System.Security.Policy.Evidence Class

Summary

Defines the set of information that constitutes input to security policy decisions. This class cannot be inherited.

C# Syntax:

[Serializable] public sealed class Evidence : ICollection, IEnumerable

Common forms of evidence include signatures and location of origin of code, but can potentially be anything. Objects of any type that are recognized by security policy represent evidence.

Security policy is composed of code groups; a particular assembly (the basic unit of code for granting security permissions) is a member of a code group if it satisfies the code group's membership condition. Evidence is the set of inputs to policy that membership conditions use to determine to which code groups an assembly belongs.

The Evidence class is a collection (see ICollection) that holds a set of objects that represent evidence. This class holds two sets that correspond to the source of the evidence: host evidence and assembly evidence.

Policy can get evidence from two different sources when evaluating permissions for code.

• Host evidence is provided by the host, and can only be provided by hosts that have been granted the SecurityPermissionFlag.ControlEvidence permission. Typically, this is evidence of the origin of the code and digital signatures on the assembly. Evidence about origin typically includes Url, Site, and Zone evidence. Signatures refer to software publisher (AuthentiCode X.509v3 signature) and strong name identities. Both kinds of digital signature-based identity are built into the assembly, but must be validated and passed to policy by the host; when loaded, the security system verifies the signature. The system then creates the appropriate evidence and passes it to policy only if the corresponding signature is valid.
• Assembly evidence is part of the assembly itself. Developers or administrators can attach custom evidence to the assembly to extend the set of evidence for policy. Assembly evidence can only be added at the time of assembly generation, which occurs before the assembly is signed. The default policy of the security system ignores assembly-provided evidence, but policy can be extended to accept it.

System.Security.Policy Namespace

System.Security.Policy.Evidence Member List:

Public Constructors

ctor #1	Overloaded: .ctor() Default constructor. This constructor is called by derived class constructors to initialize state in this type. Initializes a new empty instance of the Evidence class.
ctor #2	Overloaded: .ctor(Evidence evidence) Initializes a new instance of the Evidence class from a shallow copy of an existing one.
ctor #3	Overloaded: .ctor(object[] hostEvidence, object[] assemblyEvidence) Initializes a new instance of the Evidence class from multiple sets of host and assembly evidence.

Public Properties

Count	Read-only Gets the number of evidence objects in the evidence set.
IsReadOnly	Read-only Gets a value indicating whether the evidence set is read-only.
IsSynchronized	Read-only Gets a value indicating whether the evidence set is thread-safe.
Locked	Read-write Gets or sets a value indicating whether the evidence is locked.
SyncRoot	Read-only Gets the synchronization root.

Public Methods

AddAssembly	Adds the specified assembly evidence to the evidence set.
AddHost	Adds the specified evidence supplied by the host to the evidence set.
CopyTo	Copies evidence objects to an Array.
Equals (inherited from System.Object)	See base class member description: System.Object.Equals Derived from System.Object, the primary base class for all objects.
GetAssemblyEnumerator	Enumerates evidence provided by the assembly.
GetEnumerator	Enumerates all evidence in the set, both that provided by the host and that provided by the assembly.
GetHashCode (inherited from System.Object)	See base class member description: System.Object.GetHashCode Derived from System.Object, the primary base class for all objects.
GetHostEnumerator	Enumerates evidence supplied by the host.
GetType (inherited from System.Object)	See base class member description: System.Object.GetType Derived from System.Object, the primary base class for all objects.
Merge	Merges the specified evidence set into the current evidence set.
ToString (inherited from System.Object)	See base class member description: System.Object.ToString Derived from System.Object, the primary base class for all objects.

Protected Methods

Finalize (inherited from System.Object)	See base class member description: System.Object.Finalize Derived from System.Object, the primary base class for all objects.
MemberwiseClone (inherited from System.Object)	See base class member description: System.Object.MemberwiseClone Derived from System.Object, the primary base class for all objects.

Hierarchy:

• System.Object
• System.Security.Policy.Evidence

System.Security.Policy.Evidence Member Details

Summary

Initializes a new empty instance of the Evidence class.

Default constructor. This constructor is called by derived class constructors to initialize state in this type.

C# Syntax:

public Evidence();

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Summary

Initializes a new instance of the Evidence class from a shallow copy of an existing one.

C# Syntax:

public Evidence(Evidence(    Evidence evidence );

evidence

The Evidence instance from which to create the new instance. This instance is not deep copied.

Exceptions

Exception Type	Condition
ArgumentException	The evidence parameter is not a valid instance of Evidence.

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Summary

Initializes a new instance of the Evidence class from multiple sets of host and assembly evidence.

