This is a very common question that comes to our mind while setting up SSL in our applications. How to verify whether the key matches with the SSL certificate ?

A very easy way to verify that is given below.

We need to compare the modulus of the certificate against the modulus of the private key.

Execute the below command to get the modulus of a certificate.

openssl x509 -noout -modulus -in mycertificate.crt | openssl md5

This will generate the modulus something like e091f305089662689d62126d49910031 

Execute the below command to get the modulus of a private key.

openssl rsa -noout -modulus -in mykey.key | openssl md5

This will generate the modulus of the private key. You should get the key modulus as same as certificate modulus above. i.e e091f305089662689d62126d49910031

If both the modulus are same, we can say that the certificate and the key are matching.

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