54 lines
1.2 KiB
JavaScript
54 lines
1.2 KiB
JavaScript
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const { Crypto } = require('@peculiar/webcrypto');
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const crypto = new Crypto();
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const encoder = new TextEncoder();
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const decoder = new TextDecoder();
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module.exports = class Keychain {
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constructor(secretKeyB64) {
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if (secretKeyB64) {
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this.rawSecret = new Uint8Array(Buffer.from(secretKeyB64, 'base64'));
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} else {
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throw new Error('key is required');
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}
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this.secretKeyPromise = crypto.subtle.importKey(
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'raw',
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this.rawSecret,
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'HKDF',
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false,
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['deriveKey']
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);
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this.metaKeyPromise = this.secretKeyPromise.then(function(secretKey) {
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return crypto.subtle.deriveKey(
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{
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name: 'HKDF',
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salt: new Uint8Array(),
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info: encoder.encode('metadata'),
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hash: 'SHA-256'
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},
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secretKey,
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{
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name: 'AES-GCM',
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length: 128
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},
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false,
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['decrypt']
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);
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});
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}
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async decryptMetadata(ciphertext) {
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const metaKey = await this.metaKeyPromise;
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const plaintext = await crypto.subtle.decrypt(
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{
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name: 'AES-GCM',
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iv: new Uint8Array(12),
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tagLength: 128
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},
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metaKey,
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ciphertext
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);
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return JSON.parse(decoder.decode(plaintext));
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}
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};
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