DSP security communication designing and implementation

In this paper, we present a security data communication solution to resolve the problem of getting information in a secure way from the remote site in which no computer network is available. For this purpose, a programmed TI (Texas Instrument) product DSP (digital signal processor) TMS320LF2407 EVM is used to develop a compact DSP based device to acquire and store the information at the remote site, and be accessed via PTSN (public telephone switched network) though the serial communication interface module. Data integrity and data authentication are two important issues for secure data transmission. In this paper, two approaches are proposed to improve the security on both issues. First, a new algorithm is developed and implemented to produce a verification message for data authentication. This verification message is encrypted with an one way hash function based on the symmetric block cipher and suited for the 16-bit fix point DSP architecture. Also, this verification message will be changed for each data transmission in order to protect the eavesdroppers stealing this authentication information. Second, beside all the important data are encrypted with block cipher algorithm (Rijndael in this project), message authentication codes (MAC) approach is applied for both data transmission and the synchronous changing of the user information (e.g. user password, security key) at both sites (receiver and sender). In addition, some other functionary modules such as data format setting, timer of auto-connection and multimodem access are also implemented.