Process Flow: Generating An Initial Pairing Key - Blackberry PlayBook Security Technical Overview

Security Technical Overview
The initial key establishment protocol is designed to negotiate so that the tablet and smartphone can use the 521-
bit Random Curve, AES-256, and SHA-256 for application layer encryption and authentication, and SHA-512 for IT
policy authentication.
Related topics
Cryptosystem parameters that the BlackBerry Bridge pairing process uses to generate an initial pairing key, 11

Process flow: Generating an initial pairing key

1. The BlackBerry smartphone sends an initial echo of the value 0xC1F34151520CC9C2 to the BlackBerry PlayBook
tablet to confirm that a Bluetooth connection to the tablet exists and to verify that the smartphone and tablet
both understand the protocol.
2. The tablet receives the initial echo and replies with an echo transmission of the same value.
3. The smartphone receives the echo and replies to the tablet with a request for a list of supported algorithms.
4. The tablet creates a list of all the algorithms and elliptic curves that it supports and sends the list to the
smartphone.
5. The smartphone searches the list for matches with algorithms and elliptic curves that the smartphone supports.
• If a match is not available, the smartphone sends an error to the tablet and stops processing the list.
• If a match exists, the smartphone begins the key establishment process by sending a pairing request using
the selected algorithms, the selected elliptic curve, and a 64-byte seed to the tablet.
6. The tablet verifies the selected algorithms and elliptic curve.
7. The tablet performs the following calculation to select a short-term key (Y):
• Selects random y, 1 < y < r – 1
• Calculates Y = yS
8. The tablet sends Y to the smartphone.
9. The smartphone performs the following calculations to select a short-term key (X):
• Selects random x, 1 < x < r – 1
• Calculates X = xS
• Calculates the initial pairing key (MK) using the following information:
Parameter
K
H1
H2
• Calculates H = H1 + H2
• Calculates MK = SHA-256( H || K )
10. The smartphone sends X to the tablet.
11. The tablet calculates MK using the following information:
Parameter
K
10
Generating an initial pairing key during the BlackBerry Bridge pairing process
Value
xY = xyS
SHA-512 (sent data packets)
SHA-512 (received data packets)
Value
yX = yxS