The aim of this work is to design an algorithm which combines between steganography and cryptography that can hide a text in an image in a way that prevents, as much as possible, any suspicion of the hidden text The proposed system depends upon preparing the image data for the next step (DCT Quantization) through steganographic process and using two levels of security: the RSA algorithm and the digital signature, then storing the image in a JPEG format. In this case, the secret message will be looked as plaintext with digital signature while the cover is a coloured image. Then, the results of the algorithm are submitted to many criteria in order to be evaluated that prove the sufficiency of the algorithm and its activity. Thus, the proposed algorithm for this research can be divided into two main parts: hiding the text of the sender, and extracting it by the receiver. Moreover, part can be divided into many procedures done by the program Delphi 5. Keywords : DCT Transformation, Public...