Add the gamma generator.

src/cipher_analytical_machine/ciphers/gamma.clj

@@ -0,0 +1,32 @@
+(ns cipher-analytical-machine.ciphers.gamma
+  (:require [clojure.string :as cs])
+  (:gen-class))
+
+(defn add-mod
+  [f s module]
+  (-> (+ f s)
+      (mod module)))
+
+(defn generate-seq
+  "Generate a lazy sequence for a key (a b c)."
+  [a b c module]
+  ((fn build-seq [a b c]
+     (lazy-seq (cons a (build-seq b c (add-mod a c module))))) a b c))
+
+(defn generate-gamma-seq
+  "Generate the gamma seq from a sequence."
+  [acc seq module]
+  (if (= (second seq) nil) acc
+    (generate-gamma-seq
+     (conj acc (add-mod (first seq) (second seq) module))
+     (rest seq)
+     module)))
+
+(defn generate-gamma
+  "Generate the gamma from a key (a b c)."
+  [a b c module size]
+  (generate-gamma-seq []
+                      (->> (generate-seq a b c module)
+                           (take (inc size)))
+                      module))
+

test/cipher_analytical_machine/ciphers/gamma_test.clj

@@ -0,0 +1,34 @@
+(ns cipher-analytical-machine.ciphers.gamma-test
+  (:require
+   [clojure.test :refer :all]
+   [cipher-analytical-machine.ciphers.gamma :refer :all]))
+
+(deftest add-mod-test
+  (testing "The remainder must be as expected."
+    (are [a b module expected]
+        (= expected (add-mod a b module))
+      5 2 4 3
+      1 2 3 0
+      2 2 3 1)))
+
+(deftest generate-seq-test
+  (testing "Checking that the next element of a sequence is calculated by (e[i-1] + e[i-3] % mod)."
+    (are [a b c module size expected]
+        (= expected (take size (generate-seq a b c module)))
+      4 32 15 33 10 [4 32 15 19 18 0 19 4 4 23]
+      1 2  3  3  9  [1 2 3 1 0 0 1 1 1])))
+
+(deftest generate-gamma-seq-test
+  (testing "Checking that the next element of a sequence is calculated by (s[i] + s[i+1] % mod)."
+    (are [acc seq module expected]
+        (= expected (generate-gamma-seq acc seq module))
+      [] [4 32 15 19 18 0 19 4 4 23] 33 [3 14 1 4 18 19 23 8 27]
+      [] [1 2 3 1 0 0 1 1 1]         3  [0 2 1 1 0 1 2 2])))
+
+(deftest generate-gamma-test
+  (testing "Checking that the gamma is generated as expected."
+    (are [a b c module size expected]
+        (= expected (generate-gamma a b c module size))
+      4 32 15 33 10 [3 14 1 4 18 19 23 8 27 17]
+      1 2  3  3  9  [0 2 1 1 0 1 2 2 0])))
+