fastcrypto 0.1.9

Common cryptographic library used at Mysten Labs
Documentation 
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// Copyright (c) 2022, Mysten Labs, Inc.
// SPDX-License-Identifier: Apache-2.0

use crate::groups::ristretto255::RistrettoPoint;
use crate::groups::ristretto255::RistrettoScalar;
use crate::groups::{GroupElement, MultiScalarMul};
use crate::serde_helpers::ToFromByteArray;

#[test]
fn test_arithmetic() {
    // From https://ristretto.group/test_vectors/ristretto255.html
    let five_bp = RistrettoPoint::try_from(
        hex::decode("e882b131016b52c1d3337080187cf768423efccbb517bb495ab812c4160ff44e")
            .unwrap()
            .as_slice(),
    )
    .unwrap();

    // Test that different ways of computing [5]G gives the expected result
    let g = RistrettoPoint::generator();

    let p1 = g * RistrettoScalar::from(5);
    assert_eq!(five_bp, p1);

    let p2 = g + g + g + g + g + g - g;
    assert_eq!(five_bp, p2);

    let mut p3 = RistrettoPoint::zero();
    p3 += p2;
    assert_eq!(five_bp, p3);

    let mut p4 = g;
    p4 *= RistrettoScalar::from(5);
    assert_eq!(five_bp, p4);

    let p5 = g * (RistrettoScalar::from(7) - RistrettoScalar::from(2));
    assert_eq!(five_bp, p5);

    assert!((RistrettoPoint::generator() / RistrettoScalar::zero()).is_err());

    // Test the order of the base point
    assert_ne!(RistrettoPoint::zero(), g);
    assert_eq!(RistrettoPoint::zero(), g * RistrettoScalar::group_order());

    // RistrettoScalar::from_byte_array should accept only canonical representations.
    assert!(
        RistrettoScalar::from_byte_array(&RistrettoScalar::group_order().to_byte_array()).is_err()
    );
    assert!(RistrettoScalar::from_byte_array(
        &(RistrettoScalar::group_order() - RistrettoScalar::from(1)).to_byte_array()
    )
    .is_ok());

    // Check that u128 is decoded correctly.
    let x: u128 = 2 << 66;
    let x_scalar = RistrettoScalar::from(x);
    let in_u64 = x_scalar / RistrettoScalar::from(8);
    assert_eq!(in_u64.unwrap(), RistrettoScalar::from(2 << 63));
}

#[test]
fn test_serialize_deserialize_element() {
    let p = RistrettoPoint::generator() + RistrettoPoint::generator();
    let serialized = bincode::serialize(&p).unwrap();
    let deserialized: RistrettoPoint = bincode::deserialize(&serialized).unwrap();
    assert_eq!(deserialized, p);
}

#[test]
fn test_compress_decompress() {
    let p = RistrettoPoint::generator() + RistrettoPoint::generator();
    let compressed = p.compress();
    let decompressed: RistrettoPoint = RistrettoPoint::decompress(&compressed).unwrap();
    assert_eq!(decompressed, p);
}

#[test]
fn test_vectors() {
    // Test vectors from draft-irtf-cfrg-ristretto255-decaf448-03
    const VEC_MULGEN: [&str; 16] = [
        "0000000000000000000000000000000000000000000000000000000000000000",
        "e2f2ae0a6abc4e71a884a961c500515f58e30b6aa582dd8db6a65945e08d2d76",
        "6a493210f7499cd17fecb510ae0cea23a110e8d5b901f8acadd3095c73a3b919",
        "94741f5d5d52755ece4f23f044ee27d5d1ea1e2bd196b462166b16152a9d0259",
        "da80862773358b466ffadfe0b3293ab3d9fd53c5ea6c955358f568322daf6a57",
        "e882b131016b52c1d3337080187cf768423efccbb517bb495ab812c4160ff44e",
        "f64746d3c92b13050ed8d80236a7f0007c3b3f962f5ba793d19a601ebb1df403",
        "44f53520926ec81fbd5a387845beb7df85a96a24ece18738bdcfa6a7822a176d",
        "903293d8f2287ebe10e2374dc1a53e0bc887e592699f02d077d5263cdd55601c",
        "02622ace8f7303a31cafc63f8fc48fdc16e1c8c8d234b2f0d6685282a9076031",
        "20706fd788b2720a1ed2a5dad4952b01f413bcf0e7564de8cdc816689e2db95f",
        "bce83f8ba5dd2fa572864c24ba1810f9522bc6004afe95877ac73241cafdab42",
        "e4549ee16b9aa03099ca208c67adafcafa4c3f3e4e5303de6026e3ca8ff84460",
        "aa52e000df2e16f55fb1032fc33bc42742dad6bd5a8fc0be0167436c5948501f",
        "46376b80f409b29dc2b5f6f0c52591990896e5716f41477cd30085ab7f10301e",
        "e0c418f7c8d9c4cdd7395b93ea124f3ad99021bb681dfc3302a9d99a2e53e64e",
    ];

