Hashing

SSZ utilizes the SHA-256 hash function.

The standard specification for SHA-256 can be found in FIPS 180-4.

Hashing primitive for binary trees:

H(a: bytes32, b: bytes32) -> SHA_256(a ++ b)

• Where ++ is concatenation, i.e. tightly packing a and b into 64 bytes.
• And SHA_256 is run on the standard unmodified pre-state, and returns the digest after writing and processing the above 64 bytes.