Web Crypto Hash Generator
Compute one-way cryptographic hash digests locally in your browser. Supports SHA-256 (the hash behind HS256), SHA-384, SHA-512, and displays deprecation warnings for SHA-1.
Web Crypto Hash Generator
Calculated via native window.crypto.subtle.digest in your browser
How to Compute Cryptographic Hash Digests
1. Enter Your Input Plaintext
Type or paste your arbitrary text, JSON payload, or token string into the input field.
2. Select Output Algorithm
Review simultaneous computations for SHA-256, SHA-384, SHA-512, and legacy SHA-1.
3. Copy Hexadecimal Digest
Click Copy to capture the fixed-size hex digest directly to your clipboard.
Cryptographic Hash Functions & W3C SubtleCrypto
A cryptographic hash function maps arbitrary-length input data into a fixed-size bit string. This tool utilizes the browser native window.crypto.subtle.digest() implementation for maximum speed and security. Cryptographic hashes exhibit pre-image resistance, second pre-image resistance, collision resistance, and the avalanche effect (a 1-bit input change alters ~50% of the output bits).
| Specification / Parameter | Standard & Enforced Value |
|---|---|
| SHA-256 Digest Size | 256 bits (32 bytes / 64 hex characters) |
| SHA-384 Digest Size | 384 bits (48 bytes / 96 hex characters) |
| SHA-512 Digest Size | 512 bits (64 bytes / 128 hex characters) |
| Implementation | Native browser Web Crypto API (SubtleCrypto) |
Security Boundaries: Hashes vs. Password Storage
Cryptographic hashes like SHA-256 are fast, deterministic functions designed for data integrity and signatures (like HMAC-SHA256). They are NOT suitable for password storage because specialized hardware (ASICs/GPUs) can compute billions of SHA-256 hashes per second. For password hashing, use dedicated memory-hard functions like Argon2id, bcrypt, or scrypt.
Frequently Asked Questions: Cryptographic Hashing
Can a SHA-256 hash be reversed to recover the original text?
No. Cryptographic hashes are one-way mathematical functions. Information is irreversibly compressed. The only way to find the input is through brute-force guessing or precomputed rainbow tables.
How does SHA-256 relate to HS256 in JWTs?
HS256 uses the HMAC construction with SHA-256 as its underlying hash function: HMAC-SHA256(secret, header.payload).
Why should I avoid using plain SHA-256 for user passwords?
Because SHA-256 is designed to be extremely fast. Attackers using modern GPU rigs can test over 10 billion password guesses per second. Always use Argon2, bcrypt, or scrypt for passwords.
Does this tool compute hashes on a server?
No. All calculations are executed directly in your browser using the W3C SubtleCrypto hardware-accelerated pipeline.