Digital voice encryption block

GNU Radio
1

Hi all,

I want to simulate a voice transmission system in GNURadio Companion
(GRC) before I build a real one. My system configuration is as follows.

TX:
mic → encoder → encryption → modulator → RF

Rx:
speaker ← decoder ← decryption ← demodulator ← RF

I have succeed in simulating the above configuration in Ubuntu 12.04 LTS
machinebut without encryption/decryption blocks.

I want to encrypt my digital voice using AES (128/192/256, either one)
algorithm, but so far, I couldn’t find suitable blocks for my purpose.

I know that GNURadio will synthesize a python code when you compile your
blocks configuration in GRC. On the other hand, every python dev
installation in Ubuntu will also install PyCrypto lib in your machine,
this library has a ready-to-use function of AES algorithm. Furthermore,
I also know the concept of Out-of-Tree Module (OoTM) of GNURadio.

My questions are:

  1. My first thought is to get data stream of certain block and do
    encryption process with PyCrypto (not in the OoTM, but directly in
    synthesized python code) then put them back to the next block. Would it
    be possible and how to achieve this?

  2. Do GNURadio has a ready-to-use GRC blocks or OoTM of digital
    encryption algorithm (not scrambler)? and how do I get it (a tutorial
    would be fine)?
    So far, I can not found the block either in GRC or https://www.cgran.org

  3. Last question may be off topic a bit. Is it common to use AES
    algorithm to encrypt voice data, or is there any common encryption
    method (preferably could be implemented in GRC)?

Thank you for your time and willingness to answer these questions

Regards
tc

2

Hi all,

I want to simulate a voice transmission system in GNURadio Companion
(GRC) before I build a real one. My system configuration is as follows.

TX:
mic → encoder → encryption → modulator → RF

Rx:
speaker ← decoder ← decryption ← demodulator ← RF

I have succeed in simulating the above configuration in Ubuntu 12.04 LTS
machine but without encryption/decryption blocks.

I want to encrypt my digital voice using AES (128/192/256, either one)
algorithm, but so far, I couldn’t find suitable blocks for my purpose.

I know that GNURadio will synthesize a python code when you compile your
blocks configuration in GRC. On the other hand, every python dev
installation in Ubuntu will also install PyCrypto lib in your machine,
this library has a ready-to-use function of AES algorithm. Furthermore,
I also know the concept of Out-of-Tree Module (OoTM) of GNURadio.

My questions are:

  1. My first thought is to get data stream of certain block and do
    encryption process with PyCrypto (not in the OoTM, but directly in
    synthesized python code)
    then put them back to the next block. Would it be possible and how to
    achieve this?

  2. Do GNURadio has a ready-to-use GRC blocks or OoTM of digital
    encryption algorithm (not scrambler)? and how do I get it (a tutorial
    would be fine)?
    So far, I can not found the block either in GRC or https://www.cgran.org

  3. Last question may be off topic a bit. Is it common to use AES
    algorithm to encrypt voice data, or is there any common encryption
    method (preferably could be implemented in GRC)?

Thank you for your time and willingness to answer these questions

Regards
tc

3

Hi all,

I want to simulate a voice transmission system in GNURadio Companion
(GRC) before I build a real one. My system configuration is as follows.

TX:
mic → encoder → encryption → modulator → RF

Rx:
speaker ← decoder ← decryption ← demodulator ← RF

I have succeed in simulating the above configuration in Ubuntu 12.04 LTS
machine but without encryption/decryption blocks.

I want to encrypt my digital voice using AES (128/192/256, either one)
algorithm, but so far, I couldn’t find suitable blocks for my purpose.

I know that GNURadio will synthesize a python code when you compile your
blocks configuration in GRC. On the other hand, every python dev
installation in Ubuntu will also install PyCrypto lib in your machine,
this library has a ready-to-use function of AES algorithm. Furthermore,
I also know the concept of Out-of-Tree Module (OoTM) of GNURadio.

My questions are:

  1. My first thought is to get data stream of certain block and do
    encryption process with PyCrypto (not in the OoTM, but directly in
    synthesized
    python code)
    then put them back to the next block. Would it be possible and how to
    achieve this?

