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mofelee/OpenSSL Cheatsheet.md

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Created October 25, 2016 03:43
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OpenSSL Cheatsheet
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OpenSSL Cheatsheet.md

General OpenSSL Commands

These commands allow you to generate CSRs, Certificates, Private Keys and do other miscellaneous tasks.

  • Generate a new private key and Certificate Signing Request
openssl req -out CSR.csr -new -newkey rsa:2048 -nodes -keyout privateKey.key
  • Generate a self-signed certificate (see How to Create and Install an Apache Self Signed Certificate for more info)
openssl req -x509 -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 CSR.csr -key privateKey.key -new
  • Generate a certificate signing request based on an existing certificate
openssl x509 -x509toreq -in certificate.crt -out CSR.csr -signkey privateKey.key
  • Remove a passphrase from a private key
openssl rsa -in privateKey.pem -out newPrivateKey.pem

Checking Using OpenSSL

If you need to check the information within a Certificate, CSR or Private Key, use these commands. You can also check CSRs and check certificates using our online tools.

  • Check a Certificate Signing Request (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 Using OpenSSL

If you are receiving an error that the private doesn't match the certificate or that a certificate that you installed to a site is not trusted, try one of these commands. If you are trying to verify that an SSL certificate is installed correctly, be sure to check out the SSL Checker.

  • Check an MD5 hash of the public key to ensure that it matches with what is in a CSR or private key
openssl rsa -noout -modulus -in privateKey.key | openssl md5
openssl req -noout -modulus -in CSR.csr | openssl md5```
* Check an SSL connection. All the certificates (including Intermediates) should be displayed

openssl s_client -connect www.paypal.com:443


Converting Using OpenSSL
========================

These commands allow you to convert certificates and keys to different formats to make them compatible with specific types of servers or software. For example, you can convert a normal PEM file that would work with Apache to a PFX (PKCS#12) file and use it with Tomcat or IIS. Use our SSL Converter to convert certificates without messing with 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

You can add `-nocerts` to only output the private key or add `-nokeys` to only output 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

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