| 1 | import math |
| 2 | import math.big { Integer } |
| 3 | import crypto.rand |
| 4 | |
| 5 | struct SSS { |
| 6 | mut: |
| 7 | prime Integer = big.integer_from_string('115792089237316195423570985008687907853269984665640564039457584007913129639747')! |
| 8 | } |
| 9 | |
| 10 | // random returns a random number from the range (0, prime-1) inclusive |
| 11 | fn (s SSS) random() !Integer { |
| 12 | mut result := big.zero_int + s.prime |
| 13 | result = result - big.one_int |
| 14 | return rand.int_big(result) |
| 15 | } |
| 16 | |
| 17 | // mod_inverse computes the multiplicative inverse of the number on the field |
| 18 | // prime; more specifically, number * inverse == 1; Note: number should never be |
| 19 | // zero |
| 20 | fn mod_inverse(number Integer) Integer { |
| 21 | s := SSS{} |
| 22 | copy := number % s.prime |
| 23 | pcopy := s.prime |
| 24 | |
| 25 | _, _, y := math.egcd(pcopy.int(), copy.int()) |
| 26 | |
| 27 | return (s.prime + big.integer_from_i64(y)) % s.prime |
| 28 | } |
| 29 | |
| 30 | fn main() { |
| 31 | mod_inverse(big.integer_from_string('1')!) |
| 32 | } |
| 33 | |