Root-CA

Für meine Zertifikate erstelle ich mir eine eigene Certificate Authority. Server-Zertifikate und User-Zertifikate werden jeweils von einer eigenen CA erstellt.

Es ergibt sich folgende Struktur:

        Root-CA
        /     \
Server-CA     User-CA
   |            |
 SCert 1      UCert 1
 SCert 2      UCert 2
  ...          ...
 SCert n      UCert m

Es wird das Paket openssl benötigt:

apt-get install openssl

Folgendes Script mk_ca_struct legt in einem beliebigen Verzeichnis obige CA-Struktur im Filesystem an. Es benötigt eine angepasste openssl.cnf.tpl Datei, welche im gleichen Verzeichnis wie das Script selbst liegen muss: ./scripts

scx:~# tar tvjf ca-scripts.tgz
drwxr-xr-x root/root         0 2008-06-27 19:00 ca/
drwxr-sr-x root/root         0 2008-06-27 19:57 ca/scripts/
-rw-r--r-- root/root      6500 2008-06-27 19:11 ca/scripts/openssl.cnf.tpl
-rwxr-xr-x root/root      1559 2008-06-26 22:35 ca/scripts/mk_cert_server
-rwxr-xr-x root/root      1564 2008-06-26 22:35 ca/scripts/mk_cert_user
-rwxr--r-- root/root      2892 2008-06-26 22:49 ca/scripts/mk_ca_struct

Zuerst lege ich die CA Struktur mit den entsprechenden Zertifikaten an:

scx:~/ca# ./scripts/mk_ca_struct
Where to install the CA directories [/root/ca] /root/ca
mkdir: cannot create directory `/root/ca': File exists
cp: `./scripts' and `/root/ca/scripts' are the same file
~/ca ~/ca

----------------------
Erstelle eine Root CA:

Generating a 2048 bit RSA private key
..................................................................+++
...........+++
unable to write 'random state'
writing new private key to 'RootCA/private/RCAkey.pem'
Enter PEM pass phrase: >>rootCA-Password<<
Verifying - Enter PEM pass phrase: >>rootCA-Password<<
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [DE]:
State or Province Name (full name) [Bayern]:
Locality Name (eg, city) [Nuernberg]:
Organization Name (eg, company) [OrganisationName]:
Organizational Unit Name (eg, section or website) [OrganisationUnit]:
Common Name (SERVER / USER name) []:rootCA
Email Address (eg, YOUR email) [webmaster@company.de]:
Doing .
00.pem => 9c05fe89.0


----------------------------------------------
Erstelle eine Server CA (signiert von Root CA):

Generating a 2048 bit RSA private key
.+++
....................................................................+++
unable to write 'random state'
writing new private key to 'ServerCA/private/SCAkey.pem'
Enter PEM pass phrase: >>ServerCA-Password<<
Verifying - Enter PEM pass phrase: >>ServerCA-Password<<
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [DE]:
State or Province Name (full name) [Bayern]:
Locality Name (eg, city) [Nuernberg]:
Organization Name (eg, company) [OrganisationName]:
Organizational Unit Name (eg, section or website) [OrganisationUnit]:
Common Name (SERVER / USER name) []:serverCA
Email Address (eg, YOUR email) [webmaster@company.de]:

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
company.de []:
Using configuration from openssl.cnf
Enter pass phrase for /root/ca/RootCA/private/RCAkey.pem: >>rootCA-Password<<
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
countryName           :PRINTABLE:'DE'
stateOrProvinceName   :PRINTABLE:'Bayern'
localityName          :PRINTABLE:'Nuernberg'
organizationName      :PRINTABLE:'OrganisationName'
organizationalUnitName:PRINTABLE:'OrganisationUnit'
commonName            :PRINTABLE:'serverCA'
emailAddress          :IA5STRING:'webmaster@company.de'
Certificate is to be certified until Jun 26 18:04:15 2013 GMT (1825 days)
Sign the certificate? [y/n]:y


1 out of 1 certificate requests certified, commit? [y/n]y
Write out database with 1 new entries
Data Base Updated
unable to write 'random state'
Doing .
00.pem => 9c05fe89.0
01.pem => b99e5d4b.0


---------------------------------------------
Erstelle eine User CA (signiert von Root CA):

Generating a 2048 bit RSA private key
.................................................................+++
..........................................................................................+++
unable to write 'random state'
writing new private key to 'UserCA/private/UCAkey.pem'
Enter PEM pass phrase: >>UserCA-Password<<
Verifying - Enter PEM pass phrase: >>UserCA-Password<<
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [DE]:
State or Province Name (full name) [Bayern]:
Locality Name (eg, city) [Nuernberg]:
Organization Name (eg, company) [OrganisationName]:
Organizational Unit Name (eg, section or website) [OrganisationUnit]:
Common Name (SERVER / USER name) []:userCA
Email Address (eg, YOUR email) [webmaster@company.de]:

