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 "xio.h"
  16 #include "crypto_box_curve25519xsalsa20poly1305.h"
  17
  18 struct tai {
  19         uint64_t x;
  20 };
  21
  22 struct taia {
  23         struct tai sec;
  24         uint32_t nano;
  25         uint32_t atto;
  26 };
  27
  28 static struct taia tolerance_taia = {
  29         .sec.x = 0,
  30         .nano = 700000000ULL,
  31         .atto = 0,
  32 };
  33
  34 #define crypto_box_zerobytes            crypto_box_curve25519xsalsa20poly1305_ZEROBYTES
  35 #define crypto_box_boxzerobytes         crypto_box_curve25519xsalsa20poly1305_BOXZEROBYTES
  36
  37 #define crypto_box_noncebytes           crypto_box_curve25519xsalsa20poly1305_NONCEBYTES
  38 #define crypto_box_beforenmbytes        crypto_box_curve25519xsalsa20poly1305_BEFORENMBYTES
  39
  40 struct curve25519_proto {
  41         unsigned char enonce[crypto_box_noncebytes] __aligned_16;
  42         unsigned char dnonce[crypto_box_noncebytes] __aligned_16;
  43         unsigned char key[crypto_box_noncebytes] __aligned_16;
  44 };
  45
  46 struct curve25519_struct {
  47         unsigned char *enc_buf;
  48         unsigned char *dec_buf;
  49         size_t enc_buf_size;
  50         size_t dec_buf_size;
  51         struct spinlock enc_lock;
  52         struct spinlock dec_lock;
  53 };
  54
  55 extern void curve25519_selftest(void);
  56 extern void curve25519_alloc_or_maybe_die(struct curve25519_struct *curve);
  57 extern void curve25519_free(void *curve);
  58 extern int curve25519_pubkey_hexparse_32(unsigned char *bin, size_t blen, const char *ascii, size_t alen);
  59 extern int curve25519_proto_init(struct curve25519_proto *proto, unsigned char *pubkey_remote, size_t len,
  60                                  char *home, int server);
  61 extern ssize_t curve25519_encode(struct curve25519_struct *curve, struct curve25519_proto *proto,
  62                                  unsigned char *plaintext, size_t size, unsigned char **chipertext);
  63 extern ssize_t curve25519_decode(struct curve25519_struct *curve, struct curve25519_proto *proto,
  64                                  unsigned char *chipertext, size_t size, unsigned char **plaintext,
  65                                  struct taia *arrival_taia);
  66
  67 static inline void tai_pack(unsigned char *s, struct tai *t)
  68 {
  69         uint64_t x;
  70
  71         x = t->x;
  72         s[7] = x & 255; x >>= 8;
  73         s[6] = x & 255; x >>= 8;
  74         s[5] = x & 255; x >>= 8;
  75         s[4] = x & 255; x >>= 8;
  76         s[3] = x & 255; x >>= 8;
  77         s[2] = x & 255; x >>= 8;
  78         s[1] = x & 255; x >>= 8;
  79         s[0] = x;
  80 }
  81
  82 static inline void tai_unpack(unsigned char *s, struct tai *t)
  83 {
  84         uint64_t x;
  85
  86         x = (unsigned char) s[0];
  87         x <<= 8; x += (unsigned char) s[1];
  88         x <<= 8; x += (unsigned char) s[2];
  89         x <<= 8; x += (unsigned char) s[3];
  90         x <<= 8; x += (unsigned char) s[4];
  91         x <<= 8; x += (unsigned char) s[5];
  92         x <<= 8; x += (unsigned char) s[6];
  93         x <<= 8; x += (unsigned char) s[7];
  94         t->x = x;
  95 }
  96
  97 static inline void taia_pack(unsigned char *s, struct taia *t)
  98 {
  99         unsigned long x;
 100
 101         tai_pack(s, &t->sec);
 102         s += 8;
 103         x = t->atto;
 104         s[7] = x & 255; x >>= 8;
 105         s[6] = x & 255; x >>= 8;
 106         s[5] = x & 255; x >>= 8;
 107         s[4] = x;
