Frequently used OpenSSL Commands

General OpenSSL Commands

Generate a new private key and CSR (Unix)
openssl req -out CSR.csr -pubkey -new -keyout privateKey.key
Generate a new private key and CSR (Windows)
openssl req -out CSR.csr -pubkey -new -keyout privateKey.key -config .shareopenssl.cmf
Generate a CSR for an existing private key
openssl req -out CSR.csr -key privateKey.key -new
Generate a CSR based on an existing certificate
openssl x509 -x509toreq -in MYCRT.crt -out CSR.csr -signkey privateKey.key
Generate a self-signed certificate
openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout privateKey.key -out certificate.crt
Remove a password from a private key
openssl rsa -in privateKey.pem -out newPrivateKey.pem

Check the CSR, Private Key or Certificate using OpenSSL

Check a 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

Debugging with OpenSSL

Check the MD5 hash of the public key to check if it is equal to what is in the CSR or private key
openssl x509 -noout -modulus -in certificate.crt | openssl md5openssl rsa -noout -modulus -in privateKey.key | openssl md5openssl req -noout -modulus -in CSR.csr | openssl md5
Check an SSL connection. All certificates (also intermediate certificates) should be displayed
openssl s_client -connect

Convert certificates using 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) including the private key and certificate(s) to PEM
openssl pkcs12 -in keyStore.pfx -out keyStore.pem -nodes

Note: Add -nocerts to only convert the private key, or add -nokeys to convert only 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

Convert ssh private key to pem

openssl rsa -in ~/.ssh/id_rsa -outform pem > id_rsa.pem