What is a cryptographic hash?

A cryptographic hash is a one-way function that converts input data of any size into a fixed-size output (hash or digest). Key properties: deterministic (same input = same hash), irreversible (cannot recover input from hash), avalanche effect (tiny input change = completely different hash), collision-resistant (hard to find two inputs with same hash). Example: SHA-256("hello") always produces "2cf24dba5fb0a30e...".

What is the difference between MD5, SHA-1, SHA-256, and SHA-512?

MD5 (128-bit) and SHA-1 (160-bit) are deprecated due to collision vulnerabilities; use only for non-security checksums. SHA-256 (256-bit) is the current standard for most applications: file integrity, digital signatures, blockchain. SHA-512 (512-bit) offers higher security for long-term cryptographic needs but is slower. Recommendation: SHA-256 for general use, SHA-512 for high-security/long-term data, never MD5/SHA-1 for security.

Can I use hashes for password storage?

No. Never use fast hashes (MD5, SHA-256) for passwords. Attackers can test billions of hashes per second using GPUs. Use password-specific algorithms: bcrypt, scrypt, Argon2. These are intentionally slow (adaptive cost factor) and include salts (random data preventing rainbow table attacks). Example: Argon2 takes 100ms per hash, limiting attackers to 10 guesses/second vs 10 billion/second with SHA-256.

What are common use cases for hashes?

File integrity verification: compare file hash before/after transfer to detect corruption or tampering. Digital signatures: hash documents before signing (faster than signing entire document). Data deduplication: identify duplicate files by comparing hashes. Git version control: commit IDs are SHA-1 hashes. Blockchain: block integrity via hash chains. Caching: use hash of request as cache key. NOT for passwords (use bcrypt/Argon2).

What is a hash collision?

A hash collision occurs when two different inputs produce the same hash output. Collisions are inevitable (infinite inputs → finite outputs) but should be computationally infeasible. MD5 collisions can be found in seconds (broken algorithm). SHA-1 collisions cost $100K to generate (deprecated). SHA-256 collisions are theoretically possible but require 2^128 operations (impossible with current technology). For practical purposes, SHA-256 is collision-free.

How do I verify file integrity with hashes?

Download the file and its published hash (often on the official website). Generate the hash of your downloaded file using the same algorithm (e.g., SHA-256). Compare the two hashes character-by-character. If identical, the file is intact and authentic. If different, the file is corrupted or tampered with—do not use it. Example: Linux ISOs publish SHA-256 checksums; users verify downloads before installation to ensure no malware injection during transit.

Hash Generator - MD5, SHA-256, SHA-512

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Hash Generator Features

Multiple Algorithms: MD5, SHA-1, SHA-256, SHA-512
One-Way Hashing: Cannot reverse hash to get original
Instant Generation: Real-time hash computation
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What are Cryptographic Hashes?

Cryptographic hashes are one-way functions that produce fixed-size output from any input. Same input always produces same hash. Cannot reverse hash to get original. Even tiny changes in input produce completely different hash (avalanche effect).

MD5 (128-bit) and SHA-1 (160-bit) are deprecated due to collision attacks. Use SHA-256 (256-bit) or SHA-512 (512-bit) for security. MD5 is still acceptable for non-security use like checksums. For password hashing, use bcrypt or Argon2 instead—they're designed to be slow to resist brute force.

Use cases: File integrity verification (compare hash of downloaded file to published hash), checksums for data transmission, git commit IDs, content-addressable storage, data deduplication, and cache keys. Warning: Never use for password storage—use proper password hashing algorithms.

Privacy & Security

All hash generation happens locally in your browser. Your text is never uploaded to servers, stored, or logged. The hashing uses JavaScript crypto libraries, keeping your data completely private.