NodeJS: Validate certificate in DER format

blzn picture blzn · Aug 13, 2015 · Viewed 8.1k times · Source

I'm using crypto module to validate a certificate, but both, my certificate and my public key are in DER format. It seems that crypto module does not accept this format.

Is there a way (or module) to convert DER to PEM format using NodeJS? I couldn't find any and cannot use command line to call openssl via shell.

UPDATE: It's not about HTTPS certificates. It's about general X.509 certificates. And if you mark the question as negative, please leave a comment to justify it. Don't be a stupid if you are not able to help.

Answer

Nick Sotiros picture Nick Sotiros · Jan 17, 2018

I think the PEM format is just the DER binary data that has been base64 encoded, split into 64 character lines, and wrapped between '-----BEGIN CERTIFICATE-----' and '-----END CERTIFICATE-----'.

So you could do this:

var prefix = '-----BEGIN CERTIFICATE-----\n';
var postfix = '-----END CERTIFICATE-----';
var pemText = prefix + derBuffer.toString('base64').match(/.{0,64}/g).join('\n') + postfix;

You will not need to put a '\n' before the postfix because the last match of the der buffer should be an empty string '', so there will be a '\n' at the end of derBuffer.toString('base64').match(/.{0,64}/g).join('\n')