How to decrypt PKCS#8 encrpyted private key in javascript

I am working on ServiceNow - BOX integration using rest API. for generating access tokens, I need to generate a JWT.

I need to have a private key to sign that JWT.

They have provided the private key but it is in an encrypted format.

-----BEGIN ENCRYPTED PRIVATE KEY-----
*******Key here********** 
-----END ENCRYPTED PRIVATE KEY-----

I have also been provided with a pass code to decrypt it.

I am not sure how to decrypt above private key in ServiceNow.

Please help me in getting this done in javascript pure implementation.

Thanks,

Ali

Solution

From what you posted above it looks like you are receiving the key in PKCS#8 format https://en.wikipedia.org/wiki/PKCS_8

From some quick googling looks like this library may be your best bet for extracting this value. https://github.com/kjur/jsrsasign

Here is code in that library that decodes this:

Here they are using in a unit test. Probably similar how you will need to call.