drop.chapril.org-firefoxsend/app/keychain.js

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import { arrayToB64, b64ToArray } from './utils';
const encoder = new TextEncoder();
const decoder = new TextDecoder();
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export default class Keychain {
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constructor(secretKeyB64, nonce, ivB64) {
this._nonce = nonce || 'yRCdyQ1EMSA3mo4rqSkuNQ==';
if (ivB64) {
this.iv = b64ToArray(ivB64);
} else {
this.iv = window.crypto.getRandomValues(new Uint8Array(12));
}
if (secretKeyB64) {
this.rawSecret = b64ToArray(secretKeyB64);
} else {
this.rawSecret = window.crypto.getRandomValues(new Uint8Array(16));
}
this.secretKeyPromise = window.crypto.subtle.importKey(
'raw',
this.rawSecret,
'HKDF',
false,
['deriveKey']
);
this.encryptKeyPromise = this.secretKeyPromise.then(function(secretKey) {
return window.crypto.subtle.deriveKey(
{
name: 'HKDF',
salt: new Uint8Array(),
info: encoder.encode('encryption'),
hash: 'SHA-256'
},
secretKey,
{
name: 'AES-GCM',
length: 128
},
false,
['encrypt', 'decrypt']
);
});
this.metaKeyPromise = this.secretKeyPromise.then(function(secretKey) {
return window.crypto.subtle.deriveKey(
{
name: 'HKDF',
salt: new Uint8Array(),
info: encoder.encode('metadata'),
hash: 'SHA-256'
},
secretKey,
{
name: 'AES-GCM',
length: 128
},
false,
['encrypt', 'decrypt']
);
});
this.authKeyPromise = this.secretKeyPromise.then(function(secretKey) {
return window.crypto.subtle.deriveKey(
{
name: 'HKDF',
salt: new Uint8Array(),
info: encoder.encode('authentication'),
hash: 'SHA-256'
},
secretKey,
{
name: 'HMAC',
hash: { name: 'SHA-256' }
},
true,
['sign']
);
});
}
get nonce() {
return this._nonce;
}
set nonce(n) {
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if (n && n !== this._nonce) {
this._nonce = n;
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}
}
setIV(ivB64) {
this.iv = b64ToArray(ivB64);
}
setPassword(password, shareUrl) {
this.authKeyPromise = window.crypto.subtle
.importKey('raw', encoder.encode(password), { name: 'PBKDF2' }, false, [
'deriveKey'
])
.then(passwordKey =>
window.crypto.subtle.deriveKey(
{
name: 'PBKDF2',
salt: encoder.encode(shareUrl),
iterations: 100,
hash: 'SHA-256'
},
passwordKey,
{
name: 'HMAC',
hash: 'SHA-256'
},
true,
['sign']
)
);
}
setAuthKey(authKeyB64) {
this.authKeyPromise = window.crypto.subtle.importKey(
'raw',
b64ToArray(authKeyB64),
{
name: 'HMAC',
hash: 'SHA-256'
},
true,
['sign']
);
}
async authKeyB64() {
const authKey = await this.authKeyPromise;
const rawAuth = await window.crypto.subtle.exportKey('raw', authKey);
return arrayToB64(new Uint8Array(rawAuth));
}
async authHeader() {
const authKey = await this.authKeyPromise;
const sig = await window.crypto.subtle.sign(
{
name: 'HMAC'
},
authKey,
b64ToArray(this.nonce)
);
return `send-v1 ${arrayToB64(new Uint8Array(sig))}`;
}
async encryptFile(plaintext) {
const encryptKey = await this.encryptKeyPromise;
const ciphertext = await window.crypto.subtle.encrypt(
{
name: 'AES-GCM',
iv: this.iv,
tagLength: 128
},
encryptKey,
plaintext
);
return ciphertext;
}
async encryptMetadata(metadata) {
const metaKey = await this.metaKeyPromise;
const ciphertext = await window.crypto.subtle.encrypt(
{
name: 'AES-GCM',
iv: new Uint8Array(12),
tagLength: 128
},
metaKey,
encoder.encode(
JSON.stringify({
iv: arrayToB64(this.iv),
name: metadata.name,
type: metadata.type || 'application/octet-stream'
})
)
);
return ciphertext;
}
async decryptFile(ciphertext) {
const encryptKey = await this.encryptKeyPromise;
const plaintext = await window.crypto.subtle.decrypt(
{
name: 'AES-GCM',
iv: this.iv,
tagLength: 128
},
encryptKey,
ciphertext
);
return plaintext;
}
async decryptMetadata(ciphertext) {
const metaKey = await this.metaKeyPromise;
const plaintext = await window.crypto.subtle.decrypt(
{
name: 'AES-GCM',
iv: new Uint8Array(12),
tagLength: 128
},
metaKey,
ciphertext
);
return JSON.parse(decoder.decode(plaintext));
}
}