Difference between csr created from linux openssl v/s ruby openssl library

Question

What is the difference between csr created from linux openssl v/s ruby openssl library:

openssl req -out mytest.csr -new -newkey rsa:2048 -nodes -keyout mytest.

The public key created from above looks something like this:

-----BEGIN CERTIFICATE REQUEST-----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\nWUftUDM5l7ANFqv5ii0=\n-----END CERTIFICATE REQUEST-----

However when i try to create it from ruby's open ssl library:

irb(main):004:0> private_key = OpenSSL::PKey::RSA.new 2048

irb(main):005:0> private_key.public_key.to_pem => "-----BEGIN RSA PUBLIC KEY-----\nMIIBCgKCAQEAqDaG8Je5YY2kXM6w/a7uiTTAsJd1JwkP7w44licoYxn7N+sYuv3K\n2iFAfumP3NEWueeRcCPSiGD3BpCKwxo4tch9uOFGOuaWYiK9XC7OOZV755+hix0S\nWph45bwiOSQX0Jr6SB6T7RBXxAF7RFdMVfo4AyZkakVaMxr0lVO8E7RqO6WaeYV2\ne6GYU2BPy60U7iXVK+15RGMQIWaiUt5iCGzJqBn+IE1GQJpytbRg7melx4e6zPQf\n5Aa4Wufm7SFEVMJ5/rzTALOZa5VWlPRhb7luxYXXLDqckB8/6Bok6kpu5qkJjHHz\nwRabh7u8Vy6cRuz+Df7LTsRuamkZLG8KXQIDAQAB\n-----END RSA PUBLIC KEY-----\n"

The above public key is much smaller.

What is different between the 2?

How can i make ruby's open ssl generate a csr & private like linux openssl.

Look at the headers. They're not the same thing. One is a CSR, the other is a public key. — tadman
could you provide me a link or example to achieve the same(csr & private key-2048) using ruby's openssl — Micheal
Stack Overflow is a site for programming and development questions. This question appears to be off-topic because it is not about programming or development. See What topics can I ask about here in the Help Center. Perhaps Super User or Information Security Stack Exchange would be a better place to ask. Also Where do I post questions about Dev Ops?. — jww
jww, it is about programming. I am trying to generate the above csr using the ruby programming language. — Micheal

rhashimoto rhashimoto · Accepted Answer · 2016-06-21T01:19:03

Looking at your other question as well, it appears that your fundamental misunderstanding is that you think that a CSR is a public key. A CSR does indeed contain a public key, but it includes additional data (e.g. subject and signature) and is a distinct type of object.

You started off right with creating the RSA key pair, but you then have to generate the CSR. You can do it like this:

require 'openssl'

# Create public/private key pair.
key = OpenSSL::PKey::RSA.new 2048

print key.to_pem()
print key.public_key.to_pem()

# Create CSR.
request = OpenSSL::X509::Request.new
request.subject = OpenSSL::X509::Name.parse 'C=US/CN=foobar'
request.public_key = key.public_key
request.sign(key, OpenSSL::Digest::SHA256.new)

print request.to_pem()

Note that ruby can't prompt you for the subject fields, so you have to specify them via the API.

Difference between csr created from linux openssl v/s ruby openssl library

1 Answers