101 lines
2.9 KiB
JavaScript
101 lines
2.9 KiB
JavaScript
const crypto = require('crypto');
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const Cell = require('./Cell')
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class CircuitNodeCryptoState {
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/** @type Hash */
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_forward_digest = null;
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/** @type Hash */
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_backward_digest = null;
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/** @type Cipher */
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_backward_cipher = null;
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/** @type Cipher */
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_forward_cipher = null;
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constructor (key_material) {
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this._forward_digest = crypto.createHash('sha1');
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const df = key_material.slice(0, 20);
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this._forward_digest.update(df);
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this._backward_digest = crypto.createHash('sha1');
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const db = key_material.slice(20, 20 + 20);
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this._backward_digest.update(db);
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const kf = key_material.slice(20 + 20, 20 + 20 + 16);
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this._forward_cipher = crypto.createCipheriv('aes-128-ctr', kf, Buffer.alloc(16));
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const kb = key_material.slice(20 + 20 + 16, 20 + 20 + 16 + 16);
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this._backward_cipher = crypto.createCipheriv('aes-128-ctr', kb, Buffer.alloc(16));
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}
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/**
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* @param {RelayCell} cell
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*/
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encrypt_forward_cell(cell) {
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const relay_payload_bytes = Buffer.alloc(Cell.payload_size);
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if (cell.payload == null)
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{
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relay_payload_bytes.writeUInt8(cell.relay_command, 0);
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relay_payload_bytes.writeUInt16BE(0, 1); // 'recognized'
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relay_payload_bytes.writeUInt16BE(cell.stream_id, 3);
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relay_payload_bytes.writeInt32BE(0, 5); // digest placeholder
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relay_payload_bytes.writeUInt16BE(cell.relay_payload.length, 9);
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cell.relay_payload.copy(relay_payload_bytes, 11);
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//
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// update digest field in the payload
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//
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this._forward_digest.update(relay_payload_bytes);
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const digest = this._forward_digest.copy().digest(); // requires node >= 12.16
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digest.copy(relay_payload_bytes, 5, 0, 4);
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}
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else
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{
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cell.payload.copy(relay_payload_bytes, 0);
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}
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//
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// encrypt the payload
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//
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cell.payload = this._forward_cipher.update(relay_payload_bytes);
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// console.debug("CircuitNodeCryptoState.encrypt_forward_cell(): %s %s",
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// relay_payload_bytes.toString('hex'),
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// cell.payload.toString('hex'));
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}
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/**
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* @param {Cell} cell
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* @returns {boolean}
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*/
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decrypt_backward_cell(cell) {
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cell.payload = this._backward_cipher.update(cell.payload);
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//
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// check if this is a cell for us.
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//
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if (cell.is_recognized())
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{
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//
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// remove the digest from the payload
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//
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const payload_without_digest = Buffer.alloc(cell.payload.length);
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cell.payload.copy(payload_without_digest);
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payload_without_digest.writeInt32BE(0, 5);
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const backward_digest_clone = this._backward_digest.copy();
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backward_digest_clone.update(payload_without_digest);
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const digest = backward_digest_clone.digest();
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if (digest.compare(cell.payload, 5, 5 + 4, 0, 4) === 0)
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{
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this._backward_digest.update(payload_without_digest);
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return true;
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}
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}
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return false;
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}
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}
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module.exports = CircuitNodeCryptoState;
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