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Let's Encrypt 的 Embed SCT 支援

翻到 Let's EncryptUpcoming Features 時看到:

Embed SCT receipts in certificates
ETA: February, 2018

對 Embed SCT 不熟,所以查了查這個功能。

這指的是在簽發 SSL certficiate 後,把資料丟給 Certificate Transparency (CT) 伺服器後,伺服器會提供 signed certificate timestamp (SCT);而這個資料放到 SSL certificate 內叫做 Embed SCT:(出自 CT 的 FAQ)

What is an SCT?
An SCT is a signed certificate timestamp. When a certificate authority or a server operator submits a certificate to a log, the log responds with an SCT. An SCT is essentially a promise that the log server will add the certificate to the log in a specific time. The time, known as the maximum merge delay (MMD), helps ensure that certificates are added to logs in a reasonable time. The SCT accompanies the certificate until the certificate is revoked. A TLS server must present the SCT to a TLS client (along with the SSL certificate) during the TLS handshake.

當使用 ECC 時會小於 100 bytes:

How big is an SCT?
SCTs are less than 100 bytes, assuming elliptic curve signatures are used.

這樣才能試著解釋前幾天提到要拔掉 HPKP 的事情:「Chromium 內提案移除 HPKP (HTTP Public Key Pinning)」,也就是為什麼他們是提 CT 解,而不是 DNS CAA 解...

不過我記得 CT server 可以自己架自己 submit 不是嗎?後來有另外規定一定要用第三方的嗎?這樣又很怪...

Chromium 內提案移除 HPKP (HTTP Public Key Pinning)

Twitter 上看到這則 tweet,提到要移除 HPKP (HTTP Public Key Pinning):

blink-dev 上的討論可以參考「Intent To Deprecate And Remove: Public Key Pinning」(就是上面那個連結,只是拉出來)。

這個提案大概可以推敲出理由... 目前的作法必須寫進瀏覽器內,這樣明顯會有 scale 問題,而且這個作法本身就很 workaround,只能保護所謂「高價值」的 domain,而且因為是綁在 Public Key 上,如果 CA 換了 Intermediate Certificate 就有可能會導致檢查過不了。

另外一方面,scale 而且合理的替代方案已經發展出來了。如果瀏覽器會檢查 DNS CAA 資訊 (這個規格可以在 DNS 裡設定有哪些 CA 可以簽這個 domain),就能解這個問題 (加上 DNSSEC 會更加確保驗證過程)。像是這樣:

example.com.    IN      CAA     0 issue "letsencrypt.org"
example.com.    IN      CAA     0 issuewild ";"

不過這個提案本身提到 CT (Certificate Transparency) 怪怪的,因為 CT 無法避免惡意的簽發 (發了以後故意不送 CT):

Finally, remove support for built-in PKP (“static pins”) at a point in the future when Chrome requires Certificate Transparency for all publicly-trusted certificates (not just newly-issued publicly-trusted certificates). (We don’t yet know when this will be.)

但在瀏覽器支援 DNS CAA 可以避免,結果在討論時都沒到 DNS CAA...

另外在 Hacker News 上也有討論:「Public Key Pinning Being Removed from Chrome (groups.google.com)」可以看一下,有個人有提到用 DNS CAA 的方法...

不過印象中這群人對 DNS-based 的方案都不太喜歡,所以也有可能是這樣不考慮在瀏覽器端實作 DNS CAA 吧...

Google Chrome 支援 APNG 了...

翻資料的時候才發現 Google Chrome 從 59 版 (今年六月進 stable channel) 就支援 APNG 了,這樣所有主流瀏覽器只剩下微軟家的 IE 與 Edge 還沒支援了:

找了一下當時的新聞:「Chrome 59 will fully support animated PNGs」,以及對應的 ticket:「Request for enhancement: APNG (animated PNG)」。

APNG 相較於 GIF 多了透明的設計 (GIF 需要拿一個顏色來當作透明),以及更多的色彩,但對於瀏覽器的支援一直都不完整:

The GIF file format has better application and browser support than APNG, but it is limited to 256 colors per frame and supports only index transparency, by mapping one of the palette colors to transparent.

現在這樣讓 GIF 退休的日子又前進了一大步...

跨各平台的 Microsoft Edge 又讓搞網站的人爆炸...

還好用的人應該不會太多 (?)

