Encrypting problem while sending data via bluetooth

Encrypting problem while sending data via bluetooth

[Steffen Becker]

Hi,

At first: Sorry for my bad english, it's not my native language. So i 
wrote my problem in german and english.

My problem refers to bluez. I didn't got useful hits on Google, IRC 
didnt help and the only answer i got in a forum was: "there are not many 
people who are familiar with that". So i hope you can help me.

My problem:
After installing the latest bluez, i connected two gentoo-PC's (v2.1.6) 
via two bluetooth-dongles (BT3.0).
PC2:# rfcomm listen 0 1
PC1:# rfcomm connect 0 <bluetooth-adress> 1
This works fine.

But now, when i try to send some data:
PC2:# cat /dev/rfcomm0
PC1:# echo "test" > /dev/rfcomm0
it looks like this on the screen of PC2:
"^J^J^J^J^^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^test^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J" 

[and many more rows]

So i think it's an encrypting problem, but i really don't know how to 
solve it!
i opened /etc/bluetooth/network.conf and uncommented
DisableSecurity=true
but that didn't changed my problem.
I also tried
# hciconfig hci0 nosecmgr
but this command didn't work.

So how can i disable the Security for not getting those cryptic symbols 
(^J^J^J^J^...) ? I really hope you can help me.

Best regards,
Steffen Becker

----------------------------------------------------------------------------

Hallo,

ich habe ein Problem beim Umgang mit bluez. Ich habe bereits Google 
benutzt, IRC aufgesucht und in Foren gepostet, aber ich habe keine 
hilfreichen Informationen bekommen. Lediglich die Antwort: "Es gibt 
nicht viele Leute die sich damit auskennen".

Zu meinem Problem:
Ich habe zwei baugleiche Gentoo-Rechner(v2.1.6) mit je einem 
Bluetooth-Dongle(BT3.0) und das neueste bleuz installiert. Diese 
funktionieren soweit wunderbar. Die Verbindungsherstellung klappt ohne 
Probleme:
PC2:# rfcomm listen 0 1
PC1:# rfcomm connect 0 <bluetooth-adress> 1

Wenn ich aber nun über ">" Daten senden will passiert folgendes:
PC2:# cat /dev/rfcomm0
PC1:# echo "test" > /dev/rfcomm0
dann erscheint auf dem Bildschirm von PC2 dieses:
"^J^J^J^J^^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^test^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J" 

[und viele weitere solcher Zeilen]

Ich vermute, dass es sich um ein Verschlüsselungsproblem handelt.
Dazu habe ich die /etc/bluetooth/network.conf geöffnet und folgende 
Zeile gesetzt (welche standardmäßig auskommentiert war):
DisableSecurity=true
Das hat leider nichts geändert.
Ich habe auch versucht mit dem Befehl
# hciconfig hci0 nosecmgr
die Sicherheit zu deaktivieren, aber bei diesem Befehl ist gar nichts 
passiert, da ich hier auch nicht herausgefunden habe wie die genaue 
Syntax lautet.

Ich hoffe, Sie können mir hierbei helfen. Ist das Erscheinen der 
kryptischen Zeichen (^J^J^J^J^...) wirklich auf eine 
Verschlüsselungseinstellung zurückzuführen? Und wenn ja, wie kanndagegen 
vorgehen?

Mit freundlichen Grüßen,
Steffen Becker

Re: Encrypting problem while sending data via bluetooth

[Marcel Holtmann]

Hi Steffan,

> At first: Sorry for my bad english, it's not my native language. So i 
> wrote my problem in german and english.
> 
> My problem refers to bluez. I didn't got useful hits on Google, IRC 
> didnt help and the only answer i got in a forum was: "there are not many 
> people who are familiar with that". So i hope you can help me.
> 
> My problem:
> After installing the latest bluez, i connected two gentoo-PC's (v2.1.6) 
> via two bluetooth-dongles (BT3.0).
> PC2:# rfcomm listen 0 1
> PC1:# rfcomm connect 0 <bluetooth-adress> 1
> This works fine.
> 
> But now, when i try to send some data:
> PC2:# cat /dev/rfcomm0
> PC1:# echo "test" > /dev/rfcomm0
> it looks like this on the screen of PC2:
> "^J^J^J^J^^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^test^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J" 

it has nothing to do with encryption. These are TTY terminal settings.
That is why rfcomm tool has a -r (raw TTY mode) switch. And that switch
is documented in manpage.

Regards

Marcel

Re: Encrypting problem while sending data via bluetooth

[Steffen Becker]

Thank you very much, this helped me!
Now everything looks fine on the screen of the "PC2".

But now i got another problem regarding to this:
I use a third PC with the "BPA500" (it's for bluetooth sniffing).
When i use again the command

PC1: # echo "test" > /dev/rfcomm0

then the BPA500 software says:
"100% Payload/CRC Errors"
and it can't go after "start_encrypt_req" (that's the last Opcode in the 
Link Management Protocol).

That's why i still think i have an encryption problem.
But the manpage only shows me how to ENable the encryption.

So i hope somebody can help me a second time.

