Let's Encrypt 生了新的 Root 與 Intermediate Certificate

Let's Encrypt 弄了新的 Root Certificate 與 Intermediate Certificate:「Let's Encrypt's New Root and Intermediate Certificates」。

一方面是本來的 Intermediate Certificate 也快要要過期了,另外一方面是要利用 ECDSA 降低傳輸時的頻寬成本:

On Thursday, September 3rd, 2020, Let’s Encrypt issued six new certificates: one root, four intermediates, and one cross-sign. These new certificates are part of our larger plan to improve privacy on the web, by making ECDSA end-entity certificates widely available, and by making certificates smaller.

本來有 Let's Encrypt Authority {X1,X2,X3,X4} 四組 Intermediate Certificate,都是 RSA 2048 bits。

其中 X1 與 X2 差不多都到期了 (cross-signed 的已經過了,自家 ISRG Root X1 簽的剩不到一個月),不過這兩組已經沒在用了,這次就不管他了。

而 X3 與 X4 這兩組則是明年到期,會產生出新的 Intermediate Certificate,會叫做 R3 與 R4,跟之前一樣會被自家 ISRG Root X1 簽,以及 IdenTrust DST Root CA X3 簽:

For starters, we’ve issued two new 2048-bit RSA intermediates which we’re calling R3 and R4. These are both issued by ISRG Root X1, and have 5-year lifetimes. They will also be cross-signed by IdenTrust. They’re basically direct replacements for our current X3 and X4, which are expiring in a year. We expect to switch our primary issuance pipeline to use R3 later this year, which won’t have any real effect on issuance or renewal.

然後是本次的重頭戲,會弄出一個新的 Root Certificate,叫做 ISRG Root X2,以及兩個 Intermediate Certificate,叫做 E1 與 E2:

The other new certificates are more interesting. First up, we have the new ISRG Root X2, which has an ECDSA P-384 key instead of RSA, and is valid until 2040. Issued from that, we have two new intermediates, E1 and E2, which are both also ECDSA and are valid for 5 years.

主要的目的就是降低 TLS 連線時的 bandwidth,這次的設計預期可以降低將近 400 bytes:

While a 2048-bit RSA public key is about 256 bytes long, an ECDSA P-384 public key is only about 48 bytes. Similarly, the RSA signature will be another 256 bytes, while the ECDSA signature will only be 96 bytes. Factoring in some additional overhead, that’s a savings of nearly 400 bytes per certificate. Multiply that by how many certificates are in your chain, and how many connections you get in a day, and the bandwidth savings add up fast.

另外一個特別的修改是把名字改短 (把「Let's Encrypt Authority」拿掉),也是為了省傳輸的成本:

As an aside: since we’re concerned about certificate sizes, we’ve also taken a few other measures to save bytes in our new certificates. We’ve shortened their Subject Common Names from “Let’s Encrypt Authority X3” to just “R3”, relying on the previously-redundant Organization Name field to supply the words “Let’s Encrypt”. We’ve shortened their Authority Information Access Issuer and CRL Distribution Point URLs, and we’ve dropped their CPS and OCSP urls entirely. All of this adds up to another approximately 120 bytes of savings without making any substantive change to the useful information in the certificate.

這個部份讓我想到之前寫的「省頻寬的方法:終極版本...」這篇,裡面提到 AWS 自家的 SSL Certificate 太胖,改用 DigiCert 的反而可以省下不少錢 XDDD

另外也提到了這次 cross-sign 的部份是對 ECDSA Root Certificate 簽 (ISRG Root X2),而不是對 ECDSA Intermediate Certificate 簽 (E1 與 E2),主因是不希望多一次切換的轉移期:

In the end, we decided that providing the option of all-ECDSA chains was more important, and so opted to go with the first option, and cross-sign the ISRG Root X2 itself.

這算是蠻重要的進展,看起來各家 client 最近應該都會推出新版支援。

Let's Encrypt 從七月開始將會改用自己的 Root 簽發憑證

Let's Encrypt 宣佈了以後的憑證的簽發計畫:「Transitioning to ISRG's Root」。

主要的改變是 2019/07/08 之後提供的 intermediate CA 會改變,從現在的 cross-sign 變成只有自己的 Root CA:

On July 8, 2019, we will change the default intermediate certificate we provide via ACME. Most subscribers don’t need to do anything. Subscribers who support very old TLS/SSL clients may want to manually configure the older intermediate to increase backwards compatibility.

