【新月実装】需【Clojure・ClojureScript】

ffe7d06a :Anonymous 2016-01-16 12:03

@markdown
apollo.pyのClojure版が一応出来ました。

```clojure
(def int-to-base64-char-table
{0 "A" 16 "Q" 32 "g" 48 "w"
1 "B" 17 "R" 33 "h" 49 "x"
2 "C" 18 "S" 34 "i" 50 "y"
3 "D" 19 "T" 35 "j" 51 "z"
4 "E" 20 "U" 36 "k" 52 "0"
5 "F" 21 "V" 37 "l" 53 "1"
6 "G" 22 "W" 38 "m" 54 "2"
7 "H" 23 "X" 39 "n" 55 "3"
8 "I" 24 "Y" 40 "o" 56 "4"
9 "J" 25 "Z" 41 "p" 57 "5"
10 "K" 26 "a" 42 "q" 58 "6"
11 "L" 27 "b" 43 "r" 59 "7"
12 "M" 28 "c" 44 "s" 60 "8"
13 "N" 29 "d" 45 "t" 61 "9"
14 "O" 30 "e" 46 "u" 62 "+"
15 "P" 31 "f" 47 "v" 63 "/" })

(def base64-char-to-int-table (clojure.set/map-invert int-to-base64-char-table))

(defn- expt-mod [b e n] (bigint (.modPow (biginteger b) (biginteger e) (biginteger n))))

(defn- hex-string-to-bigint
[s]
(apply +
(map
(fn [[x y] n] (* (bigint (Integer/parseInt (str x y) 16)) (expt 256 n)))
(partition 2 s)
(range (/ (count s) 2)))))

(defn- is-nth-bit-on? [num n] (pos? (rem (quot num (expt 2 (dec n))) 2)))

(defn- bigint-to-base64-
[n]
(if (>= n 64)
(concat (list (get int-to-base64-char-table (rem n 64))) (bigint-to-base64- (quot n 64)))
(list (get int-to-base64-char-table n))))

(defn- add-padding [s] (str s (apply str (repeat (- 86 (count s)) "A"))))

(defn- bigint-to-base64
[n]
(add-padding (apply str (bigint-to-base64- n))))

(defn- base64-to-bigint
[s]
(apply +
(map (fn [c n] (* (bigint (get base64-char-to-int-table (str c))) (expt 64 n)))
s
(range (count s)))))

(defn get-prime-numbers-for-signature
[password]
(let [hashs (str (digest/md5 password)
(digest/md5 (str password "pad1"))
(digest/md5 (str password "pad2"))
(digest/md5 (str password "pad3")))
match (re-find #"^(.{56})(.{72})$" hashs)
p (hex-string-to-bigint (nth match 1))
q (hex-string-to-bigint (nth match 2))
p (if (is-nth-bit-on? p 216) p (+ p (expt 2 215)))
q (if (is-nth-bit-on? p 280) q (+ q (expt 2 279)))
p (bigint (.nextProbablePrime (biginteger p)))
q (bigint (.nextProbablePrime (biginteger q)))
t 30531
e 65537]
(loop [p p
q q]
(let [n (* p q)
d (bigint (.modInverse (biginteger e) (biginteger (* (dec p) (dec q)))))]
(if (= (expt-mod t (* e d) n) t)
[n d]
(recur (+ p 2) (+ q 2)))))))

(defn- md5-string-to-bigint
[s]
(apply +
(map
(fn [c n] (* (bigint (int c)) (expt 256 n)))
s
(range (count s)))))

(defn sign-post
[target password]
(let [[n d] (get-prime-numbers-for-signature password)
public-key (bigint-to-base64 n)
secret-key (bigint-to-base64 d)
target-bigint (md5-string-to-bigint (digest/md5 target))
c (expt-mod target-bigint d n)
signature (add-padding (apply str (bigint-to-base64 c)))]
{:public-key public-key :signature signature}))

(defn verify-signature
[target public-key signature]
(= (md5-string-to-bigint (digest/md5 target))
(expt-mod (base64-to-bigint signature) 65537 (base64-to-bigint public-key))))
```

こんなふうに使えます。

```
(ju.routes.shingetsu/sign-post "body:test" "test")
=>
{:public-key "DpmzfQSOhbpxE7xuaiEao3ztv9NAJi/loTs2N43f5hC3XpT3z9VhApcrYy94XhMBKONo5H14c8STrriPJnCcVA",
:signature "DmjCwvX8DMpsEr30bGB8XIXMgTO6Iwz8Yb5Q0CjACoqZK1kvkYluXjiW3n24QMzZ5qPb3Z49JLPV4ekLL0yRJA"}
(ju.routes.shingetsu/verify-signature "body:test" "DpmzfQSOhbpxE7xuaiEao3ztv9NAJi/loTs2N43f5hC3XpT3z9VhApcrYy94XhMBKONo5H14c8STrriPJnCcVA" "DmjCwvX8DMpsEr30bGB8XIXMgTO6Iwz8Yb5Q0CjACoqZK1kvkYluXjiW3n24QMzZ5qPb3Z49JLPV4ekLL0yRJA")
=> true
```

調べてみたら朔の素数判定の誤り率が1/4^10=1/1048576、
Clojure (Java)のは1/2^100=1/1267650600228229401496703205376だったので
とりあえず素数判定の問題は後回しにすることにします。