C# Syntax:

public Evidence(object[] hostEvidence, object[] assemblyEvidence(    object[] hostEvidence,    object[] assemblyEvidence );

hostEvidence

The host evidence from which to create the new instance.

assemblyEvidence

The assembly evidence from which to create the new instance.

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Summary

Gets the number of evidence objects in the evidence set.

C# Syntax:

public int Count {get;}

Implements:

ICollection.Count

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Summary

Gets a value indicating whether the evidence set is read-only.

C# Syntax:

public bool IsReadOnly {get;}

Application code does not normally use this property.

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Summary

Gets a value indicating whether the evidence set is thread-safe.

C# Syntax:

public bool IsSynchronized {get;}

Implements:

ICollection.IsSynchronized

Application code does not normally use this property.

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Summary

Gets or sets a value indicating whether the evidence is locked.

C# Syntax:

public bool Locked {get; set;}

SecurityPermission for the ability to set this property. Associated enumeration: SecurityPermissionFlag.ControlEvidence

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Summary

Gets the synchronization root.

C# Syntax:

public object SyncRoot {get;}

Implements:

ICollection.SyncRoot

This property is not normally used by application code.

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Summary

Adds the specified assembly evidence to the evidence set.

C# Syntax:

public void AddAssembly(    object id );

id

Any evidence object.

Use this method for evidence derived from the assembly.

Note This method does not perform a check to prevent adding duplicate types of evidence. Many assembly evidence objects can exist at the same time.

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Summary

Adds the specified evidence supplied by the host to the evidence set.

C# Syntax:

public void AddHost(    object id );

id

Any evidence object.

Exceptions

Exception Type	Condition
SecurityException	Evidence.Locked is true and the code that calls this method does not have SecurityPermissionFlag.ControlEvidence.

Use this method for evidence supplied by the host.

Note This method does not perform a check to prevent adding duplicate types of evidence. Many host evidence objects can exist at the same time.

SecurityPermission for the ability to manipulate evidence when Evidence.Locked is true. Associated enumeration: SecurityPermissionFlag.ControlEvidence

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Summary

Copies evidence objects to an Array.

C# Syntax:

public void CopyTo(    Array array,    int index );

array

The target array to which to copy evidence objects.

index

The zero-based position in the array to which to begin copying evidence objects.

Implements:

ICollection.CopyTo

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Inherited
See base class member description: System.Object.Equals

C# Syntax:

public virtual bool Equals(    object obj );

For more information on members inherited from System.Object click on the link above.

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Inherited
See base class member description: System.Object.Finalize

C# Syntax:

~Evidence();

For more information on members inherited from System.Object click on the link above.

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Summary

Enumerates evidence provided by the assembly.

C# Syntax:

public IEnumerator GetAssemblyEnumerator();

Return Value:

An enumerator for evidence added by the Evidence.AddAssembly method.

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Summary

Enumerates all evidence in the set, both that provided by the host and that provided by the assembly.

C# Syntax:

public IEnumerator GetEnumerator();

Return Value:

An enumerator for evidence added by both the Evidence.AddHost method and the Evidence.AddAssembly method.

Implements:

IEnumerable.GetEnumerator

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Inherited
See base class member description: System.Object.GetHashCode

C# Syntax:

public virtual int GetHashCode();

For more information on members inherited from System.Object click on the link above.

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Summary

Enumerates evidence supplied by the host.

C# Syntax:

public IEnumerator GetHostEnumerator();

Return Value:

An enumerator for evidence added by the Evidence.AddHost method.

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Inherited
See base class member description: System.Object.GetType

C# Syntax:

public Type GetType();

For more information on members inherited from System.Object click on the link above.

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Inherited
See base class member description: System.Object.MemberwiseClone

C# Syntax:

protected object MemberwiseClone();

For more information on members inherited from System.Object click on the link above.

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Summary

Merges the specified evidence set into the current evidence set.

C# Syntax:

public void Merge(    Evidence evidence );

evidence

The evidence set to be merged into the current evidence set.

Exceptions

Exception Type	Condition
ArgumentException	The evidence parameter is not a valid instance of Evidence.
SecurityException	Evidence.Locked is true, the code that calls this method does not have SecurityPermissionFlag.ControlEvidence, and the evidence parameter has a host list that is not empty.

Each evidence object in the specified evidence set is added to the assembly and host sets of the current evidence set, according to the sets from which it came.

Note This method does not perform a check to prevent adding duplicate types of evidence. Many assembly and host evidence objects can exist at the same time.

SecurityPermission for the ability to manipulate evidence when Evidence.Locked is true and the evidence parameter has a host list that is not empty. Associated enumeration: SecurityPermissionFlag.ControlEvidence

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Inherited
See base class member description: System.Object.ToString

C# Syntax:

public virtual string ToString();

For more information on members inherited from System.Object click on the link above.

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