Posts tagged certificate

openssl: s_client to check certificates
posted on 2016-03-18 13:47:07

In short:

openssl s_client -connect <domain.de>:443
openssl: check privkey, cert request, certificate
posted on 2016-02-26 13:50:50

Here is a one-liner that prompts you to enter the filenames of your private key, your certificate's request and your final certificate:

echo; echo $'\e[32;1m'"cd into keyfolder, enter filenames when prompted."$'\e[0m'; ls -lah; echo; read -p "privkey:  " fn; read -p "certreq:  " csr; read -p "certname: " cert; openssl rsa -in $fn -modulus -noout | openssl md5; openssl req -in $csr -modulus -noout | openssl md5; openssl x509 -in  $cert -modulus -noout | openssl md5'

Only if all hash value results are the same, your files will work. If they differ something is broken and you have to have a more in-depth look.

OpenSSL: Create a TLS certificate
posted on 2015-07-18 01:13:32

This posting is solely about handling certificates, no cryptographic background or deeper technical digging.

background and grey theory

Basically creating a certificate can be done via two ways:

  • create a private key and a certificate from it
  • create a private key, a certificate signing-request out of it, and with another certificate-authority private-key and certificate-authority certificate create an own certificate

The first approach is to be done for CA's (certificate authorities), and their (CA) certificates are shipped with the common browsers.

Website (or whatever type of service uses SSL/TLS) let their domain be secured with an own certificate, which the certificate authority created from a certificate signing request the owner sent them using their private key and certificate.

The user using the browser to access the secured domain gets the ca cert and the site owner's cert, and can check if the site owner's cert can be validated against the root CA cert.

So these are the artifacts in play: (CA = certificate authority, SRV = server owner)

  • CA privkey (CA_PK)
  • CA cert (CA_C)
  • SRV privkey (SRV_PK)
  • SRV CSR (SRV_CSR)
  • SRV cert (SRV_C)

installing them server-side

In this order they are created and installed:

         SRV                                         CA
        -----                                       ----
          |                                          |
          |                                     1. create CA_PK
          |                                     2. create CA_C
          |                                          |
    3. create SRV_PK                                 |
    4. create SRV_CSR                                |
          |                                          |
    5.    |--------------- email SRV_CSR ----------->|
          |                                          |
          |                                     6. create SRV_C
          |                                     (from CA_PK,CA_C,SRV_CSR)
          |                                          |
    7.    |<--------------  email SRV_C  ------------|
          |                                          |
    8. configure server (web,ftp,...)                |
       (to provide CA_C,SRV_PK,SRV_C)                |
          |                                          |

This is all which is needed to set TLS encryption up.

Note: CA_C and SRV_C differ in having the CA flag set to TRUE or not. Besides that, they are the same.

using them client-wise

To keep it simple, clients negotiate the connection with the server, and use the th SRV_C of aforementioned artefacts from the server. The CA_C is already part of the web browser.

practice and its complexities

To prevent some misunderstandings, even more basics:

  • CA's are just companies printing money, as these certificates tend to be very expensive but are not saver than ones you create on your own and validate these against a self-created self-signed one (With you being basically your own CA.). The only difference is, the CA's get their certificates shipped with every browser, whereas you do not get that luxury.
  • CA_PK and SRV_PK do not differ in how they were created.
  • self-signed certificate = no higher-level cert is needed for validation (for CA's)
  • messing up which one is which is the third biggest source of problems revolving around certificates
  • the second biggest problem is the unwieldiness of the tools to handle these things
  • the biggest source of FAIL when dealing with certificates is the amount of different ones being in different formats (single file or container 'containing' several 'files') and encodings (ascii/base64 vs. binary) and simple copy-paste errors when creating some of them

This sounds complexer than it really is. Haha, I know.

