A Beginner’s Guide to Password Hashing Algorithms

A Beginner’s Guide to Password Hashing Algorithms

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Arka Infotech
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7 min read

Introduction

In the digital age, securing user credentials is a critical aspect of maintaining the integrity and safety of online platforms. One of the most effective ways to store and protect passwords is through password hashing. Password hashing is a technique that converts a plain-text password into a fixed-length string of characters, known as a hash. This hash is then stored in the system’s database instead of the original password, ensuring that even if the database is compromised, the passwords remain secure.

In this blog, we will explore the concept of password hashing, why it is important, the most commonly used password hashing algorithms, and best practices for implementing them. We will also include code examples to demonstrate how to hash passwords securely.

1. What is Password Hashing?

Password hashing is the process of converting a user’s password into a unique, fixed-length string using a cryptographic hash function. The key point here is that the process is one-way—you can hash a password, but you cannot easily reverse the hash to obtain the original password.

When a user creates or updates their password, the system applies a hashing algorithm to the password and stores the resulting hash. During login, the system hashes the entered password and compares it with the stored hash. If they match, the user is authenticated.

Unlike encryption, which is reversible (you can decrypt encrypted data), hashing is designed to be irreversible, making it a more secure method for storing passwords.

2. Why is Password Hashing Important?

Storing passwords in plain text is a major security risk. If an attacker gains access to the database, they can easily retrieve and use the passwords. Hashing provides a layer of security by ensuring that the actual passwords are never stored in the database.

Here are the key reasons why password hashing is crucial:

  • Prevents Plain-Text Password Storage: By hashing passwords, even if the database is compromised, the attacker cannot see or use the original passwords.

  • Adds Complexity: Hashing algorithms generate unique hashes for each password, even if two users have the same password.

  • Protection Against Rainbow Table Attacks: Rainbow tables are precomputed tables used for reversing cryptographic hash functions. By using salt (random data added to the password before hashing), we can make rainbow table attacks ineffective.

  • Enhanced Security with Salting and Stretching: Adding a random salt to each password before hashing and applying multiple rounds of hashing makes it significantly harder for attackers to crack passwords.

3. Commonly Used Password Hashing Algorithms

Several cryptographic hash functions are designed for password hashing. These algorithms are specially designed to be slow and computationally expensive to thwart brute-force attacks.

3.1 MD5 (Message Digest Algorithm 5)

MD5 was once a popular hash function, but it is no longer considered secure for password hashing. It is fast, but this speed makes it vulnerable to brute-force attacks. MD5 is now deprecated for cryptographic purposes, and it is recommended to use more secure alternatives.

3.2 SHA-1 (Secure Hash Algorithm 1)

SHA-1 was widely used for password hashing, but it has been found to be vulnerable to collision attacks (where two different inputs produce the same hash). As a result, SHA-1 is also not recommended for password hashing today.

3.3 SHA-256

SHA-256 is part of the SHA-2 family of hash functions and is considered much more secure than MD5 and SHA-1. It produces a 256-bit hash and is resistant to many types of attacks. However, it is still relatively fast, which can make it vulnerable to brute-force attacks if not used with additional security measures like salting.

3.4 bcrypt

bcrypt is a widely used password hashing algorithm designed to be slow and resistant to brute-force attacks. It includes a salt (random data added to the password before hashing) and applies multiple rounds of hashing, making it computationally expensive and thus harder for attackers to crack passwords.

Why bcrypt is preferred:

  • Built-in salting.

  • Configurable work factor (the number of rounds of hashing).

  • Designed to be slow, which makes brute-force attacks more difficult.

3.5 scrypt

scrypt is another password hashing algorithm that is designed to be even more secure than bcrypt. It uses both CPU and memory resources to make brute-force attacks more difficult. This makes scrypt an excellent choice for securing passwords in environments where attackers might have access to specialized hardware like GPUs.

