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 static inline 32 bool __must_check curve25519(u8 mypublic[CURVE25519_KEY_SIZE], 33 const u8 secret[CURVE25519_KEY_SIZE], 34 const u8 basepoint[CURVE25519_KEY_SIZE]) 35 { 36 if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CURVE25519)) 37 curve25519_arch(mypublic, secret, basepoint); 38 else 39 curve25519_generic(mypublic, secret, basepoint); 40 return crypto_memneq(mypublic, curve25519_null_point, 41 CURVE25519_KEY_SIZE); 42 } 43 44 static inline bool 45 __must_check curve25519_generate_public(u8 pub[CURVE25519_KEY_SIZE], 46 const u8 secret[CURVE25519_KEY_SIZE]) 47 { 48 if (unlikely(!crypto_memneq(secret, curve25519_null_point, 49 CURVE25519_KEY_SIZE))) 50 return false; 51 52 if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CURVE25519)) 53 curve25519_base_arch(pub, secret); 54 else 55 curve25519_generic(pub, secret, curve25519_base_point); 56 return crypto_memneq(pub, curve25519_null_point, CURVE25519_KEY_SIZE); 57 } 58 59 static inline void curve25519_clamp_secret(u8 secret[CURVE25519_KEY_SIZE]) 60 { 61 secret[0] &= 248; 62 secret[31] = (secret[31] & 127) | 64; 63 } 64 65 static inline void curve25519_generate_secret(u8 secret[CURVE25519_KEY_SIZE]) 66 { 67 get_random_bytes_wait(secret, CURVE25519_KEY_SIZE); 68 curve25519_clamp_secret(secret); 69 } 70 71 #endif /* CURVE25519_H */ 72