    for (i, item) in VEC_MULGEN.iter().enumerate() {
        let actual = RistrettoPoint::generator() * RistrettoScalar::from(i as u128);
        let expected = RistrettoPoint::try_from(hex::decode(item).unwrap().as_slice()).unwrap();
        assert_eq!(expected, actual);
    }

    const VEC_INVALID: [&str; 29] = [
        // Non-canonical field encodings.
        "00ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff",
        "ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff7f",
        "f3ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff7f",
        "edffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff7f",
        // Negative field elements.
        "0100000000000000000000000000000000000000000000000000000000000000",
        "01ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff7f",
        "ed57ffd8c914fb201471d1c3d245ce3c746fcbe63a3679d51b6a516ebebe0e20",
        "c34c4e1826e5d403b78e246e88aa051c36ccf0aafebffe137d148a2bf9104562",
        "c940e5a4404157cfb1628b108db051a8d439e1a421394ec4ebccb9ec92a8ac78",
        "47cfc5497c53dc8e61c91d17fd626ffb1c49e2bca94eed052281b510b1117a24",
        "f1c6165d33367351b0da8f6e4511010c68174a03b6581212c71c0e1d026c3c72",
        "87260f7a2f12495118360f02c26a470f450dadf34a413d21042b43b9d93e1309",
        // Non-square x^2.
        "26948d35ca62e643e26a83177332e6b6afeb9d08e4268b650f1f5bbd8d81d371",
        "4eac077a713c57b4f4397629a4145982c661f48044dd3f96427d40b147d9742f",
        "de6a7b00deadc788eb6b6c8d20c0ae96c2f2019078fa604fee5b87d6e989ad7b",
        "bcab477be20861e01e4a0e295284146a510150d9817763caf1a6f4b422d67042",
        "2a292df7e32cababbd9de088d1d1abec9fc0440f637ed2fba145094dc14bea08",
        "f4a9e534fc0d216c44b218fa0c42d99635a0127ee2e53c712f70609649fdff22",
        "8268436f8c4126196cf64b3c7ddbda90746a378625f9813dd9b8457077256731",
        "2810e5cbc2cc4d4eece54f61c6f69758e289aa7ab440b3cbeaa21995c2f4232b",
        // Negative xy value.
        "3eb858e78f5a7254d8c9731174a94f76755fd3941c0ac93735c07ba14579630e",
        "a45fdc55c76448c049a1ab33f17023edfb2be3581e9c7aade8a6125215e04220",
        "d483fe813c6ba647ebbfd3ec41adca1c6130c2beeee9d9bf065c8d151c5f396e",
        "8a2e1d30050198c65a54483123960ccc38aef6848e1ec8f5f780e8523769ba32",
        "32888462f8b486c68ad7dd9610be5192bbeaf3b443951ac1a8118419d9fa097b",
        "227142501b9d4355ccba290404bde41575b037693cef1f438c47f8fbf35d1165",
        "5c37cc491da847cfeb9281d407efc41e15144c876e0170b499a96a22ed31e01e",
        "445425117cb8c90edcbc7c1cc0e74f747f2c1efa5630a967c64f287792a48a4b",
        // s = -1, which causes y = 0.
        "ecffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff7f",
    ];

    for item in VEC_INVALID.iter() {
        assert!(RistrettoPoint::try_from(hex::decode(item).unwrap().as_slice()).is_err());
    }

