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Symmetric Encryption using window.crypto.subtle API
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| // Read more about the API here: | |
| // https://developer.mozilla.org/en-US/docs/Web/API/SubtleCrypto | |
| export type EncryptedPayload = { ciphertext: string, iv: string }; | |
| const algorithm: string = "AES-GCM"; | |
| const keyLength: number = 256; | |
| const extractable: boolean = true; | |
| const keyUsages: KeyUsage[] = ["encrypt", "decrypt"]; | |
| export function byteArrayToBase64(byteArray: ArrayBuffer) { | |
| return btoa(String.fromCharCode(...new Uint8Array(byteArray))); | |
| } | |
| export function base64ToByteArray(base64String: string): ArrayBuffer { | |
| return Uint8Array.from(atob(base64String), char => char.charCodeAt(0)); | |
| } | |
| export function importKey(cryptoKey: string): Promise<CryptoKey> { | |
| return window.crypto.subtle.importKey( | |
| "raw", | |
| base64ToByteArray(cryptoKey), | |
| algorithm, | |
| extractable, | |
| keyUsages | |
| ); | |
| } | |
| export function generateKey(): Promise<CryptoKey> { | |
| return window.crypto.subtle.generateKey( | |
| { | |
| name: algorithm, | |
| length: keyLength, | |
| }, | |
| extractable, | |
| keyUsages | |
| ); | |
| } | |
| export async function encrypt(message: string, encryptionKey: CryptoKey): Promise<EncryptedPayload> { | |
| const enc = new TextEncoder(); | |
| const iv = window.crypto.getRandomValues(new Uint8Array(12)); | |
| const ciphertext = await window.crypto.subtle.encrypt( | |
| { | |
| name: algorithm, | |
| iv: iv | |
| }, | |
| encryptionKey, | |
| enc.encode(message) | |
| ); | |
| return { | |
| ciphertext: byteArrayToBase64(ciphertext), | |
| iv: byteArrayToBase64(iv) | |
| } | |
| } | |
| export async function decrypt(payload: EncryptedPayload, decryptionKey: CryptoKey): Promise<string> { | |
| const dec = new TextDecoder(); | |
| let decrypted = await window.crypto.subtle.decrypt( | |
| { | |
| name: algorithm, | |
| iv: base64ToByteArray(payload.iv) | |
| }, | |
| decryptionKey, | |
| base64ToByteArray(payload.ciphertext), | |
| ); | |
| return dec.decode(decrypted) | |
| } |
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a much more developed version can be found here: https://github.com/MrEliasen/sniksnak.chat