  2. Do GNURadio has a ready-to-use GRC blocks or OoTM of digital
    encryption algorithm (not scrambler)? and how do I get it (a tutorial
    would be fine)?
    So far, I can not found the block either in GRC or https://www.cgran.org

  3. Last question may be off topic a bit. Is it common to use AES
    algorithm to encrypt voice data, or is there any common encryption
    method (preferably could be implemented in GRC)?

Thank you for your time and willingness to answer these questions

Regards
tc

4

Question 3: AES is indeed a common system for voice encryption, widely
used
for example in US police / public safety radios (APCO25 standard). Older
systems used often DES, but not with a neat linear predictive voice
codec,
but just a CVSD digitizer, DES box and FSK radio link (Motorola
SECURENET).
Then there are lots of proprietary / closed source encryption systems,
some
really weak with 32 bit keys, more aimed against the casual listener /
scanner kid, but not providing real security against an advanced
eavesdropping attack.

Ralph.

From: discuss-gnuradio-bounces+ralph=removed_email_address@domain.invalid
[mailto:discuss-gnuradio-bounces+ralph=removed_email_address@domain.invalid] On Behalf Of
Tigor Christian
Sent: Thursday, April 17, 2014 3:50 PM
To: [email protected]
Subject: [Discuss-gnuradio] Digital voice encryption block

Hi all,

I want to simulate a voice transmission system in GNURadio Companion
(GRC)
before I build a real one. My system configuration is as follows.

TX:

mic → encoder → encryption → modulator → RF

Rx:

speaker ← decoder ← decryption ← demodulator ← RF

I have succeed in simulating the above configuration in Ubuntu 12.04 LTS
machine but without encryption/decryption blocks.

I want to encrypt my digital voice using AES (128/192/256, either one)
algorithm, but so far, I couldn’t find suitable blocks for my purpose.

I know that GNURadio will synthesize a python code when you compile your
blocks configuration in GRC. On the other hand, every python dev
installation in Ubuntu will also install PyCrypto lib in your machine,
this
library has a ready-to-use function of AES algorithm. Furthermore, I
also
know the concept of Out-of-Tree Module (OoTM) of GNURadio.

My questions are:

  1. My first thought is to get data stream of certain block and do
    encryption
    process with PyCrypto (not in the OoTM, but directly in synthesized
    python
    code) then put them back to the next block. Would it be possible and how
    to
    achieve this?

  2. Do GNURadio has a ready-to-use GRC blocks or OoTM of digital
    encryption
    algorithm (not scrambler)? and how do I get it (a tutorial would be
    fine)?
    So far, I can not found the block either in GRC or https://www.cgran.org
    https://www.cgran.org/

  3. Last question may be off topic a bit. Is it common to use AES
    algorithm
    to encrypt voice data, or is there any common encryption method
    (preferably
    could be implemented in GRC)?

Thank you for your time and willingness to answer these questions

Regards
tc

5

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Hash: SHA1

Also, if using encryption over a wireless link, you’ll need some way
to ensure that damaged data gets resent, or to ensure a damaged block
does not affect the decryptability of following data.

So I think your flowgraphs should read

Mic/Soundcard → low pass → source coding (at least some uLaw or so)

  • → encryption → frame building & channel coding → symbol
    mapping/modulation → pulse shaping → tx system

rx system → freq/time/clock sync (might include deframing) → channel
decoding (equalizing might happen somewhere here) → decryption →
source decode → soundcard

As Sean pointed out, this does not necessarily translate nicely into a
GNU Radio sample flow graph and you might be better of with a
combination of sample flows and message passing.

With encryption, you really really need the channel code, since a
single flipped bit will render your transmission unusable.

Also, I don’t really understand: GRC creates python flow graphs out
of graphical representations. It can generate hier blocks, which are
just flow sub-graphs internally, but it can not generate blocks that
have a work function.