You can import the self-created self-signed CA cert into your browser by hand, so you don't get the warning about visiting unsecure sites anymore, but the rest of the world will still get the error. Plus your google ranking for your website should be lower, as far as I can remember.

a script for automating things

When having to have to create certificates from time to time, this may come handy:

openssl genrsa 2048 > ca-key.pem && \
openssl req -new -x509 -nodes -days 3650 -key ca-key.pem -out ca-cert.pem && \
openssl req -newkey rsa:2048 -days 3650 -nodes -keyout server-key.pem -out server-req.pem && \
openssl rsa -in server-key.pem -out server-key.pem && \
openssl x509 -req -in server-req.pem -days 3650 -CA ca-cert.pem -CAkey ca-key.pem -set_serial 01 -out server-cert.pem

For automated generation, the openssl tool is way more nicer than certtool from GnuTLS. For checking contents or creating a .p12 / pkcs #12 container, the latter is better:

# check contents
certtool --certificate-info --infile C.pem

# create .p12
certtool --to-p12 --load-ca-certificate CA_C.pem --load-privkey PK.key --load-certificate C.pem --outfile CONTAINER.p12 --outder

show certificate information

certtool --certificate-info --infile C.pem
Raspberry Pi: Seafile installation from scratch plus WebDAV access
posted on 2015-04-21 21:34:33

the use case

After dropbox cut a program I took part in my free space went down from 25gb to 3gb, I had a reason to get an alternative up and running. iOS apps should work with it, too, as long as the can work via WebDAV.

There are a lot of comparisons of owncloud, pydio, seafile and all the alternatives, but I am somehow suspicious of pydio, owncloud has problems once you start having too many files it seems, so I ended up with a seafile test. The results were great, so a pi was bought and this guide is the result.

what will be covered

Here a rather detailed setup howto is given, to get a seafile install on a brand new raspberry pi. It will contain side info's on the networking stuff. These tend to be not covered in almost all the other guides usually since all this is in general considered 'trivial'. Which just means everybody was to lazy to give hints where that stuff just is NOT trivial, and actual work to explain properly.

Seafile will run with a mysql backend, and with an nginx webserver so I can get some education on it myself, having worked almost only with apaches until now.

However there are no guarantees, as once again, this is partly written just from memory.

prerequisites

You need these items:

  • a raspberry pi (get the latest model and be happy)
  • a case for the rasp, so it won't lie around in the open
  • a micro SD card with 4gb, with an SD card adapter
  • a cardreader (to write the pi's OS onto the micro SD with the SD adapter)
  • an AC adapter for the pi with a micro USB B connector
  • an ethernet cable (just a network cable with rj45 plugs)

And one of these:

  • a HDD/SSD with own power connection
  • or a usb-only HDD/SSD plus an USB hub with own power supply

If you try an external drive without an extra power supply, it won't run. The pi simply cannot provide enough power via its USB ports. You can see this through the red LED. If the voltage drops below 4.6V or something, it will flicker or just turn off.

DynDNS

Also some kind of DynDNS service would be helpful. Since there seemed to be a lot of trouble with the free ones, either spend some money or set up your own.

Since I was bored and have already a DNS server running and have a domain, I chose to roll my own setup. In that way you either run your whole domain via your DNS server (means your DNS is the primary domain server for your domain), or you can try using 'subzone delegation', so your DNS server runs only a subdomain whereas the domain hoster will run your 'main' domain.

On how to do this, get some other tutorials, I covered it here.

setup the system

get the OS

Install the hardware, which should not pose a problem. If it does, seriously get someone with more knowledge on computers to help you!

Get the Raspbian image, which is a debian-based OS for the pi. Download and unzip it.

get the OS onto the SD card

Open one console and enter watch -d -n1 lsblk, then insert the SD card. That way you will know what the device is called on your linux box.

Open another shell window, and then put the raspbian image onto the card:

dd if=/path/to/the/<raspbian-file.iso> of=/dev/sdX

Of course, fix path and device in the line above.

If you want to know how fast the copy process runs, try:

ps aux | grep dd

And search for the process id of the dd process from above. Then do in another shell window:

watch -n5 kill -usr1 <dd-process-id>

That way the copy process stats will be shown in the dd window every five seconds, which is nice since the 3GB image takes some time to copy. But pardon, I disgress.

fix ssh and networking

Once the copying is finished, mount the card and fix ssh. That way you will not need to hook up the pi to a keyboard and monitor (I have no HDMI capable screen here, so ...) but just connect the ethernet cable and be done.

