OpenSSL commands to check and verify your SSL certificate, key and CSR
It can be useful to check a certificate and key before applying them to your server. The following commands help verify the certificate, key, and CSR (Certificate Signing Request).
Check a certificate
Check a certificate and return information about it (signing authority, expiration date, etc.):
openssl x509 -in server.crt -text -noout
Check a key
Check the SSL key and verify the consistency:
openssl rsa -in server.key -check
Check a CSR
Verify the CSR and print CSR data filled in when generating the CSR:
openssl req -text -noout -verify -in server.csr
Verify a certificate and key matches
These two commands print out md5 checksums of the certificate and key; the checksums can be compared to verify that the certificate and key match.
openssl x509 -noout -modulus -in server.crt| openssl md5 openssl rsa -noout -modulus -in server.key| openssl md5
Source : https://support.asperasoft.com