A Novel Three-Layer QR Code Based on Secret Sharing Scheme and Liner Code

Algorithm 4

Extraction Algorithm of the third layer information.

	Input: Shares QR1, QR2, …, QR2^p with size of 3m × 3n, the length l of the secret information, the shared key seed.
	Output: The third level information s.
	Step 1: Construct a pixel matrix block .
	Step 2: Let i = 1, j = 1. i and j represent the rows and columns of the carrier QR code, respectively.
	Step 3: Let , , where “” represents the merger of the matrix.
	Step 4: Let j = j + 3, if j < 3n, go to Step 3. Else, go to Step 5.
	Step 5: Let i = i + 3, if i < 3m, go to Step 3. Else, go to Step 6.
	Step 6: cover and seed are used as input of the wet paper code decoding algorithm to solve the embedded information.
	Step 7: The first l bit is output as the third layer information, and the algorithm ends.