安全与隐私theguardian.com
我为何被迫关闭 Lavabit
Why I was forced to shut down Lavabit
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导读
这篇是 Lavabit 创始人 Ladar Levison 在《卫报》上的自述，解释他为何被迫关闭这家曾为约 41 万人提供服务的加密邮件公司。美国政府要求他交出 SSL 私钥，以便监控包括 Edward Snowden 在内的账户；他拒绝后选择关停。文章还写到政府以“机器检查”为由规避第四修正案，呈现了小公司对抗大规模监控时的法律困境。
为什么经久不衰：它把 Snowden 时代一次具体的技术与法律对抗讲清楚，是理解加密服务、政府监控与后门争议的经典文本，今天重读仍能解释前向保密和秘密法庭为何重要。
HN 评论精选
质疑创始人措辞，并批评政府用“机器检查”规避第四修正案。
“我的公司 Lavabit 为 41 万人提供邮件服务——据新闻报道，其中包括 Edward Snowden——[...]。”他写“据新闻报道”是出于法律原因吗？显然他应该知道，我觉得。 “政府主张，既然对数据的‘检查’将由机器执行，他们就不受第四修正案正常的搜查和扣押保护。”这太疯狂了。
pdknsk查看英文原文
> My company, Lavabit, provided email services to 410,000 people – including Edward Snowden, according to news reports – [...]. Does he write "according to news reports" for legal reasons? Obviously he should know, I think. > The government argued that, since the "inspection" of the data was to be carried out by a machine, they were exempt from the normal search-and-seizure protections of the Fourth Amendment. That's insane.
肯定关停是正确选择，并指出即便懂安全存储也无法预见政府会如此施压。
我赞赏 Ladar 在这件事上做出了正确选择。一方面，很多人怀疑一个私钥被偷走安全性就崩溃的邮件服务；另一方面，假设 Ladar 是知道如何安全存储私钥的聪明人（他确实是），他也不可能预见到政府会把他卷进一场猫鼠游戏。
primitivesuave查看英文原文
I applaud Ladar for making the right choice on this one. On one hand, there's a lot of skepticism about an email service whose security breaks as soon as the private keys are stolen. On the other hand, assuming Ladar is a smart individual who knows how to securely store the keys (he is), he couldn't possibly have foreseen that the government would embroil him in a cat-and-mouse game.
前向保密能让服务商在私钥被交出时也保护历史流量，Lavabit 若用 DHE/ECDHE 政府将一无所获。
如果我没记错，Lavabit 案是当前推动 TLS 采用前向保密密码套件的原因之一（也许是最强的原因），TLS 1.3 甚至只允许这类套件。Lavabit 用的是较旧的 RSA 密钥交换而非 DHE，所以被迫交出的私钥能解密所有过往 HTTPS 连接；改用 DHE/ECDHE 的前向保密后，私钥只能冒充服务器，不能解密过去或未来的 HTTPS 连接。若 Lavabit 用了 DHE/ECDHE，政府就没什么可拿；即便装后门或中间人记录设备也拿不到有用数据，除非目标在安装后才登录。他们本可回答“我们没有有用的东西可给”就结束，就像 Whispersystems 最近遇到的那样。
cesarb查看英文原文
IIRC, the Lavabit case was one of the reasons (and perhaps the strongest one) for the current push towards forward secrecy cipher suites in TLS (with TLS 1.3 even having them as the only option). Since Lavabit used the older RSA key exchange, instead of a DHE key exchange, the private key they were forced to hand over could decrypt all past HTTPS connections. With forward secret (DHE/ECDHE) key exchanges, the private key can only be used to impersonate the server; it cannot be used to decrypt any past (or future) HTTPS connections. Had Lavabit used DHE/ECDHE, they would have nothing to give. Even adding a backdoor to their servers (or a MITM logging middlebox) would gain nothing, unless the target logged in after it was installed. They would be able to simply respond "we have nothing useful to give" and be done with it, like recently happened to Whispersystems.
批评无差别窃听和加密后门，认为服务商迁往隐私友好国家只是打地鼠。
我不喜欢的是，政府要求窃听每个人的账户，而每个账户都未被怀疑犯罪。这怎么能被正当化？为了阻止未来的举报者？这让我想起英国的《调查权力法》：它要求 ISP 记录所有人的上网历史，并终结端到端加密，因为所有加密都必须留后门。最终只会发生一件事：匿名邮件服务商会迁往隐私友好的国家。这是打地鼠游戏。已经有 Sigaint 这种托管在 Tor 上的匿名邮件服务商了。等我上线匿名网站时会用 Sigaint、离岸主机和 I2VPN。
desbest查看英文原文
What I don't like is how the government demands to wiretap EVERY person's account regardless of there being no suspicion of crime in every account. How can that be justified? To stop future whistleblowers? It reminds me of the Investigatory Powers Act in Britain which demands ISPs to log everyone's internet browsing history and the end of end-to-end encryption as all encryption will have to have backdoors. All that will happen, is that anonymous email providers will move to countries which are privacy friendly. It's a game of whack a mole. There's already Sigaint which is an anonymous email provider which is hosted on Tor. I'll be using Sigaint, offshore hosting and I2VPN when I launch my anonymous website.
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