So:

mkdir asdf
sudo mount /dev/sdX asdf
cd asdf
vim etc/network/interfaces

then either hand the eth0 interface a DHCP configuration (which is stupid), ar just give it a fixed ip.

If your home network is set to the 192.168.0.0/24 net, try configuring this:
If your network is 192.168.178.0/24 or 10.0.0.0/24, fix the ip in the following examples.

allow-hotplug eth0
iface eth0 inet static
    address 192.168.0.254
    netmask 255.255.255.0
    gateway 192.168.0.1
    network 192.168.0.0
    broadcast 192.168.0.255
    dns-nameservers 192.168.0.1

If you cannot use vim, try the damned nano or whatever editor you fancy.

Also these might be a good idea:

echo pi > etc/hostname

and

vim etc/resolv.conf

where you'd enter this line:

nameserver 192.168.0.1

Save and quit.

vim etc/ssh/sshd_config

and make sure there is this:

PermitRootLogin yes

If it were PermitRootLogin without-password, you'd not be able to connect. Save, close.

cd 
sudo umount /dev/sdX

And you can pull the SD card out and put it into the pi.

Hook up your pi to the network via network cable to your home router.

Try ping 192.168.0.254 and see if something answers after the pie has booted (which should take no longer than some minutes, I never measured the time.). If it doesn't work, you either have network issues, or misconfigured something above.

If it answers your ping, get a host entry so connecting to the pi is easier: (/etc/hosts entries are basically local DNS records, this will do you no harm.)

echo '192.168.0.254 pi' >> /etc/hosts

and copy your ssh key onto it, so passwordless login will work:

ssh-copy-id root@pi

You could also use ssh-copy-id 192.168.0.254 - it will work the same, but in the further text the pi ip will be referenced by the local dns name 'pi'. Period. Try it:

ssh root@pi

And you should be connected.

disk preparation

For the following it is assumed, that you have plugged in the usb hub/hdd already, partitioned it and created a file system. Choose your tools and filesystem to use, do it and do not forget to mount the disk afterwards.

To get the disk to be permanently included (across reboots), add it to /etc/fstab.

My entry looks like this:

/dev/sdb1       /var/seafile    btrfs   defaults          0       2

(Since the harddisk is /dev/sdb, with a single partition, filesystem btrfs or what you have to specify for mount -t when mounting by hand, default mount -o options, no dump, not root. In case you doubt what disk your harddisk is, try lsblk, the size should tell you which one to use. The last number is actually about the filesystem check: 0=off, 1=first, 2=afterwards. root is set to 1.)

The directory /var/seafile was created by me for later usage via mkdir, so I have a working mountpoint.

To reload /etc/fstab, a mount -a will do. All this was done as the root user.

Sidenote:
lsblk will not show the mountpoints for btrfs volumes, so you have to use mount to check if everthing looks as expected.

actual seafile install

Install will be done with the MySQL Backend, as the installer tells about Problems when using an USB disk (which we do) and SQLite.

get the install files

Head over to the official download section, so you will get the newest install files. Here choose the raspberry package. Intel Stuff, wether 32 or 64 bit, will not work, since the raspberry has an ARM processor. See the output of uname -m if in doubt.

prepare the system

Copy the link location, for wget'ing it later. Lets also create a dedicated user, too, as it is better to run the program without root rights, security-wise.

apt-get install python2.7 python-setuptools python-imaging mysql-server python-mysqldb -y

Remember the mysql root password, you will need it later on.

mkdir /opt/seafile
useradd seafile
chown seafile.seafile /opt/seafile

Also chown the seafile folder for the seafile user else the installer will have troubles:

chown seafile.seafile /var/seafile
chmod 775 /var/seafile

installing

su - seafile
wget https://github.com/haiwen/seafile-rpi/releases/download/v4.1.2/seafile-server_4.1.2_pi.tar.gz
tar xzvf seafile-server_4.1.2_pi.tar.gz
mkdir installed
mv seafile-server_4.1.2_pi.tar.gz installed/
cd seafile-server-4.1.2/

seafile setup

./setup-seafile-mysql.sh

Enter information:

