In the present work, an encryption/decryption technique, using a new bit-level scrambling and a new diffusion algorithm is presented. The proposed system uses a modified Chua's circuit (MCC) for the chaotic number generation for the first time to our knowledge. In 2006, the MCC, which exhibited a hyper-chaotic behavior for a wide parameter regime due to its double frequency excitation feature was suggested by one of the authors of the present paper. However, it has not been used for secure communication issues. According to present technique, the generated data are transformed to the developed algorithm for the encryption and decryption purposes. Following the encryption procedure, the encrypted colored images are evaluated by a variety of tests including the analyses of secret key size, secret key sensitivity, histogram, correlation, differential attack, information entropy, and noise attack. The results prove that the suggested colored image encryption/decryption technique is satisfactory for the secure communication issues in terms of efficiency and speed.