Menu
Home
People
Places
Arts
History
Plants & Animals
Science
Life & Culture
Technology
Reference.org
Object-capability model
open-in-new
<p>The object-capability model is a <a href="/facts/Computer_security_model/IAFFooof">computer security model</a>. A <a href="/facts/Capability-based_security/negzSwhS">capability</a> describes a transferable right to perform one (or more) operations on a given object. It can be obtained by the following combination: </p> <ul><li>An unforgeable reference (in the sense of object references or protected pointers) that can be sent in messages.</li> <li>A message that specifies the operation to be performed.</li></ul> <p>The security model relies on not being able to forge references. </p> <ul><li>Objects can interact only by sending messages on references.</li> <li>A reference can be obtained by:</li></ul> <ol><li>Initial conditions: In the initial state of the computational world being described, object A may already have a reference to object B.</li> <li>Parenthood: If A creates B, at that moment A obtains the only reference to the newly created B.</li> <li>Endowment: If A creates B, B is born with that subset of A's references with which A chose to endow it.</li> <li>Introduction: If A has references to both B and C, A can send to B a message containing a reference to C. B can retain that reference for subsequent use.</li></ol> <p>In the object-capability model, <i>all</i> computation is performed following the above rules. </p><p>Advantages that motivate <a href="/facts/Object_(computer_science)/eX99dtAw">object-oriented programming</a>, such as encapsulation or <a href="/facts/Information_hiding/dnSDPMaz">information hiding</a>, <a href="/facts/Modularity_(programming)/sNoqKvRD">modularity</a>, and <a href="/facts/Separation_of_concerns/Tx8jawNT">separation of concerns</a>, correspond to security goals such as <a href="/facts/Principle_of_least_privilege/sqsT4tln">least privilege</a> and <a href="/facts/Privilege_separation/gLMQVMrp">privilege separation</a> in capability-based programming. </p><p>The object-capability model was first proposed by <a href="/facts/Jack_Dennis/MnReKxax">Jack Dennis</a> and Earl C. Van Horn in 1966. </p>