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OpenSSL Cheatsheet

CSR

  • Create a CSR with an existing private key
openssl req -out CSR.csr -key privateKey.key -new
  • Create a CSR with a brand new private key
openssl req -out CSR.csr -new -newkey rsa:2048 -nodes -keyout privateKey.key
  • Create a CSR from an existing certificate
openssl x509 -x509toreq -in certificate.crt -out CSR.csr -signkey privateKey.key
  • Check a CSR
openssl req -text -noout -verify -in CSR.csr

Certificates

  • Generate a self-signed certificate
openssl req -x509 -sha256 -nodes -days 365 -newkey rsa:2048 -keyout privateKey.key -out certificate.crt
  • Check a certificate
openssl x509 -in certificate.crt -text -noout
  • Convert to PEM (from .der, .cer or .crt)
openssl x509 -inform der -in certificate.cer -out certificate.pem
  • Get server certificate and chain
openssl s_client -connect www.paypal.com:443

Private Keys

  • Remove a passphrase from a private key
openssl rsa -in privateKey.pem -out newPrivateKey.pem
  • Check a private key
openssl rsa -in privateKey.key -check

PKCS12

  • Check a PKCS#12 file
openssl pkcs12 -info -in keyStore.p12
  • Convert to PEM
openssl pkcs12 -in keyStore.pfx -out keyStore.pem -nodes

PEM

  • Convert to DER
openssl x509 -outform der -in certificate.pem -out certificate.der
  • Convert to PKCS#12
openssl pkcs12 -export -out certificate.pfx -inkey privateKey.key -in certificate.crt -certfile CACert.crt

Checking Certificate vs Private Key

  • Certificate signature
openssl x509 -noout -modulus -in certificate.crt | openssl md5
  • CSR signature
openssl req -noout -modulus -in CSR.csr | openssl md5
  • Private key signature
openssl rsa -noout -modulus -in privateKey.key | openssl md5

Encode or Decode

  • Encode to base64
openssl enc -base64 <<< "Hello, World!"
openssl base64 -in <infile> -out <outfile>
  • Decode from base64
openssl enc -base64 -d <<< SGVsbG8sIFdvcmxkIQo=
openssl base64 -d -in <infile> -out <outfile>

Utilities

  • Generate random
openssl rand -base64 10
openssl rand -hex 10
  • Get a list of available ciphers
openssl list-cipher-algorithms

Disclaimer
  1. License under CC BY-NC 4.0
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  3. Not all the commands and scripts are tested in production environment, use at your own risk
  4. No privacy information is collected here
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