Archive for: ‘December 2011’

Checking the Modulus of your SSL certificates

December 15, 2011 Posted by admin

If your private key and certificate do not contain the same modulus, then Apache will sometimes refuse to start or it may not respond properly to SSL requests. You can check the modulus of your private key and SSL certificate with these commands:

openssl rsa -noout -modulus -in server.key | openssl md5
openssl x509 -noout -modulus -in server.crt | openssl md5

If the MD5 checksums match, then the certificate and key will work together. However, if they are different, then you cannot use them together. Generally, this means that you used the wrong CSR (that corresponded to some other private key) when you obtained/created your SSL certificate.