Hard Lattice Generator#
This module contains lattice related functions relevant in cryptography.
Feel free to add more functionality.
AUTHORS:
Richard Lindner <rlindner@cdc.informatik.tu-darmstadt.de>
Michael Schneider <mischnei@cdc.informatik.tu-darmstadt.de>
- sage.crypto.lattice.gen_lattice(type='modular', n=4, m=8, q=11, seed=None, quotient=None, dual=False, ntl=False, lattice=False)#
This function generates different types of integral lattice bases of row vectors relevant in cryptography.
Randomness can be set either with
seed, or by usingsage.misc.randstate.set_random_seed().INPUT:
type– one of the following strings'modular'(default) – A class of lattices for which asymptotic worst-case to average-case connections hold. For more refer to [Aj1996].'random'– Special case of modular (n=1). A dense class of lattice used for testing basis reduction algorithms proposed by Goldstein and Mayer [GM2002].'ideal'– Special case of modular. Allows for a more compact representation proposed by [LM2006].'cyclotomic'– Special case of ideal. Allows for efficient processing proposed by [LM2006].
n– Determinant size, primal:\(det(L) = q^n\), dual:\(det(L) = q^{m-n}\). For ideal lattices this is also the degree of the quotient polynomial.m– Lattice dimension, \(L \subseteq Z^m\).q– Coefficient size, \(q-Z^m \subseteq L\).seed– Randomness seed.quotient– For the type ideal, this determines the quotient polynomial. Ignored for all other types.dual– Set this flag if you want a basis for \(q-dual(L)\), for example for Regev’s LWE bases [Reg2005].ntl– Set this flag if you want the lattice basis in NTL readable format.lattice– Set this flag if you want aFreeModule_submodule_with_basis_integerobject instead of an integer matrix representing the basis.
OUTPUT:
Ba unique size-reduced triangular (primal: lower_left, dual: lower_right) basis of row vectors for the lattice in question.EXAMPLES:
Modular basis:
sage: sage.crypto.gen_lattice(m=10, seed=42) [11 0 0 0 0 0 0 0 0 0] [ 0 11 0 0 0 0 0 0 0 0] [ 0 0 11 0 0 0 0 0 0 0] [ 0 0 0 11 0 0 0 0 0 0] [ 2 4 3 5 1 0 0 0 0 0] [ 1 -5 -4 2 0 1 0 0 0 0] [-4 3 -1 1 0 0 1 0 0 0] [-2 -3 -4 -1 0 0 0 1 0 0] [-5 -5 3 3 0 0 0 0 1 0] [-4 -3 2 -5 0 0 0 0 0 1]
Random basis:
sage: sage.crypto.gen_lattice(type='random', n=1, m=10, q=11^4, seed=42) [14641 0 0 0 0 0 0 0 0 0] [ 431 1 0 0 0 0 0 0 0 0] [-4792 0 1 0 0 0 0 0 0 0] [ 1015 0 0 1 0 0 0 0 0 0] [-3086 0 0 0 1 0 0 0 0 0] [-5378 0 0 0 0 1 0 0 0 0] [ 4769 0 0 0 0 0 1 0 0 0] [-1159 0 0 0 0 0 0 1 0 0] [ 3082 0 0 0 0 0 0 0 1 0] [-4580 0 0 0 0 0 0 0 0 1]
Ideal bases with quotient x^n-1, m=2*n are NTRU bases:
sage: sage.crypto.gen_lattice(type='ideal', seed=42, quotient=x^4-1) [11 0 0 0 0 0 0 0] [ 0 11 0 0 0 0 0 0] [ 0 0 11 0 0 0 0 0] [ 0 0 0 11 0 0 0 0] [-2 -3 -3 4 1 0 0 0] [ 4 -2 -3 -3 0 1 0 0] [-3 4 -2 -3 0 0 1 0] [-3 -3 4 -2 0 0 0 1]
Ideal bases also work with polynomials:
sage: R.<t> = PolynomialRing(ZZ) sage: sage.crypto.gen_lattice(type='ideal', seed=1234, quotient=t^4-1) [11 0 0 0 0 0 0 0] [ 0 11 0 0 0 0 0 0] [ 0 0 11 0 0 0 0 0] [ 0 0 0 11 0 0 0 0] [ 1 4 -3 3 1 0 0 0] [ 3 1 4 -3 0 1 0 0] [-3 3 1 4 0 0 1 0] [ 4 -3 3 1 0 0 0 1]
Cyclotomic bases with n=2^k are SWIFFT bases:
sage: sage.crypto.gen_lattice(type='cyclotomic', seed=42) [11 0 0 0 0 0 0 0] [ 0 11 0 0 0 0 0 0] [ 0 0 11 0 0 0 0 0] [ 0 0 0 11 0 0 0 0] [-2 -3 -3 4 1 0 0 0] [-4 -2 -3 -3 0 1 0 0] [ 3 -4 -2 -3 0 0 1 0] [ 3 3 -4 -2 0 0 0 1]
Dual modular bases are related to Regev’s famous public-key encryption [Reg2005]:
sage: sage.crypto.gen_lattice(type='modular', m=10, seed=42, dual=True) [ 0 0 0 0 0 0 0 0 0 11] [ 0 0 0 0 0 0 0 0 11 0] [ 0 0 0 0 0 0 0 11 0 0] [ 0 0 0 0 0 0 11 0 0 0] [ 0 0 0 0 0 11 0 0 0 0] [ 0 0 0 0 11 0 0 0 0 0] [ 0 0 0 1 -5 -2 -1 1 -3 5] [ 0 0 1 0 -3 4 1 4 -3 -2] [ 0 1 0 0 -4 5 -3 3 5 3] [ 1 0 0 0 -2 -1 4 2 5 4]
Relation of primal and dual bases:
sage: B_primal=sage.crypto.gen_lattice(m=10, q=11, seed=42) sage: B_dual=sage.crypto.gen_lattice(m=10, q=11, seed=42, dual=True) sage: B_dual_alt=transpose(11*B_primal.inverse()).change_ring(ZZ) sage: B_dual_alt.hermite_form() == B_dual.hermite_form() True