1 /* 2 * Copyright (c) 2016, Intel Corporation 3 * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com> 4 * 5 * This program is free software; you can redistribute it and/or 6 * modify it under the terms of the GNU General Public License 7 * as published by the Free Software Foundation; either version 8 * 2 of the License, or (at your option) any later version. 9 */ 10 #include <linux/kernel.h> 11 #include <linux/export.h> 12 #include <linux/err.h> 13 #include <linux/string.h> 14 #include <crypto/ecdh.h> 15 #include <crypto/kpp.h> 16 17 #define ECDH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 2 * sizeof(short)) 18 19 static inline u8 *ecdh_pack_data(void *dst, const void *src, size_t sz) 20 { 21 memcpy(dst, src, sz); 22 return dst + sz; 23 } 24 25 static inline const u8 *ecdh_unpack_data(void *dst, const void *src, size_t sz) 26 { 27 memcpy(dst, src, sz); 28 return src + sz; 29 } 30 31 unsigned int crypto_ecdh_key_len(const struct ecdh *params) 32 { 33 return ECDH_KPP_SECRET_MIN_SIZE + params->key_size; 34 } 35 EXPORT_SYMBOL_GPL(crypto_ecdh_key_len); 36 37 int crypto_ecdh_encode_key(char *buf, unsigned int len, 38 const struct ecdh *params) 39 { 40 u8 *ptr = buf; 41 struct kpp_secret secret = { 42 .type = CRYPTO_KPP_SECRET_TYPE_ECDH, 43 .len = len 44 }; 45 46 if (unlikely(!buf)) 47 return -EINVAL; 48 49 if (len != crypto_ecdh_key_len(params)) 50 return -EINVAL; 51 52 ptr = ecdh_pack_data(ptr, &secret, sizeof(secret)); 53 ptr = ecdh_pack_data(ptr, ¶ms->curve_id, sizeof(params->curve_id)); 54 ptr = ecdh_pack_data(ptr, ¶ms->key_size, sizeof(params->key_size)); 55 ecdh_pack_data(ptr, params->key, params->key_size); 56 57 return 0; 58 } 59 EXPORT_SYMBOL_GPL(crypto_ecdh_encode_key); 60 61 int crypto_ecdh_decode_key(const char *buf, unsigned int len, 62 struct ecdh *params) 63 { 64 const u8 *ptr = buf; 65 struct kpp_secret secret; 66 67 if (unlikely(!buf || len < ECDH_KPP_SECRET_MIN_SIZE)) 68 return -EINVAL; 69 70 ptr = ecdh_unpack_data(&secret, ptr, sizeof(secret)); 71 if (secret.type != CRYPTO_KPP_SECRET_TYPE_ECDH) 72 return -EINVAL; 73 74 ptr = ecdh_unpack_data(¶ms->curve_id, ptr, sizeof(params->curve_id)); 75 ptr = ecdh_unpack_data(¶ms->key_size, ptr, sizeof(params->key_size)); 76 if (secret.len != crypto_ecdh_key_len(params)) 77 return -EINVAL; 78 79 /* Don't allocate memory. Set pointer to data 80 * within the given buffer 81 */ 82 params->key = (void *)ptr; 83 84 return 0; 85 } 86 EXPORT_SYMBOL_GPL(crypto_ecdh_decode_key); 87