Cole Leavitt
2d9559838c
Performance improvements: - Replace O(n²) schoolbook multiplication with O(n log n) NTT using Cooley-Tukey/Gentleman-Sande - ~4x speedup on polynomial multiplication (44ms -> 10ms in tests) Security improvements: - Replace branching normalization in sample_small/sample_random_small with ct_normalize - Add ct_is_negative and ct_normalize constant-time primitives - All coefficient normalization now uses constant-time operations NTT implementation: - Uses q=65537 Fermat prime with primitive 512th root of unity ψ=256 - Precomputed twiddle factors for forward and inverse transforms - Iterative in-place butterfly with bit-reverse permutation - Negacyclic convolution for Z_q[X]/(X^n+1) All 219 tests passing