Skein
Skein is a SHA-3 competition submission by Schneier et al., based on the UBI (Unique Block Input) mode over the Threefish block cipher.
Purpose
A SHA-3 finalist providing a fast, configurable, tree-mode flexible hash.
Mechanism
The Threefish-256/512/1024 block ciphers are composed in UBI mode: each block is encrypted with Threefish keyed by a key and a block-type tag, outputting a chaining value. Supports tree mode, keyed mode, and arbitrary output length.
Use cases
- SHA-3 competition submission
- Flexible hash configuration
- Tree-mode hashing