Verify a certificat (crt) and a private key

openssl.md

Let's check

Check the certificat openssl x509 -in certificate.crt -text -noout

Compare the certificat & the private key; This :

openssl x509 -modulus -noout -in mycomp.com.crt | openssl md5

Should return the same as :

openssl rsa -modulus -noout -in mycomp.com.key | openssl md5

Let's test it (in this case it's rsa encryption) :

1 - First : retrieve the public key in the certificat

openssl x509 -in mycomp.com.crt -pubkey -noout > mycomp.com-pub.pem

2 - encrypt a string

openssl rsautl -encrypt -inkey mycomp.com-pub.pem -pubin -in <(echo "my string to encrypt") -out /tmp/data.enc cat /tmp/data.enc

3 - Check that file is well encrypted

openssl rsautl -decrypt -inkey mycomp.com.key -in /tmp/data.enc rm /tmp/data.enc

Links :

• https://raymii.org/s/tutorials/Encrypt_and_decrypt_files_to_public_keys_via_the_OpenSSL_Command_Line.html

• https://gist.github.com/ezimuel/3cb601853db6ebc4ee49

• https://www.acunetix.com/blog/articles/tls-security-what-is-tls-ssl-part-1/

• https://gist.github.com/rustymagnet3000/e1bad38d30827e2f9f68bedc7534084d