N.N. Evtikhiev, V.V. Krasnov, S.N. Starikov

One of the most important aspects of digital data transfer applications is confidentiality. Therefore various methods of data encryption are widely used and new ones are actively developing. Currently most of them implemented on electronic devices. There are exist specialized electronic encryption systems and software encryption applications which can be used on different platforms. Common disadvantage of electronic encryption systems (including universal platforms such as PC) is low encryption speed if long keys are used, or low strength if short ones are used. Modern encryption algorithms commonly use keys with lengths measured in hundreds of bits. For example in popular encryption standard AES 256 keys with length of 256 bit are used. Currently optical encryption methods are actively developing. Optical methods allow to achieve high speed, due to high frequency of light waves, and big length of encryption keys, due to possibility of light spatial modulation. Developing optical encryption methods inclined to encryption of real objects images. Significant interest introduces optical encryption of scenes which represent digital information in binary form - two-dimensional arrays of binary digits. This implies more strict conditions on quality of decrypted images. In this case criterion of quality of decrypted images is bit error rate - ratio of quantity of incorrectly decrypted bits to total quantity of encrypted bits. For state of the art systems this parameter usually not higher than 10-9. Therefore, purpose of this paper is development of scheme of system of optical encryption of digital information, determination of principal components of its hardware-based implementation, estimation of its speed, bit error rate and strength. In this paper scheme of system of optical encryption of digital information using spatially-incoherent light was proposed. Considering features of modern components, principal components of its hardware-based implementation were determined. Numerical modeling of proposed system, based on two DLP modulators and high-speed camera, was conducted. According to obtained results, proposed system has high speed - 4.2 Gbit/s, low bit error rate 1,2-10-15 and potentially high strength: equivalent length of binary key - 128 Kbit. Proposed scheme of optical encryption of digital information allows to effectively combine methods of numerical and optical encryption to further enhance strength of the system.