OpenSSL Cheat Sheet

openssl-cheat-sheet.sh

# Generate new CSR and private key
openssl req -out CSR.csr -new -newkey rsa:2048 -nodes -keyout privateKey.key

# Generate new self-signed certificate
openssl req -x509 -sha256 -nodes -days 365 -newkey rsa:2048 -keyout privateKey.key -out certificate.crt

# Generate a new CSR from existing private key
openssl req -out CSR.csr -key privateKey.key -new

# Generate new CSR from certificate (must have private key)
openssl x509 -x509toreq -in certificate.crt -out CSR.csr -signkey privateKey.key

# Remove passphrase from key
openssl rsa -in privateKey.pem -out newPrivateKey.pem

# Check what is in a 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 pkcs12 container
openssl pkcs12 -info -in keyStore.p12

# Verify hashes
openssl x509 -noout -modulus -in certificate.crt | openssl md5
openssl rsa -noout -modulus -in privateKey.key | openssl md5
openssl req -noout -modulus -in CSR.csr | openssl md5

# Verify SSL servers
openssl s_client -connect www.paypal.com:443

# Convert certificates
# DER <-> PEM
openssl x509 -inform der -in certificate.cer -out certificate.pem
openssl x509 -outform der -in certificate.pem -out certificate.der

# PKCS12 -> PEM
openssl pkcs12 -in keyStore.pfx -out keyStore.pem -nodes
# -nocerts (only keys)
openssl pkcs12 -in keyStore.pfx -out keyStore.pem -nodes -nocerts
# -nokeys (only certs)
openssl pkcs12 -in keyStore.pfx -out keyStore.pem -nodes -nokeys

# PEM -> PKCS12
openssl pkcs12 -export -out certificate.pfx -inkey privateKey.key -in certificate.crt -certfile CACert.crt

# creating a pkcs#7 format certificate in DER format
openssl crl2pkcs7 -nocrl -certfile user.crt -certfile ca.crt -outform DER -out user.p7c

# creating a pkcs#12 format certificate (IIS)
openssl pkcs12 -export -in user.crt -inkey user.key -out server.pkcs12

# provide an ssl server to test against
openssl s_server -accept 9000 -cert user.crt -key user.key

# verify a s/mime signature
openssl smime -CAfile /usr/local/lib/openssl/certs/ca-bundle.crt -verify -in messagefile >/dev/null

# extract the s/mime certificate
openssl smime -pk7out -in messagefile | openssl pkcs7 -print_certs

# show subject, startdate, enddate (validy-time / expire-date)
openssl x509 -noout -subject -startdate -enddate -in user.crt

# verify if the ca.crt has really signed user.crt
openssl verify -CAfile ca.crt user.crt

# decrypting the key
openssl rsa -in user.key -out user.key.decrypted

# Subject Alternate Name
openssl req \
  -newkey rsa:4096 \
  -days 3650 \
  -nodes \
  -x509 \
  -subj "/C=US/ST=Blah/L=Blah/O=Blah/CN=*.foo.com" \
  -extensions SAN \
  -config <( cat $( [[ "Darwin" -eq "$(uname -s)" ]]  && echo /System/Library/OpenSSL/openssl.cnf || echo /etc/ssl/openssl.cnf  ) \
    <(printf "[SAN]\nsubjectAltName='DNS.1:*.foo.com,DNS.2:bar.foo.com,DNS.3:zoo.foo.com'")) \
  -keyout private_key.pem \
  -out server.crt