Generate a new private key and Certificate Signing Request

openssl req -out CSR.csr -new -newkey rsa:2048 -nodes -keyout privateKey.key

Generate a self-signed certificate

openssl req -x509 -sha256 -nodes -days 365 -newkey rsa:2048 -keyout privateKey.key -out certificate.crt

Generate a certificate signing request (CSR) for an existing private key

openssl req -out CSR.csr -key privateKey.key -new

Generate a certificate signing request based on an existing certificate

openssl x509 -x509toreq -in certificate.crt -out CSR.csr -signkey privateKey.key

Remove a passphrase from a private key

openssl rsa -in privateKey.pem -out newPrivateKey.pem


Check a Certificate Signing Request (CSR)

openssl req -text -noout -verify -in CSR.csr

Check a private key

openssl rsa -in privateKey.key -check

Check a certificate

openssl x509 -in certificate.crt -text -noout

Check a PKCS#12 file (.pfx or .p12)

openssl pkcs12 -info -in keyStore.p12

Verify that the private key and certificate match

openssl x509 -noout -modulus -in certificate.pem | openssl md5
openssl rsa -noout -modulus -in ssl.key | openssl md5

The output of these two commands must be exactly the same

Check the dates are valid

openssl x509 -noout -in certificate.pem -dates

Ensure that the current date is between the certificate’s start and end dates

Check the validity of the certificate chain

openssl verify -CAfile certificate-chain.pem certificate.pem

If the response is OK, the check is valid

Verify that the public keys contained in the private key file and the certificate are the same

openssl x509 -in certificate.pem -noout -pubkey
openssl rsa -in ssl.key -pubout

The output of these two commands should be the same

Check cert order

openssl crl2pkcs7 -nocrl -certfile $CERT_FILE | openssl pkcs7 -print_certs -noout

Decrypt the private RSA key

openssl rsa -in server.pem -out server_unprotected.pem


Check an MD5 hash of the public key to ensure that it matches with what is in a CSR or private key

openssl x509 -noout -modulus -in certificate.crt | openssl md5
openssl rsa -noout -modulus -in privateKey.key | openssl md5
openssl req -noout -modulus -in CSR.csr | openssl md5

Check an SSL connection. All the certificates (including Intermediates) should be displayed

openssl s_client -connect


Convert a DER file (.crt .cer .der) to PEM

openssl x509 -inform der -in certificate.cer -out certificate.pem

Convert a PEM file to DER

openssl x509 -outform der -in certificate.pem -out certificate.der

Convert a PKCS#12 file (.pfx .p12) containing a private key and certificates to PEM

openssl pkcs12 -in keyStore.pfx -out keyStore.pem -nodes

You can add -nocerts to only output the private key or add -nokeys to only output the certificates.

Convert a PEM certificate file and a private key to PKCS#12 (.pfx .p12)

openssl pkcs12 -export -out certificate.pfx -inkey privateKey.key -in certificate.crt -certfile CACert.crt