Just Shake Them Together: Imitation-Resistant Secure Pairing of Smart Devices via Shaking

Algorithm 4

Mutual authentication and key extraction.

Require: 1) The bit series: , its length is . 2) The number of bits required in key generation: . 3) The threshold for mutual authentication: .

Ensure: The extracted key: .

1: Initialize a sliding window of size along the bit series . Set the index .

2: whiledo

3: Obtain the bit string inside window as , generate a random number , and call HMAC() to obtain a bit string .

4: Forward the window along the bit series with 1 bit.

5: Send the series with length to the peer device via broadcasting.

6: Receive the series with length from the peer device.

7: Compute the edit distance between and , compute , find the matching components of and from and accordingly.

8: ifthen

9: Authenticate the peer device as an authorized device.

10: Find the first matching components of and from and , verify the consistency between the locally generated bits with the bits from the peer device based on the following matching results.

11: Compute the edit distance between and , find the matching bits and divide them into multiple blocks, calculate the hash code for each block , i.e., =HMAC(), assemble them as a bit series, and extract the first bits into the key .