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JavaScript - One-time Pad encryption with XOR on strings
9 points
In this short article, we would like to show a simple JavaScript implementation of the most save encryption that was invented by humans - One-time Pad encryption with XOR on strings.
Encryption example:
xxxxxxxxxx1
Used secret keys (one key per one byte):2
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[238, 203, 230, 91, 223, 161, 59, 10, 105, 200, 45, 145, 64, 145, 210]4
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Input string --> Encrypted string bytes --> Decrypted string7
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abc --> [143, 169, 133] --> abc9
123 --> [106, 237, 146] --> 12310
abc --> [90, 104, 10] --> abc
In this section you can find example One-time Pad strings encryption. In the example we encode strings to UTF-8 bytes. To show the main idea we encoded 3 strings: abc, 123 and abc again - as we can see encoded text is always different that makes algorithm stronger.
Hint: the below algorithm source code extends this article - adds posibility to encrypt and decrypt strings.
The algorithm is as strong as perfectly random numbers have been used as secret keys.
xxxxxxxxxx1
// Converts string to UTF-8 bytes.2
// Source: https://dirask.com/posts/JavaScript-convert-string-to-bytes-array-1XkbEj3
//4
const toBytes = (text) => {5
const surrogate = encodeURIComponent(text);6
const result = [];7
for (let i = 0; i < surrogate.length;) {8
const character = surrogate[i];9
i += 1;10
if (character == '%') {11
const hex = surrogate.substring(i, i += 2);12
if (hex) {13
result.push(parseInt(hex, 16));14
}15
} else {16
result.push(character.charCodeAt(0));17
}18
}19
return result;20
};21
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// Converts UTF-8 bytes to string.23
// Source: https://dirask.com/posts/JavaScript-convert-bytes-array-to-string-Dn0e7j24
//25
const toString = (bytes) => {26
var result = '';27
for (var i = 0; i < bytes.length; ++i) {28
const byte = bytes[i];29
const text = byte.toString(16);30
result += (byte < 16 ? '%0' : '%') + text;31
}32
return decodeURIComponent(result);33
};34
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// Provides simple implementation of One-time Pad encryption with XOR.36
// Source: https://dirask.com/posts/JavaScript-One-time-Pad-encryption-with-XOR-DlKdw137
//38
const BytesCipher = (secretKeys) => {39
const createScope = () => {40
let secretOffset = 0;41
const execute = (inputBytes) => {42
if (secretOffset + inputBytes.length > secretKeys.length) {43
throw new Error('There is not enought secret keys to encode / decode bytes.');44
}45
const outputBytes = Array(inputBytes.length);46
for (let i = 0; i < inputBytes.length; i += 1, secretOffset += 1) {47
outputBytes[i] = secretKeys[secretOffset] ^ inputBytes[i];48
}49
return outputBytes;50
};51
return execute;52
};53
return {54
encrypt: createScope(),55
decrypt: createScope() // to decrypt we use same formula like in the encryption case56
};57
};58
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// Provides simple implementation of One-time Pad encryption with XOR on strings.60
//61
const StringsCipher = (secretKeys) => {62
const cipher = BytesCipher(secretKeys);63
return {64
encrypt: (inputString) => {65
const inputBytes = toBytes(inputString);66
return cipher.encrypt(inputBytes);67
},68
decrypt: (inputBytes) => {69
const outputBytes = cipher.decrypt(inputBytes);70
return toString(outputBytes);71
}72
};73
};74
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// Usage example:77
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// common - the information that know both (sender and recipient)79
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// in our case we use random bytes - be sure that the values are from 0 to 25581
const secretKeys = [238, 203, 230, 91, 223, 161, 59, 10, 105, 200, 45, 145, 64, 145, 210]; // random numbers sequence used as secret key82
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// sender85
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const senderCipher = StringsCipher(secretKeys);87
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const encryptedBytes1 = senderCipher.encrypt('abc');89
const encryptedBytes2 = senderCipher.encrypt('123');90
const encryptedBytes3 = senderCipher.encrypt('abc');91
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console.log(`Encrypted 1: ${encryptedBytes1}`); // Encrypted 1: [143, 169, 133]93
console.log(`Encrypted 2: ${encryptedBytes2}`); // Encrypted 2: [106, 237, 146]94
console.log(`Encrypted 3: ${encryptedBytes3}`); // Encrypted 3: [90, 104, 10]95
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// recipient98
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const recipientCipher = StringsCipher(secretKeys);100
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const decryptedBytes1 = recipientCipher.decrypt(encryptedBytes1);102
const decryptedBytes2 = recipientCipher.decrypt(encryptedBytes2);103
const decryptedBytes3 = recipientCipher.decrypt(encryptedBytes3);104
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console.log(`Decrypted 1: ${decryptedBytes1}`); // Decrypted 1: abc106
console.log(`Decrypted 2: ${decryptedBytes2}`); // Decrypted 2: 123107
console.log(`Decrypted 3: ${decryptedBytes3}`); // Decrypted 3: abcConclusions:
abcencrypted 2 times returned 2 different results:[143,169,133]and[90,104,10]- it is provided by once time secret key usage composed of random numbers.
