Part 1: Design a Cipher allow user to use a “key” to encrypt and decrypt the...

Part 1: Design a Cipher allow user to use a “key” to encrypt and decrypt the message.
Use at least two ciphers combined to design your own cipher
Specify the min. and max. length of the message user can enter to encrypt
Specify the length of the “key” user can enter to encrypt and decrypt the message
Part 2: Programme the cipher and make it available to validate. Cleartext for the original programming scripts has to submitted. A frontend webpage is provided to allow for validation of the programme and the cipher. Provide a frontend interface for your professor to validate the design with clear instructions (like the length of the input message and key). You can use java or HTML.User enter the message with the key of his/her choice, your cipher will convert them to ciphertext.User cut and paste the ciphertext to your decryption session and input the same “key”, the original message is decrypted and is the same as what the user enters in the encryption session.

Expert Solution

Code to encrypt and decrypt the message.

<html>
<head>
    <title> Caesar Cipher</title>
</head>

<body background="https://cdn.pixabay.com/photo/2016/08/13/16/49/computer-1591018_1280.jpg">
    <center>
        <h1><Strong>
                <font face="" color="white" >JAVASCRIPT CODING
            </strong></font>
        </h1>

        <h2><U><font color= "grey" >Caesar Cipher</U></font></h2>
        <script type="text/javascript">
            function Encrypt() {
                plaintext = document.getElementById("p").value.toLowerCase();
                if (plaintext.length < 1) { alert("please enter some plaintext"); return; }
                var shift = parseInt(document.getElementById("key").value);
                ciphertext = ""; var re = /[a-z]/;
                for (i = 0; i < plaintext.length; i++) {
                    if (re.test(plaintext.charAt(i)))
                        ciphertext += String.fromCharCode((plaintext.charCodeAt(i) - 97 + shift) % 26 + 97);
                    else
                        ciphertext += plaintext.charAt(i);
                }
                document.getElementById("c").value = ciphertext;
            }

            function Decrypt(f) {
                ciphertext = document.getElementById("c").value.toLowerCase();
                // do some error checking 
                if (ciphertext.length < 1) { alert("please enter some ciphertext"); return; }
                var shift = parseInt(document.getElementById("key").value);
                plaintext = ""; var re = /[a-z]/;
                for (i = 0; i < ciphertext.length; i++) {
                    if (re.test(ciphertext.charAt(i))) plaintext += String.fromCharCode((ciphertext.charCodeAt(i) - 97 + 26 - shift) % 26 + 97);
                    else plaintext += ciphertext.charAt(i);
                }
                document.getElementById("p").value = plaintext;
            } 
        </script>

        <h3><b><U>
                    <Font color="black" face="Serif"> Plain text</Font>
                </U></b></h3><br />
        <textarea id="p" name="p" rows="3" cols="50" placeholder=" Here type your plaintext."></textarea>
        <p> shift: <select id="key" name="key" size="1">
                <option value="0">0</option>
                <option value="1">1</option>
                <option value="2">2</option>
                <option value="3" selected="selected">3</option>
                <option value="4">4</option>
                <option value="5">5</option>
                <option value="6">6</option>
                <option value="7">7</option>
                <option value="8">8</option>
                <option value="9">9</option>
                <option value="10">10</option>
                <option value="11">11</option>
                <option value="12">12</option>
                <option value="13">13</option>
                <option value="14">14</option>
                <option value="15">15</option>
                <option value="16">16</option>
                <option value="17">17</option>
                <option value="18">18</option>
                <option value="19">19</option>
                <option value="20">20</option>
                <option value="21">21</option>
                <option value="22">22</option>
                <option value="23">23</option>
                <option value="24">24</option>
                <option value="25">25</option>
            </select></p>
        <p><input name="btnEn" value="v Encrypt v" onclick="Encrypt()" type="button" />
            <input name="btnDe" value="^ Decrypt ^" onclick="Decrypt()" type="button" /></p>
        <p><b><U><br>
                    <Font color="black" face="Arial">Ciphertext</Font> <br>
                </U></b></br><textarea id="c" name="c" rows="3" cols="50"
                placeholder="Here you will get your cipher text. "></textarea>
        </p>

    </center>

</html>

venereology answered 1 year ago

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Part 1: Design a Cipher allow user to use a “key” to encrypt and decrypt the...

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