If you’re already at ease with designing oot modules, then using a
python library to encode a block of data seems to be rather trivial,
and I don’t see how that should be possible or easier from withing GRC
:wink:

Greetings,
Marcus

On 17.04.2014 16:37, Ralph A. Schmid, dk5ras wrote:

I have succeed in simulating the above configuration in Ubuntu
Furthermore, I also know the concept of Out-of-Tree Module (OoTM)
encryption algorithm (not scrambler)? and how do I get it (a

mailing list [email protected]
Discuss-gnuradio Info Page

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6

There is no crypto in the main GNU Radio installation. I am not aware of
any public out-of-tree modules that implement crypto. Your best bet
would probably be handling crypto at the data socket layer and pushing
to a GNU Radio PDU-to-tagged-stream or using GR’s message passing
interface to pass encrypted data packet between the upper layer and GR
mod/demod layer. You could use PyCrypto, as you suggested, or libgcrypt
in C/C++. Libgcrypt - GNU Project - Free Software Foundation (FSF)

GNU Radio is best suited for the PHY and basic MAC layers, but of course
this doesn’t preclude wrapping libgcrypt functions into GNU Radio
blocks. I just think it would be more efficient to do crypto at a layer
above the GR mod/demod blocks. You would essentially pass data between
the layers using message queues and message handlers.

Sean

From: discuss-gnuradio-bounces+sean.nowlan=removed_email_address@domain.invalid
[mailto:discuss-gnuradio-bounces+sean.nowlan=removed_email_address@domain.invalid] On
Behalf Of Ralph A. Schmid, dk5ras
Sent: Thursday, April 17, 2014 10:38 AM
To: ‘Tigor Christian’; [email protected]
Subject: Re: [Discuss-gnuradio] Digital voice encryption block

Question 3: AES is indeed a common system for voice encryption, widely
used for example in US police / public safety radios (APCO25 standard).
Older systems used often DES, but not with a neat linear predictive
voice codec, but just a CVSD digitizer, DES box and FSK radio link
(Motorola SECURENET). Then there are lots of proprietary / closed source
encryption systems, some really weak with 32 bit keys, more aimed
against the casual listener / scanner kid, but not providing real
security against an advanced eavesdropping attack.

Ralph.

From:
discuss-gnuradio-bounces+ralph=removed_email_address@domain.invalidmailto:discuss-gnuradio-bounces+ralph=removed_email_address@domain.invalid
[mailto:discuss-gnuradio-bounces+ralph=removed_email_address@domain.invalid] On Behalf Of
Tigor Christian
Sent: Thursday, April 17, 2014 3:50 PM
To: [email protected]mailto:[email protected]
Subject: [Discuss-gnuradio] Digital voice encryption block

Hi all,

I want to simulate a voice transmission system in GNURadio Companion
(GRC) before I build a real one. My system configuration is as follows.

TX:
mic → encoder → encryption → modulator → RF

Rx:
speaker ← decoder ← decryption ← demodulator ← RF

I have succeed in simulating the above configuration in Ubuntu 12.04 LTS
machine but without encryption/decryption blocks.

I want to encrypt my digital voice using AES (128/192/256, either one)
algorithm, but so far, I couldn’t find suitable blocks for my purpose.

I know that GNURadio will synthesize a python code when you compile your
blocks configuration in GRC. On the other hand, every python dev
installation in Ubuntu will also install PyCrypto lib in your machine,
this library has a ready-to-use function of AES algorithm. Furthermore,
I also know the concept of Out-of-Tree Module (OoTM) of GNURadio.

My questions are:

  1. My first thought is to get data stream of certain block and do
    encryption process with PyCrypto (not in the OoTM, but directly in
    synthesized python code) then put them back to the next block. Would it
    be possible and how to achieve this?

  2. Do GNURadio has a ready-to-use GRC blocks or OoTM of digital
    encryption algorithm (not scrambler)? and how do I get it (a tutorial
    would be fine)?
    So far, I can not found the block either in GRC or
    https://www.cgran.orghttps://www.cgran.org/

  3. Last question may be off topic a bit. Is it common to use AES
    algorithm to encrypt voice data, or is there any common encryption
    method (preferably could be implemented in GRC)?

Thank you for your time and willingness to answer these questions

Regards
tc