Crate cyber_hemera 

Poseidon2 hash over the Goldilocks field (Hemera parameters).

WARNING

This is novel, unaudited cryptography. The parameter set, sponge construction, and self-bootstrapping round constant generation have not been reviewed by third-party cryptographers. Do not use in production systems where cryptographic guarantees are required. Use at your own risk.

The Hemera hash is not finalized and may change. Hash outputs, round constants, and the sponge construction are subject to breaking changes until a stable release.

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This crate provides a streaming hash API backed by the Poseidon2 algebraic hash function operating over the Goldilocks prime field (p = 2^64 - 2^32 + 1).

Hemera Parameters

• Field: Goldilocks (p = 2^64 - 2^32 + 1)
• State width: t = 16
• Full rounds: R_F = 8
• Partial rounds: R_P = 64
• S-box degree: d = 7 (x^7)
• Rate: 8 elements (56 input bytes per block)
• Capacity: 8 elements
• Output: 8 elements (64 bytes)
• Padding: 0x01 || 0x00*
• Encoding: little-endian canonical

Examples

use cyber_hemera::{hash, derive_key};

let digest = hash(b"hello world");
println!("{digest}");

let key = derive_key("my app v1", b"key material");

Modules

tree

BAO-style Merkle tree construction.

Structs

Hash

A 64-byte Poseidon2 hash output (Hemera: 8 Goldilocks elements).

Hasher

A streaming Poseidon2 hasher.

OutputReader

An extendable-output reader that can produce arbitrary-length output.

Constants

CAPACITY

Number of capacity elements in the sponge.

CHUNK_SIZE

Canonical chunk size for content tree construction (4 KB).

COLLISION_BITS

Classical collision resistance in bits.

OUTPUT_BYTES

Number of output bytes per squeeze (8 elements × 8 bytes).

OUTPUT_ELEMENTS

Number of output elements extracted per squeeze (= rate).

RATE

Number of rate elements in the sponge.

RATE_BYTES

Number of input bytes that fill one rate block (8 elements × 7 bytes).

ROUNDS_F

Number of full (external) rounds — 4 initial + 4 final.

ROUNDS_P

Number of partial (internal) rounds.

SBOX_DEGREE

S-box degree (x → x^d).

WIDTH

Width of the Poseidon2 state (number of Goldilocks field elements).

Functions

derive_key

Derive a key from a context string and key material.

hash

Hash the input bytes and return a 64-byte digest.

keyed_hash

Hash the input bytes with a key.