The present disclosure provides a description of a computer implemented method and system for protecting a software program from attack during runtime. The system comprises a plurality of software blocks for providing desired functions during execution of a software program and a trusted address server having a table for mapping predetermined source tokens to destination tokens. The trusted address server couples each of the plurality of software blocks for receipt of predetermined source tokens from any one of the plurality of software blocks, while returning a mapped destination token from the predetermined destination tokens to said any one of the plurality of software blocks in dependence upon the table for mapping predetermined source tokens to destination tokens.