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
company.de []:
Using configuration from openssl.cnf
Enter pass phrase for /root/ca/RootCA/private/RCAkey.pem: >>rootCA-Password<<
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
countryName           :PRINTABLE:'DE'
stateOrProvinceName   :PRINTABLE:'Bayern'
localityName          :PRINTABLE:'Nuernberg'
organizationName      :PRINTABLE:'OrganisationName'
organizationalUnitName:PRINTABLE:'OrganisationUnit'
commonName            :PRINTABLE:'userCA'
emailAddress          :IA5STRING:'webmaster@company.de'
Certificate is to be certified until Jun 26 18:04:42 2013 GMT (1825 days)
Sign the certificate? [y/n]:y


1 out of 1 certificate requests certified, commit? [y/n]y
Write out database with 1 new entries
Data Base Updated
unable to write 'random state'
Doing .
00.pem => 9c05fe89.0
01.pem => b99e5d4b.0
02.pem => 47efd334.0
~/ca

scx:~/ca# l
total 32
drwxr-xr-x 2 root root 4096 2008-06-27 20:04 certs/
-rw-r--r-- 1 root root 6657 2008-06-27 20:03 openssl.cnf
drwxr-xr-x 2 root root 4096 2008-06-27 20:03 private/
drwxr-xr-x 5 root root 4096 2008-06-27 20:04 RootCA/
drwxr-sr-x 2 root root 4096 2008-06-27 19:57 scripts/
drwxr-xr-x 5 root root 4096 2008-06-27 20:03 ServerCA/
drwxr-xr-x 5 root root 4096 2008-06-27 20:04 UserCA/

Im Anschluss erzeuge mein Server Zertifikat mit mk_cert_server z.B. für einen Imap-Server (analog mit mk_cert_user für User):

scx:~/ca# ./scripts/mk_cert_server
~/ca ~/ca

Server-Cert Name: imap
--------
imapKey.pem & imapReq.pem ...

Generating a 1024 bit RSA private key
....................++++++
......................................++++++
unable to write 'random state'
writing new private key to 'imapKey.pem'
Enter PEM pass phrase: >>imapCA-Passwort<<
Verifying - Enter PEM pass phrase: >>imapCA-Passwort<<
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [DE]:
State or Province Name (full name) [Bayern]:
Locality Name (eg, city) [Nuernberg]:
Organization Name (eg, company) [OrganisationName]:
Organizational Unit Name (eg, section or website) [OrganisationUnit]:
Common Name (SERVER / USER name) []:imap.company.de
Email Address (eg, YOUR email) [webmaster@company.de]:

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
company.de []:

Passwort aus imapKey.pem entfernen [y] ?
Enter pass phrase: >>imapCA-Passwort<<
writing RSA key
====================
imapCert.pem  ...
====================
Using configuration from openssl.cnf
Enter pass phrase for /root/ca/ServerCA/private/SCAkey.pem: >>ServerCA-Password<<
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
countryName           :PRINTABLE:'DE'
stateOrProvinceName   :PRINTABLE:'Bayern'
localityName          :PRINTABLE:'Nuernberg'
organizationName      :PRINTABLE:'OrganisationName'
organizationalUnitName:PRINTABLE:'OrganisationUnit'
commonName            :PRINTABLE:'imap.company.de'
emailAddress          :IA5STRING:'webmaster@company.de'
Certificate is to be certified until Jun 26 18:20:44 2013 GMT (1825 days)
Sign the certificate? [y/n]:y


1 out of 1 certificate requests certified, commit? [y/n]y
Write out database with 1 new entries
Data Base Updated
unable to write 'random state'
----------------------------------------------

certs:
total 28
-rw-r--r-- 1 root root 1911 2008-06-27 20:03 00.pem
-rw-r--r-- 1 root root 5643 2008-06-27 20:04 01.pem
-rw-r--r-- 1 root root 5641 2008-06-27 20:04 02.pem
lrwxrwxrwx 1 root root    6 2008-06-27 20:04 47efd334.0 -> 02.pem
lrwxrwxrwx 1 root root    6 2008-06-27 20:04 9c05fe89.0 -> 00.pem
lrwxrwxrwx 1 root root    6 2008-06-27 20:04 b99e5d4b.0 -> 01.pem
-rw------- 1 root root 4909 2008-06-27 20:20 imapCert.pem

private:
total 8
-rw------- 1 root root 887 2008-06-27 20:20 imap-Key.pem
-rw------- 1 root root 963 2008-06-27 20:20 imapKey.pem

~/ca
scx:~/ca#

Ein Test (nach der Installation des Zertifikates auf dem host imap) sieht dann so aus:

scx:/root/ca# openssl s_client -CApath /root/ca/certs -port 993 -host imap > /tmp/foo
...