AssemblySignatureKeyAttribute Class

Definition

Namespace:

System.Reflection

Assembly:

System.Runtime.dll

Source:

AssemblySignatureKeyAttribute.cs

Provides migration from an older, simpler strong name key to a larger key with a stronger hashing algorithm.

public ref class AssemblySignatureKeyAttribute sealed : Attribute

[System.AttributeUsage(System.AttributeTargets.Assembly, AllowMultiple=false, Inherited=false)]
public sealed class AssemblySignatureKeyAttribute : Attribute

[<System.AttributeUsage(System.AttributeTargets.Assembly, AllowMultiple=false, Inherited=false)>]
type AssemblySignatureKeyAttribute = class
    inherit Attribute

Public NotInheritable Class AssemblySignatureKeyAttribute
Inherits Attribute

Inheritance

Object

Attribute

AssemblySignatureKeyAttribute

Attributes

AttributeUsageAttribute

Remarks

The new larger key is the signature key. In versions before the .NET Framework 4.5, the signature key was identical to the identity key. Starting with the .NET Framework 4.5, the AssemblySignatureKeyAttribute attribute allows the assembly metadata to continue to have the old public key token and binary large object (BLOB) so that existing assembly references continue to work. It also ensures that the mapping comes from an owner of the identity key.

The presence of the attribute does not necessarily mean that strong name validation takes place. In common full-trust scenarios, the attribute is never considered, because strong name signatures are never validated. However, when the strong name signature does have to be validated, both the strong name signature and the countersignature must be validated. The assembly's identity key does not have to be identical to the signature key (the key used to do the actual signing and validation). The identity key can be mapped to a different (more robust) signing key. This lets you set the identity of an assembly, and update the signing keys and algorithms to more secure versions.

The countersignature addresses security concerns when a malicious assembly claims some other identity. For example, a malicious System.Core.dll assembly could contain the Microsoft public key in its metadata, and use the attribute to tell strong name validation to use the attacker's signature key if no countersignature is present. Thus, it could masquerade as a strong name-validated Microsoft assembly.

For information about how to sign assemblies for use with this new attribute, see Enhanced Strong Naming.

Constructors

AssemblySignatureKeyAttribute(String, String)

Creates a new instance of the AssemblySignatureKeyAttribute class by using the specified public key and countersignature.

Properties

Countersignature	Gets the countersignature for the strong name for this assembly.
PublicKey	Gets the public key for the strong name used to sign the assembly.
TypeId	When implemented in a derived class, gets a unique identifier for this Attribute. (Inherited from Attribute)

Methods

Equals(Object)	Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute)
GetHashCode()	Returns the hash code for this instance. (Inherited from Attribute)
GetType()	Gets the Type of the current instance. (Inherited from Object)
IsDefaultAttribute()	When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute)
Match(Object)	When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
ToString()	Returns a string that represents the current object. (Inherited from Object)