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<!DOCTYPE html>
<html>
<head>
<title>Encryption tutorial</title>
</head>
<bodyonload="" style="background-color:#dddddd; ">
<table>
<tr><td>Input:</td><tdcolspan="3">
<svgid="svgIn" width="1040" height="40">
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<circleid="CircleIn1" cx="60" cy="20" r="15" style="stroke: #000000; fill: #eeeeee;" ></circle>
<textid="TextIn1" x="57" y="25" visibility="visible" font-size="12">B</text>
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<textid="TextIn2" x="97" y="25" visibility="visible" font-size="12">C</text>
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<textid="TextIn3" x="137" y="25" visibility="visible" font-size="12">D</text>
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<textid="TextIn5" x="217" y="25" visibility="visible" font-size="12">F</text>
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<textid="TextIn8" x="337" y="25" visibility="visible" font-size="12">I</text>
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<textid="TextIn10" x="417" y="25" visibility="visible" font-size="12">K</text>
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<textid="TextIn15" x="617" y="25" visibility="visible" font-size="12">P</text>
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<textid="TextIn16" x="657" y="25" visibility="visible" font-size="12">Q</text>
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<textid="TextIn17" x="697" y="25" visibility="visible" font-size="12">R</text>
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<textid="TextIn19" x="777" y="25" visibility="visible" font-size="12">T</text>
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<textid="TextIn20" x="817" y="25" visibility="visible" font-size="12">U</text>
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<textid="TextIn25" x="1017" y="25" visibility="visible" font-size="12">Z</text>
</svg></td></tr>
<tr><td>Output:</td><tdcolspan="3">
<svgid="svgOut" width="1040" height="40">
<circleid="CircleOut0" cx="20" cy="20" r="15" style="stroke: #000000; fill: #ee8888;" ></circle>
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<textid="TextOut1" x="57" y="25" visibility="visible" font-size="12">B</text>
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<textid="TextOut4" x="177" y="25" visibility="visible" font-size="12">E</text>
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<textid="TextOut5" x="217" y="25" visibility="visible" font-size="12">F</text>
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<textid="TextOut6" x="257" y="25" visibility="visible" font-size="12">G</text>
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<textid="TextOut7" x="297" y="25" visibility="visible" font-size="12">H</text>
<circleid="CircleOut8" cx="340" cy="20" r="15" style="stroke: #000000; fill: #8888ee;" ></circle>
<textid="TextOut8" x="337" y="25" visibility="visible" font-size="12">I</text>
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<textid="TextOut9" x="377" y="25" visibility="visible" font-size="12">J</text>
<circleid="CircleOut10" cx="420" cy="20" r="15" style="stroke: #000000; fill: #eeeeee;" ></circle>
<textid="TextOut10" x="417" y="25" visibility="visible" font-size="12">K</text>
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<textid="TextOut11" x="457" y="25" visibility="visible" font-size="12">L</text>
<circleid="CircleOut12" cx="500" cy="20" r="15" style="stroke: #000000; fill: #eeeeee;" ></circle>
<textid="TextOut12" x="497" y="25" visibility="visible" font-size="12">M</text>
<circleid="CircleOut13" cx="540" cy="20" r="15" style="stroke: #000000; fill: #eeeeee;" ></circle>
<textid="TextOut13" x="537" y="25" visibility="visible" font-size="12">N</text>
