ptwist.h 2.6 KB

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  1. /* Slitheen - a decoy routing system for censorship resistance
  2. * Copyright (C) 2017 Ian Goldberg (iang@cs.uwaterloo.ca)
  3. *
  4. * This program is free software: you can redistribute it and/or modify
  5. * it under the terms of the GNU General Public License as published by
  6. * the Free Software Foundation, version 3.
  7. *
  8. * This program is distributed in the hope that it will be useful,
  9. * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10. * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  11. * GNU General Public License for more details.
  12. *
  13. * You should have received a copy of the GNU General Public License
  14. * along with this program. If not, see <http://www.gnu.org/licenses/>.
  15. *
  16. * Additional permission under GNU GPL version 3 section 7
  17. *
  18. * If you modify this Program, or any covered work, by linking or combining
  19. * it with the OpenSSL library (or a modified version of that library),
  20. * containing parts covered by the terms of the OpenSSL Licence and the
  21. * SSLeay license, the licensors of this Program grant you additional
  22. * permission to convey the resulting work. Corresponding Source for a
  23. * non-source form of such a combination shall include the source code
  24. * for the parts of the OpenSSL library used as well as that of the covered
  25. * work.
  26. */
  27. #ifndef PTWIST_H
  28. #define PTWIST_H
  29. #define PTWIST_BITS 168 /* must be a multiple of 8 */
  30. #define PTWIST_BYTES (PTWIST_BITS/8)
  31. #define PTWIST_TAG_BITS 224 /* must be a multiple of 8 */
  32. #define PTWIST_TAG_BYTES (PTWIST_TAG_BITS/8)
  33. #define PTWIST_PUZZLE_STRENGTH 0 /*21*/ /* set to 0 to disable client puzzle */
  34. #define PTWIST_PUZZLE_MASK ((1<<PTWIST_PUZZLE_STRENGTH)-1)
  35. #if PTWIST_PUZZLE_STRENGTH == 0
  36. #define PTWIST_RESP_BITS 0
  37. #else
  38. #define PTWIST_RESP_BITS (PTWIST_PUZZLE_STRENGTH+6)
  39. #endif
  40. #define PTWIST_RESP_BYTES ((PTWIST_RESP_BITS+7)/8)
  41. #define PTWIST_RESP_MASK ((1<<(((PTWIST_RESP_BITS&7)==0)?8:(PTWIST_RESP_BITS&7)))-1)
  42. #define PTWIST_HASH_SHOWBITS (PTWIST_TAG_BITS-PTWIST_BITS-PTWIST_RESP_BITS)
  43. #define PTWIST_HASH_TOTBITS (PTWIST_HASH_SHOWBITS+PTWIST_PUZZLE_STRENGTH)
  44. #define PTWIST_HASH_TOTBYTES ((PTWIST_HASH_TOTBITS+7)/8)
  45. #define PTWIST_HASH_MASK ((1<<(((PTWIST_HASH_TOTBITS&7)==0)?8:(PTWIST_HASH_TOTBITS&7)))-1)
  46. typedef unsigned char byte;
  47. /* Figure out whether there's a point with x-coordinate x on the main
  48. * curve. If not, then there's one on the twist curve. (There are
  49. * actually two, which are negatives of each other; that doesn't
  50. * matter.) Multiply that point by seckey and set out to the
  51. * x-coordinate of the result. */
  52. void ptwist_pointmul(byte out[PTWIST_BYTES], const byte x[PTWIST_BYTES],
  53. const byte seckey[PTWIST_BYTES]);
  54. #endif