueOf(2)).multiply(t1).add(BigInteger.valueOf(2).pow(n.intValue()));
            if (i == 0) {
                hash = x.toString();
                continue;
            }
            // bitwise rotate left with the modulo of x
            String binary = (new BigInteger(hash)).toString(2);
            x = x.mod(BigInteger.valueOf(binary.length()));

            char[] slice_1 = binary.substring(x.intValue()).toCharArray();
            // keep as '1' to preserve hash size
            slice_1[0] = '1';

            String slice_2 = binary.substring(0, x.intValue());

            hash = String.valueOf(slice_1) + slice_2;
            hash = (new BigInteger(hash, 2)).toString();
        }
        hash = (new BigInteger(hash)).toString(16);
        hash = hash.toUpperCase();

        return hash;
    }
}

Java Code for Hashes - Main Class

package miscellaneous;

public class Miscellaneous {

    public static void main(String[] args) {
        char[] message = "merry xmas".toCharArray();

        Hashes one_way = new Hashes();
        String hashed = one_way.hashWord(message);

        System.out.println("Message is '" + String.valueOf(message) +
                "';\nMessage hash is " + hashed);
    }

}

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