Excerpt
PBKDF2withHMACSHA1 refers to using PBKDF2 and HMAC-SHA1 together to enhance password hashing security. This article explains what PBKDF2 and HMAC-SHA1 are and their role in cryptography.
Passwords are a common means of authentication used by many applications and services. Protecting passwords against threats like brute force attacks is crucial. PBKDF2withHMACSHA1 refers to an enhanced key derivation technique that applies cryptographic hashing to safeguard passwords. In this post, we’ll explore what exactly PBKDF2 and HMAC-SHA1 are, and why combining them provides stronger security for password-based systems.
Introduction
Many applications require users to authenticate via passwords. But passwords in their raw form are vulnerable to brute force attacks that can crack them through guessing. Password-based key derivation functions (PBKDFs) are techniques that apply multiple rounds of cryptographic hashing to passwords to protect against such threats.
PBKDF2withHMACSHA1 is a specific implementation defined in RSA Laboratories’ Public-Key Cryptography Standards (PKCS). It combines two layers of key strengthening based on the PBKDF2 algorithm and HMAC-SHA1 cryptographic hash. When used together correctly, PBKDF2withHMACSHA1 can significantly enhance password security.
Understanding Password-Based Key Derivation Function 2 (PBKDF2)
PBKDF2 is a key derivation function designed to securely generate cryptographic keys from passwords with adjustable computational workload. Here’s an overview:
Published as part of PKCS #5 v2.0 standard by RSA Labs in 2000.
Applies pseudo-random function (PRF) such as hash-based HMAC on input password.
Repeats PRF in adjustable iterations with added salt at each stage.
Output derived key size and iteration count can be configured.
PBKDF2 provides tunable computation workload to frustrate brute force attacks even against weak passwords.
The Role of HMAC-SHA1 in PBKDF2
PBKDF2 allows the use of any pseudorandom function (PRF) or hash function. A popular choice is HMAC-SHA1:
HMAC-SHA1 applies SHA-1 cryptographic hash multiple times with a secret key.
This combines the cryptographic strength of SHA-1 with a secret value.
Using HMAC-SHA1 as the PRF in PBKDF2 enhances its security capabilities.
Each iteration provides additional protection by re-hashing previous outputs.
Together they create a powerful password hardening technique.
Exploring PBKDF2withHMACSHA1
PBKDF2withHMACSHA1 refers specifically to PBKDF2 implementation using HMAC-SHA1 as the PRF algorithm.
Key points about PBKDF2withHMACSHA1:
Significantly strengthens password security versus plain hashing.
Tunes computational workload required via iterations.
Adds salt at each stage to frustrate precomputed attacks.
Output size can be adjusted as per application requirements.
Combines cryptographic benefits of PBKDF2 and HMAC-SHA1.
Overall, it provides a flexible and highly secure password hashing scheme.
Advantages of PBKDF2withHMACSHA1
Some key advantages of using PBKDF2withHMACSHA1 for password security:
Resilient against brute force and dictionary attacks.
Customizable workload through iteration tuning slows cracking.
Salting each iteration defeats precomputed lookup table attacks.
Built-in randomness enhances entropy beyond just the password.
Modular design allows switching PRF algorithm if needed.
These features make password cracking extremely resource intensive.
Implementing PBKDF2withHMACSHA1
Here is sample code demonstrating usage of PBKDF2withHMACSHA1 in Python:
1import hashlib
2from pbkdf2 import PBKDF2
3
4password = "password123"
5salt = "NaCl"
6
7pbkdf2 = PBKDF2(password, salt, iterations=100000, hmac_hash_module=hashlib.sha1)
8key = pbkdf2.read_unicode(32)
9
10print(key.hex())
This applies 100,000 iterations of HMAC-SHA1 hash to strengthen the password. The output is a 256-bit derived key suitable for cryptographic use.
Alternatives to PBKDF2withHMACSHA1
Some other key derivation functions include:
- BCrypt - Uses Blowfish cipher instead of hashing.
- Scrypt - Enhances PBKDF2 with memory hardness.
- Argon2 - Optimized against GPU and other accelerated attacks.
Each have their own advantages and use cases depending on needs.
Conclusion
PBKDF2withHMACSHA1 combines password-based key derivation and cryptographic hashing to provide strong password security. The flexible workload tuning and salting frustrate brute force attacks even against weak passwords. While newer schemes exist, PBKDF2withHMACSHA1 remains a robust, widely supported means of hardening password systems. Proper implementation is key to maximizing its protection capabilities.
