Abstract

Author: dr Mladen Veinovic, dipl.ing.

Institute of Applied Mathematics and Electronics
Belgrade

Title: Problems in protecting communications

Abstract: Encryption refers to hiding information during transmission, thus making this information unintelligible to all but its intended recipient. The messages to be encrypted, known as plaintext, are modified by the encryption/decryption algorithm in a unique way determined by a cryptographic key shared between the parties that wish to communicate in privacy. The output of the encryption process, known as the ciphertext, is then transmitted to the intended recipient. The basic idea behind any encryption technique is that an intruder does not know the cryptographic key, and thus, cannot decrypt the ciphertext and reconstruct the original information. While designing the encryption systems it is necessary to consider the communications systems characteristics, such as bit-rate of information transmission, a number of errors on the communication line, maximum synchronization time, expected number of resynchronizations, as well as the number of messages in time. On the basis of the analysis of these data and on the basis of required transmitted information level secrecy the algorithm complexity is defined, its input cryptological parameters, encryption realization technology and the way of enciphering. Own designed encryption systems are the basis for security of overall information system. Provision of foreign solutions entails all dangers related to low algorithm quality and its verification, insufficient length of cryptographic keys and other parameters, possibility of trap-doors in realization and et al.