Regards,
Steffen


Am 14.03.2012 18:49, schrieb Marcel Holtmann:
> Hi Steffan,
>
>> At first: Sorry for my bad english, it's not my native language. So i
>> wrote my problem in german and english.
>>
>> My problem refers to bluez. I didn't got useful hits on Google, IRC
>> didnt help and the only answer i got in a forum was: "there are not many
>> people who are familiar with that". So i hope you can help me.
>>
>> My problem:
>> After installing the latest bluez, i connected two gentoo-PC's (v2.1.6)
>> via two bluetooth-dongles (BT3.0).
>> PC2:# rfcomm listen 0 1
>> PC1:# rfcomm connect 0<bluetooth-adress>  1
>> This works fine.
>>
>> But now, when i try to send some data:
>> PC2:# cat /dev/rfcomm0
>> PC1:# echo "test">  /dev/rfcomm0
>> it looks like this on the screen of PC2:
>> "^J^J^J^J^^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^test^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J^J"
> it has nothing to do with encryption. These are TTY terminal settings.
> That is why rfcomm tool has a -r (raw TTY mode) switch. And that switch
> is documented in manpage.
>
> Regards
>
> Marcel
>
>

RE: Encrypting problem while sending data via bluetooth

[james.steele]

Hi Steffen

> But now i got another problem regarding to this:
> I use a third PC with the "BPA500" (it's for bluetooth sniffing).
> When i use again the command
>
>
> PC1: # echo "test" > /dev/rfcomm0
>
> then the BPA500 software says:
> "100% Payload/CRC Errors"
> and it can't go after "start_encrypt_req" (that's the last Opcode in the Link
> Management Protocol).
>
> That's why i still think i have an encryption problem.
> But the manpage only shows me how to ENable the encryption.
>
> So i hope somebody can help me a second time.

>From what you've said it appears that there is no problem with encryption - after the start_encrypt_req LMP message if the decoder is failing to decode the sniffed data then that is a good sign that encryption is working correctly.

If you want to decode the encrypted sniffed data then you have to configure your sniffing set-up appropriately.  Normally this requires observing the pairing process so that the sniffer can also compute the link key (and therefore encryption key).  If using Bluetooth v2.0 and earlier you may be able to enter the PIN code you are going to use in the sniffing tool prior to performing pairing.  If using Bluetooth v2.1 and later you will need to configure one of the Bluetooth devices to enter "SSP debug mode".

For the latter (Bluetooth v2.1 and later) case, we have a patch that adds the ability to enable/disable SSP debug mode using the hciconfig tool - I'll push it out to the mailing list as soon as possible, as it appears it would be useful for others.

Regards,
James

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RE: Encrypting problem while sending data via bluetooth

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Re: Encrypting problem while sending data via bluetooth

[Andrei Emeltchenko]

Hi James,

On Thu, Mar 15, 2012 at 11:08:35AM +0000, james.steele@accenture.com wrote:
> Hi Steffen
> 
> > But now i got another problem regarding to this:
> > I use a third PC with the "BPA500" (it's for bluetooth sniffing).
> > When i use again the command
> >
> >
> > PC1: # echo "test" > /dev/rfcomm0
> >
> > then the BPA500 software says:
> > "100% Payload/CRC Errors"
> > and it can't go after "start_encrypt_req" (that's the last Opcode in the Link
> > Management Protocol).
> >
> > That's why i still think i have an encryption problem.
> > But the manpage only shows me how to ENable the encryption.
> >
> > So i hope somebody can help me a second time.
> 
> From what you've said it appears that there is no problem with encryption - after the start_encrypt_req LMP message if the decoder is failing to decode the sniffed data then that is a good sign that encryption is working correctly.
> 
> If you want to decode the encrypted sniffed data then you have to configure your sniffing set-up appropriately.  Normally this requires observing the pairing process so that the sniffer can also compute the link key (and therefore encryption key).  If using Bluetooth v2.0 and earlier you may be able to enter the PIN code you are going to use in the sniffing tool prior to performing pairing.  If using Bluetooth v2.1 and later you will need to configure one of the Bluetooth devices to enter "SSP debug mode".
> 
> For the latter (Bluetooth v2.1 and later) case, we have a patch that adds the ability to enable/disable SSP debug mode using the hciconfig tool - I'll push it out to the mailing list as soon as possible, as it appears it would be useful for others.

You can just issue HCI command like:

hcitool cmd 0x06 0x0004 0x01

Best regards 
Andrei Emeltchenko 

Re: Encrypting problem while sending data via bluetooth

[Steffen Becker]

Hi James,

Am 15.03.2012 12:08, schrieb james.steele@accenture.com:
> Hi Steffen
>   If using Bluetooth v2.1 and later you will need to configure one of the Bluetooth devices to enter "SSP debug mode".
>
> For the latter (Bluetooth v2.1 and later) case, we have a patch that adds the ability to enable/disable SSP debug mode using the hciconfig tool - I'll push it out to the mailing list as soon as possible, as it appears it would be useful for others.
>
> Regards,
> James
>
>
Do you know when you will push out that patch to the mailing list? It 
would be nice if it appears within this week.

Regards,
Steffen