my openssl cheatsheet.
create
- unencrypted rsa private key (in pem format): umask 066; openssl genrsa -out key.pem [-des3] 1024- add/change passphrase of a key file: openssl rsa -des3 -in key.pem -out [key.new.pem|key.pem]
 
- add/change passphrase of a key file: 
- certificate signing request (CSR) using this private key: openssl req -new -key key.pem -out req.csr
- self-sign the CSR: openssl x509 -req -days 3650 -in req.csr -signkey key.pem -out cert.pem- or just in one command: sudo openssl req -new -key key.pem -x509 -days 3650 -out ../cert.pem
 
- or just in one command: 
- ca sign: openssl ca -in req.csr -out cert.pem -days 365- check ca config in /etc/ssl/openssl.cnfbeforehand.
 
- check ca config in 
- dhparam: openssl dhparam -out dhparam.pem 1024
read
- read a key file: openssl rsa -in key.pem -check -text
- read a CSR: openssl req -noout -text -in req.csr
- read a certificate: openssl x509 -noout -text -in cert.pem
- read md5 fingerprint of a cert: openssl x509 -fingerprint -noout -in newcert.pem
- dhparam: openssl dhparam -in dhparam.pem -text -noout -check
convert
- Convert a DER file (.crt .cer .der) to PEM: openssl x509 -inform der -in certificate.cer -out certificate.pem
- PEM to DER: openssl x509 -outform der -in certificate.pem -out certificate.der