The Dev Tools - Free Online Developer Utilities

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About Hash Generation

A hash function is a mathematical function that converts an input (or 'message') into a fixed-size string of bytes. The output is typically a 'digest' that is unique to each unique input.

Hash Function Properties

Good hash functions are deterministic (same input always produces same output), fast to compute, and have a low probability of collisions (different inputs producing the same output).

Common Use Cases

Password Storage: Hash passwords before storing them in databases (use salt for security)
Data Integrity: Verify that data hasn't been tampered with during transmission
Digital Signatures: Create digital signatures for authentication and non-repudiation
File Verification: Verify file integrity by comparing hash values

Tips

SHA1 is considered cryptographically weak - use SHA256 or SHA512 for security
Always use salt when hashing passwords to prevent rainbow table attacks
Hash functions are one-way - you cannot reverse a hash to get the original input
Use HMAC (Hash-based Message Authentication Code) for message authentication
Consider using bcrypt or scrypt for password hashing instead of simple hash functions

Hash Algorithm Comparison

SHA1: 160-bit hash, deprecated for security purposes but still widely used
SHA256: 256-bit hash, widely used and secure (recommended)
SHA384: 384-bit hash, higher security than SHA256
SHA512: 512-bit hash, most secure but larger output

Note about MD5

MD5 is not supported by the Web Crypto API due to security vulnerabilities. For legacy MD5 support, use server-side implementations or dedicated libraries.