SSL

Links

• Networking 4 All - Most used OpenSSL commands

Questions

• What are file types .crt, .pem, .key
• Given a file, how can recognize its type?

Split PKCS#12 certificate into CA / Cert / Private key

Use openssl pkcs12 to split a pkcs#12 data into the CA / certificates / private keys component. By default, PKCS#12 produces PEM files [1].

openssl pkcs12 -in mywindowscert.pfx -nocerts -out mycert.key
openssl pkcs12 -in mywindowscert.pfx -clcerts -nokeys -out mycert.crt.pem
openssl pkcs12 -in mywindowscert.pfx -cacerts -nokeys -out mycert.ca.pem

Splitting the certificates is for instance needed to import a Windows certificate needed to connect to an enterprise WiFi (see Linux Admin).

Checking Certificate Chain with OpenSSL

Checking A Remote Certificate Chain With OpenSSL

Change .p12 / .pfx password

Say you have a private key / certificate file mycert.pfx, and you want to change its password:

# Strangely we cannot pipe output of 1st command into 2nd (error 'No certificate matches private key')
openssl pkcs12 -in mycert.pfx -out mycert.pem -nodes         # Don't encrypt private key at all
openssl pkcs12 -export -in mycert.pem -out mycert-new.pfx
rm mycert.pem                                               # DON'T FORGET THIS!

Extract key from .p12/ .pfx

• openssl pkcs12 takes a file in pkcs#12 format (.p12/.pfx) and produces a file in PEM format, that is parseable with openssl rsa. The PEM may contain either private key, certificates, root certificates or even public keys.

openssl pkcs12 -in mycert.pfx -out mycert.pem -nocerts -nodes  # Don't encrypt private key at all, don't output certificates
openssl rsa -noout -modulus -in mycert.pem                     # To extract the modulus
openssl rsa -noout -text -in mycert.pem                        # To extract all the fields

Query a public key certificate

openssl x509 -in ssl-cert-www.immie.org.pem -noout -subject       # Query certificate name. Must match Apache ServerName
# For instance:
#   subject= /C=BE/ST=BBW/L=Brussels/O=immie.org/CN=www.immie.org

Generate a new self-signed SSL certificate for Apache server

See Apache.

Accept self-signed certificates (bypass browser warning)

Internet Explorer

• Click on the error certificate icon in address bar,
• Cick View certificates,
• then click Install certificate....
• Server public certificate must be imported in the Trusted Root Certification Authorities (and *not* in Intermediate CA which is chosen in automatic mode).