<circleid="CircleOut14" cx="580" cy="20" r="15" style="stroke: #000000; fill: #eeee88;" ></circle>
<textid="TextOut14" x="577" y="25" visibility="visible" font-size="12">O</text>
<circleid="CircleOut15" cx="620" cy="20" r="15" style="stroke: #000000; fill: #eeeeee;" ></circle>
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<textid="TextOut16" x="657" y="25" visibility="visible" font-size="12">Q</text>
<circleid="CircleOut17" cx="700" cy="20" r="15" style="stroke: #000000; fill: #eeeeee;" ></circle>
<textid="TextOut17" x="697" y="25" visibility="visible" font-size="12">R</text>
<circleid="CircleOut18" cx="740" cy="20" r="15" style="stroke: #000000; fill: #eeeeee;" ></circle>
<textid="TextOut18" x="737" y="25" visibility="visible" font-size="12">S</text>
<circleid="CircleOut19" cx="780" cy="20" r="15" style="stroke: #000000; fill: #eeeeee;" ></circle>
<textid="TextOut19" x="777" y="25" visibility="visible" font-size="12">T</text>
<circleid="CircleOut20" cx="820" cy="20" r="15" style="stroke: #000000; fill: #88eeee;" ></circle>
<textid="TextOut20" x="817" y="25" visibility="visible" font-size="12">U</text>
<circleid="CircleOut21" cx="860" cy="20" r="15" style="stroke: #000000; fill: #eeeeee;" ></circle>
<textid="TextOut21" x="857" y="25" visibility="visible" font-size="12">V</text>
<circleid="CircleOut22" cx="900" cy="20" r="15" style="stroke: #000000; fill: #eeeeee;" ></circle>
<textid="TextOut22" x="897" y="25" visibility="visible" font-size="12">W</text>
<circleid="CircleOut23" cx="940" cy="20" r="15" style="stroke: #000000; fill: #eeeeee;" ></circle>
<textid="TextOut23" x="937" y="25" visibility="visible" font-size="12">X</text>
<circleid="CircleOut24" cx="980" cy="20" r="15" style="stroke: #000000; fill: #eeeeee;" ></circle>
<textid="TextOut24" x="977" y="25" visibility="visible" font-size="12">Y</text>
<circleid="CircleOut25" cx="1020" cy="20" r="15" style="stroke: #000000; fill: #eeeeee;" ></circle>
<textid="TextOut25" x="1017" y="25" visibility="visible" font-size="12">Z</text>
</svg>
</td></tr>
<tr><tdcolspan="2">Enter message:</td><td><inputtype="text" id='Message1' style="width:500px;"></td><td></td></tr>
<tr><tdcolspan="2">Cipher:</td><td><inputtype="text" id="Cipher1" readonlystyle="background-color:#dddddd; border-style:none; width:500px;"></td><td></td></tr>
<tr><tdcolspan="2">Decrypted:</td><td><inputtype="text" id="Decrypted1" readonlystyle="background-color:#dddddd; border-style:none; width:500px;"></td><td></td></tr>
<tr><tdcolspan="5"><br></td></tr>
<tr>
<td>
<buttonid="Button1" onclick='ClickSimple()'>Simple Caesar<br>Cipher Encryption</button>
</td>
<td></td><td>The Caesar cipher (or shift cipher) is one of the simplest forms of encryption. It shifts each letter a set number of places farther along in the alphabet.</td>
</tr>
<tr>
<td>
<buttonid="Button2" onclick='ClickProgressive()'>Progressive Caesar<br>Cipher Encryption</button>
</td>
<td></td><td>The progressive Caesar cipher shifts each letter in the message one step further than the previous letter to make it harder to crack without being much harder to encrypt and decrypt.</td>
</tr>
<tr>
<td>
<buttonid="Button3" onclick='ClickVigenere()'>Vigenère Cipher<br>Encryption</button>
</td>
<td></td><td>The Vigenère cipher combines a message with a code word adding the first letters of both, second letters of both, etc.</td>
</tr>
<tr>
<td>
<buttonid="Button4" onclick='ClickBase26()'>Base26 Block Cipher<br>Encryption</button>
</td>
<td></td><td>This method performs a mathematical calculation on the letters of the message in a reversible way. This is a block cipher with 8-character blocks.</td>
</tr>
<tr><tdcolspan="5"><br></td></tr>
<tr><tdcolspan="5" id="debugBox1" style="visibility:visible;"></td></tr>
