What is SipHash-128-2-4?
SipHash-128-2-4 is a fast keyed hash function designed for short messages and hash-table protection. It uses a 128-bit secret key and produces a 128-bit output, usually displayed as a 32-character hexadecimal value.
When to use it
- Protect server-side hash tables from hash-flooding attacks when the key stays private.
- Build deterministic keyed checksums for cache keys, sharding, or internal lookup tables.
- Compare text snippets or files with the same key when cryptographic authentication is not required.
Key format
Enter the key as exactly 16 bytes of hexadecimal data, such as 0x000102030405060708090a0b0c0d0e0f. The 0x prefix is optional, and the tool accepts spaces, colons, hyphens, and underscores to make long keys easier to read.
Security notes
SipHash-128-2-4 is not a replacement for HMAC, digital signatures, or password hashing. Use it for keyed hash-table and checksum workflows, not for proving authenticity across systems that need cryptographic security guarantees.