curve.h

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * Copyright 2011 - 2013 Daniel Borkmann.
   4  * Subject to the GPL, version 2.
   5  */
   6
   7 #ifndef CURVE_H
   8 #define CURVE_H
   9
  10 #include <stdint.h>
  11 #include <sys/time.h>
  12
  13 #include "locking.h"
  14 #include "built_in.h"
  15 #include "ioops.h"
  16 #include "rnd.h"
  17 #include "crypto.h"
  18
  19 struct tai {
  20         uint64_t x;
  21 };
  22
  23 struct taia {
  24         struct tai sec;
  25         uint32_t nano;
  26         uint32_t atto;
  27 };
  28
  29 static struct taia tolerance_taia = {
  30         .sec.x = 0,
  31         .nano = 700000000ULL,
  32         .atto = 0,
  33 };
  34
  35 struct curve25519_proto {
  36         unsigned char enonce[crypto_box_noncebytes] __aligned_16;
  37         unsigned char dnonce[crypto_box_noncebytes] __aligned_16;
  38         unsigned char key[crypto_box_noncebytes] __aligned_16;
  39 };
  40
  41 struct curve25519_struct {
  42         unsigned char *enc_buf;
  43         unsigned char *dec_buf;
  44         size_t enc_buf_size;
  45         size_t dec_buf_size;
  46         struct spinlock enc_lock;
  47         struct spinlock dec_lock;
  48 };
  49
  50 extern void curve25519_selftest(void);
  51 extern void curve25519_alloc_or_maybe_die(struct curve25519_struct *curve);
  52 extern void curve25519_free(void *curve);
  53 extern int curve25519_pubkey_hexparse_32(unsigned char *bin, size_t blen, const char *ascii, size_t alen);
  54 extern int curve25519_proto_init(struct curve25519_proto *proto, unsigned char *pubkey_remote, size_t len,
  55                                  char *home, int server);
  56 extern ssize_t curve25519_encode(struct curve25519_struct *curve, struct curve25519_proto *proto,
  57                                  unsigned char *plaintext, size_t size, unsigned char **chipertext);
  58 extern ssize_t curve25519_decode(struct curve25519_struct *curve, struct curve25519_proto *proto,
  59                                  unsigned char *chipertext, size_t size, unsigned char **plaintext,
  60                                  struct taia *arrival_taia);
  61
  62 static inline void tai_pack(unsigned char *s, struct tai *t)
  63 {
  64         uint64_t x;
  65
  66         x = t->x;
  67         s[7] = x & 255; x >>= 8;
  68         s[6] = x & 255; x >>= 8;
  69         s[5] = x & 255; x >>= 8;
  70         s[4] = x & 255; x >>= 8;
  71         s[3] = x & 255; x >>= 8;
  72         s[2] = x & 255; x >>= 8;
  73         s[1] = x & 255; x >>= 8;
  74         s[0] = x;
  75 }
  76
  77 static inline void tai_unpack(unsigned char *s, struct tai *t)
  78 {
  79         uint64_t x;
  80
  81         x = (unsigned char) s[0];
  82         x <<= 8; x += (unsigned char) s[1];
  83         x <<= 8; x += (unsigned char) s[2];
  84         x <<= 8; x += (unsigned char) s[3];
  85         x <<= 8; x += (unsigned char) s[4];
  86         x <<= 8; x += (unsigned char) s[5];
  87         x <<= 8; x += (unsigned char) s[6];
  88         x <<= 8; x += (unsigned char) s[7];
  89         t->x = x;
  90 }
  91
  92 static inline void taia_pack(unsigned char *s, struct taia *t)
  93 {
  94         unsigned long x;
  95
  96         tai_pack(s, &t->sec);
  97         s += 8;
  98         x = t->atto;
  99         s[7] = x & 255; x >>= 8;
 100         s[6] = x & 255; x >>= 8;
 101         s[5] = x & 255; x >>= 8;
 102         s[4] = x;
 103         x = t->nano;
 104         s[3] = x & 255; x >>= 8;
