diff --git a/src/cypher.ts b/src/cypher.ts
index eec8389..dc4d960 100644
--- a/src/cypher.ts
+++ b/src/cypher.ts
@@ -61,6 +61,7 @@ export class Cypher {
     for (let i = 0; i < message.length; i++) {
       const char: string = message.charAt(i);
       const index: number = dictSource.indexOf(char);
+      if(!dictTarget[index]) continue;
       result += dictTarget[index];
     }
     return result;
@@ -71,6 +72,6 @@ export class Cypher {
   }
 
   public encrypt(message: string): string {
-    return this._translate(this._alphabet, this._decryptionKey, message);
+    return this._translate(this._alphabet, this._decryptionKey, message.toLowerCase());
   }
 }
diff --git a/src/index.ts b/src/index.ts
index a420803..4121ad7 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1 +1,5 @@
+import {Cypher} from "@src/cypher";
+
 console.log('Hello World!');
+const cypher: Cypher = new Cypher();
+console.log(cypher.encrypt('Hello World!'));
diff --git a/tests/cypher.test.ts b/tests/cypher.test.ts
index 0951aa1..bf21c57 100644
--- a/tests/cypher.test.ts
+++ b/tests/cypher.test.ts
@@ -1,4 +1,4 @@
-import { Cypher } from '@src/cypher';
+import {Cypher} from '@src/cypher';
 
 describe('Cypher', () => {
   it('should be OK', () => {
@@ -6,6 +6,14 @@ describe('Cypher', () => {
     expect(cypher).toBeDefined();
     expect(cypher).toBeInstanceOf(Cypher);
   });
+  it('should decrypt h', () => {
+    const cypher: Cypher = new Cypher();
+    expect(cypher.decrypt('&')).toBe('h');
+  });
+  it('should decrypt he', () => {
+    const cypher: Cypher = new Cypher();
+    expect(cypher.decrypt('&£')).toBe('he');
+  });
   it('should decrypt hello', () => {
     const cypher: Cypher = new Cypher();
     expect(cypher.decrypt('&£aad')).toBe('hello');
@@ -14,6 +22,14 @@ describe('Cypher', () => {
     const cypher: Cypher = new Cypher();
     expect(cypher.decrypt('ldga(')).toBe('world');
   });
+  it('should encrypt h', () => {
+    const cypher: Cypher = new Cypher();
+    expect(cypher.encrypt('h')).toBe('&');
+  });
+  it('should encrypt he', () => {
+    const cypher: Cypher = new Cypher();
+    expect(cypher.encrypt('he')).toBe('&£');
+  });
   it('should encrypt hello', () => {
     const cypher: Cypher = new Cypher();
     expect(cypher.encrypt('hello')).toBe('&£aad');
@@ -22,4 +38,12 @@ describe('Cypher', () => {
     const cypher: Cypher = new Cypher();
     expect(cypher.encrypt('world')).toBe('ldga(');
   });
+  it('should handle cases', () => {
+    const cypher: Cypher = new Cypher();
+    expect(cypher.encrypt('Hello')).toBe('&£aad');
+  });
+  it('should handle unknown characters', () => {
+    const cypher: Cypher = new Cypher();
+    expect(cypher.encrypt('Hello !')).toBe('&£aad');
+  });
 });