src/curve.h

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * By Daniel Borkmann <daniel@netsniff-ng.org>
   4  * Copyright 2011 Daniel Borkmann.
   5  * Subject to the GPL, version 2.
   6  */
   7
   8 #ifndef CURVE_H
   9 #define CURVE_H
  10
  11 #include <stdint.h>
  12 #include <sys/time.h>
  13
  14 #include "locking.h"
  15 #include "mtrand.h"
  16 #include "compiler.h"
  17 #include "crypto_box_curve25519xsalsa20poly1305.h"
  18
  19 /* Some parts derived from public domain code from curveprotect project */
  20
  21 struct tai {
  22         uint64_t x;
  23 };
  24
  25 struct taia {
  26         struct tai sec;
  27         uint32_t nano;  /* 0...999999999 */
  28         uint32_t atto;  /* 0...999999999 */
  29 };
  30
  31 /* Delay tolerance for packets! */
  32 static struct taia tolerance_taia = {
  33         .sec.x = 0,
  34         .nano = 700000000ULL,
  35         .atto = 0,
  36 };
  37
  38 #define crypto_box_zerobytes    crypto_box_curve25519xsalsa20poly1305_ZEROBYTES
  39 #define crypto_box_boxzerobytes crypto_box_curve25519xsalsa20poly1305_BOXZEROBYTES
  40
  41 #define crypto_box_noncebytes crypto_box_curve25519xsalsa20poly1305_NONCEBYTES
  42 #define crypto_box_beforenmbytes crypto_box_curve25519xsalsa20poly1305_BEFORENMBYTES
  43
  44 /* Per connection */
  45 struct curve25519_proto {
  46         unsigned char enonce[crypto_box_noncebytes] __aligned_16;
  47         unsigned char dnonce[crypto_box_noncebytes] __aligned_16;
  48         unsigned char key[crypto_box_noncebytes] __aligned_16;
  49 };
  50
  51 /* Per thread */
  52 struct curve25519_struct {
  53         /* Encode buffer */
  54         size_t enc_buf_size;
  55         unsigned char *enc_buf;
  56         struct spinlock enc_lock;
  57         /* Decode buffer */
  58         size_t dec_buf_size;
  59         unsigned char *dec_buf;
  60         struct spinlock dec_lock;
  61 };
  62
  63 extern void curve25519_selftest(void);
  64 extern int curve25519_pubkey_hexparse_32(unsigned char *y, size_t ylen,
  65                                          const char *x, size_t len);
  66 extern int curve25519_alloc_or_maybe_die(struct curve25519_struct *c);
  67 extern void curve25519_free(void *vc);
  68 extern int curve25519_proto_init(struct curve25519_proto *p,
  69                                  unsigned char *pubkey_remote, size_t len,
  70                                  char *home, int server);
  71 extern ssize_t curve25519_encode(struct curve25519_struct *c,
  72                                  struct curve25519_proto *p,
  73                                  unsigned char *plaintext, size_t size,
  74                                  unsigned char **chipertext);
  75 extern ssize_t curve25519_decode(struct curve25519_struct *c,
  76                                  struct curve25519_proto *p,
  77                                  unsigned char *chipertext, size_t size,
  78                                  unsigned char **plaintext,
  79                                  struct taia *arrival_taia);
  80
  81 static inline void tai_pack(unsigned char *s, struct tai *t)
  82 {
  83         uint64_t x;
  84         x = t->x;
  85         s[7] = x & 255; x >>= 8;
  86         s[6] = x & 255; x >>= 8;
  87         s[5] = x & 255; x >>= 8;
  88         s[4] = x & 255; x >>= 8;
  89         s[3] = x & 255; x >>= 8;
  90         s[2] = x & 255; x >>= 8;
  91         s[1] = x & 255; x >>= 8;
  92         s[0] = x;
  93 }
  94
  95 static inline void tai_unpack(unsigned char *s, struct tai *t)
  96 {
  97         uint64_t x;
  98         x = (unsigned char) s[0];
  99         x <<= 8; x += (unsigned char) s[1];
 100         x <<= 8; x += (unsigned char) s[2];
 101         x <<= 8; x += (unsigned char) s[3];
 102         x <<= 8; x += (unsigned char) s[4];
 103         x <<= 8; x += (unsigned char) s[5];
 104         x <<= 8; x += (unsigned char) s[6];
 105         x <<= 8; x += (unsigned char) s[7];
 106         t->x = x;
 107 }
 108
 109 static inline void taia_pack(unsigned char *s, struct taia *t)
 110 {
