diff --git a/src/cipher_analytical_machine/analyzers/simple_substitution.clj b/src/cipher_analytical_machine/analyzers/simple_substitution.clj
index 717b49b..802887b 100644
--- a/src/cipher_analytical_machine/analyzers/simple_substitution.clj
+++ b/src/cipher_analytical_machine/analyzers/simple_substitution.clj
@@ -1,8 +1,10 @@
 (ns cipher-analytical-machine.analyzers.simple-substitution
   (:require [clojure.string :as cs]
             [clojure.math.combinatorics :as comb]
+            [cipher-analytical-machine.symbols.frequencies :as frequencies]
             [cipher-analytical-machine.ciphers.simple-substitution :as ss]
             [cipher-analytical-machine.analyzers.analyzers :as analyzers]
+            [cipher-analytical-machine.analyzers.analyzers :as ca]
             [cipher-analytical-machine.analyzers.caesar :as caesar])
   (:gen-class))
 
@@ -42,3 +44,35 @@
   (->> (map get-all-permutation-for-block possible-key-vector)
        (get-all-combinations-for-blocks)))
 
+(defn get-possible-keys
+  "Return keys for a cipher text. A key is a map {\\a \\e, ...} to decrypt a text."
+  [cipher-text frequency-table]
+  (let [freq-symbol-str (frequencies/map-to-string frequency-table) ; "etaoinsrhldcumfpgwybvkxjqz"
+        char-map (-> (analyzers/count-characters cipher-text)
+                     (analyzers/reverse-count-characters))]
+    (map (fn [comb] (zipmap comb freq-symbol-str))
+         (-> (get-possible-key-vector-from-reversed-count-map char-map)
+             (get-possible-key-combinations)))))
+
+
+(defn get-plain-data
+  "Return the plain data (score, text, key) from a ciphertext (a string of character). The function is case-insensitive."
+  [cipher-text letter-frequencies]
+  (let [cipher-text (cs/lower-case cipher-text)
+        keys (get-possible-keys cipher-text letter-frequencies)]
+    (->> (map (fn [key] [(ss/decrypt-message-by-symbol-table key cipher-text) key]) keys)
+         (map (fn [[text key]] [(ca/chi-squared-statistic text letter-frequencies) text key]))
+         )))
+
+(defn get-plaintext-and-key
+  "Return the possible plaintext from a ciphertext that encoded with numbers. The function is case-insensitive."
+  [cipher-text letter-frequencies]
+  (let [maybe-key   (->> (frequencies/map-to-string letter-frequencies)
+                         (ss/generate-sorted-substitution-table))
+        cipher-text (->> (cs/split cipher-text #",")
+                         (map #(Integer/parseInt %))
+                         (ss/decrypt-message-by-symbol-table maybe-key))]
+
+    (->> (get-plain-data cipher-text letter-frequencies)
+         (map (fn [el] (drop 1 el)) ))))
+