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Task/Vigen-re-cipher/Java/vigen-re-cipher.java

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+public class VigenereCipher {
+    public static void main(String[] args) {
+        String key = "VIGENERECIPHER";
+        String ori = "Beware the Jabberwock, my son! The jaws that bite, the claws that catch!";
+        String enc = encrypt(ori, key);
+        System.out.println(enc);
+        System.out.println(decrypt(enc, key));
+    }
+
+    static String encrypt(String text, final String key) {
+        String res = "";
+        text = text.toUpperCase();
+        for (int i = 0, j = 0; i < text.length(); i++) {
+            char c = text.charAt(i);
+            if (c < 'A' || c > 'Z') continue;
+            res += (char)((c + key.charAt(j) - 2 * 'A') % 26 + 'A');
+            j = ++j % key.length();
+        }
+        return res;
+    }
+
+    static String decrypt(String text, final String key) {
+        String res = "";
+        text = text.toUpperCase();
+        for (int i = 0, j = 0; i < text.length(); i++) {
+            char c = text.charAt(i);
+            if (c < 'A' || c > 'Z') continue;
+            res += (char)((c - key.charAt(j) + 26) % 26 + 'A');
+            j = ++j % key.length();
+        }
+        return res;
+    }
+}