Bluetooth Security System Study with Safer + algorithm

Safer + algorithm
The general structure of encryption and decryption algorithms Safer + shown in the figure-12. In the image input block of plaintext encryption is 16 bytes. Plaintext block is passed through the encryption round r, where r is determined based on the encryption key length chosen, as follows:

- If the key length = 128 bits, then r = 8 rounds
- If the key length = 192 bits, then r = 12 rounds
- If the key length = 256 bits, then r = 16 rounds

Round Two 16-byte subkey used in each round of encryption. Round subkey (K1, K2, ...., K2r) is determined based on the keywords chosen by the user in accordance with the key schedule. At the end of the round subkey dilakkukan round sum K2r +1 with block encryption generated by r rounds. Its provisions bytes 1, 4, 5, 8, 9, 12, 13, and 16 are both aggregated bits-per-bit with Modulo two (operation "exlusive-or"), and bytes 2, 3, 6, 7, 10 , 11, 14, and 15 together with Modulo 256 sum (sum operations bytes). Addition of K2r +1 round subkey is "output transformation" for encryption Safer + which produces 16-byte block of ciphertext.
As shown in the figure-12, the input for decryption is the 16-byte block of ciphertext. Decryption begins with "input transformation" that returns (to undo) output transformation in the encryption process. On the input transformation, round subkey with K2r deducted +1 ciphertext blocks, namely subkey byte 1, 4, 5, 8, 9, 12, 13, and 16 are both aggregated bits-per-bit in the Modulo two (operation "exlusive - or ") with the ciphertext bytes, and bytes 2, 3, 6, 7, 10, 11, 14, and 15 together in Modulo 256 deductible (the sum of operating bytes) with ciphertext bytes. The results of this operation with 16-byte blocks generated by the encryption prior to transformation output. The next block is passed to the decryption round r, round 1 is the inverse of the encryption round r, round 2 is the reverse of encryption round r-1, and r is the reverse cycle of the encryption round 1 which will produce original plaintext block.

Round Encryption 4.1 Safer +
Details of each round of encryption on Safer + algorithm is shown in the picture-13a. The first operation in round i, for 1  i  r, is the sum of the round subkey K2i-1 with 16-byte input round. Its provisions, bytes 1, 4, 5, 8, 9, 12, 13 and 16 are both aggregated bits-per-bit in Modulo two, and bytes 2, 3, 6, 7, 10, 11, 14 and 15 joint - the same sum in Modulo 256. Sixteen bytes of result of this operation further processed by the nonlinear layer. For byte-byte j = 1, 4, 5, 8, 9, 12, 13 and 16 then the value of j in the byte convert to 45x mod 257 (with the convention that if x = 128 then 257 = 45,128 mod 256 is represented by 0 ), another byte is 2, 3, 6, 7, 10, 11, 14 and 15, the value of byte x j is converted to log45 (x) (with the convention that if x = 0 then the result log45 (0) is represented by 128) . Key rotation K2i summed with the results from the nonlinear layer, which is bytes 2, 3, 6, 7, 10, 11, 14 and 15 are both aggregated bits-per-bit in Modulo two, the other bytes 1, 4, 5, 8, 9, 12, 13, and 16 joint-sam summed in Modulo 256. Sixteen bytes of this sum is:

x = [x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, X13, X14, x15, x16]

then the matrix M postmultiplied with Modulo lap 256 to get 16 bytes of output, namely:

y = [y1, y2, y3, y4, y5, y6, Y7, Y8, y9, Y10, y11, y12, y13, y14, y15, y16]

or

y = xm