78 lines
2.6 KiB
JavaScript
78 lines
2.6 KiB
JavaScript
/* global libsignal, textsecure */
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/* eslint-disable more/no-then */
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// eslint-disable-next-line func-names
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(function() {
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function ProvisioningCipher() {}
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ProvisioningCipher.prototype = {
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decrypt(provisionEnvelope) {
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const masterEphemeral = provisionEnvelope.publicKey.toArrayBuffer();
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const message = provisionEnvelope.body.toArrayBuffer();
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if (new Uint8Array(message)[0] !== 1) {
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throw new Error('Bad version number on ProvisioningMessage');
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}
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const iv = message.slice(1, 16 + 1);
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const mac = message.slice(message.byteLength - 32, message.byteLength);
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const ivAndCiphertext = message.slice(0, message.byteLength - 32);
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const ciphertext = message.slice(16 + 1, message.byteLength - 32);
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return libsignal.Curve.async
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.calculateAgreement(masterEphemeral, this.keyPair.privKey)
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.then(ecRes =>
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libsignal.HKDF.deriveSecrets(
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ecRes,
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new ArrayBuffer(32),
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'TextSecure Provisioning Message'
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)
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)
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.then(keys =>
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libsignal.crypto
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.verifyMAC(ivAndCiphertext, keys[1], mac, 32)
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.then(() => libsignal.crypto.decrypt(keys[0], ciphertext, iv))
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)
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.then(plaintext => {
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const provisionMessage = textsecure.protobuf.ProvisionMessage.decode(
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plaintext
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);
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const privKey = provisionMessage.identityKeyPrivate.toArrayBuffer();
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return libsignal.Curve.async.createKeyPair(privKey).then(keyPair => {
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const ret = {
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identityKeyPair: keyPair,
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number: provisionMessage.number,
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provisioningCode: provisionMessage.provisioningCode,
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userAgent: provisionMessage.userAgent,
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readReceipts: provisionMessage.readReceipts,
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};
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if (provisionMessage.profileKey) {
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ret.profileKey = provisionMessage.profileKey.toArrayBuffer();
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}
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return ret;
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});
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});
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},
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getPublicKey() {
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return Promise.resolve()
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.then(() => {
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if (!this.keyPair) {
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return libsignal.Curve.async.generateKeyPair().then(keyPair => {
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this.keyPair = keyPair;
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});
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}
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return null;
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})
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.then(() => this.keyPair.pubKey);
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},
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};
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libsignal.ProvisioningCipher = function ProvisioningCipherWrapper() {
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const cipher = new ProvisioningCipher();
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this.decrypt = cipher.decrypt.bind(cipher);
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this.getPublicKey = cipher.getPublicKey.bind(cipher);
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};
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})();
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