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use group::{Affine, Jacobian, AffineStorage, set_table_gej_var, globalz_set_table_gej, AFFINE_G}; use field::Field; use scalar::Scalar; pub const WINDOW_A: usize = 5; pub const WINDOW_G: usize = 16; pub const ECMULT_TABLE_SIZE_A: usize = 1 << (WINDOW_A - 2); pub const ECMULT_TABLE_SIZE_G: usize = 1 << (WINDOW_G - 2); pub struct ECMultContext { pre_g: [AffineStorage; ECMULT_TABLE_SIZE_G], } pub struct ECMultGenContext { prec: [[AffineStorage; 16]; 64], blind: Scalar, initial: Jacobian, } pub static ECMULT_CONTEXT: ECMultContext = ECMultContext { pre_g: include!("const.rs"), }; pub static ECMULT_GEN_CONTEXT: ECMultGenContext = ECMultGenContext { prec: include!("const_gen.rs"), blind: Scalar([2217680822, 850875797, 1046150361, 1330484644, 4015777837, 2466086288, 2052467175, 2084507480]), initial: Jacobian { x: field_const_raw!(586608, 43357028, 207667908, 262670128, 142222828, 38529388, 267186148, 45417712, 115291924, 13447464), y: field_const_raw!(12696548, 208302564, 112025180, 191752716, 143238548, 145482948, 228906000, 69755164, 243572800, 210897016), z: field_const_raw!(3685368, 75404844, 20246216, 5748944, 73206666, 107661790, 110806176, 73488774, 5707384, 104448710), infinity: false, } }; pub fn odd_multiples_table(prej: &mut [Jacobian], zr: &mut [Field], a: &Jacobian) { debug_assert!(prej.len() == zr.len()); debug_assert!(prej.len() > 0); debug_assert!(!a.is_infinity()); let d = a.double_var(None); let d_ge = Affine { x: d.x.clone(), y: d.y.clone(), infinity: false, }; let mut a_ge = Affine::default(); a_ge.set_gej_zinv(a, &d.z); prej[0].x = a_ge.x; prej[0].y = a_ge.y; prej[0].z = a.z.clone(); prej[0].infinity = false; zr[0] = d.z.clone(); for i in 1..prej.len() { prej[i] = prej[i-1].add_ge_var(&d_ge, Some(&mut zr[i])); } let l = &prej.last().unwrap().z * &d.z; prej.last_mut().unwrap().z = l; } fn odd_multiples_table_globalz_windowa(pre: &mut [Affine; ECMULT_TABLE_SIZE_A], globalz: &mut Field, a: &Jacobian) { let mut prej: [Jacobian; ECMULT_TABLE_SIZE_A] = Default::default(); let mut zr: [Field; ECMULT_TABLE_SIZE_A] = Default::default(); odd_multiples_table(&mut prej, &mut zr, a); globalz_set_table_gej(pre, globalz, &prej, &zr); } fn table_get_ge(r: &mut Affine, pre: &[Affine], n: i32, w: usize) { debug_assert!(n & 1 == 1); debug_assert!(n >= -((1 << (w-1)) - 1)); debug_assert!(n <= ((1 << (w-1)) - 1)); if n > 0 { *r = pre[((n-1)/2) as usize].clone(); } else { *r = pre[((-n-1)/2) as usize].neg(); } } fn table_get_ge_storage(r: &mut Affine, pre: &[AffineStorage], n: i32, w: usize) { debug_assert!(n & 1 == 1); debug_assert!(n >= -((1 << (w-1)) - 1)); debug_assert!(n <= ((1 << (w-1)) - 1)); if n > 0 { *r = pre[((n-1)/2) as usize].clone().into(); } else { *r = pre[((-n-1)/2) as usize].clone().into(); *r = r.neg(); } } pub fn ecmult_wnaf(wanf: &mut [i32], a: &Scalar, w: usize) -> i32 { let mut s = a.clone(); let mut last_set_bit: i32 = -1; let mut bit = 0; let mut sign = 1; let mut carry = 0; debug_assert!(wanf.len() >= 0 && wanf.len() <= 256); debug_assert!(w >= 2 && w <= 31); for i in 0..wanf.len() { wanf[i] = 0; } if s.bits(255, 1) > 0 { s = s.neg(); sign = -1; } while bit < wanf.len() { let mut now; let mut word; if s.bits(bit, 1) == carry as u32 { bit += 1; continue; } now = w; if now > wanf.len() - bit { now = wanf.len() - bit; } word = (s.bits_var(bit, now) as i32) + carry; carry = (word >> (w-1)) & 1; word -= carry << w; wanf[bit] = sign * word; last_set_bit = bit as i32; bit += now; } debug_assert!(carry == 0); debug_assert!({ let mut t = true; while bit < 256 { t = t && (s.bits(bit, 1) == 0); bit += 1; } t }); last_set_bit + 1 } impl ECMultContext { pub fn ecmult( &self, r: &mut Jacobian, a: &Jacobian, na: &Scalar, ng: &Scalar ) { let mut tmpa = Affine::default(); let mut pre_a: [Affine; ECMULT_TABLE_SIZE_A] = Default::default(); let mut z = Field::default(); let mut wnaf_na = [0i32; 256]; let mut wnaf_ng = [0i32; 256]; let bits_na = ecmult_wnaf(&mut wnaf_na, na, WINDOW_A); let mut bits = bits_na; odd_multiples_table_globalz_windowa(&mut pre_a, &mut z, a); let bits_ng = ecmult_wnaf(&mut wnaf_ng, &ng, WINDOW_G); if bits_ng > bits { bits = bits_ng; } r.set_infinity(); for i in (0..bits).rev() { let mut n; *r = r.double_var(None); n = wnaf_na[i as usize]; if i < bits_na && n != 0 { table_get_ge(&mut tmpa, &pre_a, n, WINDOW_A); *r = r.add_ge_var(&tmpa, None); } n = wnaf_ng[i as usize]; if i < bits_ng && n != 0 { table_get_ge_storage(&mut tmpa, &self.pre_g, n, WINDOW_G); *r = r.add_zinv_var(&tmpa, &z); } } if !r.is_infinity() { r.z *= &z; } } } impl ECMultGenContext { pub fn ecmult_gen( &self, r: &mut Jacobian, gn: &Scalar ) { let mut adds = AffineStorage::default(); *r = self.initial.clone(); let mut gnb = gn + &self.blind; let mut add = Affine::default(); add.infinity = false; for j in 0..64 { let mut bits = gnb.bits(j * 4, 4); for i in 0..16 { adds.cmov(&self.prec[j][i], i as u32 == bits); } add = adds.clone().into(); *r = r.add_ge(&add); bits = 0; } add.clear(); gnb.clear(); } }