Hash Generator

What is a Hash Function?

A cryptographic hash function takes an input of any size and produces a fixed-length string of characters called a digest (or hash). The key property is determinism: the same input always produces the same output. Even a single-bit change in the input produces a completely different hash — this is known as the avalanche effect.

Hash functions are one-way: it is computationally infeasible to reverse a hash back to its original input. This makes them essential for password storage, data integrity verification, and digital signatures.

Supported Algorithms

• MD5 — 128-bit (32 hex characters). Developed by Ronald Rivest in 1991. Fast but cryptographically broken since 2004 (collision attacks by Xiaoyun Wang). Still widely used for non-security checksums, such as verifying file downloads.
• SHA-1 — 160-bit (40 hex characters). Designed by the NSA, published in 1995. Deprecated for cryptographic use since 2017 after Google's SHAttered attack demonstrated practical collisions. Major browsers and CAs stopped accepting SHA-1 certificates.
• SHA-256 — 256-bit (64 hex characters) from the SHA-2 family. The most widely used secure hash today: Bitcoin mining, TLS certificates, code signing, and digital signatures all rely on SHA-256.
• SHA-384 — 384-bit (96 hex characters) from SHA-2. A truncated version of SHA-512 that provides stronger security margins. Used in government and financial applications where higher assurance is required.
• SHA-512 — 512-bit (128 hex characters) from SHA-2. The strongest hash in this family. Paradoxically, it can be faster than SHA-256 on 64-bit processors. Used in critical security applications and long-term data protection.

Common Use Cases

• File integrity verification — compare a downloaded file's hash against the publisher's checksum to detect corruption or tampering
• Password storage — databases store hashed passwords instead of plaintext (combined with salting and key stretching like bcrypt or Argon2)
• Digital signatures — sign the hash of a document rather than the document itself for efficiency
• Blockchain — Bitcoin uses double-SHA-256 to secure blocks and transactions
• Data deduplication — identify duplicate files by comparing their hashes instead of full content
• HMAC — Hash-based Message Authentication Codes verify both data integrity and authenticity

Security Considerations

Not all hash algorithms are created equal. MD5 and SHA-1 are vulnerable to collision attacks and should not be used for security purposes. For cryptographic applications, use SHA-256 or stronger. For password hashing specifically, use purpose-built algorithms like bcrypt, scrypt, or Argon2 — they include salting and are intentionally slow to resist brute-force attacks.