Frequently Answered Questions regarding Classified Ads
Seems like some things regarding Classified Ads are not immediately
obvious to user, so
- How to set up discussion group internal to a working team?
A group more or less needs to be constructed around a profile, reason
for this is that a profile has list of readers and that means your
team members. Because profiles may be created at will, it may be
handy to create one profile for each group needed, with following steps:
Your team members should after publish delay (may be between 1 second
and ~10 minutes, depending on your publish queue length)
be able to see the profile and add comments
to it ; Comments are visible to every team member and can also carry
binary attachments. If there is need to permanently share files
associated with the team, the team profile needs to be opened in
the machine where it was originally created and list of shared files
- From file-menu create a new profile and assign a unique password
for it ; CA uses only passwords for selecting between user
profiles in single computer.
- Assign a nifty name for the profile, like "Classified ads
testing team", or leave blank. If all
information regarding profile is left blank, the SHA1
fingerprint is the only identifying information regarding
- Make this new profile private. While this is not exactly necessary, not
doing this means that your teams discussions are public and
anyone can comment on anything so your working team actually
is the whole world.
- In profile readers include each team member you have.
Task is easier if you have viewed profile of each team member
to make sure that encryption key associated with the members
profile is in local database and the member is found from
address book of the new private profile as the
search function in profile readers-dialog makes use
of local nicknames in address book.
From new profile send a private message to each team member. Reason
for this is that private profile does not appear in search results,
indexing encrypted data is a bit problematic. As each team member
gets a message from the new profile, they can add the team profile
to their own address books (and also assign trust to it, if there
is any question in the future about which profile is which).
- What are the benefits of not having a central server somewhere?
- Everything works in slow pace, fetching items from DHT is not very snappy. This is internet for the lazy.
- There is no concept of service provider that would require
you to make a contract with if you want to use the system. Here
everybody provides storage and data transfer to everybody else
and there is no central authority to decide who's in and who's out
and with what conditions.
- There is no easy method to cut someone off from network.
- As copying of Classified Ads is free of charge, so is
usage ; there is no owner or organization that would ask for
money or other valuables from installing and using full feature set of
the Classified Ads. Due to nature of LGPL license this situation
is also very unlikely to change in the future so Classified Ads
may very well be regarded as long term viable solution for
public and private messaging needs.
Where are images embedded into documents?
This feature has been working since release 0.08. Size-limit of documents
is still 2MB so really big images may need to be downscaled first.
Why I can't read my private messages using my neighbours computer even if I know my password?
The private encryption key required to open your messages is stored only
in that computer where the profile was originally created. When you
open Classified Ads for the first time, it automatically
generates one profile for you and its private encryption keys remain
in that computer only. This is slightly difficult technical item and
current implementation is that private keys never leave the computer.
Because data storage is variant of DHT and any user may have copies of other users messages, why can't he read messages destined to others?
Generally all messages destined to some limited set of recipients
are encypted using recipients public encryption key. Reader of the message
needs to have copy of the private encryption key in order to open the message
for reading. Under the hood Classified Ads currently is using RSA-2048
for public-key encryption and actual content inside messages is
encrypted using AES-256 algorithm. These encryption methods are currently
difficult to crack for average citizen but things may change in the
future and data items that really for reason or another should
remain private, should not be put into any computer, not even computer
running copy of Classified Ads.
Why I can't access more than one profile even tough I created multiple?
This thing is poorly documented. Profile password is only method of
selecting between profiles. If you have multiple profiles with same
password, the system will only open one of them. To rectify the
situation, first open one profile, change its password to something else,
then open the previously created profile using its password.
There is no easy way to list private profiles in the system. The password
for each must be known.
Note that this system simply has no easy password recovery system. Forget
your word and there is no easy way to access your messages or other private
Why are my private messages not showing up?
Generally they should. At least note that the "private messages" tab
shows only message of the profile that is open. If you have multiple
profiles, you need switch in order to have all messages displayed.
Naturally same applies to profile comments.
Are VoIP calls encrypted from end-to-end?
Yes. Currently (in v0.10) all real-time data like call data is sent
directly between nodes with no 3rd node acting as intermediator and all
this traffic is inside TLS socket.
What are storage limits of distributed database?
Depends on how DB is used. The db api has concept of
collection a little same way as mongodb has collections - records
in same collection may or may not belong together or can be similar
in structure or different. Practically documents going to same
collection are stored in same nodes of distributed hash table network.
By default the number database records in storage per node is 50000
and classified-ads makes several redundant copies of same records
into multiple nodes so in practice programmer could safely store some
50000-10000 records in single collection without fear that they
start falling off the network. If number of records exceeds that,
the application needs to be designed so that it uses multiple
How is consistency ensured in distributed database?
It is not. The distributed database of classified ads is suitable
for applications, that do not require concept of database transaction
or care about ACID properties. When a new database record is stored
(e.g. published in the network) it will get propagated through
nodes in the DHT. If record is published in one node and another
node immediately makes a query that would match the new record but
there is no direct connection between these 2 nodes, it is likely
that the querying node will come up with record as it was before
the publish. Of ACID principles the D is indeed honoured: it is
very difficult to completely erase a database record. It is possible
to publish empty record with same identifier and have it overwrite
previous non-empty record but apart from that, there is no delete
Last modified: Tue Dec 19 22:16:59 EET 2017