concrete_boolean/parameters/
mod.rs

1//! The cryptographic parameter set.
2//!
3//! This module provides the structure containing the cryptographic parameters required for the
4//! homomorphic evaluation of Boolean circuit as well as a list of secure cryptographic parameter
5//! sets.
6//!
7//! Two parameter sets are provided:
8//!  * `concrete_boolean::parameters::DEFAULT_PARAMETERS`
9//!  * `concrete_boolean::parameters::TFHE_LIB_PARAMETERS`
10//!
11//! They ensure the correctness of the Boolean circuit evaluation result (up to a certain
12//! probability) along with 128-bits of security.
13//!
14//! The two parameter sets offer a trade-off in terms of execution time versus error probability.
15//! The `DEFAULT_PARAMETERS` set offers better performances on homomorphic circuit evaluation
16//! with an higher probability error in comparison with the `TFHE_LIB_PARAMETERS`.
17//! Note that if you desire, you can also create your own set of parameters.
18//! This is an unsafe operation as failing to properly fix the parameters will potentially result
19//! with an incorrect and/or insecure computation.
20// TODO: speak about the lattice estimator and give the explicit used commit for the parameters
21
22pub use concrete_core::prelude::{
23    DecompositionBaseLog, DecompositionLevelCount, GlweDimension, LweDimension, PolynomialSize,
24    StandardDev,
25};
26use serde::{Deserialize, Serialize};
27
28/// A set of cryptographic parameters for homomorphic Boolean circuit evaluation.
29#[derive(Copy, Clone, Debug, PartialEq, Serialize, Deserialize)]
30pub struct BooleanParameters {
31    pub lwe_dimension: LweDimension,
32    pub glwe_dimension: GlweDimension,
33    pub polynomial_size: PolynomialSize,
34    pub lwe_modular_std_dev: StandardDev,
35    pub glwe_modular_std_dev: StandardDev,
36    pub pbs_base_log: DecompositionBaseLog,
37    pub pbs_level: DecompositionLevelCount,
38    pub ks_base_log: DecompositionBaseLog,
39    pub ks_level: DecompositionLevelCount,
40}
41
42impl BooleanParameters {
43    /// Constructs a new set of parameters for boolean circuit evaluation.
44    ///
45    /// # Safety
46    ///
47    /// This function is unsafe, as failing to fix the parameters properly would yield incorrect
48    /// and insecure computation. Unless you are a cryptographer who really knows the impact of each
49    /// of those parameters, you __must__ stick with the provided parameters [`DEFAULT_PARAMETERS`]
50    /// and [`TFHE_LIB_PARAMETERS`], which both offer correct results with 128 bits of security.
51    #[allow(clippy::too_many_arguments)]
52    pub unsafe fn new_insecure(
53        lwe_dimension: LweDimension,
54        glwe_dimension: GlweDimension,
55        polynomial_size: PolynomialSize,
56        lwe_modular_std_dev: StandardDev,
57        glwe_modular_std_dev: StandardDev,
58        pbs_base_log: DecompositionBaseLog,
59        pbs_level: DecompositionLevelCount,
60        ks_base_log: DecompositionBaseLog,
61        ks_level: DecompositionLevelCount,
62    ) -> BooleanParameters {
63        BooleanParameters {
64            lwe_dimension,
65            glwe_dimension,
66            polynomial_size,
67            lwe_modular_std_dev,
68            glwe_modular_std_dev,
69            pbs_base_log,
70            pbs_level,
71            ks_level,
72            ks_base_log,
73        }
74    }
75}
76
77/// Default parameter set.
78///
79/// This parameter set ensures 128-bits of security, and a probability of error is upper-bounded by
80/// $2^{-25}$. The secret keys generated with this parameter set are uniform binary.
81/// This parameter set allows to evaluate faster Boolean circuits than the `TFHE_LIB_PARAMETERS`
82/// one.
83pub const DEFAULT_PARAMETERS: BooleanParameters = BooleanParameters {
84    lwe_dimension: LweDimension(586),
85    glwe_dimension: GlweDimension(2),
86    polynomial_size: PolynomialSize(512),
87    lwe_modular_std_dev: StandardDev(0.000_092_511_997_467_675_6), // 2^{-13.4}
88    glwe_modular_std_dev: StandardDev(0.000_000_034_233_878_701_836_9), // 2^{-24.8}
89    pbs_base_log: DecompositionBaseLog(8),
90    pbs_level: DecompositionLevelCount(2),
91    ks_base_log: DecompositionBaseLog(2),
92    ks_level: DecompositionLevelCount(5),
93};
94
95/// Parameter set used in [TFHE library](https://tfhe.github.io/tfhe/) for 128-bits of security.
96///
97/// Details about this set are provided
98/// [here](https://github.com/tfhe/tfhe/blob/master/src/libtfhe/tfhe_gate_bootstrapping.cpp).
99/// The secret keys generated with this parameter set are uniform binary.
100/// This parameter set ensures a probability of error is upper-bounded by $2^{-165}$.
101pub const TFHE_LIB_PARAMETERS: BooleanParameters = BooleanParameters {
102    lwe_dimension: LweDimension(630),
103    glwe_dimension: GlweDimension(1),
104    polynomial_size: PolynomialSize(1024),
105    lwe_modular_std_dev: StandardDev(0.000_043_158_372_875_155_5), // 2^{-14.5}
106    glwe_modular_std_dev: StandardDev(0.000_000_034_233_878_701_836_9), // 2^{-24.8}
107    pbs_base_log: DecompositionBaseLog(7),
108    pbs_level: DecompositionLevelCount(3),
109    ks_base_log: DecompositionBaseLog(2),
110    ks_level: DecompositionLevelCount(8),
111};
concrete_boolean/parameters/mod.rs

concrete_boolean/parameters/
mod.rs
