Ashish Singh Baghel's Blog

OpenSSL | Common Commands

January 20, 2020

General OpenSSL Commands

OpenSSL CLI

Generate a new private key and Certificate Signing Request

openssl req -out myCSR.csr -new -newkey rsa:2048 -nodes -keyout privateKey.key

Generate a self-signed certificate

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 myCSR.csr -key privateKey.key -new

Generate a certificate signing request based on an existing certificate

openssl x509 -x509toreq -in certificate.crt -out myCSR.csr -signkey privateKey.key

Remove a passphrase from a private key

openssl rsa -in privateKey.pem -out newPrivateKey.pem

Debugging Using OpenSSL

Check an SSL connection. All the certificates (including Intermediates) should be displayed

openssl s_client -connect www.paypal.com:443

Converting 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) containing a private key and certificates to PEM

openssl pkcs12 -in keyStore.pfx -out keyStore.pem -nodes

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

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