From f172a5dcee37fb24e699193281f14a7b4e6447e9 Mon Sep 17 00:00:00 2001
From: David Florness <david@florness.com>
Date: Sun, 10 Nov 2019 05:46:09 -0700
Subject: [PATCH] Create endpoint to retrieve server's key

---
 crypto.rkt | 30 ++++++++++++++++--------------
 main.rkt   |  8 +++++---
 server.rkt |  9 +++++++++
 3 files changed, 30 insertions(+), 17 deletions(-)

diff --git a/crypto.rkt b/crypto.rkt
index 2adf34a..674b8df 100644
--- a/crypto.rkt
+++ b/crypto.rkt
@@ -1,22 +1,24 @@
 #lang racket
 (require math/number-theory)
 
-(provide keylen e p q d n)
+(provide keylen e gen-key)
 
 (define keylen 1024)
 (define e 65537)
 
-(define (gen)
-  (let* ([p (random-prime (expt 2 (/ keylen 2)))]
-         [q (random-prime (expt 2 (/ keylen 2)))]
-         [λn (lcm (sub1 p) (sub1 q))])
-    (if (and (eq? (gcd e λn) 1)
-             (not (eq? (arithmetic-shift (abs (- p q))
-                                         (- (- (/ keylen 2) 100)))
-                       0)))
-        (values p q λn)
-        (gen))))
+(define (gen-key)
+  (define (gen)
+    (let* ([p (random-prime (expt 2 (/ keylen 2)))]
+           [q (random-prime (expt 2 (/ keylen 2)))]
+           [λn (lcm (sub1 p) (sub1 q))])
+      (if (and (eq? (gcd e λn) 1)
+               (not (eq? (arithmetic-shift (abs (- p q))
+                                           (- (- (/ keylen 2) 100)))
+                         0)))
+          (values p q λn)
+          (gen))))
 
-(define-values (p q λn) (gen))
-(define n (* p q))
-(define d (modular-inverse e λn))
+  (let-values ([(p q λn) (gen)])
+    (list (* p q) ; n
+          (modular-inverse e λn) ; d
+          )))
diff --git a/main.rkt b/main.rkt
index f867d53..8ca9130 100644
--- a/main.rkt
+++ b/main.rkt
@@ -1,9 +1,9 @@
 #lang racket
 (require binaryio)
-(require "crypto.rkt")
 (require racket/random)
 (require net/url)
 (require json)
+(require "crypto.rkt")
 
 (define/contract (vohea-url path)
   (-> string? url?)
@@ -31,6 +31,8 @@
 (display "Your ranking: ")
 (define ranking (string-split (read-line)))
 
+(define n (bytes->integer (port->bytes (get-pure-port (vohea-url "/key"))) #f))
+
 (define m (bytes->integer (string->bytes/utf-8 (string-join ranking ":")) #f))
 
 (define r
@@ -42,5 +44,5 @@
 
 (define M (modulo (* m (expt r e)) n))
 
-(read (post-pure-port (vohea-url "/sign")
-                      (integer->bytes M (/ keylen 8) #f)))
+(define S (port->bytes (post-pure-port (vohea-url "/sign")
+                                       (integer->bytes M (/ keylen 8) #f))))
diff --git a/server.rkt b/server.rkt
index a247d31..7ed2630 100644
--- a/server.rkt
+++ b/server.rkt
@@ -4,8 +4,11 @@
          web-server/servlet-env
          web-server/http)
 (require json)
+(require "crypto.rkt")
+(require binaryio)
 
 (define cands (list "ohea" "rtsn" "qfuy"))
+(define k (gen-key))
 
 ; how this is not a provided function is beyond me
 (define/contract (response/json jsexpr)
@@ -27,11 +30,17 @@
   (response/xexpr
    '(html (body (p "hello there")))))
 
+(define (key req)
+  (response/full
+   200 #f (current-seconds) #"application/octet-stream"
+   empty (list (integer->bytes (car k) (/ keylen 8) #f))))
+
 (define-values (dispatcher url-generator)
   (dispatch-rules
    [("candidates") candidates]
    [("vote") vote]
    [("sign") #:method "post" sign]
+   [("key") key]
    [else candidates]))
 
 (serve/servlet dispatcher
-- 
2.38.4