Question

The following command generates a file which contains both public and private key:

openssl genrsa -des3 -out privkey.pem 2048

Source: here

With OpenSSL, the private key contains the public key information as well, so a public key doesn’t need to be generated separately

How can we extract the public key from the privkey.pem file?

Thanks.

stewe · Accepted Answer · 2012-04-22 19:19:02Z

openssl rsa -in privkey.pem -pubout > key.pub

That writes the public key to key.pub

answered Apr 22 ’12 at 19:19

stewe
13.6k13247

Thanks a lot !! – Jake Apr 22 ’12 at 19:23

You’re welcome 🙂 – stewe Apr 22 ’12 at 19:28

score 1 · Answer 2

For those interested in the details – you can see what’s inside the public key file (generated as explained above), by doing this:-

openssl rsa -noout -text -inform PEM -in key.pub -pubin

or for the private key file, this:-

openssl rsa -noout -text -in key.private

which outputs as text on the console the actual components of the key (modulus, exponents, primes, …)

openSSL: how to extract public key? – Stack Overflow

2 Answers