 111         unsigned long x;
 112         tai_pack(s, &t->sec);
 113         s += 8;
 114         x = t->atto;
 115         s[7] = x & 255; x >>= 8;
 116         s[6] = x & 255; x >>= 8;
 117         s[5] = x & 255; x >>= 8;
 118         s[4] = x;
 119         x = t->nano;
 120         s[3] = x & 255; x >>= 8;
 121         s[2] = x & 255; x >>= 8;
 122         s[1] = x & 255; x >>= 8;
 123         s[0] = x;
 124 }
 125
 126 static inline void taia_unpack(unsigned char *s, struct taia *t)
 127 {
 128         unsigned long x;
 129         tai_unpack(s, &t->sec);
 130         s += 8;
 131         x = (unsigned char) s[4];
 132         x <<= 8; x += (unsigned char) s[5];
 133         x <<= 8; x += (unsigned char) s[6];
 134         x <<= 8; x += (unsigned char) s[7];
 135         t->atto = x;
 136         x = (unsigned char) s[0];
 137         x <<= 8; x += (unsigned char) s[1];
 138         x <<= 8; x += (unsigned char) s[2];
 139         x <<= 8; x += (unsigned char) s[3];
 140         t->nano = x;
 141 }
 142
 143 #define tai_unix(t, u) ((void) ((t)->x = 4611686018427387914ULL + (uint64_t) (u)))
 144
 145 static inline void taia_now(struct taia *t)
 146 {
 147         struct timeval now;
 148         gettimeofday(&now, NULL);
 149         tai_unix(&t->sec, now.tv_sec);
 150         t->nano = 1000 * now.tv_usec + 500;
 151         t->atto = mt_rand_int32();
 152 }
 153
 154 /* XXX: breaks tai encapsulation */
 155
 156 /* calcs u - v */
 157 static inline void taia_sub(struct taia *res,
 158                             const struct taia *u,
 159                             const struct taia *v)
 160 {
 161         unsigned long unano = u->nano;
 162         unsigned long uatto = u->atto;
 163         res->sec.x = u->sec.x - v->sec.x;
 164         res->nano = unano - v->nano;
 165         res->atto = uatto - v->atto;
 166         if (res->atto > uatto) {
 167                 res->atto += 1000000000UL;
 168                 --res->nano;
 169         }
 170         if (res->nano > unano) {
 171                 res->nano += 1000000000UL;
 172                 --res->sec.x;
 173         }
 174 }
 175
 176 /* XXX: breaks tai encapsulation */
 177
 178 /* calcs u + v */
 179 static inline void taia_add(struct taia *res,
 180                             const struct taia *u,
 181                             const struct taia *v)
 182 {
 183         res->sec.x = u->sec.x + v->sec.x;
 184         res->nano = u->nano + v->nano;
 185         res->atto = u->atto + v->atto;
 186         if (res->atto > 999999999UL) {
 187                 res->atto -= 1000000000UL;
 188                 ++res->nano;
 189         }
 190         if (res->nano > 999999999UL) {
 191                 res->nano -= 1000000000UL;
 192                 ++res->sec.x;
 193         }
 194 }
 195
 196 /* 1 if t is less than u, 0 otherwise */
 197 static inline int taia_less(const struct taia *t, const struct taia *u)
 198 {
 199         if (t->sec.x < u->sec.x)
 200                 return 1;
 201         if (t->sec.x > u->sec.x)
 202                 return 0;
 203         if (t->nano < u->nano)
 204                 return 1;
 205         if (t->nano > u->nano)
 206                 return 0;
 207         return t->atto < u->atto;
 208 }
 209
 210 static inline int is_good_taia(struct taia *arrival_taia,
 211                                struct taia *packet_taia)
 212 {
 213         int is_ts_good = 0;
 214         struct taia sub_res;
 215         if (taia_less(arrival_taia, packet_taia)) {
 216                 taia_sub(&sub_res, packet_taia, arrival_taia);
 217                 if (taia_less(&sub_res, &tolerance_taia))
 218                         is_ts_good = 1;
 219                 else
 220                         is_ts_good = 0;
 221         } else {
 222                 taia_sub(&sub_res, arrival_taia, packet_taia);
 223                 if (taia_less(&sub_res, &tolerance_taia))
 224                         is_ts_good = 1;
 225                 else
 226                         is_ts_good = 0;
 227         }
 228         return is_ts_good;
 229 }
 230
 231 #endif /* CURVE_H */