NAME: is just a label
IP / DOMAIN: enter the pi's ip if you use seafile only on LAN / via VPN, or the dynamic dns
CCNET PORT: default on 10001, since there isn't anything running besides
PATH: /var/seafile/seafile-data, since /opt/seafile is on the SD card, and the data should go to the harddisk's mountpoint
SERVER PORTS: defaults, respectively 12001, and 8082
DATABASE INIT: 1, create new tables
MYSQL HOST: default, localhost
MYSQL PORT: default, 3306
MYSQL ROOT PASSWORT: the one you gave to mysql during install
MYSQL USER: seafile
MYSQL SEAFILE PASSWORT: use a new one
DATABASE NAMES: all default

After all this, the configuration is almost done. Basically the server can be started and run:

Since we want to use the services like any other ones usually, we will just link the scripts into /etc/init.d/. The following stuff is again done as root user:

ln /opt/seafile/seafile-server-latest/seafile.sh /etc/init.d/seafile
ln /opt/seafile/seafile-server-latest/seahub.sh /etc/init.d/seahub

I used hard links on purpose, but I cannot remember why I though this was a good idea.

Anyway, now you can do just:

service seafile start
service seahub start

and you will be asked to setup an seafile admin account, this time the one for the web interface, not the DB user.

Just use your email and yet another password, and remember them. You have to use this account for creating new user accounts, libraries, in short everything.

If your webinterface does not work, you might have to (re)start both services, in case you forgot one.

test seahub

Now, going into your browser, and entering the raspberry's local IP plus port 8000 should get you to the login screen. pi:8000 in the addressbar should do btw, when you set up the above mentioned /etc/hosts entry.

With the web login you just created, you should be able to login. :)

Looks promising so far.

open your firewall for external access

When using the service externally, without a VPN connection, don't forget to open port 8000 in your firewall/router. For testing the webgui, this is enough. To actually use seafile, these must be reachable: (copy-paste from the seafile install message)

port of ccnet server:         10001
port of seafile server:       12001
port of seafile fileserver:   8082
port of seahub:               8000

Later we will also open 8080 so WebDAV can be used. And 80 and 443 where the nginx will be listening to, too.

Of course, the services can be run on arbitrary ports. You might as well leave everything on default for the pi, but use different ports in the router forwarding to the actual ones on the pi, for security reasons. If you know what you are doing are bored when reading this, oh well. Just change it to your liking. Everybody else use default ports, makes the setup easier to debug.

security considerations

When using the service from the outside without a VPN or SSH tunnel, your traffic is plaintext. 'Thou shalt use thee TLS encryption!' in that case, but for that you will have to use a proper web server instead of the built-in one that comes with seafile.

Read: apache or nginx.

WebDAV

Since this is not everything which is needed, the WebDAV plugin has to be integrated.

configure webdav

Without a dedicated webserver this is rather easy.

In /opt/seafile/conf/seafdav.conf, set:

enabled = true

Save and close, plus afterwards:

service seafile restart

test webdav

Besides using webdav from the iOS app in question, you can as well us the linux command line to test, via the davfs2 package. Install it on your home computer (if you ran a linux there, else have a look at the official manual). As root do these:

In /etc/davfs2/davfs2.conf set:

use_locks 0

Save, close.

mkdir /mnt/davtest
mount -t davfs -o uid=<your linux system user> http://pi:8080 /mnt/davtest

Then you will be prompted for user credentials, you might just use the Web UI login from above. The one you entered, when you first started the seahub service.

The /mnt/davtest should now contain some more stuff, meaning WebDAV access works.

If in doubt, create a file with i.e. touch testfile in that folder, which you then can see in the web interface.

Now I have to repeat, using this externally means unencrypted data over the wire. Set up a proper webserver with TLS and configure WebDAV there, if you plan on using this setup from the outside of your home LAN without a VPN. That way you can also use proper fastcgi. ;)

a proper webserver - nginx with TLS

Since I need some nginx practice, this one will be used here.