<tr><tdcolspan="5" id="debugBox2" style="visibility:hidden;"></td><td></td><td></td></tr>
<tr><tdcolspan="2"></td><td></td><td></td></tr>
<tr><tdcolspan="5">
Definitions:<br>
<ul>
<li><b>Cryptology:</b> the study of codes, or the art of writing and solving them.</li>
<li><b>Cryptography:</b> the art of creating codes.</li>
<li><b>Cryptanalysis (or "cracking"):</b> the art of revealing the contents of coded messages, breaking codes, that were not intended for you as a recipient.</li>
<li><b>Cipher:</b> a secret or disguised way of writing; a code.</li>
<li><b>Encryption:</b> the process of converting information or data into a code, especially to prevent unauthorized access.</li>
<li><b>Decryption:</b> converting an encrypted cipher into readable text or usable data.</li>
<li><b>Block cipher:</b> a method of encrypting text in which a key and algorithm are applied to a block of data at once as a group rather than to one bit at a time.</li>
</ul>
<BR>
Helpful links:<br>
<ul>
<li>There are many ways to write HTML and JavaScript, but I personally use <ahref="https://notepad-plus-plus.org/">Notepad++</a></li>
<li><ahref="https://ws680.nist.gov/publication/get_pdf.cfm?pub_id=908084">Encryption Basics from NIST</a></li>
<li><ahref="http://www.eastoftheweb.com/games/index.php?p=games/cryptoquote/random">Try cracking a random substitution code here</a></li>
</ul>
</td></tr>
<tr><tdcolspan="2"></td><td></td><td></td></tr>
</table>
<script>
functionClickSimple(){
vartemp_string="";
varrotation=0;
temp_string=prompt("Please enter number of positions to rotate (positive or negative integer):","1");
if(temp_string==null||temp_string==""){
alert("Please enter a rotation amount to proceed.");
}
else{
rotation=parseInt(temp_string);
Caesar("Message1","Cipher1",rotation,1,true)// Input box, output box, rotation steps, encryption, simple
Caesar("Cipher1","Decrypted1",rotation,-1,true)// Input box, output box, rotation steps, decryption, simple
}
}
functionClickProgressive(){
vartemp_string="";
varrotation=0;
temp_string=prompt("Please enter number of positions to rotate (positive or negative integer):","1");
if(temp_string==null||temp_string==""){
alert("Please enter a rotation amount to proceed.");
}
else{
rotation=parseInt(temp_string);
Caesar("Message1","Cipher1",rotation,1,false);// Input box, output box, rotation steps, encryption, progressive
Caesar("Cipher1","Decrypted1",rotation,-1,false);// Input box, output box, rotation steps, decryption, progressive
}
}
// This handles the click event for the Vigenere button.
functionClickVigenere(){
varkey=prompt("Please enter your codeword","TEST");
if(key==null||key==""){
alert("Please enter a keyword to proceed.");
}else{
Vigenere("Message1","Cipher1",1,key);// Input box, output box, encryption, progressive
Vigenere("Cipher1","Decrypted1",-1,key);// Input box, output box, decryption, progressive
}
}
functionClickBase26(){
Base26Encrypt("Message1","Cipher1",26,8);// Input box, output box, base, block size
Base26Decrypt("Cipher1","Decrypted1",26,8);// Input box, output box, base, block size
}
// This applies a Caesar substitution cipher. It can run in simple [single rotation] and progressive modes.
functionCaesar(inbox,outbox,rotation,direction,simple){
varmessageBox=document.getElementById(inbox);
varrotationBox=document.getElementById("Rotation1");
varcipherBox=document.getElementById(outbox);
vardebugBox=document.getElementById("debugBox1");
constA_offset="A".charCodeAt(0);
varmessage="";
varcipher="";
//var rotation = 1; //parseInt(rotationBox.value);
vari=0;// Counter for loop through message;
varj=0;// Counter for loop through debug;
vard;// Direction to rotate letters. 1 for encryption and -1 for decryption;
varnum_rotations=0;// Number of rotations to apply. 1 for simple encryption. i + 1 for progressive encryption.
