SSL server

SSL: Cryptography & authentication

Principle and law disclaimer

Reminder

An Authority of Certification is required to ensure your certificates.

Theses one provides:

• Confidentiality
• Integrity
• Authentication

Usages

There's three options:

• You can create your own Authority of Certification ;
• Use a trusted Authority of Certification (commercial). Unfortunately, it's very expansive to use such ones ;
• Use an Open Source Authority of Certification: www.cacert.org

Legal aspects

You are not allowed to use any cryptography. The maximum cryptographic level is set by the law.

Region	Law
France	http://www.ssi.gouv.fr/fr/reglementation-ssi/cryptologie/tableau-de-synthese-de-reglementation-en-matiere-de-cryptologie.html
Sweden	to be done
European Union	to be done

Installation

Install packages

apt-get install openssl

Prep folders

Create working directory

mkdir -p /srv/ssl
cd /srv/ssl

Create ssl structure

mkdir certs crl newcerts private export

Initialize values

echo 01 > serial
touch index.txt
cp /usr/lib/ssl/openssl.cnf .

OpenSSL root configuration

During the process you’ll have to enter the same data many times:

>> You should edit the default values

Adjust default values

Edit openssl.cnf:

vim /srv/ssl/openssl.cnf

Set the working directory:

dir = /srv/ssl                            # Where everything is kept  [line 42]

[ req_distinguished_name ]
countryName_default             = SE                        # [line 128]   
stateOrProvinceName_default     = Västra Götaland           # [line 134]
localityName_default            = Goteborg                  # [line 137]
0.organizationName_default      = Daxiongmao.eu             # [line 140]
emailAddress_default            = guillaume@qin-diaz.com    # [line 154]

Authority of Certification (CA)

Difference between local / commercial Authority of Certification [CA]

Either you create your own Authority of Certification or you can use a commercial one.

Main differences:

	Personal	Commercial
Price	free	from 50$ / year (Go Daddy)
Validity	you choose	Usually 1 or 2 year
Browser alerts	Yes	No
Can be used for e-commerce	No	Yes

• July 2013: "Go Daddy" seems to be the cheapest authority.

Choose an authority of certification and subscribe to a wildcard domain certification.

In either case you need to:

• Create a private key
• Generate a request (that will slightly change)

Create CA private key

Generate a RSA private key (4096 bits length) for the CA and protect it with AES256 encryption.

openssl genrsa -aes256 -out private/cakey.key -rand ./ 4096

You have to enter a password.

!! This password will be required to perform all next operations

Create a personal CA [or Domain root certificate]

Auto-sign your Certification Authority for 10 years

openssl req -config openssl.cnf \
-new -x509 -sha256 -nodes \
-key private/cakey.key \
-out cacerts.pem \
-days 3600

Answer the questions:

• Country Name (2 letter code) [SE]:
• State or Province Name (full name) [Västra Götaland]:
• Locality Name (eg, city) [Göteborg]:
• Organization Name (eg, company) [Daxiongmao.eu]:
• Organizational Unit Name (eg, section) []:
• Common Name (e.g. server FQDN or YOUR name) []: Daxiongmao.eu CA
• Email Address [guillaume@qin-diaz.com]:

Some explanations:

Header text	Header text
Parameter	meaning
-config openssl.cnf	to use the local OpenSSL configuration file
-new	to request a new certificate
-x509	auto-sign this certificate
-sha256	hash algorithm to use
-key	certificate private key
-out	Target output file to create
-days	Certificate validity time (in days)

You can check result by:

openssl x509 -in cacerts.pem -text -noout

[Alternative] Request for a domain root certificate

Create a new server certificate request for target CA.

• See process below to generate server’s certificate requestServer certificate

Server certificate

Go to the working directory:

cd /srv/ssl

Create server private key

Generate encrypt private key

openssl genrsa -aes256 -out private/serverName.key -rand ./ 4096

ServerName must match the server FQDN.

Ex: dev.daxiongmao.eu

openssl genrsa -aes256 -out private/dev.daxiongmao.eu.key -rand ./ 4096

Decipher private key

If your key is encrypted, then you have to manually give the password each and every time a service starts.

!! If your private key is encrypt then it cannot be used at startup !!

So, for services like Apache2, you have to decipher the key:

openssl rsa -in private/serverName.key -out private/serverName.nopass.key

Create server’s certificate request

openssl req -config openssl.cnf \
-new -nodes \
-key private/serverName.key \
-out certs/serverName.req

Answer the questions:

• Country Name (2 letter code) [SE]:
• State or Province Name (full name) [Västra Götaland]:
• Locality Name (eg, city) [Göteborg]:
• Organization Name (eg, company) [Daxiongmao.eu]:
• Organizational Unit Name (eg, section) []:
• Common Name (e.g. server FQDN or YOUR name) []: dev.daxiongmao.eu
• Email Address [guillaume@qin-diaz.com]:

!! Do not use a challenge password !!

Sign the server request

Auto-sign - using your personal CA

openssl ca -config openssl.cnf \
-in certs/serverName.req \
-out certs/serverName.cert.pem \
-cert cacerts.pem \
-days 3600

Some explanations:

Parameter	meaning
-config	the local OpenSSL configuration file
-in	Incoming certificate request. = previous .req file
-out	Target certificate file
-cert	CA certificate to use
-days	Certificate validity time (in days)

You can check result by:

cat /srv/ssl/certs/serverName.cert.pem

[Alternate] Send the request to the CA

You have to send the “.req” file to the CA. They will send you back the certificate.

Export certificate

To export a certificate, it must be in PKCS12 format.

You have to perform the following for each and every certificate you’d like to export.

cd /srv/ssl

openssl pkcs12 -export \
-descert -inkey private/serverName.key \
-in certs/serverName.cert.pem \
-certfile cacerts.pem \
-name "Certicate name" \
-out export/serverName.p12

• Do not put an export password.
• You should use the non-protected key if you want to use that export with some Linux services.

Example:

openssl pkcs12 -export \
-descert -inkey private/dev.daxiongmao.eu.nopass.key \
-in certs/dev.daxiongmao.eu.cert.pem \
-certfile cacerts.pem \
-name "Certicate dev.daxiongmao.eu development server" \
-out export/dev.daxiongmao.eu.p12

Distribute the certificate with Apache2

see Apache 2 - SSL certificates page