SHA-256 (Cryptographic Hash)

Maps data of any length to a fixed 256-bit digest in a way that is hard to reverse or collide.

Difficulty: Advanced

How it works

  1. A hash function like SHA-256 takes any input (a short message or a whole file) and produces a fixed-size output called a digest or hash.
  2. Good cryptographic hashes are one-way: given a hash, it should be infeasible to find any input that produces it.
  3. They are also collision-resistant: it should be infeasible to find two different inputs with the same hash value.
  4. Hashes are used to check file integrity, build digital signatures, store password verifiers (with extra protection) and construct many advanced protocols.
  5. Remember that hashes are not encryption: you cannot decrypt a hash to recover the original input.
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What is it?

SHA-256 (Secure Hash Algorithm 256-bit) is a cryptographic hash function published by the NSA. A hash function is not an encryption algorithm; rather, it is a one-way mathematical function that takes an input of any size and produces a fixed-size 256-bit output (the hash or digest). It is designed to be collision-resistant, meaning it should be impossible to find two different inputs that produce the same output. SHA-256 is the absolute backbone of digital trust today, securing SSL certificates, digital signatures, and the Bitcoin blockchain.

Try it yourself

Can you decrypt this challenge?

VHVY GUVF ZRNGL (example ciphertext)

Where this shows up today

To provide a secure, collision-resistant way to verify data integrity without revealing the data itself.