diff options
| author | Nguyễn Gia Phong <mcsinyx@disroot.org> | 2020-11-14 11:10:22 +0700 |
|---|---|---|
| committer | Nguyễn Gia Phong <mcsinyx@disroot.org> | 2020-11-14 11:10:22 +0700 |
| commit | 82048ad9e3e4a96a38c8fa6a529798f40e33acb1 (patch) | |
| tree | ad1d22488baa85f0b0f6bde25cfd75375eeda5b6 /usth/ICT3.4/powmod.scm | |
| parent | 4e280d6460a16b971ca76da632c9b20e55812f0c (diff) | |
| download | cp-82048ad9e3e4a96a38c8fa6a529798f40e33acb1.tar.gz | |
[usth/ICT3.4] Secure information
Diffstat (limited to 'usth/ICT3.4/powmod.scm')
| -rw-r--r-- | usth/ICT3.4/powmod.scm | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/usth/ICT3.4/powmod.scm b/usth/ICT3.4/powmod.scm new file mode 100644 index 0000000..b21e995 --- /dev/null +++ b/usth/ICT3.4/powmod.scm @@ -0,0 +1,9 @@ +(define (square x) (* x x)) +(display + (let powmod ((x (read)) (e (read)) (m (read))) + ; let's ignore negative e here + (cond ((= e 0) 1) + ((= e 1) (remainder x m)) + ((even? e) (remainder (square (powmod x (/ e 2) m)) m)) + (else (remainder (* (square (powmod x (quotient e 2) m)) x) m))))) +(newline) |