1 | /* SPDX-License-Identifier: GPL-2.0 OR MIT */ |
2 | /* |
3 | * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. |
4 | */ |
5 | |
6 | #ifndef CURVE25519_H |
7 | #define CURVE25519_H |
8 | |
9 | #include <crypto/algapi.h> // For crypto_memneq. |
10 | #include <linux/types.h> |
11 | #include <linux/random.h> |
12 | |
13 | enum curve25519_lengths { |
14 | CURVE25519_KEY_SIZE = 32 |
15 | }; |
16 | |
17 | extern const u8 curve25519_null_point[]; |
18 | extern const u8 curve25519_base_point[]; |
19 | |
20 | void curve25519_generic(u8 out[CURVE25519_KEY_SIZE], |
21 | const u8 scalar[CURVE25519_KEY_SIZE], |
22 | const u8 point[CURVE25519_KEY_SIZE]); |
23 | |
24 | void curve25519_arch(u8 out[CURVE25519_KEY_SIZE], |
25 | const u8 scalar[CURVE25519_KEY_SIZE], |
26 | const u8 point[CURVE25519_KEY_SIZE]); |
27 | |
28 | void curve25519_base_arch(u8 pub[CURVE25519_KEY_SIZE], |
29 | const u8 secret[CURVE25519_KEY_SIZE]); |
30 | |
31 | bool curve25519_selftest(void); |
32 | |
33 | static inline |
34 | bool __must_check curve25519(u8 mypublic[CURVE25519_KEY_SIZE], |
35 | const u8 secret[CURVE25519_KEY_SIZE], |
36 | const u8 basepoint[CURVE25519_KEY_SIZE]) |
37 | { |
38 | if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CURVE25519)) |
39 | curve25519_arch(out: mypublic, scalar: secret, point: basepoint); |
40 | else |
41 | curve25519_generic(out: mypublic, scalar: secret, point: basepoint); |
42 | return crypto_memneq(a: mypublic, b: curve25519_null_point, |
43 | size: CURVE25519_KEY_SIZE); |
44 | } |
45 | |
46 | static inline bool |
47 | __must_check curve25519_generate_public(u8 pub[CURVE25519_KEY_SIZE], |
48 | const u8 secret[CURVE25519_KEY_SIZE]) |
49 | { |
50 | if (unlikely(!crypto_memneq(secret, curve25519_null_point, |
51 | CURVE25519_KEY_SIZE))) |
52 | return false; |
53 | |
54 | if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CURVE25519)) |
55 | curve25519_base_arch(pub, secret); |
56 | else |
57 | curve25519_generic(out: pub, scalar: secret, point: curve25519_base_point); |
58 | return crypto_memneq(a: pub, b: curve25519_null_point, size: CURVE25519_KEY_SIZE); |
59 | } |
60 | |
61 | static inline void curve25519_clamp_secret(u8 secret[CURVE25519_KEY_SIZE]) |
62 | { |
63 | secret[0] &= 248; |
64 | secret[31] = (secret[31] & 127) | 64; |
65 | } |
66 | |
67 | static inline void curve25519_generate_secret(u8 secret[CURVE25519_KEY_SIZE]) |
68 | { |
69 | get_random_bytes_wait(buf: secret, nbytes: CURVE25519_KEY_SIZE); |
70 | curve25519_clamp_secret(secret); |
71 | } |
72 | |
73 | #endif /* CURVE25519_H */ |
74 | |