To enhance security of the bit-plane decomposition based multimedia encryption methods, this thesis introduces novel multimedia encryption algorithms using binary bit-planes of a source image as security key images. One is TFPBS multimedia encryption algorithm using Truncated PFibonacci bit-plane decomposition and the other is DecomCrypt algorithm using several binary bit-plane decompositions. The users have the flexibility to choose (1) any existing or newly generated image as the source image; (2) any decomposition method for generating the bitplanes; (3) a flexible number of decomposed bitplanes as security key images; (4) any scrambling method for bit-level permutation. Simulations and security analysis are provided to demonstrate the proposed algorithms’ excellent multimedia encryption performance.