Secure Hash Algorithms (SHAs) are cryptographic functions designed to take an input of any size and produce a fixed-size hash value (message digest).
- These hashes help verify data integrity, authenticity, and security in various applications such as password hashing, digital signatures, SSL/TLS encryption, and blockchain technology.
- The Secure Hash Algorithms (SHA) family were developed by NIST (National Institute of Standards and Technology) for stronger security than MD5.
Key Features of SHA:
- Fixed-Length Output – The hash function converts input of any length into a fixed-size hash (e.g., 256-bit for SHA-256).
- Fast Computation – Efficient to compute for any given input.
- Pre-Image Resistance – Given a hash output, it should be computationally infeasible to reverse-engineer the original
- Deterministic – The same input always produces the same hash value.
- Irreversible – The hash cannot be converted back into the original input.
- Unique Hashes (Collision Resistance) – It should be extremely difficult for two different inputs to produce the same hash.
- Avalanche Effect – A small change in input drastically changes the output.
Applications of SHAs:
- Digital Signatures: Verifying the authenticity of digital documents and messages.
- Password Storage: Storing hashed passwords instead of plain text to protect against data breaches.
- Data Integrity: Detecting unauthorized modifications to data.
- Blockchain Technology: Ensuring the security and integrity of blockchain transactions.
Importance of SHA Security:
- The security of many cryptographic systems relies on the security of the underlying SHA algorithm. If a SHA algorithm is found to be vulnerable, it can compromise the security of numerous applications. It is essential to use strong and up-to-date SHA algorithms to protect sensitive data.
Common SHA Algorithms:
- SHA-1
- SHA-2
- SHA-3
1.) SHA-1 (Secure Hash Algorithm 1):
SHA-1 is a cryptographic hash function developed by NIST (National Institute of Standards and Technology) that produces a 160-bit fixed-length hash value.
- It was widely used in SSL/TLS encryption, digital signatures, and code signing.
- More secure than MD5, but still vulnerable to collision attacks.
- Deprecated since 2017 due to security vulnerabilities.
2.) SHA-2 (Secure Hash Algorithm 2):
SHA-2 is a family of cryptographic hash functions developed by NIST as an improved version of SHA-1.
- It includes multiple variants such as SHA-224, SHA-256, SHA-384, and SHA-512, which differ in output size and security strength.
- SHA-256 (256-bit output) is widely used in blockchain technology, SSL/TLS encryption, and digital certificates.
- SHA-2 is highly resistant to collision attacks and brute-force attacks, making it one of the most secure cryptographic hash functions in use today.
