Security for decentralized health information systems.

Health care information systems must reflect at least two basic characteristics of the health care community: the increasing mobility of patients and the personal liability of everyone giving medical treatment. Open distributed information systems bear the potential to reflect these requirements. But the market for open information systems and operating systems hardly provides secure products today. This 'missing link' is approached by the prototype SECURE Talk that provides secure transmission and archiving of files on top of an existing operating system. Its services may be utilized by existing medical applications. SECURE Talk demonstrates secure communication utilizing only standard hardware. Its message is that cryptography (and in particular asymmetric cryptography) is practical for many medical applications even if implemented in software. All mechanisms are software implemented in order to be executable on standard-hardware. One can investigate more or less decentralized forms of public key management and the performance of many different cryptographic mechanisms. That of, e.g. hybrid encryption and decryption (RSA+DES-PCBC) is about 300 kbit/s. That of signing and verifying is approximately the same using RSA with a DES hash function. The internal speed, without disk accesses etc., is about 1.1 Mbit/s. (Apple Quadra 950 (MC 68040, 33 MHz, RAM: 20 MB, 80 ns. Length of RSA modulus is 512 bit).