What is a Cryptographic Hash?
A cryptographic hash function takes an input (or 'message') and returns a fixed-size string of bytes. The output, called a hash or digest, is unique to each unique input. Even a small change to the input produces a completely different hash.
Hashes are one-way functions â you can't reverse a hash to get the original input. This makes them perfect for password storage, data integrity verification, and digital signatures.
Hash Algorithm Comparison
MD5 (Message Digest 5)
Produces a 128-bit (32 character) hash. Fast but considered cryptographically broken and unsuitable for security purposes.
â ī¸ Not recommended for security applications
SHA-1 (Secure Hash Algorithm 1)
Produces a 160-bit (40 character) hash. No longer considered secure due to successful collision attacks.
â ī¸ Deprecated for security use
SHA-256 (SHA-2 family)
Produces a 256-bit (64 character) hash. Currently considered secure and widely used in blockchain, SSL, and password hashing.
â Recommended for most applications
SHA-512 (SHA-2 family)
Produces a 512-bit (128 character) hash. Offers higher security than SHA-256 with slower performance.
â Best for maximum security
Common Use Cases
đ Password Storage
Hash passwords before storing them in databases. Even if your database is compromised, attackers can't retrieve the original passwords. (Note: Use specialized password hashing like bcrypt or Argon2 for production.)
â Data Integrity
Verify that downloaded files haven't been corrupted or tampered with by comparing their hashes against published values.
đ Digital Signatures
Create unique identifiers for documents or data that change if the content is modified.
⥠Caching Keys
Generate unique cache keys from request parameters or file contents.
Frequently Asked Questions
Can I reverse a hash to get the original text?
No. Hash functions are one-way. However, weak hashes like MD5 can be cracked using rainbow tables or brute force if the input is simple.
Is my input data secure?
Yes. All hashing happens locally in your browser using JavaScript's Web Crypto API. Your data never leaves your device.
Which algorithm should I use?
For security: Use SHA-256 or SHA-512. For non-security checksums: MD5 is faster. For password storage: Use bcrypt, scrypt, or Argon2 (not available in this tool).
Why do hashes have different lengths?
Different algorithms produce different bit lengths: MD5 (128-bit), SHA-1 (160-bit), SHA-256 (256-bit), SHA-512 (512-bit). Longer hashes are generally more secure.