How to Decode a SHA-256 Hashed and Base64 Encoded String?

Is it possible to reverse a salted SHA-256 hash and retrieve the original string?

SHA-256 is a cryptographic hashing algorithm that is designed to be one-way, meaning it's meant to take input data and generate a fixed-size string of characters, which is unique for every unique input. When you combine this with salting and base64 encoding, the original data cannot be decrypted back to its original form. Instead, the correct approach involves understanding the process of hashing and what can be done.

// Example of hashing a plaintext password with SHA-256
const crypto = require('crypto');

function hashPassword(password, salt) {
    const hash = crypto.createHash('sha256');
    hash.update(salt + password);  // Combine salt and password
    return hash.digest('base64');  // Return base64 encoded hash
}

const salt = 'your_unique_salt';
const password = 'plain_text_password';
const hashed = hashPassword(password, salt);
console.log(hashed); // Use this hash to verify future logins.

Causes

• Understanding that SHA-256 hashing is not reversible; it cannot be decrypted.
• Salting adds random data to the original string before hashing, making it even harder to retrieve any original input.
• Base64 encoding is for representing binary data in an ASCII string format; it's not encryption.

Solutions

• For verification, use the original plain text to generate a new hash and compare it with the hashed value.
• If you want to store passwords securely, remember to use techniques such as hashing with a unique salt for each password and techniques like PBKDF2, bcrypt, or Argon2 instead of trying to decrypt SHA-256.
• To check if a plain text matches the hashed string, re-hash the plain text string in the same way and compare hash outputs.

Mistake: Assuming that hashing can be reversed for any input.

Solution: Remember that hashing is a one-way function, and cannot be decrypted.

Mistake: Not using a unique salt for each password/hash.

Solution: Always incorporate a unique salt for each hashing attempt to enhance security.