A computer network (20) including secure nodes (26) and unsecured nodes (28). The secure nodes (26) may communicate private data without compromising security provisions. The secure nodes (26) include a security kernel (36) that implements communication security provisions and a trusted operating system (40) that imposes computer data security provisions. A trusted interface (44) is used to transfer data between the trusted operating system (40) and the security kernel (36). In addition, this interface (44) insures that computer security attributes are compatible with communication security attributes. If incompatibilities are discovered, requested communications are thwarted and audit records for the security linkage violations are recorded.