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TypeScript - One-time Pad encryption with XOR
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In this short article, we would like to show a simple TypeScript implementation of the most save encrytion that was invented by humans - One-time Pad encryption with XOR.
Used XOR formula:
xxxxxxxxxx1
Encryption:2
3
00110100 input byte4
XOR 11000111 secret key5
--------6
11110011 encrypted byte7
8
Decription:9
10
11110010 encrypted byte11
XOR 11000111 secret key12
--------13
11110011 decrypted byte == input byte
Quick solution:
1. single-byte encryption
xxxxxxxxxx1
const inputByte: number = 97;2
const secretKey: number = 238; // random byte used as secret key3
4
const encryptedByte: number = inputByte ^ secretKey; // Encryption5
const decryptedByte: number = encryptedByte ^ secretKey; // Decription6
7
console.log(inputByte); // 978
console.log(encryptedByte); // 1439
console.log(decryptedByte); // 972. multiple bytes encryption
xxxxxxxxxx1
// Logic:2
3
const encryptBytes = (secretKeys: number[], inputBytes: number[]): number[] => {4
const encryptedBytes = Array(inputBytes.length);5
for (let i = 0; i < inputBytes.length; ++i) {6
encryptedBytes[i] = inputBytes[i] ^ secretKeys[i];7
}8
return encryptedBytes;9
};10
11
const decryptBytes = (secretKeys: number[], encryptedBytes: number[]): number[] => {12
const decryptedBytes = Array(encryptedBytes.length);13
for (let i = 0; i < encryptedBytes.length; ++i) {14
decryptedBytes[i] = encryptedBytes[i] ^ secretKeys[i];15
}16
return decryptedBytes;17
};18
19
// Input:20
21
const inputBytes: number[] = [97, 98, 99]; // what is 'abc' when we use UTF-8 bytes22
const secretKeys: number[] = [238, 203, 230]; // 3 random bytes used as secret keys23
24
// Encryption / Decryption:25
26
const encryptedBytes: number[] = encryptBytes(secretKeys, inputBytes);27
const decryptedBytes: number[] = decryptBytes(secretKeys, encryptedBytes);28
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// Result:30
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console.log(inputBytes); // [97, 98, 99]32
console.log(encryptedBytes); // [143, 169, 133]33
console.log(decryptedBytes); // [97, 98, 99]The algorithm is as strong as perfectly random numbers have been used as secret keys.
The main concept of the algorithm is to:
- use XOR formula on the data units to encode and decode,
Hint: check Wikipedia reference to see other than XOR encryption formula.
- store on sender and recipient devices, secret keys composed of perfect random numbers
(the numbers from computer algorithms may be predictable, so use nature-based approaches), - never share the random numbers with others than the sender and the recipient,
- use always only part of secret keys to encrypt or decrypt some sent message (one byte encoded by one secret key),
- never use 2 times the same secret keys.
