TWC: Small: Self-Recovering Certificate Authorities using Backward and Forward Secure Key Management

近年来证明了证书颁发机构（ca）的谬论；内部人员能够窃取主签名密钥和冒充证书，利用系统漏洞和其他渗透手段允许攻击者访问ca并复制其密钥，等等。关键是公钥基础设施的生存，因为对它们的信任来自于对将公钥绑定到已知身份的证书的信任。ca暴露的当前攻击面使得对其颁发的证书的信任存疑。主要的问题是当前被盗密钥泄露的信息，这些信息将用于签署未来的证书。该项目引入了向后安全的新概念，允许CA在攻击者能够签署有效证书之前撤销新重建的密钥，这些密钥被攻击者恶意修改并为攻击者所知。该项目还提供了有效的自我恢复，这意味着，在强大的对手存在的情况下，ca能够用一个新的未妥协的签名密钥序列替换被吊销的密钥。自我恢复的ca承诺强大的安全保证，可以抵御最强大的攻击者，这些攻击者可以读取所有数字状态，这将产生重大的社会影响：企业和个人将能够信任这样的ca，并将重新获得对整个公钥基础设施的信任。自我恢复的ca消除了对我们经济和社会的严重安全威胁。

Recent years have shown the fallacy of Certificate Authorities (CAs); insiders are able to steal master signing keys and impersonate certificates, exploitation of system vulnerabilities and other means of infiltration allow attackers to gain access to CAs and copy their keys, etc. At stake is the mere survival of public key infrastructures as trust in them is bootstrapped from trust in certificates that bind public keys to known identities. The current attack surface exposed by CAs makes trust in their issued certificates questionable. The main problem is the information that a current stolen key leaks about to-be-used future keys for signing future certificates. This project introduces a new notion of backward security allowing a CA to revoke newly reconstructed secret keys, which were maliciously modified by an attacker and are known to the attacker, before the attacker is even able to sign valid certificates. The project also provides efficient self-recovery meaning that, in the presence of a powerful adversary, CAs are able to replace revoked keys by a new non-compromised signing key sequence. Self-recovering CAs promise strong security guarantees against the most powerful attacker who can read all digital state and this will have a major societal impact: enterprises and individuals will be able to trust such CAs and will regain trust in public key infrastructures as a whole. Self-recovering CAs eliminate a serious security threat to our economy and society.