微軟宣佈在 iOSAndroid 以及微軟自家的系統上都推出 Microsoft Edge:「Announcing Microsoft Edge for iOS and Android, Microsoft Launcher」,另外也很「貼心」的整理了一篇不同平台上的差異 (尤其是 iOS 與 Android):「Microsoft Edge for iOS and Android: What developers need to know」。

不過 Twitter 上微軟自家人 Kyle Pflug‏ 講的比較簡單:

把重點講的超清楚,然後順建讓人有種 WTF 的感覺 XDDD (等於是一次推出三個不同行為的 browser 啊!)

設計師鐵定會詛咒他不要流行起來 XDDD

Google 打算更廣泛的預設使用 HSTS

Google 宣佈了更廣泛開啟 HSTS 的計畫:「Broadening HSTS to secure more of the Web」。

然後先提到 .foo.dev 的「Google Chrome 將 .dev 設為 HSTS Preload 名單」這件事情:

In 2015 we created the first secure TLD when we added .google to the HSTS preload list, and we are now rolling out HSTS for a larger number of our TLDs, starting with .foo and .dev.

接下來希望拋磚可以引玉:

We hope to make some of these secure TLDs available for registration soon, and would like to see TLD-wide HSTS become the security standard for new TLDs.

最新的 Firefox 56 對 AES-GCM 效能的改善

昨天釋出的 Firefox 56 對於 AES-GCM 在老電腦上改善了不少效能:「Improving AES-GCM Performance」。

首先是 Firefox 自己的數據分析,可以看到 AES-GCM 佔目前加密連線裡的大宗,再來是 AES-CBC:

先以 Linux 64bits 環境的數據來看,Firefox 56 的 NSS 3.32 大幅改善了老電腦的效能 (不支援 AES-NI 硬體加解密的 CPU,甚至是不支援 PCLMUL 的 CPU,以及不支援 AVX 的 CPU):

在 Linux 32bits 環境上則是連預設值大幅改善,不過用的人應該少很多了:

Windows 下則是因為 64bits 或是 32bits 都有足夠的使用者,所以平常就花了不少力氣。但也可以看出對於老電腦的速度提升:

Mac (64bits only) 算是這次比較大的提升,連新電腦的預設值都大幅變快:

加上之後陸續的改善 (尤其是下一版 Firefox 57 的 Project Quantum),這幾版應該會拉出不少效能...

Mozilla 的提案「HTTP Immutable Responses」

狀態已經是 Category: Standards Track 了,RFC 8246 的「HTTP Immutable Responses」:

The immutable HTTP response Cache-Control extension allows servers to identify resources that will not be updated during their freshness lifetime. This ensures that a client never needs to revalidate a cached fresh resource to be certain it has not been modified.

Cache-Control 介紹了 immutable,像是這樣:

Cache-Control: max-age=31536000, immutable

依照 MDN 上的資料 (Cache-Control - HTTP | MDN),目前只有 EdgeFirefox 支援,不過既然成為標準了,後續其他瀏覽器應該都會支援 (吧):

Google Chrome 對 Symantec 全系列憑證的不信任計畫

Google Chrome 前陣子整理了一份對 Symantec 憑證的不信任計畫:「Chrome’s Plan to Distrust Symantec Certificates」。

這包括了一卡車的品牌,像是 ThawteVeriSignGeoTrustRapidSSL,不過 Equifax 跟 Symantec 的關係我沒查到...:

Symantec’s PKI business, which operates a series of Certificate Authorities under various brand names, including Thawte, VeriSign, Equifax, GeoTrust, and RapidSSL, had issued numerous certificates that did not comply with the industry-developed CA/Browser Forum Baseline Requirements.

反正整個計畫會在 Google Chrome 70 推出時告一段落 (變成完全不信任),會是 2018/09/13 (預定時間) 與 2018/10/23 (預定時間) 在 beta channel 與 stable channel 上推出。

中間比較重要的時間點是 2018/03/15 (預定時間) 與 2018/04/17 (預定時間),Google Chrome 66 在 beta channel 與 stable channel 上推出,這個版本不會信任 2016/06/01 前發出的憑證:

Chrome 66 released to beta, which will remove trust in Symantec-issued certificates with a not-before date prior to June 1, 2016. As of this date Site Operators must be using either a Symantec-issued TLS server certificate issued on or after June 1, 2016 or a currently valid certificate issued from any other trusted CA as of Chrome 66.
Site Operators that obtained a certificate from Symantec’s old infrastructure after June 1, 2016 are unaffected by Chrome 66 but will need to obtain a new certificate by the Chrome 70 dates described below.

整個計畫的時間軸清楚多了...

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