Possible to use letsencrypt to generate certificates from a Salesforce CA Request?

Update 2016-03-04

letsencrypt still cannot sign CSRs without a Subject Alt Name (SAN). But it may be on their road map:

letsencrypt example of CSR without SAN

Vote for the Salesforce Idea to Include Subject Alt Name (SAN) to CA-Signed Certificate Requests.

Original

https://letsencrypt.org/ is a Certificate Authority (CA) that provides free SSL Certs.

I have a Domain in Salesforce that I’d like to get an SSL Certificate for, and I created a CA Signed Certificate in Salesforce’s Certificate and Key Management, and I downloaded the Certificate Signing Request (csr).

I installed letsencrypt on a Linux box (with Advice for using letsencrypt for Windows Users), and tried to generate a SSL Certificate with the following command using the csr, but I am getting an error.

~/letsencrypt $ ./letsencrypt-auto --csr subdomain_mydomain_com.csr

It has been noted that to use letsencrypt with a csr, the csr has to:

  1. Be in der format
  2. Contain a subjectAltName (SAN)

But I can’t figure out how to add a SAN in Salesforce before creating a CA Signed Certificate nor converting the csr to der format. (I can’t change a csr once it’s been signed.)

Has anyone figured out how to use letsencrypt with Salesforce?


Update

@AlexTennant provided a snippet where OpenSSL converts a PEM CSR to DER format:

openssl req -inform pem -outform der -in foo.csr -out foo.der

I converted my CSR to DER format with the above snippet, but I ran into another issue when trying to generate a Certificate from letsencrypt:

AssertionError: Authorizations list is empty

https://github.com/letsencrypt/letsencrypt/issues/1052 suggests that this Exception is thrown when no SAN is given in the CSR.

https://github.com/letsencrypt/boulder/issues/40 suggests that since subjectAltName (SAN) is the new standard over commonName (CN), if a CN is given, it must also be in the SAN.

http://serverfault.com/questions/253960/adding-subject-alternate-names-san-to-an-existing-cert-signing-request-csr says that a CSR cannot be altered after it’s been signed. If we could get the Private Key from Salesforce, we could generate another CSR with OpenSSL — but this seems silly and unlikely that Salesforce would hand over the Private Key.

To me, the only option is to ask Salesforce to include the CN in the SAN when it generates a CA Signed CSR. Is this correct? Or are there other alternatives? And if so, do you have any recommendation on how to proceed asking Salesforce for this?

Many thanks!

Answer

To turn a PEM to a DER, you can use OpenSSL:

openssl x509 -in cert.crt -outform der -out cert.der

as per: https://support.ssl.com/Knowledgebase/Article/View/19/0/der-vs-crt-vs-cer-vs-pem-certificates-and-how-to-convert-them

It’s my understanding that subjectAltName is optional for Let’s Encrypt, but I can’t seem to find anything in support of or against that.

Attribution
Source : Link , Question Author : Scott Pelak , Answer Author : Christian Carter

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