vardebugOutput="Encryption debug output:<BR>";
vartemp_string="";
message=messageBox.value.toUpperCase();
for(i=0;i<message.length;i++){
n=message.charCodeAt(i);
d=(direction>=0) ? 1 : -1;
if((n>="A".charCodeAt(0))&&(n<="Z".charCodeAt(0))){
num_rotations=(simple===true) ? 1 : num_rotations+1;
n=n-A_offset;// A = 0
n=Mod((n+(d*(num_rotations*rotation))),26);
n=n+A_offset;
debugOutput=debugOutput+message[i];
for(j=0;j<num_rotations;j++){
debugOutput=debugOutput+(rotation>=0 ? " + " : " - ")+Math.abs(rotation);
}
debugOutput=debugOutput+" = "+String.fromCharCode(n)+"<BR>";
}
cipher=cipher+String.fromCharCode(n);
}
cipherBox.value=cipher
if(direction>=0){
debugBox.innerHTML=debugOutput;
ResetBubbles();
if(rotation>=0){
MoveBubbles(0,Math.abs(num_rotations*rotation),.1,4);
}
else{
MoveBubbles(0,Math.abs(num_rotations*rotation),.1,-4);
}
}
};
// This resets all of the letter bubbles back to their original positions.
functionResetBubbles(){
vari=0;
for(i=0;i<26;i++){
document.getElementById("CircleOut"+i).setAttribute("cx",20+(40*i));
document.getElementById("TextOut"+i).setAttribute("x",17+(40*i));
}
}
// A rough, simple animation of moving letters to show the rotation of letters.
functionMoveBubbles(current_pos,num_rotations,step_size,move_pixels){
vari=0;
vartemp_circle;
vartemp_text;
vartemp_x;
for(i=0;i<26;i++){
temp_circle=document.getElementById("CircleOut"+i);
temp_x=parseInt(temp_circle.getAttribute("cx"));
temp_x=Mod(temp_x-move_pixels,1040);
temp_circle.setAttribute("cx",temp_x);
temp_text=document.getElementById("TextOut"+i);
temp_x=parseInt(temp_text.getAttribute("x"));
temp_x=Mod(temp_x-move_pixels,1040);
temp_text.setAttribute("x",temp_x);
}
if(current_pos+step_size<num_rotations){
setTimeout(MoveBubbles,100,current_pos+step_size,num_rotations,step_size,move_pixels);
}
}
// Fix JavaScript modulo bug.
functionMod(n,b){
return((n%b)+b)%b;
}
// This function applies a Vigenere polyalphabetic codeword cipher.
functionVigenere(inbox,outbox,direction,key){
varmessageBox=document.getElementById(inbox);
varrotationBox=document.getElementById("Rotation1");
varcipherBox=document.getElementById(outbox);
vardebugBox=document.getElementById("debugBox1");
constA_offset="A".charCodeAt(0);
varmessage="";
varcipher="";
varnum_rotations=0;
vari=0;// Counter for loop through message;
varj=0;// Counter for loop through debug;
vard;// Direction to rotate letters. 1 for encryption and -1 for decryption;
varnum_rotations;// Number of rotations to apply. 1 for simple encryption. i + 1 for progressive encryption.
vardebugOutput="Encryption debug output:<BR>";
vartemp_key="";
message=messageBox.value.toUpperCase();
key=key.toUpperCase();
for(i=0;i<key.length;i++){
n=key.charCodeAt(i);
if((n>="A".charCodeAt(0))&&(n<="Z".charCodeAt(0))){
temp_key=temp_key+key[i];
}
}
key=temp_key;// All non-alphabetic characters removed from the key message to make one long keyword.
for(i=0;i<message.length;i++){
n=message.charCodeAt(i);
d=(direction>=0) ? 1 : -1;
if((n>="A".charCodeAt(0))&&(n<="Z".charCodeAt(0))){
num_rotations=num_rotations+1;
n=n-A_offset;// A = 0
n=Mod((n+(d*(key.charCodeAt(j)-A_offset))),26);
n=n+A_offset;
debugOutput=debugOutput+message[i];
debugOutput=debugOutput+(direction>=0 ? " + " : " - ")+key[j];
debugOutput=debugOutput+" = "+String.fromCharCode(n)+"<BR>";
j=Mod(j+1,key.length);
}
cipher=cipher+String.fromCharCode(n);
}
cipherBox.value=cipher
if(direction>=0){
debugBox.innerHTML=debugOutput;// Only output the steps during encryption.