 105         s[2] = x & 255; x >>= 8;
 106         s[1] = x & 255; x >>= 8;
 107         s[0] = x;
 108 }
 109
 110 static inline void taia_unpack(unsigned char *s, struct taia *t)
 111 {
 112         unsigned long x;
 113
 114         tai_unpack(s, &t->sec);
 115         s += 8;
 116         x = (unsigned char) s[4];
 117         x <<= 8; x += (unsigned char) s[5];
 118         x <<= 8; x += (unsigned char) s[6];
 119         x <<= 8; x += (unsigned char) s[7];
 120         t->atto = x;
 121         x = (unsigned char) s[0];
 122         x <<= 8; x += (unsigned char) s[1];
 123         x <<= 8; x += (unsigned char) s[2];
 124         x <<= 8; x += (unsigned char) s[3];
 125         t->nano = x;
 126 }
 127
 128 #define tai_unix(t, u) ((void) ((t)->x = 4611686018427387914ULL + (uint64_t) (u)))
 129
 130 static inline void taia_now(struct taia *t)
 131 {
 132         struct timeval now;
 133
 134         gettimeofday(&now, NULL);
 135
 136         tai_unix(&t->sec, now.tv_sec);
 137         t->nano = 1000 * now.tv_usec + 500;
 138         t->atto = secrand();
 139 }
 140
 141 static inline void taia_sub(struct taia *res, const struct taia *u, const struct taia *v)
 142 {
 143         unsigned long unano = u->nano;
 144         unsigned long uatto = u->atto;
 145
 146         res->sec.x = u->sec.x - v->sec.x;
 147         res->nano = unano - v->nano;
 148         res->atto = uatto - v->atto;
 149
 150         if (res->atto > uatto) {
 151                 res->atto += 1000000000UL;
 152                 --res->nano;
 153         }
 154
 155         if (res->nano > unano) {
 156                 res->nano += 1000000000UL;
 157                 --res->sec.x;
 158         }
 159 }
 160
 161 static inline void taia_add(struct taia *res, const struct taia *u, const struct taia *v)
 162 {
 163         res->sec.x = u->sec.x + v->sec.x;
 164         res->nano = u->nano + v->nano;
 165         res->atto = u->atto + v->atto;
 166
 167         if (res->atto > 999999999UL) {
 168                 res->atto -= 1000000000UL;
 169                 ++res->nano;
 170         }
 171
 172         if (res->nano > 999999999UL) {
 173                 res->nano -= 1000000000UL;
 174                 ++res->sec.x;
 175         }
 176 }
 177
 178 static inline int taia_less(const struct taia *t, const struct taia *u)
 179 {
 180         if (t->sec.x < u->sec.x)
 181                 return 1;
 182         if (t->sec.x > u->sec.x)
 183                 return 0;
 184         if (t->nano < u->nano)
 185                 return 1;
 186         if (t->nano > u->nano)
 187                 return 0;
 188         return t->atto < u->atto;
 189 }
 190
 191 static inline int is_good_taia(struct taia *arrival_taia, struct taia *packet_taia)
 192 {
 193         int is_ts_good = 0;
 194         struct taia sub_res;
 195
 196         if (taia_less(arrival_taia, packet_taia)) {
 197                 taia_sub(&sub_res, packet_taia, arrival_taia);
 198                 if (taia_less(&sub_res, &tolerance_taia))
 199                         is_ts_good = 1;
 200                 else
 201                         is_ts_good = 0;
 202         } else {
 203                 taia_sub(&sub_res, arrival_taia, packet_taia);
 204                 if (taia_less(&sub_res, &tolerance_taia))
 205                         is_ts_good = 1;
 206                 else
 207                         is_ts_good = 0;
 208         }
 209
 210         return is_ts_good;
 211 }
 212
 213 #endif /* CURVE_H */