MITM attacks

[sara]

Hello,

We avoid MITM attacks by using a static passkey. Does it mean that the attacker can decrypt the connection if attacker get the passkey? What I transfer or receive data will be captured by the attacker?

[Petter Myhre]

It depends.

If you use the passkey to identify the device the attacker can pretend to be a trusted device, while it is not.

If not, the attacker can only decrypt an encrypted link if he has the passkey and sniffs the pairing process, only then will he get the keys used to actually encrypt the link.

[Bill Siever]

sara: Encryption with Passkey and Just Works are both very weak if someone is able to collect all the packets when the keys are exchanged (a poor OOB system would be equally weak). If you use bonding, the keys are usually only exchanged on the first connection. As long as the link is always encrypted and the first exchange is done in a secure place (or perhaps, as Anders suggests, with low power transmissions to limit sniffing) there should be pretty good security for most applications.