A link demand differs from a regular permission demand in that the run-time demands permissions only from the immediate caller and does not perform a full stack walk. Link demands are performed at JIT compilation time and can only be specified declaratively.
Carefully consider before using a link demand because it is easy to introduce security vulnerabilities if you use them. If you do use link demands, consider the following issues:
Performance and link demands
Calling methods with link demands
Mixing class and method level link demands
Interfaces and link demands
Structures and link demands
Virtual methods and link demands
If you protect code with a link demand, it is vulnerable to luring attacks, where malicious ...