diff --git a/src/cipher_analytical_machine/parsers/gamma.clj b/src/cipher_analytical_machine/parsers/gamma.clj
new file mode 100644
index 0000000..22e2ac3
--- /dev/null
+++ b/src/cipher_analytical_machine/parsers/gamma.clj
@@ -0,0 +1,9 @@
+(ns cipher-analytical-machine.parsers.gamma
+  (:gen-class))
+
+(defn key?
+  "Return true if the string is an key of three integers."
+  [str]
+  (if (re-matches #"[+-]?\b\d+\b,[+-]?\b\d+\b,[+-]?\b\d+\b" str)
+    true false))
+
diff --git a/test/cipher_analytical_machine/parsers/gamma_test.clj b/test/cipher_analytical_machine/parsers/gamma_test.clj
new file mode 100644
index 0000000..11992b2
--- /dev/null
+++ b/test/cipher_analytical_machine/parsers/gamma_test.clj
@@ -0,0 +1,20 @@
+(ns cipher-analytical-machine.parsers.gamma-test
+  (:require
+   [clojure.test :refer :all]
+   [cipher-analytical-machine.parsers.gamma :refer :all]))
+
+(deftest key?-test
+  (testing "The function return true only if the key in the format '%d,%d,%d'."
+    (are [str expected]
+        (= expected
+           (key? str))
+      "9"         false
+      "9,10"      false
+      "10,9,8"    true
+      "-10,9,-8"  true
+      "-10,-9,-8" true
+      "asd 10 "   false
+      " 10 "      false
+      "-10"       false
+      "abc"       false)))
+