End-user stuff

Poor man's benchmark

Quick way to compare processing power of CPUs.

openssl speed sha1

To test whether the CPU and installed version of OpenSSL can work with crypto acceleration (i.e. AES-NI):

openssl speed aes-256-cbc
openssl speed -evp aes-256-cbc

throughput should be faster (bigger numbers) with the second command.

Create certificate request/unsigned key

# Create a key at the same time
openssl req -nodes -new -sha256 -keyout $DOMAIN.key.pem -out $DOMAIN.csr.pem
# Use an existing key
openssl req -nodes -new -sha256 -key $DOMAIN.key.pem -out $DOMAIN.csr.pem

$DOMAIN.key.pem will act as an SSLCertificateKeyFile for mod_ssl in Apache.

Create certificate request w/ SubjectAltName fields

SubjectAltName fields let a certificate apply to more than 1 domain. Unfortunately, OpenSSL does not allow to create these easily from the command line.

Create a configuration file, $DOMAIN.conf:

   1 cat > $DOMAIN.conf << EOF
   3 [req]
   4 distinguished_name = req_distinguished_name
   5 req_extensions = req_ext
   7 [req_distinguished_name]
   8 countryName = Country Name (2 letter code)
   9 countryName_default = US
  10 stateOrProvinceName = State or Province Name (full name)
  11 stateOrProvinceName_default = New York
  12 localityName = Locality Name (eg, city)
  13 localityName_default = New York City
  14 organizationalUnitName = Organizational Unit Name (eg, section)
  15 commonName = Common Name
  16 commonName_default = $DOMAIN
  17 commonName_max = 64
  19 [req_ext]
  20 subjectAltName = @alt_names
  22 [alt_names]
  23 DNS.1   = $DOMAIN
  24 DNS.2   = www.$DOMAIN
  26 EOF

Then use this configuration file to create a CSR:

openssl req -nodes -new -sha256 -key $DOMAIN.key.pem -out $DOMAIN.csr.pem -config $DOMAIN.conf

Show key fingerprint

openssl x509 -subject -dates -fingerprint -in $DOMAIN.key.pem

Generate key

# RSA key
openssl genrsa -out $DOMAIN.key.pem 4096
# EC key (using prime256v1 curve)
openssl ecparam -out $DOMAIN.key.pem -name prime256v1 -genkey

Display certificate information

# For a certificate signing request
openssl req -text -noout -in $DOMAIN.csr.pem
# For a generated certificate
openssl x509 -in $DOMAIN.crt.pem -noout -text

Creating a PEM file for servers

cat $DOMAIN.key.pem $DOMAIN.crt.pem $DOMAIN.dhp.pem > $DOMAIN.pem

Used by courier-imap, etc.

If there are intermediate certificates, those must be concatenated AFTER the other certificates.

Creating a PKCS12-format file

openssl pkcs12 -export -in $DOMAIN.crt.pem -inkey $DOMAIN.key.pem -out blah.p12 -name "Bill Gates"

Used for creating certificates used in e-mail clients and web browsers

Signing e-mails

openssl smine -sign -in msg.txt -text -out msg.encrypted -signer $DOMAIN.crt.pem -inkey $DOMAIN.key.pem

Certificate Authority stuff

When setting up a new CA on a system, make sure index.txt and serial exist (empty and set to 01, respectively), and create directories private and newcert. Edit openssl.cnf - change default_days, certificate and private_key, possibly key size (1024, 1280, 1536, 2048) to whatever is desired.

Create CA certificate

openssl req -new -x509 -keyout private/something-CA.key.pem -out ./something-CA.crt.pem -days 3650

Export CA certificate in DER format

openssl x509 -in something-CA.crt.pem -outform der -out something-CA.crt

Used by web browsers.

Revoke certificate

openssl ca -revoke $DOMAIN.crt.pem

Generate Certificate Revocation List (CRL)

openssl ca -gencrl -out crl/$DOMAIN-CA.crl

Sign Certificate Request

openssl ca -out blah.crt.pem -in $DOMAIN.req.pem

blah.crt.pem acts as SSLCertificateFile for Apache

Create Diffie-Hoffman Parameters for Current CA

openssl dhparam -out $DOMAIN-CA.dhp.pem 1536

Create self-signed certificate from generated key

openssl req -new -x509 -sha256 -key $DOMAIN.key.pem -out $DOMAIN.crt.pem

Use only when you've no CA and will only be generating one key/certificate (useless for anything that requires signed certificates on both ends)

Command-line tricks

Simple file encryption

openssl enc -bf -A -in file_to_encrypt.txt

Simple file decryption

openssl enc -bf -d -A -in file_to_encrypt.txt

Verify hosts

   1 # IMAP
   2 openssl s_client -connect localhost:993 -quiet > /dev/null
   3 # SMTP
   4 openssl s_client -connect localhost:465 -quiet > /dev/null
   5 # HTTP
   6 echo HEAD / | openssl s_client -connect localhost:443 -quiet > /dev/null

Depth (first line) should be 2, with a return value of 0.


SamatsWiki: CheatSheet/OpenSSL (last edited 2014-12-16 18:55:37 by SamatJain)