    const VEC_MAP: [(&str, &str); 11] = [
        ("5d1be09e3d0c82fc538112490e35701979d99e06ca3e2b5b54bffe8b4dc772c14d98b696a1bbfb5ca32c436cc61c16563790306c79eaca7705668b47dffe5bb6",
            "3066f82a1a747d45120d1740f14358531a8f04bbffe6a819f86dfe50f44a0a46"),
        ("f116b34b8f17ceb56e8732a60d913dd10cce47a6d53bee9204be8b44f6678b270102a56902e2488c46120e9276cfe54638286b9e4b3cdb470b542d46c2068d38",
            "f26e5b6f7d362d2d2a94c5d0e7602cb4773c95a2e5c31a64f133189fa76ed61b"),
        ("8422e1bbdaab52938b81fd602effb6f89110e1e57208ad12d9ad767e2e25510c27140775f9337088b982d83d7fcf0b2fa1edffe51952cbe7365e95c86eaf325c",
            "006ccd2a9e6867e6a2c5cea83d3302cc9de128dd2a9a57dd8ee7b9d7ffe02826"),
        ("ac22415129b61427bf464e17baee8db65940c233b98afce8d17c57beeb7876c2150d15af1cb1fb824bbd14955f2b57d08d388aab431a391cfc33d5bafb5dbbaf",
            "f8f0c87cf237953c5890aec3998169005dae3eca1fbb04548c635953c817f92a"),
        ("165d697a1ef3d5cf3c38565beefcf88c0f282b8e7dbd28544c483432f1cec7675debea8ebb4e5fe7d6f6e5db15f15587ac4d4d4a1de7191e0c1ca6664abcc413",
            "ae81e7dedf20a497e10c304a765c1767a42d6e06029758d2d7e8ef7cc4c41179"),
        ("a836e6c9a9ca9f1e8d486273ad56a78c70cf18f0ce10abb1c7172ddd605d7fd2979854f47ae1ccf204a33102095b4200e5befc0465accc263175485f0e17ea5c",
            "e2705652ff9f5e44d3e841bf1c251cf7dddb77d140870d1ab2ed64f1a9ce8628"),
        ("2cdc11eaeb95daf01189417cdddbf95952993aa9cb9c640eb5058d09702c74622c9965a697a3b345ec24ee56335b556e677b30e6f90ac77d781064f866a3c982",
            "80bd07262511cdde4863f8a7434cef696750681cb9510eea557088f76d9e5065"),
        ("edffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff1200000000000000000000000000000000000000000000000000000000000000",
            "304282791023b73128d277bdcb5c7746ef2eac08dde9f2983379cb8e5ef0517f"),
        ("edffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff7fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff",
            "304282791023b73128d277bdcb5c7746ef2eac08dde9f2983379cb8e5ef0517f"),
        ("0000000000000000000000000000000000000000000000000000000000000080ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff7f",
            "304282791023b73128d277bdcb5c7746ef2eac08dde9f2983379cb8e5ef0517f"),
        ("00000000000000000000000000000000000000000000000000000000000000001200000000000000000000000000000000000000000000000000000000000080",
            "304282791023b73128d277bdcb5c7746ef2eac08dde9f2983379cb8e5ef0517f")
        ];

    for (i, o) in VEC_MAP.iter() {
        let actual =
            RistrettoPoint::from_uniform_bytes(&hex::decode(i).unwrap().try_into().unwrap());
        let expected = hex::decode(o).unwrap();
        assert_eq!(expected, actual.compress());
    }
}

#[test]
fn test_multiscalar_mul() {
    let g = RistrettoPoint::generator();
    let h = RistrettoPoint::multi_scalar_mul(
        &[
            RistrettoScalar::from(1),
            RistrettoScalar::from(2),
            RistrettoScalar::from(3),
        ],
        &[g, g, g],
    )
    .unwrap();
    assert_eq!(g * RistrettoScalar::from(6), h);

    // Invalid lengths
    assert!(RistrettoPoint::multi_scalar_mul(
        &[RistrettoScalar::from(1), RistrettoScalar::from(2)],
        &[g, g, g]
    )
    .is_err());
}