在TPM内部签署TLS握手

一项新的技术方案展现了在可信平台模块（TPM）内部直接进行TLS握手签名的可行性，从而保护机器身份认证。1这种方法将私钥存储在TPM内部而非文件形式，确保密钥始终不会泄露到内存或磁盘中。1

该方案在Google Cloud机密虚拟机上进行了测试。1使用ECDSA P-256密钥进行冷握手时，总耗时为3.35毫秒，其中签名操作占用2.21毫秒。1相比之下，持久化密钥的性能显著优于瞬时密钥，前者耗时约2.08毫秒，而后者需要20.04毫秒，性能差异达到约10倍。1单机吞吐量上限为每秒数百个新的相互认证连接。1

该实现方案使用ECDSA P-256或P-384曲线，但不支持RSA密钥的TLS 1.3签名。1相对于文件权限、短期证书和密钥管理服务（KMS）等现有方案各自存在的缺陷，TPM被认为是唯一能够同时满足四项要求的方案。1尽管TPM密钥仍然无法防止机器内部的攻击者使用该密钥，但它能够有效防止密钥被带出机器外。1

A technical approach has been developed to perform TLS handshake signing directly within a Trusted Platform Module (TPM), thereby protecting machine identity in confidential environments 1. The method stores private keys inside the TPM rather than in files or memory, ensuring that cryptographic material never leaves the secure module and cannot be leaked to disk or RAM 1.

Implementation testing on Google Cloud Confidential VMs revealed specific performance characteristics 1. Cold handshakes using P-256 elliptic curve keys require 3.35 milliseconds total, with the signature operation consuming 2.21 milliseconds 1. Persistent keys demonstrate significantly faster performance than ephemeral keys, completing in approximately 2.08 milliseconds compared to 20.04 milliseconds respectively 1. Single-machine throughput capacity is limited to several hundred new mutually authenticated connections per second 1.

The solution supports ECDSA signatures with P-256 or P-384 curves but does not support RSA keys for TLS 1.3 signing 1. While this TPM-based approach prevents keys from being removed from the machine, it cannot defend against attackers operating from within the machine itself 1. The architecture addresses recognized limitations of alternative methods, including file permissions, short-lived certificates, and key management systems (KMS), positioning TPM as the sole option meeting four critical security requirements 1.