Crate pqc_sphincsplus

SPHINCS⁺

A rust implementation of the SPHINCS⁺ stateless hash-based signature scheme, which has been included in NIST’s post-quantum cryptographic standard.

It is highly recommended to use SPHINCS⁺ in a hybrid system alongside a traditional signature algorithm such as RSA or ed25519.

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Usage

To compile this library needs one from each of the following categories to be enabled, using more than one from each group will result in a compile error.

For example in Cargo.toml:

[dependencies]
pqc_sphincsplus = {version = "0.1.0", features = ["haraka", "f128", "simple"]}

To generate a keypair and sign a message with it:

 use pqc_sphincsplus::*;
 let keys = keypair();
 let msg = [0u8; 32];
 let sig = sign(&msg, &keys);
 let sig_verify = verify(&sig, &msg, &keys);
 assert!(sig_verify.is_ok());

The security levels target 128, 192 and 256 bit equivalents, corresponding to NIST levels 1,3,5 respectively. They are also separated into fast (f) and small (s) subtypes, which make the tradeoff between either quicker signing or smaller signatures sizes.

SPHINCS+ introduces a split of the signature schemes into a simple and a robust variant for each choice of hash function. The robust variant is from the original NIST PQC first round submission and comes with all the conservative security guarantees given before. The simple variants are pure random oracle instantiations. These instantiations achieve about a factor three speed-up compared to the robust counterparts. This comes at the cost of a purely heuristic security argument.

• Hash

  • haraka
  • sha2
  • shake

• Security Level

  • f128
  • f192
  • f256
  • s128
  • s192
  • s256

• TreeHash

  • simple
  • robust

A comparison of the different security levels is below.

	n	h	d	log(t)	k	w	bit security	pk bytes	sk bytes	sig bytes
SPHINCS+-128s	16	63	7	12	14	16	133	32	64	7,856
SPHINCS+-128f	16	66	22	6	33	16	128	32	64	17,088
SPHINCS+-192s	24	63	7	14	17	16	193	48	96	16,224
SPHINCS+-192f	24	66	22	8	33	16	194	48	96	35,664
SPHINCS+-256s	32	64	8	14	22	16	255	64	128	29,792
SPHINCS+-256f	32	68	17	9	35	16	255	64	128	49,856