3.6 Argon2

Argon2 is the winner of the Password Hashing Competition (PHC) and is considered one of the most secure password hashing algorithms available today. It is designed to be memory-hard, CPU-intensive, and resistant to parallel attacks. Argon2 has three variants: Argon2d, Argon2i, and Argon2id, each optimized for different use cases.

4. How to Implement Password Hashing

The implementation of password hashing depends on the algorithm you choose. Below are code examples using bcrypt, scrypt, and Argon2 in Python.

4.1 bcrypt Example (Python)

pythonCopy codeimport bcrypt

# Hash a password
password = b"my_secure_password"
salt = bcrypt.gensalt()  # Generate a salt
hashed_password = bcrypt.hashpw(password, salt)

# Verify the password
entered_password = b"my_secure_password"
if bcrypt.checkpw(entered_password, hashed_password):
    print("Password is correct!")
else:
    print("Invalid password.")

4.2 scrypt Example (Python)

pythonCopy codeimport hashlib

# Hash a password using scrypt
password = b"my_secure_password"
salt = b"random_salt"
hashed_password = hashlib.scrypt(password, salt=salt, n=16384, r=8, p=1, dklen=64)

# Print the hashed password
print(f"Hashed Password: {hashed_password.hex()}")

4.3 Argon2 Example (Python)

pythonCopy codefrom argon2 import PasswordHasher

# Initialize the Argon2 password hasher
ph = PasswordHasher()

# Hash a password
password = "my_secure_password"
hashed_password = ph.hash(password)

# Verify the password
try:
    ph.verify(hashed_password, password)
    print("Password is correct!")
except:
    print("Invalid password.")

5. Best Practices for Password Hashing

To ensure the highest level of security, follow these best practices when implementing password hashing:

  • Always use a salt: A salt is a random string added to the password before hashing. It ensures that even if two users have the same password, their hashes will be different.

  • Use a slow hashing algorithm: Choose algorithms like bcrypt, scrypt, or Argon2, which are designed to be slow and computationally expensive. This makes brute-force attacks more difficult.

  • Apply multiple rounds of hashing: Use a work factor or iteration count to apply multiple rounds of hashing, making it harder for attackers to crack the password.

  • Never store plain-text passwords: Always store the hashed version of the password, never the original password.

  • Use secure libraries: Use well-maintained cryptographic libraries (like bcrypt, argon2, or hashlib) rather than implementing your own hashing functions.

  • Keep your hashing algorithms up-to-date: Cryptographic algorithms can become vulnerable over time, so it's important to stay informed about security developments and update your systems accordingly.

6. Conclusion

Password hashing is a critical component of securing user credentials in modern applications. By using strong cryptographic hash functions like bcrypt, scrypt, or Argon2, you can protect your users' passwords from being exposed even in the event of a data breach. Always remember to use salting, slow algorithms, and secure key management practices to strengthen the security of your application.

As cyber threats evolve, password hashing remains one of the most effective ways to ensure that user data is protected. By following best practices and choosing the right hashing algorithm, you can build a secure system that keeps your users' information safe.

FAQs

Q1: What is the difference between encryption and hashing? Encryption is reversible, meaning that data can be decrypted using a key. Hashing is a one-way process, meaning the original data cannot be recovered from the hash.

Q2: Why is bcrypt better than MD5 for password hashing? bcrypt is specifically designed to be slow, making brute-force attacks more difficult. MD5 is fast and vulnerable to such attacks, which is why it is no longer considered secure for password hashing.

Q3: Can I use Argon2 for password hashing in my web application? Yes, Argon2 is an excellent choice for password hashing due to its security features and resistance to attacks. It is widely supported by modern cryptographic libraries.

Comments Section

What password hashing algorithms do you use in your projects? Share your experiences and any additional tips in the comments below!

Hashtags

#PasswordHashing #Cryptography #bcrypt #Argon2 #Cybersecurity

#passwordhashingCryptographyBcrypt Argon2#cybersecurity