OpenSSL

Get sha256 fingerprint of cert

openssl x509 -noout -sha256 -fingerprint -in <file>

Utf8 output

-nameopt utf8

Convert RSA DER public key to PEM

openssl rsa -pubin -inform DER -in slot3_pub.key -outform PEM -out slot3_pub.pem

Convert DER certificate to PEM

openssl x509 -inform der -in cert.der -out cert.pem

Convert DER CSR to PEM

openssl req -inform der -in der-csr.csr -out pem-csr.pem

Get pub key of CSR

openssl req -pubkey -noout -in <csr-file>.csr

Get pub key from certificate

openssl x509 -pubkey -noout -in <cert-file>.crt

Modulus of Pub Key

openssl rsa -noout -text -modulus -in [public_key_filename]

Modulus of Certificate

openssl x509 -noout -text -modulus -in [certificate_filename]

View chained certificate

openssl storeutl -text -noout -certs CAFile.pem

View CSR 

openssl req -noout -text -in <csr-file>.csr

View PEM certificate

openssl x509 -in cert.pem -text -noout

View RSA public key

openssl rsa -pubin -in slot3_pub.pem -text