Question 1

What is SHA-256?

Accepted Answer

SHA-256 (Secure Hash Algorithm 256-bit) is a cryptographic hash function in the SHA-2 family. It converts input of any length into a fixed 256-bit (32-byte) hash value. SHA-256 is widely used in digital signatures, certificate verification, blockchain, and file integrity verification.

Question 2

What is the difference between SHA-256 and MD5?

Accepted Answer

Both are hash functions, but they differ in security. MD5 produces a 128-bit output and has known collision vulnerabilities, so it is not recommended for security-sensitive scenarios. SHA-256 produces a 256-bit output with no known collision attacks, making it the preferred choice for security-sensitive applications. Performance-wise, MD5 is faster, but SHA-256 is far more secure.

Question 3

Does the same input always produce the same hash?

Accepted Answer

Yes, this is a fundamental property of hash functions — determinism. The same input through SHA-256 always produces the same output. This is why SHA-256 is commonly used for file verification: compute the hash of a downloaded file and compare it with the officially published hash to verify the file has not been tampered with.

Question 4

Can the original content be derived from the hash?

Accepted Answer

No. SHA-256 is a one-way function; the original input cannot be reverse-engineered from the hash value. This is a core security property of hash functions. While collisions (different inputs producing the same output) theoretically exist, the computational complexity of finding a collision is approximately 2^128, which is practically infeasible.

SHA256

SHA256 Hash Tool Guide

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Use Cases

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