SHA-1 is another important cryptographic concept with a fascinating history in computing. Here’s a breakdown:

🔐 What Is SHA-1?

SHA-1 stands for Secure Hash Algorithm 1. It’s a hash function developed by the U.S. National Security Agency (NSA) and published by NIST in 1995. Like MD5, it takes an input (any size) and produces a 160-bit (20-byte) hash—usually represented as a 40-character hexadecimal string, like:

a9993e364706816aba3e25717850c26c9cd0d89d

🧠 What Does It Do?

SHA-1 acts like a digital fingerprint for data:

• You input a file, text, or message—and SHA-1 generates a fixed-size hash.
• Even a tiny change in input will dramatically change the output.
• This makes it useful for verifying data hasn’t been changed or corrupted.

🛠 Common Uses (Past & Some Present)

• File integrity checks (e.g., checking for tampering or transmission errors).
• Version control systems like Git (though newer versions support SHA-256).
• Digital certificates & signatures (though it’s now deprecated in many cases).

⚠️ Security Warning

SHA-1 is no longer considered secure for cryptographic use because:

• It’s vulnerable to collision attacks, where two different inputs produce the same hash.
• In 2017, Google demonstrated a practical collision, effectively “breaking” SHA-1.

Modern systems now prefer stronger algorithms like:

• SHA-256
• SHA-3
• Or other encryption algorithms depending on the context