SHACAL-2
SHACAL-2 is a derived cipher that treats the SHA-256 compression function as a block cipher, with the chaining value as plaintext and the message block as key.
Purpose
It builds a block cipher from the SHA-256 compression function, used to analyze SHA-256 and design SHA-2-based cryptographic schemes.
Mechanism
The SHA-256 compression function is invertible in the chaining value (given the message block), yielding a block cipher keyed by the 512-bit message block with the 256-bit chaining value as plaintext. NESSIE once evaluated it.
Use cases
- SHA-256 security analysis
- Hash-derived ciphers
- NESSIE evaluation