目前的簽發用的兩個中介憑證 (Let's Encrypt Authority X3Let's Encrypt Authority X4) 是由 Let's Encrypt 自己的 ISRG Root X1IdenTrustDST Root CA X3 所 共同簽署的:

這是因為 IdenTrust 的 DST Root CA X3 憑證很久前就被各家瀏覽器信任 (像是 Mozilla 的「Request to add two additional IdenTrust root CA certificates」這篇,可以看到 2007 年就被放進去了),而 Let's Encrypt 當時為了更快把可用的產品推出,所以跟 IdenTrust 合作,採用 cross sign 的方式讓 Let's Encrypt 簽出來的憑證被一般瀏覽器與函式庫所信任。

現在差不多過了三年半,Let's Encrypt 成為目前世界上最大的 SSL Certificate 發放單位,加上自己的 Root CA (ISRG Root X1) 也都差不多被整合進各家系統內了,所以打算要獨立自己簽了。

不過系統上可以設定,使用者如果有遇到相容性問題 (太舊的系統可能還是不包含 Let's Encrypt 自家的 ISRG Root X1),還是可以設定使用有 cross-sign 的版本 (維持現狀)。與 IdenTrust 的 cross-sign 會維持到 2021 年九月,大約再兩年多一些:

Our current cross-signature from IdenTrust expires on March 17, 2021. The IdenTrust root that we are cross-signed from expires on September 30, 2021. Within the next year we will obtain a new cross-signature that is valid until September 29, 2021. This means that our subscribers will have the option to manually configure a certificate chain that uses IdenTrust until September 29, 2021.


Amazon EC2 推出 4TB 的機器

之前 Amazon EC2 記憶體最大的機器是 x1.32xlarge 的 2TB RAM (更精確是 1952GB),現在推出了 4TB RAM 的 x1e.32xlarge (3904GB):「Now Available – EC2 Instances with 4 TB of Memory」。

現在這個時間點在 us-east-1 的價錢是 USD$26.688/hour (一個月 USD$19215.36),用的到的人應該付得起?

另外值得注意的是,x1e.32xlarge 雖然比 x1.32xlarge 多了一倍的記憶體,但 vCPU 不變 (都是 128),而且 ECU 下降了 (從 349 降到 340)。

這個機器目前在 us-east-1us-west-2eu-west-1ap-northeast-1 四區提供服務:

The x1e.32xlarge instances can be launched in On-Demand and Reserved Instance form via the AWS Management Console, AWS Command Line Interface (CLI), AWS SDKs, and AWS Marketplace in the US East (Northern Virginia), US West (Oregon), EU (Ireland), and Asia Pacific (Tokyo) Regions.

AWS 最新的 x1.32xlarge...

Amazon EC2 推出了 x1.32xlarge:「X1 Instances for EC2 – Ready for Your Memory-Intensive Workloads」。


Processor: 4 x Intel™ Xeon E7 8880 v3 (Haswell) running at 2.3 GHz – 64 cores / 128 vCPUs.
Memory: 1,952 GiB with Single Device Data Correction (SDDC+1).
Instance Storage: 2 x 1,920 GB SSD.


If you are ready to start using the X1 instances in the US East (Northern Virginia), US West (Oregon), Europe (Ireland), Europe (Frankfurt), Asia Pacific (Tokyo), Asia Pacific (Singapore), or Asia Pacific (Sydney) Regions, please request access and we’ll get you going as soon as possible.

這樣以後就不能說「用 C4 就對了」...

EC2 推出超大的 X1 系列與超小的 T2.Nano

都還沒上線,先公告而已:「EC2 Instance Update – X1 (SAP HANA) & T2.Nano (Websites)」。

Amazon EC2 將會推出了超大的 X1 系列,Intel Xeon E7 系列與 2TB RAM (比很多人硬碟大小還大 XDDD),拿來跑各種暴力應用的:

The X1 instances will be powered by up to four Intel® Xeon® E7 processors. The processors have high memory bandwidth and large L3 caches, both designed to support high-performance, memory-bound applications. With over 100 vCPUs, these instances will be able to handle highly concurrent workloads with ease.

X1 系列預定 2016 年上半年會開放使用:

We expect to have the X1 available in the first half of 2016. I’ll share pricing and other details at launch time.

另外是 T2.Nano,只有 512MB RAM,預定是今年會開放使用:

Later this year we will introduce the t2.nano instance. You’ll get 1 vCPU and 512 MB of memory, and the ability run at full core performance for over an hour on a full credit balance. Each newly launched t2.nano starts out with sufficient CPU Credits to allow you to get started as quickly as possible.