Class AESGCMCipher

ref/gateway_client.js:20–65

// ==================== AES-GCM ====================
class AESGCMCipher {
    constructor(key, nonce) {
        if (key.length !== 16) throw new Error('key must be 16 bytes');
        if (nonce.length !== 8) throw new Error('nonce must be 8 bytes');
        this.key = key;
        this.nonce = nonce;
        this.encryptCounter = 1;
        this.decryptCounter = 0;
    }

    _makeIV(counter) {
        const iv = Buffer.alloc(12);
        this.nonce.copy(iv, 0);
        iv.writeUInt32LE(counter, 8);
        return iv;
    }

    encrypt(data) {
        const counter = this.encryptCounter++;
        const iv = this._makeIV(counter);
        const cipher = crypto.createCipheriv('aes-128-gcm', this.key, iv);
        const encrypted = Buffer.concat([cipher.update(data), cipher.final()]);
        const tag = cipher.getAuthTag();
        
        const result = Buffer.alloc(4 + encrypted.length + tag.length);
        result.writeUInt32LE(counter, 0);
        encrypted.copy(result, 4);
        tag.copy(result, 4 + encrypted.length);
        return result;
    }

    decrypt(data) {
        if (data.length < 20) throw new Error('Data too short');
        const counter = data.readUInt32LE(0);
        if (counter <= this.decryptCounter) throw new Error('Replay attack');
        this.decryptCounter = counter;
        
        const ciphertext = data.slice(4, data.length - 16);
        const tag = data.slice(data.length - 16);
        const iv = this._makeIV(counter);
        
        const decipher = crypto.createDecipheriv('aes-128-gcm', this.key, iv);
        decipher.setAuthTag(tag);
        return Buffer.concat([decipher.update(ciphertext), decipher.final()]);
    }
}

// ==================== 压缩/解压 ====================
function compress(data) {