如何使用PHP离线签名Tron API生成的USDT交易？

关键说明 #

USDT属于TRC20代币，不能使用原生TRX的createtransaction接口，需调用智能合约触发接口构造交易。以下是完整的离线签名流程实现：

1. 构造未签名的USDT转账交易 #

调用接口生成未签名交易结构，无需传入私钥：

public function createUnsignedUsdtTransaction() {
    $curl = curl_init();

    // USDT主网合约地址
    $usdtContractAddress = 'TR7NHqjeKQxGTCi8q8ZY4pL8otSzgjLj6t';
    $ownerAddress = 'OWNER_BASE58_ADDRESS'; // 你的钱包地址（Base58格式）
    $toAddress = 'TO_BASE58_ADDRESS'; // 收款地址（Base58格式）
    $amount = 1000000; // 转账1 USDT（最小单位为6位小数，1 USDT = 1000000）

    $postData = json_encode([
        'contract_address' => $usdtContractAddress,
        'function_selector' => 'transfer(address,uint256)',
        'parameter' => $this->encodeTrc20TransferParams($toAddress, $amount),
        'owner_address' => $ownerAddress,
        'visible' => true,
        'fee_limit' => 100000000 // 手续费上限：1 TRX
    ]);

    curl_setopt_array($curl, [
        CURLOPT_URL => "https://api.trongrid.io/wallet/triggersmartcontract",
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_POST => true,
        CURLOPT_POSTFIELDS => $postData,
        CURLOPT_HTTPHEADER => [
            "accept: application/json",
            "content-type: application/json"
        ],
    ]);

    $response = curl_exec($curl);
    $err = curl_error($curl);
        
    curl_close($curl);
        
    if ($err) {
        die("cURL Error #:" . $err);
    }

    $result = json_decode($response, true);
    if ($result['result']['code'] != 0) {
        die("构造交易失败: " . $result['result']['message']);
    }

    return $result['transaction'];
}

// 编码TRC20 transfer方法的参数
private function encodeTrc20TransferParams($toAddress, $amount) {
    // Base58地址转十六进制（去掉前缀）
    $toHex = str_replace('0x', '', $this->base58ToHex($toAddress));
    $toHex = str_pad($toHex, 64, '0', STR_PAD_LEFT); // 补全为64位十六进制
    $amountHex = str_pad(dechex($amount), 64, '0', STR_PAD_LEFT); // 金额转64位十六进制
    return $toHex . $amountHex;
}

// Base58地址转十六进制
private function base58ToHex($base58) {
    $alphabet = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz';
    $base = strlen($alphabet);
    $hex = '0';

    for ($i = 0; $i < strlen($base58); $i++) {
        $char = $base58[$i];
        $index = strpos($alphabet, $char);
        if ($index === false) {
            throw new Exception("无效的Base58字符");
        }
        $hex = bcadd(bcmul($hex, $base), $index);
    }

    $hex = dechex(hexdec($hex));
    return str_pad($hex, 40, '0', STR_PAD_LEFT); // 补全为40位十六进制
}

2. 离线签名交易 #

按照官方流程完成哈希计算、私钥签名、添加签名到交易：

public function signTransaction($unsignedTransaction, $privateKey) {
    // 1. 序列化交易并计算哈希（生产环境建议用官方Protobuf规则序列化）
    $transactionBytes = $this->serializeTransaction($unsignedTransaction);
    $hash = hash('sha256', $transactionBytes, true);

    // 2. 用私钥对哈希进行ECDSA签名（secp256k1曲线）
    $pemKey = "-----BEGIN PRIVATE KEY-----\n" . chunk_split(base64_encode(hex2bin($privateKey)), 64) . "-----END PRIVATE KEY-----";
    $privateKeyResource = openssl_pkey_get_private($pemKey);
    openssl_sign($hash, $signature, $privateKeyResource, OPENSSL_ALGO_SHA256);
    openssl_free_key($privateKeyResource);

    // 3. 将签名添加到交易结构
    $unsignedTransaction['signature'] = [bin2hex($signature)];

    return $unsignedTransaction;
}

// 简化版交易序列化（生产环境请用官方Protobuf定义实现）
private function serializeTransaction($tx) {
    $rawData = json_encode($tx['raw_data']);
    return hash('sha256', $rawData, true);
}

注意：完整的TRON交易序列化需严格遵循Protobuf协议，上述简化版仅作示例。生产环境建议使用官方Protobuf文件生成序列化代码，避免签名失败。

3. 广播已签名交易 #

将签名后的交易广播到TRON网络：

public function broadcastSignedTransaction($signedTransaction) {
    $curl = curl_init();

    $postData = json_encode($signedTransaction);

    curl_setopt_array($curl, [
        CURLOPT_URL => "https://api.trongrid.io/wallet/broadcasttransaction",
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_POST => true,
        CURLOPT_POSTFIELDS => $postData,
        CURLOPT_HTTPHEADER => [
            "accept: application/json",
            "content-type: application/json"
        ],
    ]);

    $response = curl_exec($curl);
    $err = curl_error($curl);
        
    curl_close($curl);
        
    if ($err) {
        die("cURL Error #:" . $err);
    }

    return json_decode($response, true);
}

完整调用示例 #

// 替换为你的私钥（十六进制格式）
$ownerPrivateKey = 'YOUR_PRIVATE_KEY_HEX';

// 1. 创建未签名交易
$unsignedTx = $this->createUnsignedUsdtTransaction();

// 2. 离线签名
$signedTx = $this->signTransaction($unsignedTx, $ownerPrivateKey);

// 3. 广播交易
$result = $this->broadcastSignedTransaction($signedTx);

print_r($result);

内容的提问来源于stack exchange，提问作者eren