First lets get the certificates up and running:

mkdir /etc/ssl/nginx
cd /etc/ssl/nginx
openssl genrsa 2048 > ca-key.pem
openssl req -new -x509 -nodes -days 3650 -key ca-key.pem -out ca-cert.pem
openssl req -newkey rsa:2048 -days 3650 -nodes -keyout server-key.pem -out server-req.pem
openssl rsa -in server-key.pem -out server-key.pem
openssl x509 -req -in server-req.pem -days 3650 -CA ca-cert.pem -CAkey ca-key.pem -set_serial 01 -out server-cert.pem

When prompted to enter something, do as you like. You could also hit just ENTER all the time until it's finished.

Then lets fix the domains the server is bound to:

In /opt/seafile/ccnet/ccnet.conf:

SERVICE_URL = https://www.yourdomain.com

In /opt/seafile/seahub_settings.py:

FILE_SERVER_ROOT = https://www.yourdomain.com/seafhttp

Now onto the nginx config, you just have to change your domain below. Open /etc/nginx/sites-available/yourdomain.com and change it accordingly, to have http directed to https and a working https:

server {
        listen       80;
        server_name  dyn.sjas.de;

        # force redirect http to https
        rewrite ^ https://$http_host$request_uri? permanent;
}

server {
        listen   443;
        server_name yourdomain.com;

        ssl on;
        ssl_certificate /etc/ssl/nginx/server-cert.pem;
        ssl_certificate_key /etc/ssl/nginx/server-key.pem;
        ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
        ssl_session_timeout 5m;
        ssl_prefer_server_ciphers on;

        proxy_set_header X-Forwarded-For $remote_addr;
        proxy_connect_timeout       300;
        proxy_send_timeout          300;
        proxy_read_timeout          300;
        send_timeout                300;

        location / {
                fastcgi_pass   127.0.0.1:8000;
                fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
                fastcgi_read_timeout 300;

                fastcgi_param  HTTPS            on;
                fastcgi_param  HTTP_SCHEME      https;
                fastcgi_param  PATH_INFO        $fastcgi_script_name;
                fastcgi_param  SERVER_PROTOCOL  $server_protocol;
                fastcgi_param  QUERY_STRING     $query_string;
                fastcgi_param  REQUEST_METHOD   $request_method;
                fastcgi_param  CONTENT_TYPE     $content_type;
                fastcgi_param  CONTENT_LENGTH   $content_length;
                fastcgi_param  SERVER_ADDR      $server_addr;
                fastcgi_param  SERVER_PORT      $server_port;
                fastcgi_param  SERVER_NAME      $server_name;
                fastcgi_param  REMOTE_ADDR      $remote_addr;

                access_log      /var/log/nginx/seahub.access.log;
                error_log       /var/log/nginx/seahub.error.log;
        }

        location /seafhttp {
                rewrite ^/seafhttp(.*)$ $1 break;
                proxy_pass http://127.0.0.1:8082;
                client_max_body_size 0;
                proxy_connect_timeout  36000s;
                proxy_read_timeout  36000s;
        }

        location /media {
                root /opt/seafile/seafile-server-latest/seahub;
        }
}

Now just create a proper link for sites-enabled and restart nginx:

ln -s /etc/nginx/sites-available/yourdomain.com /etc/nginx/sites-enabled/yourdomain.com
service nginx restart

From the browser you should be able to test things now, https://pi.

automatically start everything

Let us make them known as services to be run on startup. This should be not too hard, but turned out to be a hairy problem.

Just using update-rc.d on the already present files won't work. seahub will start, but seafile will not.

Just putting service seafile start; service seahub start into /etc/rc.local will not work either. That way seafile will start, but seahub will not. Oh my.

Also, seahub tries to find seafile. (... ... ...)

Long story short: Open /etc/init.d/seafile and comment out in about line 150 the "warning_if_seafile_not_running" function:

function before_start() {
    check_python_executable;
    validate_ccnet_conf_dir;
    read_seafile_data_dir;

    #warning_if_seafile_not_running;

That way the check is turned off, and seahub will come up. I honestly have no idea where the problem lies, but its related to no proper startscripts being provided.

In the official manual there does exist a skeleton that you can adapt... Sadly that stuff over there is pretty outdated. Also I simply chose not to put up with it, as it will just wrap the scripts we are currently using.