 108         x = t->nano;
 109         s[3] = x & 255; x >>= 8;
 110         s[2] = x & 255; x >>= 8;
 111         s[1] = x & 255; x >>= 8;
 112         s[0] = x;
 113 }
 114
 115 static inline void taia_unpack(unsigned char *s, struct taia *t)
 116 {
 117         unsigned long x;
 118
 119         tai_unpack(s, &t->sec);
 120         s += 8;
 121         x = (unsigned char) s[4];
 122         x <<= 8; x += (unsigned char) s[5];
 123         x <<= 8; x += (unsigned char) s[6];
 124         x <<= 8; x += (unsigned char) s[7];
 125         t->atto = x;
 126         x = (unsigned char) s[0];
 127         x <<= 8; x += (unsigned char) s[1];
 128         x <<= 8; x += (unsigned char) s[2];
 129         x <<= 8; x += (unsigned char) s[3];
 130         t->nano = x;
 131 }
 132
 133 #define tai_unix(t, u) ((void) ((t)->x = 4611686018427387914ULL + (uint64_t) (u)))
 134
 135 static inline void taia_now(struct taia *t)
 136 {
 137         struct timeval now;
 138
 139         gettimeofday(&now, NULL);
 140
 141         tai_unix(&t->sec, now.tv_sec);
 142         t->nano = 1000 * now.tv_usec + 500;
 143         t->atto = secrand();
 144 }
 145
 146 static inline void taia_sub(struct taia *res, const struct taia *u, const struct taia *v)
 147 {
 148         unsigned long unano = u->nano;
 149         unsigned long uatto = u->atto;
 150
 151         res->sec.x = u->sec.x - v->sec.x;
 152         res->nano = unano - v->nano;
 153         res->atto = uatto - v->atto;
 154
 155         if (res->atto > uatto) {
 156                 res->atto += 1000000000UL;
 157                 --res->nano;
 158         }
 159
 160         if (res->nano > unano) {
 161                 res->nano += 1000000000UL;
 162                 --res->sec.x;
 163         }
 164 }
 165
 166 static inline void taia_add(struct taia *res, const struct taia *u, const struct taia *v)
 167 {
 168         res->sec.x = u->sec.x + v->sec.x;
 169         res->nano = u->nano + v->nano;
 170         res->atto = u->atto + v->atto;
 171
 172         if (res->atto > 999999999UL) {
 173                 res->atto -= 1000000000UL;
 174                 ++res->nano;
 175         }
 176
 177         if (res->nano > 999999999UL) {
 178                 res->nano -= 1000000000UL;
 179                 ++res->sec.x;
 180         }
 181 }
 182
 183 static inline int taia_less(const struct taia *t, const struct taia *u)
 184 {
 185         if (t->sec.x < u->sec.x)
 186                 return 1;
 187         if (t->sec.x > u->sec.x)
 188                 return 0;
 189         if (t->nano < u->nano)
 190                 return 1;
 191         if (t->nano > u->nano)
 192                 return 0;
 193         return t->atto < u->atto;
 194 }
 195
 196 static inline int is_good_taia(struct taia *arrival_taia, struct taia *packet_taia)
 197 {
 198         int is_ts_good = 0;
 199         struct taia sub_res;
 200
 201         if (taia_less(arrival_taia, packet_taia)) {
 202                 taia_sub(&sub_res, packet_taia, arrival_taia);
 203                 if (taia_less(&sub_res, &tolerance_taia))
 204                         is_ts_good = 1;
 205                 else
 206                         is_ts_good = 0;
 207         } else {
 208                 taia_sub(&sub_res, arrival_taia, packet_taia);
 209                 if (taia_less(&sub_res, &tolerance_taia))
 210                         is_ts_good = 1;
 211                 else
 212                         is_ts_good = 0;
 213         }
 214
 215         return is_ts_good;
 216 }
 217
 218 #endif /* CURVE_H */