Securely hash passwords with `sha256sum` and a salt

How to Securely Hash Passwords with `sha256sum` and a Salt in Linux Bash

In the digital realm, securing passwords is paramount. One of the common methods for securing passwords is through hashing. In this article, we will explore how to securely hash passwords using sha256sum along with a salt in Linux Bash.

Q1: What is hashing and why is it necessary?

A: Hashing is the process of converting an input (like a password) into a fixed-size string of bytes, typically a hash, which appears to be random. It's necessary because it secures passwords in a way that even if someone accesses the hashed version, they cannot easily deduce the original password.

Q2: What is `sha256sum`?

A: sha256sum is a Linux command-line utility that computes and checks SHA256 (256-bit) cryptographic hash values. It's widely used to verify data integrity but can also be used to hash passwords.

Q3: Why add a salt?

A: A salt is a random data that is used as an additional input to the hash function to safeguard against attacks on widely used passwords or those found in a password dictionary. Essentially, it provides a unique touch to each password, even if two users have the same password.

Q4: How can I hash a password using `sha256sum` with a salt in Bash?

A: You can follow these steps: 1. Generate a random salt. 2. Concatenate the password and the salt. 3. Use sha256sum to hash the combination. 4. Store both the salt and the hash.

Background and Simpler Explanation

Hashing is like mixing your password into a secret recipe that nobody else knows, even if someone sees the finished dish (the hash), they cannot figure out the ingredients (your original password and the salt). The sha256sum utility helps by taking the combined mixture (password and salt) and turning it into a consistent, fixed-size format.

Here’s a quick example:

Generate a Salt: salt=$(openssl rand -base64 12)
Hash a Password with Salt: echo -n "yourPassword${salt}" | sha256sum

This will output a hash which you would store along with the salt.

Executable Script

#!/bin/bash

# Script to securely hash a password with sha256sum and a salt.

read -sp "Enter your password: " user_password
echo
salt=$(openssl rand -base64 12)
echo "Generated Salt: $salt"

hash=$(echo -n "${user_password}${salt}" | sha256sum | awk '{print $1}')
echo "Your hashed password is: $hash"
echo "Store this hash and the salt securely."

# Always remember to never store or print user_password in practice.

This script starts by asking the user for a password, generates a random salt, hashes the password together with the salt, and then outputs the hash and stores the salt. Remember, never store the actual password or print it out in a real application.

Summary Conclusion

Hashing passwords using sha256sum and a salt is a powerful method to secure passwords in Linux-based systems. By adding a salt and using a robust cryptographic hash function, you ensure that your passwords are not only secure from theft but also from different types of cryptographic attacks. It’s a straightforward yet efficient way to handle passwords, and with the script provided, you can adopt this method in your own applications to bolster their security.

Always remember, security is not just a feature, it is a crucial foundation of any system that handles sensitive information.

How to Securely Hash Passwords with sha256sum and a Salt in Linux Bash

Q1: What is hashing and why is it necessary?

Q2: What is sha256sum?