}
};// End of Vigenere
functionBase26Encrypt(inbox,outbox,base,block_size){
varmessageBox=document.getElementById(inbox);// Where to read in the plaintext message from.
varcipherBox=document.getElementById(outbox);// Where to write the encrypted ciphertext to.
vardebugBox=document.getElementById("debugBox1");// Where to output each step of the encryption process.
constA_offset="A".charCodeAt(0);// Shift all of the letter values down to A = 0 to allow modulo math.
varmessage="";// Variable to store the plaintext message.
vartemp_message="";
varcipher="";// Variable to store the encrypted cipher.
vari=0;// Counter for loop through message;
varj=0;// Counter for loop through debug;
varexponent=0;// Keep track of the current exponent as we work on a block of text.
vardebugOutput="Encryption debug output:<BR>";// Variable to store the steps of the encryption process.
varsum=0;
vartemp_sum=0;
message=messageBox.value.toUpperCase();// Convert to uppercase for simplicity.
for(i=0;i<message.length;i++){
n=message.charCodeAt(i);
if((n>="A".charCodeAt(0))&&(n<="Z".charCodeAt(0))){
temp_message=temp_message+String.fromCharCode(n);// For this cipher we will remove all non-alphabetic characters.
}
}
message=temp_message;
while(Mod(message.length,block_size)!=0){
// This is a block cipher, so we need to pad out the message to an whole number of blocks.
// We add the least-common character to make it obvious later.
message=message+'Z';
}
exponent=0;
for(i=0;i<message.length;i++){
n=message.charCodeAt(i);
n=n-A_offset;// A = 0
temp_sum=n*Math.pow(base,exponent);
sum=sum+temp_sum;
debugOutput=debugOutput+message[i];
for(j=1;j<=exponent;j++){
debugOutput=debugOutput+" * "+base;
}
debugOutput=debugOutput+" = "+(n*Math.pow(base,exponent))+"<BR>";
exponent=Mod(exponent+1,block_size);// Increase the exponent for each character in the block. Reset exponent when reaching a new block.
if(exponent==0){
cipher=cipher+" "+sum;
debugOutput=debugOutput+sum+"<BR><BR>";
sum=0;
}
}
cipherBox.value=cipher
debugBox.innerHTML=debugOutput;
};// End of Base26Encrypt
functionBase26Decrypt(inbox,outbox,base,block_size){
varmessageBox=document.getElementById(inbox);// Where to read in the encrypted ciphertext from.
varcipherBox=document.getElementById(outbox);// Where to write the decrypted plaintext to.
constA_offset="A".charCodeAt(0);// Shift all of the letter values down to A = 0 to allow modulo math.
varmessage="";// Variable to store the plaintext message.
vartemp_message="";
varcipher="";// Variable to store the encrypted cipher.
vari=0;// Counter for loop through message;
varj=0;// Counter for loop through debug;
vardebugOutput="Encryption debug output:<BR>";// Variable to store the steps of the encryption process.
varsum=0;
vartemp_sum=0;
message=messageBox.value.toUpperCase().trim();// Convert to uppercase for simplicity.
varstr_array=message.split(' ');// Split the ciphertext into an array of numbers at each space.
for(i=0;i<str_array.length;i++){
//
str_array[i]=str_array[i].trim()// Trim the excess whitespace; Use str_array[i].replace(/^\s*/, "").replace(/\s*$/, "") for really old browsers.;
sum=parseInt(str_array[i]);// Convert from string to integer.
for(j=0;j<block_size;j++){
temp_sum=Mod(sum,base);
sum=sum-temp_sum;
sum=sum/base;
cipher=cipher+String.fromCharCode(temp_sum+A_offset);
}
}
cipherBox.value=cipher;
};// End of Base26Decrypt
</script>
</body>
</html>