[ClosedTalk]
Secure Voice
Communication
[ClosedTalk] is incorporated in version 4.20 of the FREE CompuSec® - PC
Security Suite which is designed to protect notebook and desktop PCs
by providing Access Control, Hard Disk Encryption, VPN, File Encryption, and Single Sign On. This free software bundle provides you with robust security features and secure voice communication.
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About [ClosedTalk]
Feature Overview
Why Use [ClosedTalk]?
Secure Registration &
Activation
Security and Privacy
Commitment from
CE-Infosys |
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About [ClosedTalk] |
[ClosedTalk] is a secure VoIP solution to enable internet calls to be made in total privacy by encrypting the voice communications made over the computer networks. It securely transports the voice data through strong encryption technology, advanced key exchange process, and user authentication through digital certificates
(optional). A gatekeeper service is provided to locate communication partners on the private/public network. This secure VoIP solution is provided free for unlimited usage and distribution for both personal and professional use.
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Feature Overview |
Robust security
features are balanced with user-friendly functionalities, including:
- Using the built-in sound system of
the computer, [ClosedTalk] users communicate without the need for
IP telephones. All you need are a sound card, speaker and microphone
functions.
- Secure
registration process requires user to provide their own email address to
initiate a safe registration at the gatekeeper. The email address will
not be stored in the database nor be made known to any third parties.
Your privacy is protected as the Gatekeeper will erase your email
address after sending the unique activation code to your email account.
Using your own email address ensures that only you can activate your
account and nobody else. The Gatekeeper calculates a signature (SHA-1
hash) from your email address which is stored in the database to
identify you. From this signature, nobody can calculate backwards to the
original email address. Please read information
on 'Secure Registration & Activation' for protection of user's confidentiality.
- Caller contacts the other party using the email
address. The email address of the person you want to talk to is hashed
in your computer before it is sent to the gatekeeper. By using this
signature, the Gatekeeper does not know to whom you want to talk. [ClosedTalk]
does not need the old-fashioned telephone numbers. The gatekeeper
locates the other party on the private/public networks and provides the
IP address of the destination to the caller. A direct IP connection is
then established between the two parties.
- Text
Chat facility supports instant messaging communications when callers
are busy on the line. Chat enables users to type messages for the
other party to see on his or her chat window panel.
- Address Book feature helps user to maintain and update contact
details.
- History Log provides records of connected calls and offline parties.
- Ringtone function is customisable to
allow for user personalisation.
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Why Use [ClosedTalk]? |
As a key difference to other
VoIP solutions, the development target of [ClosedTalk] is to protect the
privacy of the talking parties. [ClosedTalk] should be used when you want
to keep your identity and the contents of the talk secret. The advantages of
using [ClosedTalk] are many, including the following user benefits:
- [ClosedTalk] calls are made using
the internet connection which are not chargeable. It is a free VoIP
solution for making free internet calls.
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[ClosedTalk] is unlimited in usage and distribution which makes it
a widely popular VoIP solution for small to large group of users.
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Strong
encryption technology, advanced key exchange process, and user
authentication through digital certificates (optional) are the high-end
security features incorporated into [ClosedTalk] to provide users
with a commercial-quality, secure voice communication. Users do not
pay for the security features, nor for the internet calls.
- There is no need for user's configuration of any system
requirements. Simply download software, install and launch program.
It is an easy-to-install and user-friendly VoIP solution suitable
for home and business use.
- Users start making calls using a
simple process - Click and Dial by entering the other party's
email address or select from Address Book. It is particularly well
suited for use by individuals or employees who may be unfamiliar
with making internet calls for the first time.
- Companies with a larger user base can opt for a private
gatekeeper service to cater for their communication needs. [ClosedTalk] is highly scalable, customisable and easy to maintain as a
business VoIP solution.
- CE-Infosys is committed to continuously develop and enhance user
features in [ClosedTalk] with user support provided. The free
software is a full product with robust security features, therefore
it is not a demo or limited-period trial version.
- User support is available through the free online forum, or
alternatively, business users can opt for a maintenance contract to
provide one-to-one phone, email or onsite assistance for larger
deployments.
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Secure Registration & Activation |
Secure
Registration
[ClosedTalk] identifies
users at a central connection server called the Gatekeeper anonymously. The
Gatekeeper uses the signature (SHA-1 hash code) of the user's email address
for this. During the Registration process, the Gatekeeper will generate an
activation code and send it to your own email address. For this reason, you
are required to provide a VALID and ACTIVE email address. The
activation code is in a second-step resent from your computer to the
Gatekeeper to complete the registration. This is called the Activation
process. By this procedure, we guarantee that nobody else can fake your
identity and later on receive your calls. The hashed value, called
signature, cannot be calculated backward into the email address. Please read information
on 'Security & Privacy' for security implementation of [ClosedTalk]
service.
After receiving the unique activation code, it must be entered in your
computer. This is done through the Activation process which you can complete
once you have received your activation code in the email. Again, the unique
activation code prevents hackers from using your identity and receiving your
calls. Your activation code will be kept for 30 minutes in the Gatekeeper.
After that time, the Gatekeeper will erase your activation code. Any
activation after that time lapse will fail. CE-Infosys guarantees that
during the short moment your email address is known at the Gatekeeper, it
will not used for any other purpose. All the communications between the
Gatekeeper and the your computer during this registration process is
encrypted using an ECC Diffie-Hellman key exchange protocol and an AES 256
bit encryption.

