ring/ec/suite_b/ops/
p384.rs

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1// Copyright 2016-2023 Brian Smith.
2//
3// Permission to use, copy, modify, and/or distribute this software for any
4// purpose with or without fee is hereby granted, provided that the above
5// copyright notice and this permission notice appear in all copies.
6//
7// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
14
15use super::{
16    elem::{binary_op, binary_op_assign},
17    elem_sqr_mul, elem_sqr_mul_acc, PublicModulus, *,
18};
19
20pub(super) const NUM_LIMBS: usize = 384 / LIMB_BITS;
21
22pub static COMMON_OPS: CommonOps = CommonOps {
23    num_limbs: elem::NumLimbs::P384,
24
25    q: PublicModulus {
26        p: limbs_from_hex("fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffeffffffff0000000000000000ffffffff"),
27        rr: PublicElem::from_hex("10000000200000000fffffffe000000000000000200000000fffffffe00000001"),
28    },
29    n: PublicElem::from_hex("ffffffffffffffffffffffffffffffffffffffffffffffffc7634d81f4372ddf581a0db248b0a77aecec196accc52973"),
30
31    a: PublicElem::from_hex("fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffbfffffffc0000000000000003fffffffc"),
32    b: PublicElem::from_hex("cd08114b604fbff9b62b21f41f022094e3374bee94938ae277f2209b1920022ef729add87a4c32ec081188719d412dcc"),
33
34    elem_mul_mont: p384_elem_mul_mont,
35    elem_sqr_mont: p384_elem_sqr_mont,
36};
37
38pub(super) static GENERATOR: (PublicElem<R>, PublicElem<R>) = (
39    PublicElem::from_hex("4d3aadc2299e1513812ff723614ede2b6454868459a30eff879c3afc541b4d6e20e378e2a0d6ce383dd0756649c0b528"),
40    PublicElem::from_hex("2b78abc25a15c5e9dd8002263969a840c6c3521968f4ffd98bade7562e83b050a1bfa8bf7bb4a9ac23043dad4b03a4fe"),
41);
42
43pub static PRIVATE_KEY_OPS: PrivateKeyOps = PrivateKeyOps {
44    common: &COMMON_OPS,
45    elem_inv_squared: p384_elem_inv_squared,
46    point_mul_base_impl: p384_point_mul_base_impl,
47    point_mul_impl: p384_point_mul,
48    point_add_jacobian_impl: p384_point_add,
49};
50
51fn p384_elem_inv_squared(q: &Modulus<Q>, a: &Elem<R>) -> Elem<R> {
52    // Calculate a**-2 (mod q) == a**(q - 3) (mod q)
53    //
54    // The exponent (q - 3) is:
55    //
56    //    0xfffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffe\
57    //      ffffffff0000000000000000fffffffc
58
59    #[inline]
60    fn sqr_mul(q: &Modulus<Q>, a: &Elem<R>, squarings: LeakyWord, b: &Elem<R>) -> Elem<R> {
61        elem_sqr_mul(&COMMON_OPS, a, squarings, b, q.cpu())
62    }
63
64    #[inline]
65    fn sqr_mul_acc(q: &Modulus<Q>, a: &mut Elem<R>, squarings: LeakyWord, b: &Elem<R>) {
66        elem_sqr_mul_acc(&COMMON_OPS, a, squarings, b, q.cpu())
67    }
68
69    let b_1 = &a;
70    let b_11 = sqr_mul(q, b_1, 1, b_1);
71    let b_111 = sqr_mul(q, &b_11, 1, b_1);
72    let f_11 = sqr_mul(q, &b_111, 3, &b_111);
73    let fff = sqr_mul(q, &f_11, 6, &f_11);
74    let fff_111 = sqr_mul(q, &fff, 3, &b_111);
75    let fffffff_11 = sqr_mul(q, &fff_111, 15, &fff_111);
76
77    let fffffffffffffff = sqr_mul(q, &fffffff_11, 30, &fffffff_11);
78
79    let ffffffffffffffffffffffffffffff = sqr_mul(q, &fffffffffffffff, 60, &fffffffffffffff);
80
81    // ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
82    let mut acc = sqr_mul(
83        q,
84        &ffffffffffffffffffffffffffffff,
85        120,
86        &ffffffffffffffffffffffffffffff,
87    );
88
89    // fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff_111
90    sqr_mul_acc(q, &mut acc, 15, &fff_111);
91
92    // fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffeffffffff
93    sqr_mul_acc(q, &mut acc, 1 + 30, &fffffff_11);
94    sqr_mul_acc(q, &mut acc, 2, &b_11);
95
96    // fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffeffffffff
97    // 0000000000000000fffffff_11
98    sqr_mul_acc(q, &mut acc, 64 + 30, &fffffff_11);
99
100    // fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffeffffffff
101    // 0000000000000000fffffffc
102    q.elem_square(&mut acc);
103    q.elem_square(&mut acc);
104
105    acc
106}
107
108fn p384_point_mul_base_impl(a: &Scalar, cpu: cpu::Features) -> Point {
109    // XXX: Not efficient. TODO: Precompute multiples of the generator.
