diff --git a/CHANGELOG.md b/CHANGELOG.md
index abeb70a..3282f15 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,7 +7,27 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.9.15] - 2023-11-26
+
+### Changed
+- Update the CHANGELOG.
+- Update the version.
+- Update the README.
+
+## [0.9.14] - 2023-11-26
+
+### Added
+- Add analyzer for the simple substitution cipher.
+- Add the analyzer options and their actions for the simple substiotution.
+
+## [0.9.13] - 2023-11-26
+
+### Fixed
+- Fix the test name.
+
 ## [0.9.12] - 2023-11-20
+
+### Changed
 - Update the CHANGELOG.
 - Update the version.
 - Update the README.
@@ -291,7 +311,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 - Project initialization.
 
-[Unreleased]: https://gitlab.com/KKlochko/cipher-analytical-machine/-/compare/0.9.12...main?from_project_id=50218541&straight=false
+[Unreleased]: https://gitlab.com/KKlochko/cipher-analytical-machine/-/compare/0.9.15...main?from_project_id=50218541&straight=false
+[0.9.15]: https://gitlab.com/KKlochko/cipher-analytical-machine/-/compare/0.9.14...0.0.9.15?from_project_id=50218541&straight=false
+[0.9.14]: https://gitlab.com/KKlochko/cipher-analytical-machine/-/compare/0.9.13...0.0.9.14?from_project_id=50218541&straight=false
+[0.9.13]: https://gitlab.com/KKlochko/cipher-analytical-machine/-/compare/0.9.12...0.0.9.13?from_project_id=50218541&straight=false
 [0.9.12]: https://gitlab.com/KKlochko/cipher-analytical-machine/-/compare/0.9.11...0.0.9.12?from_project_id=50218541&straight=false
 [0.9.11]: https://gitlab.com/KKlochko/cipher-analytical-machine/-/compare/0.9.10...0.0.9.11?from_project_id=50218541&straight=false
 [0.9.10]: https://gitlab.com/KKlochko/cipher-analytical-machine/-/compare/0.9.9...0.9.10?from_project_id=50218541&straight=false
diff --git a/README.md b/README.md
index 4a7f018..c83e7ee 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ You need install java, before run the application.
 Run the application with a command:
 
     $ java -jar cipher-analytical-machine-VERSION-standalone.jar [args]
-    $ java -jar cipher-analytical-machine-0.9.12-standalone.jar [args]
+    $ java -jar cipher-analytical-machine-0.9.15-standalone.jar [args]
 
 ## License
 
diff --git a/project.clj b/project.clj
index 45bb729..895b5cf 100644
--- a/project.clj
+++ b/project.clj
@@ -1,4 +1,4 @@
-(defproject cipher-analytical-machine "0.9.12"
+(defproject cipher-analytical-machine "0.9.15"
   :description "A program helps to learn how ciphers works."
   :url "https://gitlab.com/KKlochko/cipher-analytical-machine"
   :license {:name "LGPL"
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)) ))))
+
diff --git a/src/cipher_analytical_machine/cli/actions/cracking.clj b/src/cipher_analytical_machine/cli/actions/cracking.clj
index db4a8ab..4162727 100644
--- a/src/cipher_analytical_machine/cli/actions/cracking.clj
+++ b/src/cipher_analytical_machine/cli/actions/cracking.clj
@@ -1,6 +1,7 @@
 (ns cipher-analytical-machine.cli.actions.cracking
   (:require
    [cipher-analytical-machine.analyzers.caesar :as caesar-analyzers]
+   [cipher-analytical-machine.analyzers.simple-substitution :as ss-analyzers]
    [cipher-analytical-machine.symbols.frequencies :as symbol-frequencies])
   (:gen-class))
 
@@ -18,10 +19,27 @@
       :else
       (caesar-analyzers/get-plaintext message symbols frequencies))))
 
+(defn cracking-simple-substitution-with-caesar
+  [options arguments]
+  (let [analyzer (:analyzer options)
+        message (:message options)
+        symbols (:symbols options)
+        frequencies (-> (get options :language "en")
+                        (symbol-frequencies/default-frequency-factory))]
+    (cond
+      (= analyzer "Chi^2")
+      (ss-analyzers/get-plaintext-and-key message frequencies)
+
+      :else
+      (ss-analyzers/get-plaintext-and-key message frequencies))))
+
 (defn cracking-actions
   [options arguments action-type]
   (let [cipher (:cipher options)]
     (cond
       (= cipher "Caesar")
-      (cracking-caesar options arguments))))
+      (cracking-caesar options arguments)
+
+      (= cipher "Simple substitution and Caesar")
+      (cracking-simple-substitution-with-caesar options arguments))))
 
diff --git a/src/cipher_analytical_machine/cli/options.clj b/src/cipher_analytical_machine/cli/options.clj
index dd93152..61624d7 100644
--- a/src/cipher_analytical_machine/cli/options.clj
+++ b/src/cipher_analytical_machine/cli/options.clj
@@ -32,7 +32,8 @@
   (option-values-as-row "Ciphers" cipher-options))
 
 (def analyzers-options
-  {"Caesar" #{"Chi^2"}})
+  {"Caesar" #{"Chi^2" "Frequency"}
+   "Simple substitution and Caesar" #{"Chi^2" "Frequency"}})
 
 (defn get-available-analyzers-options-as-string
   "Return the formatted string of analyzers options."
diff --git a/test/cipher_analytical_machine/symbols/frequencies_test.clj b/test/cipher_analytical_machine/symbols/frequencies_test.clj
index 6f6e098..edb79b0 100644
--- a/test/cipher_analytical_machine/symbols/frequencies_test.clj
+++ b/test/cipher_analytical_machine/symbols/frequencies_test.clj
@@ -3,7 +3,7 @@
    [clojure.test :refer :all]
    [cipher-analytical-machine.symbols.frequencies :refer :all]))
 
-(deftest calculate-char-index-test
+(deftest map-to-string-test
   (let [symbol-map english-letter-frequencies]
     (testing "The map must be converted to 'etaoinsrhldcumfpgwybvkxjqz'"
       (is (= "etaoinsrhldcumfpgwybvkxjqz"