Question 1

What is SHA-256?

Accepted Answer

SHA-256 (Secure Hash Algorithm 256-bit) is a cryptographic hash function producing a 256-bit (32-byte) fixed-length hash. It's part of the SHA-2 family designed by the NSA. SHA-256 is used in TLS/SSL certificates, Bitcoin blockchain, password verification, and data integrity checks.

Question 2

Is SHA-256 safe for passwords?

Accepted Answer

SHA-256 alone is NOT recommended for password hashing because it's too fast — attackers can try billions of guesses per second with GPUs. For passwords, use bcrypt, Argon2, or scrypt which are intentionally slow and have built-in salting.

Question 3

Can SHA-256 produce the same hash for different inputs?

Accepted Answer

Theoretically yes (collisions exist), but no practical SHA-256 collision has ever been found. The 256-bit output space (2^256 possible values) makes collision probability astronomically small. SHA-256 is considered collision-resistant — unlike MD5 and SHA-1, which have known practical collisions and should not be used for security.

Question 4

What is the output size of SHA-256?

Accepted Answer

SHA-256 always produces a 256-bit (32-byte) output, displayed as 64 hexadecimal characters. The output size is fixed regardless of the input size — whether the input is 1 byte or 1GB.

Question 5

How do I compute SHA-256 in different languages?

Accepted Answer

JavaScript: crypto.subtle.digest('SHA-256', data). Python: hashlib.sha256(data).hexdigest(). Go: sha256.Sum256(data). Java: MessageDigest.getInstance('SHA-256'). Linux command: sha256sum file.txt.

Question 6

How do I generate a SHA-256 hash?

Accepted Answer

Type or paste your text into the input above and click Generate. The SHA-256 hash appears instantly using the browser's built-in Web Crypto API — no data is sent to any server. SHA-256 always produces a 64-character hexadecimal string (256 bits). For file hashing, use the file upload option. For keyed hashing, use DevDecode's HMAC-SHA256 tool.

Question 7

Can you decrypt a SHA-256 hash?

Accepted Answer

No — SHA-256 is a one-way hash function, not encryption. You cannot reverse it mathematically. The only way to find the original input is brute-force or rainbow table attacks (which is why passwords should be hashed with bcrypt, not SHA-256). SHA-256 is used for data integrity verification, not secrecy. For password hashing, use DevDecode's Bcrypt Generator.

SHA-256 Hash Generator — Free Online SHA256 Tool

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SHA-256: The Standard for Cryptographic Hashing

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