110    let generator = (Elem::from(&GENERATOR.0), Elem::from(&GENERATOR.1));
111    PRIVATE_KEY_OPS.point_mul(a, &generator, cpu)
112}
113
114pub static PUBLIC_KEY_OPS: PublicKeyOps = PublicKeyOps {
115    common: &COMMON_OPS,
116};
117
118pub static SCALAR_OPS: ScalarOps = ScalarOps {
119    common: &COMMON_OPS,
120    scalar_mul_mont: p384_scalar_mul_mont,
121};
122
123pub static PUBLIC_SCALAR_OPS: PublicScalarOps = PublicScalarOps {
124    scalar_ops: &SCALAR_OPS,
125    public_key_ops: &PUBLIC_KEY_OPS,
126    twin_mul: |g_scalar, p_scalar, p_xy, cpu| {
127        twin_mul_inefficient(&PRIVATE_KEY_OPS, g_scalar, p_scalar, p_xy, cpu)
128    },
129
130    q_minus_n: PublicElem::from_hex("389cb27e0bc8d21fa7e5f24cb74f58851313e696333ad68c"),
131
132    // TODO: Use an optimized variable-time implementation.
133    scalar_inv_to_mont_vartime: |s, cpu| PRIVATE_SCALAR_OPS.scalar_inv_to_mont(s, cpu),
134};
135
136pub static PRIVATE_SCALAR_OPS: PrivateScalarOps = PrivateScalarOps {
137    scalar_ops: &SCALAR_OPS,
138
139    oneRR_mod_n: PublicScalar::from_hex("c84ee012b39bf213fb05b7a28266895d40d49174aab1cc5bc3e483afcb82947ff3d81e5df1aa4192d319b2419b409a9"),
140    scalar_inv_to_mont: p384_scalar_inv_to_mont,
141};
142
143fn p384_scalar_inv_to_mont(a: Scalar<R>, _cpu: cpu::Features) -> Scalar<R> {
144    // Calculate the modular inverse of scalar |a| using Fermat's Little
145    // Theorem:
146    //
147    //    a**-1 (mod n) == a**(n - 2) (mod n)
148    //
149    // The exponent (n - 2) is:
150    //
151    //    0xffffffffffffffffffffffffffffffffffffffffffffffffc7634d81f4372ddf\
152    //      581a0db248b0a77aecec196accc52971
153
154    fn mul(a: &Scalar<R>, b: &Scalar<R>) -> Scalar<R> {
155        binary_op(p384_scalar_mul_mont, a, b)
156    }
157
158    fn sqr(a: &Scalar<R>) -> Scalar<R> {
159        binary_op(p384_scalar_mul_mont, a, a)
160    }
161
162    fn sqr_mut(a: &mut Scalar<R>) {
163        unary_op_from_binary_op_assign(p384_scalar_mul_mont, a);
164    }
165
166    // Returns (`a` squared `squarings` times) * `b`.
167    fn sqr_mul(a: &Scalar<R>, squarings: LeakyWord, b: &Scalar<R>) -> Scalar<R> {
168        debug_assert!(squarings >= 1);
169        let mut tmp = sqr(a);
170        for _ in 1..squarings {
171            sqr_mut(&mut tmp);
172        }
173        mul(&tmp, b)
174    }
175
176    // Sets `acc` = (`acc` squared `squarings` times) * `b`.
177    fn sqr_mul_acc(acc: &mut Scalar<R>, squarings: LeakyWord, b: &Scalar<R>) {
178        debug_assert!(squarings >= 1);
179        for _ in 0..squarings {
180            sqr_mut(acc);
181        }
182        binary_op_assign(p384_scalar_mul_mont, acc, b)
183    }
184
185    // Indexes into `d`.