By now this article is finished, and you should have a raspberry with a working seafile+webdav install.

offtopic

For fun and educational purposes, some words on initialization scripts, through a very pointy little anecdote:

Wrapping scripts with another script will cause endless headaches when things go haywire.

On a legacy system of rather complex web application with borked initscripts three really great people could not find the error over the course of like 1,5 years, and not for the lack of trying. File encodings, no proper initscripts, a subcontractor playing dumb (and not really having a clue, developers just ain't sysadmins, restarting via 'their' scripts did work, after all), all for a medium-sized clustered (but partly dysfunctional, of course) production system with harsh uptime requirements. To further worsen everything, several people on customer side had nagios notifications for EVERY SINGLE SERVICE, which got checked every 5 minutes, each. You could not count the SMS arriving, when a host went down. Even rebooting a service could cause a MESS, which did of course not help for locating the error. The initscripts (several application instances on each of the machines running) wrapping scripts which wrapped a script which wrapped scripts. Encoding was set in several applications, the system, also on boot time within grub. You name it, a puzzle in a puzzle in a puzzle in a puzzle.

I love bash, but debugging bash environments from scripts referencing each other is something you might have to do, when you happen to be in hell where you have to burn for your sins. At least that is how I imagine it.

Final result somewhere was a forgotten - after a su. Once I found it, my day was over. Will never forget this moment I found the cause, even if get a hundred years old. WRITE PROPER INITSCRIPTS, PEOPLE!

TODO

On the TODO list for this system could be:

  • logrotate and proper logging, since these are written in /opt/seafile/logs on the SD card, which is bad
  • a ramdisk for the /tmp folder
  • a custom fail2ban setup using the seafile configs

But for now, this post is finished.

To the brave soul reading this:
I hope you did like this little write up.

OpenSSL Ciphers
posted on 2014-12-10 18:00:06

This will show you the currently availably secure ciphers:

openssl ciphers 'HIGH:MEDIUM:!MD5:!RC4:!aNULL:!eNULL:!EXPORT:!SEED:!PSK' | sed 's/:/\n/g'

The sed afterwards is just so you will have the output with one cipher per line.

The part after 'ciphers' and before the pipe is what you actually have to put into your apache config.

Certificates, OpenSSL in depth and GnuTLS
posted on 2014-07-10 14:37:52

This post should give an overview on the most used OpenSSL commands, and how SSL/TLS/X.509 in general works.

EDIT:
Since this post was written a long time ago, it might get revisited in the future. But this will be a major overhaul, so this will not happen in the near future either.

But there will come some ascii art on a schematic PKI in general, the section about the filenames will get cleaned up as well as the openssl section.

post vocabulary and some notes

The most used terms are abbreviated in the following.

PK = Private Key
C = Certificate
CSR = Certificate Signing Request
CA = Certificate Authority

Usually this seems way harder than it is in reality, once you get the hang of it. Hardest part is to understand which file belonging to which server is needed for the current step.

Certificates...

Some more abbreviations first:

SSL : Secure Sockets Layer
TLS : Transport Layer Security
X.509 : Public Key Infrastructure (PKI) and Priviledge Management Infrastructure (PMI) standard by the "International Telecommunication Union Telecommunication Standardization Sector" (ITU-T).

SSL and its successor TLS, which includes SSL, are protocols for encrypting internet communication. The C infrastructure setup is defined in the X.509 standard. That is why these acronyms are popping up in any discussion about this topic.

On a sidenote, a more general equation:

HTTPS = HTTP + SSL/TLS + TCP

Since this post is focused on usability, the techniques in question that are used in a PKI or PMI are of no concern here.

The C chain looks usually like this: (intermeadiates can, but need not exist)

  1. Root C
  2. Intermediate C
  3. C

The last C is the one issued by the CA where you subitted your CSR to.

Only if all C's are present and used correctly, SSL checking tools (See here or here.) will tell you your C's are set up accordingly.

