General OpenSSL Commands
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 (see How to Create and Install an Apache Self Signed Certificate for more info)
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
Generate an RSA public and private key
openssl genrsa -out id_rsa 2048
ssh-keygen -y -f id_rsa > id_rsa.pub
Match crt, csr, and key files
openssl req -noout -modulus -in mycsr.csr | md5
openssl x509 -noout -modulus -in mycert.crt | md5
openssl rsa -noout -modulus -in mykey.key | md5
Extracting from PFX file
Openssl 3.x may require -legacy
domain=foo.com; openssl pkcs12 -legacy -in ${domain}.pfx -nocerts -out ${domain}.key -nodes
domain=foo.com; openssl pkcs12 -legacy -in ${domain}.pfx -nokeys -out ${domain}.pem
Checking Using OpenSSL
Check a Certificate Signing Request (CSR)
openssl req -text -noout -verify -in CSR.csr
Check a private key
openssl rsa -check -in privateKey.key
Check a local cert file
openssl x509 -text -noout -in certificate.crt -noout -dates -subject -issuer -ext subjectAltName
Check a PKCS#12 file (.pfx or .p12)
openssl pkcs12 -info -in keyStore.p12
Check a cert via HTTPS
echo | openssl s_client -connect $SITEHOST_OR_IP:443 -servername $SITEHOST 2>/dev/null | openssl x509 -noout -subject -dates -issuer -ext subjectAltName
Debugging Using OpenSSL
If you are receiving an error that the private doesn't match the certificate or that a certificate that you installed to a site is not trusted, try one of these commands. If you are trying to verify that an SSL certificate is installed correctly, be sure to check out the SSL Checker.
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 www.paypal.com:443
Converting Using OpenSSL
These commands allow you to convert certificates and keys to different formats to make them compatible with specific types of servers or software. For example, you can convert a normal PEM file that would work with Apache to a PFX (PKCS#12) file and use it with Tomcat or IIS. Use our SSL Converter to convert certificates without messing with OpenSSL.
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
Check a cert's CN and Expiration date via https
echo | openssl s_client -connect SERVER_IP-OR-HOSTNAME:443 -servername SNI_HOST 2>/dev/null | openssl x509 -noout -dates -subject -issuer -ext subjectAltName
JWT
for pyjwt, use openssl to gen RSA pub/priv keys - do not use ssh-keygen
openssl genrsa -out id_rsa 4096
openssl rsa -in id_rsa -pubout > dotcdn_id_rsa.pub
https://www.sslshopper.com/article-most-common-openssl-commands.html