186    const B_1: usize = 0;
187    const B_11: usize = 1;
188    const B_101: usize = 2;
189    const B_111: usize = 3;
190    const B_1001: usize = 4;
191    const B_1011: usize = 5;
192    const B_1101: usize = 6;
193    const B_1111: usize = 7;
194    const DIGIT_COUNT: usize = 8;
195
196    let mut d = [Scalar::zero(); DIGIT_COUNT];
197    d[B_1] = a;
198    let b_10 = sqr(&d[B_1]);
199    for i in B_11..DIGIT_COUNT {
200        d[i] = mul(&d[i - 1], &b_10);
201    }
202
203    let ff = sqr_mul(&d[B_1111], 0 + 4, &d[B_1111]);
204    let ffff = sqr_mul(&ff, 0 + 8, &ff);
205    let ffffffff = sqr_mul(&ffff, 0 + 16, &ffff);
206
207    let ffffffffffffffff = sqr_mul(&ffffffff, 0 + 32, &ffffffff);
208
209    let ffffffffffffffffffffffff = sqr_mul(&ffffffffffffffff, 0 + 32, &ffffffff);
210
211    // ffffffffffffffffffffffffffffffffffffffffffffffff
212    let mut acc = sqr_mul(&ffffffffffffffffffffffff, 0 + 96, &ffffffffffffffffffffffff);
213
214    // The rest of the exponent, in binary, is:
215    //
216    //    1100011101100011010011011000000111110100001101110010110111011111
217    //    0101100000011010000011011011001001001000101100001010011101111010
218    //    1110110011101100000110010110101011001100110001010010100101110001
219
220    #[allow(clippy::cast_possible_truncation)]
221    static REMAINING_WINDOWS: [(u8, u8); 39] = [
222        (2, B_11 as u8),
223        (3 + 3, B_111 as u8),
224        (1 + 2, B_11 as u8),
225        (3 + 2, B_11 as u8),
226        (1 + 4, B_1001 as u8),
227        (4, B_1011 as u8),
228        (6 + 4, B_1111 as u8),
229        (3, B_101 as u8),
230        (4 + 1, B_1 as u8),
231        (4, B_1011 as u8),
232        (4, B_1001 as u8),
233        (1 + 4, B_1101 as u8),
234        (4, B_1101 as u8),
235        (4, B_1111 as u8),
236        (1 + 4, B_1011 as u8),
237        (6 + 4, B_1101 as u8),
238        (5 + 4, B_1101 as u8),
239        (4, B_1011 as u8),
240        (2 + 4, B_1001 as u8),
241        (2 + 1, B_1 as u8),
242        (3 + 4, B_1011 as u8),
243        (4 + 3, B_101 as u8),
244        (2 + 3, B_111 as u8),
245        (1 + 4, B_1111 as u8),
246        (1 + 4, B_1011 as u8),
247        (4, B_1011 as u8),
248        (2 + 3, B_111 as u8),
249        (1 + 2, B_11 as u8),
250        (5 + 2, B_11 as u8),
251        (2 + 4, B_1011 as u8),
252        (1 + 3, B_101 as u8),
253        (1 + 2, B_11 as u8),
254        (2 + 2, B_11 as u8),
255        (2 + 2, B_11 as u8),
256        (3 + 3, B_101 as u8),
257        (2 + 3, B_101 as u8),
258        (2 + 3, B_101 as u8),
259        (2, B_11 as u8),
260        (3 + 1, B_1 as u8),
261    ];
262
263    for &(squarings, digit) in &REMAINING_WINDOWS[..] {
264        sqr_mul_acc(&mut acc, LeakyWord::from(squarings), &d[usize::from(digit)]);
265    }
266
267    acc
268}
269
270unsafe extern "C" fn p384_elem_sqr_mont(
271    r: *mut Limb,   // [COMMON_OPS.num_limbs]
272    a: *const Limb, // [COMMON_OPS.num_limbs]
273) {
274    // XXX: Inefficient. TODO: Make a dedicated squaring routine.
275    unsafe {
276        p384_elem_mul_mont(r, a, a);
277    }
278}
279
280prefixed_extern! {
281    fn p384_elem_mul_mont(
282        r: *mut Limb,   // [COMMON_OPS.num_limbs]
283        a: *const Limb, // [COMMON_OPS.num_limbs]
284        b: *const Limb, // [COMMON_OPS.num_limbs]
285    );
286
287    fn p384_point_add(
288        r: *mut Limb,   // [3][COMMON_OPS.num_limbs]
289        a: *const Limb, // [3][COMMON_OPS.num_limbs]
290        b: *const Limb, // [3][COMMON_OPS.num_limbs]
291    );
292    fn p384_point_mul(
293        r: *mut Limb,          // [3][COMMON_OPS.num_limbs]
294        p_scalar: *const Limb, // [COMMON_OPS.num_limbs]
295        p_x: *const Limb,      // [COMMON_OPS.num_limbs]
296        p_y: *const Limb,      // [COMMON_OPS.num_limbs]
297    );
298
299    fn p384_scalar_mul_mont(
300        r: *mut Limb,   // [COMMON_OPS.num_limbs]
301        a: *const Limb, // [COMMON_OPS.num_limbs]
302        b: *const Limb, // [COMMON_OPS.num_limbs]
303    );
304}
ring/ec/suite_b/ops/p384.rs

ring/ec/suite_b/ops/
p384.rs