File types

There exist a bunch of file types, you have to be able to differentiate.

file types

.key : private key file (PK), but that's just a convention
.csr : certificate signing request (CSR)
.crt : certificate (C)
.cer : certificate (C), Microsoft used this naming scheme earlier

For .pem and .der files, see next section.

PK.key, CSR.csr, C.crt are kind of placeholders for your actual filenames in the following sections. A good naming scheme would be subdomain_domain_tld-year, without dots. Dots happen to either not work or cause other problems. Appending the year your C was issued helps with distinguishing in case you renew a certain certificate.

containers and encodings

Containers are used for grouping together C's (and) into a single file.

.pem: ascii / base64 encoded container
.der: container in binary format

The extension hints at the encoding being used, for the container. A container usually consists of the set of all C's (the entire trust chain), and can optionally also contain the PK.

All the files from the section before can be in PEM or DER format, IIRC!

For more information on the Distinguished Encoding Rules (DER) or the Privacy-enhanced Electronic Mail (PEM), just click these links.

OPENSSL

PK / CSR generation

For usage with Certificate Authorities (CA's)

Generate a PK and a CSR:

openssl req -out CSR.csr -new -newkey rsa:2048 -nodes -keyout PK.key

If you already have an existing PK and just need a CSR:

openssl req -out CSR.csr -key PK.key -new

Create a new CSR for an existing C:

openssl x509 -x509toreq -in C.crt -out CSR.csr -signkey PK.key

Complete self-signed certificate

Generation of a self-signed (ss) C, based on a newly generated PK with a term of validity of one year (365 days):

openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout PK.key -out C.crt

ss-C's for https are still better than traffic over plain http, but for private websites for example, StartSSL Certificates provide C's for free. Free as in 'no money needed'.

convert PEM to DER

openssl x509 -in C.crt -outform der -out C.der

convert DER to PEM

openssl x509 -in C.crt -inform der -outform pem -out C.pem

viewing PEM encoded files containing a C

For debugging reasons, this might actually be the most used command.

openssl x509 -in C.pem -text -noout
openssl x509 -in C.crt -text -noout
openssl x509 -in C.cer -text -noout

This will not work on a single PK file.

GNUTLS

Get it:

apt-get install gnutls-bin -y

Use:

certtool

Instead of the openssl tool suite, this is actually self-explanatory.

Examples

In the following, keyfiles are called .key extension-wise, but that is just a name differentiation. They are in reality just .pem files, too, but with this practice files are easier to differentiate.

generate PK's (private keys)

certtool --generate-privkey --outfile PK.key --rsa

Use --dsa or --ecc flags if you want to change the used cryptosystem.

generate CSR's (certificate signing requests)

certtool --generate-request --load-privkey PK.key --outfile CSR.pem

generate C (certificate) from CSR (certificate signing request)

Usually this is a CA_C.pem, a CA certificate.

certtool --generate-certificate --load-ca-privkey CA_PK.key --load-ca-certificate CA_C.pem --load-request CSR.pem --outfile C.pem

generate C (certificate) from PK (private key), lacking a CSR

certtool --generate-certificate --load-ca-privkey CA_PK.key --load-ca-certificate CA_C.pem --load-privkey PK.key --outfile C.pem

generate a self-signed C (certificate), the fast way

certtool --generate-privkey --outfile CA_PK.key --rsa
certtool --generate-self-signed --load-privkey CA_PK.key --outfile CA_C.pem

Here's a one-liner to copy-paste:

certtool --generate-privkey --outfile CA_PK.key --rsa && certtool --generate-self-signed --load-privkey CA_PK.key --outfile CA_C.pem

create a .p12 / pkcs #12 container file

A .p12 file includes all three part usually needed on the server side:

  • CA certificate

  • server PK

  • server C

    certtool --to-p12 --load-ca-certificate CA_C.pem --load-privkey PK.key --load-certificate C.pem --outfile CONTAINER.p12 --outder

show certificate information

certtool --certificate-info --infile C.pem
Certificate content viewed with OpenSSL
posted on 2014-07-07 11:27:04

To show the contents of a ssl/tls certificate with openssl, do:

openssl x509 -in C.crt -text -noout

where C.crt is the name of your actual certificate. Should work for .pem, .cer and .key files as well.

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