Secure Activation Email may take up to several minutes to arrive,
and some email providers require up to 7 minutes to deliver each email. When
you have received the activation code in your email, you are required to copy and
paste this unique code to the corresponding field in the Service Activation
page before clicking on the ACTIVATE button. This will complete the
activation of [ClosedTalk] service.

Important Note
The activation code
must be entered within 25 minutes (5 minutes buffer) upon the registration.
Otherwise, the Gatekeeper will erase the registration request. In this case,
you must retry the registration. If you have entered an invalid email
address, you will not be able to receive the email containing the
activation code. If this happens, you must click on the RETRY REGISTRATION
button.
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Security and Privacy |
A first Look at How [ClosedTalk]
Works [ClosedTalk] is for secure communication,
therefore a connection to traditional phone systems is not included and not
planned. At the gateway to a traditional phone system, the encrypted data
would have to be decrypted. At that point, the privacy would be lost. Telephone numbers are therefore not needed. The concept of
building a connection using the email address is not new, but is very
useful because remembering an email address is much easier than a long
string of numbers. After the initial registration at the Gatekeeper, the
email address is erased in the Gatekeeper. When a [ClosedTalk] Client is
switched on, a hash value of the email address is sent to the Gatekeeper
together with the IP address of the user. This hashed value cannot be
calculated backward into the email address.
When the caller enters the email address of
the communication partner, [ClosedTalk] calculates the hash value of the
other party and contacts the Gatekeeper. The Gatekeeper will locate the
other party in its table of online clients and provide the IP address of the
destination to the caller. A direct IP connection is then established
between the two parties. The communication to the Gatekeeper is encrypted
using an ECC key generation protocol.

How [ClosedTalk] Secures the Voice
Communication Conversations between the [ClosedTalk]
users are protected using an ECC based Diffie-Hellman Key Generation
Protocol to provide secure session keys and a strong 256 Bit AES encryption
to secure the voice data.

It is known that traditional VoIP
communications can be easily intercepted. Interceptions happen when conversations
fall vulnerable to a third-party’s eavesdropping. Key exchange and voice
content are intercepted, opened for retrieval, and sent back to the
destination almost undetected. This form of interception is commonly known
as the ‘man in the middle’ attack. The diagram shows how a ‘man in the
middle attack works during the session key generation.

Whenever ‘The Bad Guy’ has its own keys
shared with both the unsuspecting communication partners, the automatic
decryption of their voice channel will be very easy and cannot be detected!
[ClosedTalk] exposes such attacks by
calculating a hash value of the generated session key and displays some byte
of it as security code on both the callers’ screens. This security code is
like a checksum of the session keys. If an attack does take place, this
‘checksum’ will be different on both end-points of the communication as seen
on the users’ screens. The users can exchange these codes verbally to verify
with each other. So long as the security codes are identical, there is no
interception of the voice data.

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Commitment from CE-Infosys |
Management Commitment The FREE version of [ClosedTalk] will be
kept free of charge for all of the future. We will sell hardware
enhancements such as [ClosedTalk] Handsets, approved Headsets, [ClosedTalk] USB Handsets, e-Identity Tokens and Smart Cards, digital certificates
as well as private Gatekeepers. A [ClosedTalk] version will be included in
the CompuSec Pocket. CompuSec Pocket with [ClosedTalk] is chargeable.
We also commit that [ClosedTalk] will be
further developed and enhanced with useful functions and features over time. We do not seek to make the most profit in the shortest
time, but we want to win customers over with [ClosedTalk] for those who
needs an independent and trustful security. We guarantee that we will
provide fixes and corrections for the product if problems are found by our
customers or by ourselves. We further promise that we are committed to an
open policy. If security weaknesses should be found, we will inform the
community and provide solutions.
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How to Build Trust? It is not easy for a user
to trust an IT product when private information may be send over Internet.
To help the community to build trust in our product, we at CE-Infosys will
provide technical details of the security implementation. We will explain
how the product works and why you can trust the product. We will publish
White Papers explaining concepts and protocols. We will not publish the
source code in detail due to our commercial obligations for our investments
and skills, but we will answer questions that can help people to understand
the security implementation.
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