-----BEGIN PGP SIGNED MESSAGE----- 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 ;) Greetings, Marcus On 17.04.2014 16:37, Ralph A. Schmid, dk5ras wrote: > 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: [email protected] > [mailto:[email protected]] 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 > > > > > > > > > > > _______________________________________________ Discuss-gnuradio > mailing list [email protected] > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBAgAGBQJTT+1xAAoJEBQ6EdjyzlHtZwEIAJk86sf0TWhP+z976wDd8Oi4 tMk6Nk2rcUMEFP4TopDo4fo0uCH3n6oO9jL+6Wuh2M1gqrpj3jvdfUvPMJRPHVDo LpWzE6V2XIcNbShA/XOp56sf3/OqS+qDAXLD2Wa1xnZIW4cPttJ0bWWNaukjxpUO 5z2M8zkWSy7pIl4eMDIexY6fedzko0ZfO7sw8ynLNmRSA2mNHsJ9qiwrhmVuzqLS a7xgQBkFlTpmOx6t4g254uB0wWakPPcw3Td1GzSr3j5p1/Lk/FskJdM/mLTLbGuw 5CAB2Kl4fBwOy6mPTcNHrF3pDAoPrPqtNSEjFFuvaCytATYo92DeoIc6kYOZHEE= =yCnV -----END PGP SIGNATURE----- _______________________________________________ Discuss-gnuradio mailing list [email protected] https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
