63 lines
2.3 KiB
JavaScript
63 lines
2.3 KiB
JavaScript
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(function() {
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'use strict';
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function ProvisioningCipher() {}
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ProvisioningCipher.prototype = {
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decrypt: function(provisionEnvelope) {
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var masterEphemeral = provisionEnvelope.publicKey.toArrayBuffer();
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var 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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var iv = message.slice(1, 16 + 1);
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var mac = message.slice(message.byteLength - 32, message.byteLength);
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var ivAndCiphertext = message.slice(0, message.byteLength - 32);
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var ciphertext = message.slice(16 + 1, message.byteLength - 32);
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return libsignal.Curve.calculateAgreement(
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masterEphemeral, this.keyPair.privKey
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).then(function(ecRes) {
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return libsignal.HKDF.deriveSecrets(
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ecRes, new ArrayBuffer(32), "TextSecure Provisioning Message"
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);
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}).then(function(keys) {
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return libsignal.crypto.verifyMAC(ivAndCiphertext, keys[1], mac, 32).then(function() {
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return libsignal.crypto.decrypt(keys[0], ciphertext, iv);
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});
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}).then(function(plaintext) {
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var provisionMessage = textsecure.protobuf.ProvisionMessage.decode(plaintext);
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var privKey = provisionMessage.identityKeyPrivate.toArrayBuffer();
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return libsignal.Curve.createKeyPair(privKey).then(function(keyPair) {
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return {
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identityKeyPair : keyPair,
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number : provisionMessage.number,
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provisioningCode : provisionMessage.provisioningCode
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};
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});
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});
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},
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getPublicKey: function() {
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return Promise.resolve().then(function() {
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if (!this.keyPair) {
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return libsignal.Curve.generateKeyPair().then(function(keyPair) {
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this.keyPair = keyPair;
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}.bind(this));
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}
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}.bind(this)).then(function() {
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return this.keyPair.pubKey;
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}.bind(this));
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}
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};
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libsignal.ProvisioningCipher = function() {
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var 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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