Certificates X.509

certificates.sh

## PEM Format
# Base64 encoded ASCII files and contain "-----BEGIN CERTIFICATE-----"
# and "-----END CERTIFICATE-----" statements.

## DER Format
# Binary from a certificate

## Convert from hex to binary
# xxd Concerts from binary to hex.
# Option "-r" reverts the conversion (from hex to binary)
# Option "-p" outputs in postscript style
cat certificate.crt | xxd -r -p > certificate.der

## Convert PEM to DER
openssl x509 -outform der -in certificate.pem -out certificate.der

## Convert DER to PEM
openssl x509 -inform der -in certificate.cer -out certificate.pem

## Show certificate information in text form
# -in file       input file
# -inform arg    input format SMIME (default), PEM or DER
# -text          include or delete text MIME headers
# -noout          don't print key out
openssl x509 -in certificate.der -inform der -text -noout

## Send OCSP Request
# -text          show all request and response data
# -url           URL of the OCSP server
openssl ocsp -issuer chain.pem -cert wikipedia.pem -text -url http://ocsp.digicert.com

## Verify Certificate chain
# Certificates must be in PEM format
# -untrusted     Used to add more than one untrusted certificate of the chain to verify
openssl verify -CAfile ca_cert.pem -verbose issued_cert.pem