/// <summary>
/// Implement <see cref="IPermission.Copy"/>. This creates an identical copy of the current
/// permission instance and returns it to the caller.
/// </summary>
/// <returns></returns>
public override IPermission Copy()
{
CryptographicPermission permission = new CryptographicPermission(PermissionState.None);
permission._permFlag = this._permFlag;
return(permission);
}
/// <summary>
/// Implement the IPermission.IsSubsetOf. This method returns a bool to indicate
/// whether or not the current permission is a subset of the supplied permission. To be a subset, every item of state in the current permission must also be in the target permission.
/// </summary>
/// <param name="target">See <see cref="IPermission"/>.</param>
/// <returns></returns>
public override bool IsSubsetOf(IPermission target)
{
// An input of null indicates a permission with no state.
// The permission can only be a subset if it's in a similar empty state.
bool canEncrypt, canDecrypt, canSign;
bool canTargetEncrypt, canTargetDecrypt, canTargetSignature;
canEncrypt = (this._permFlag & CryptographicPermissionFlags.Encrypt).Equals(CryptographicPermissionFlags.Encrypt);
canDecrypt = (this._permFlag & CryptographicPermissionFlags.Decrypt).Equals(CryptographicPermissionFlags.Decrypt);
canSign = (this._permFlag & CryptographicPermissionFlags.Sign).Equals(CryptographicPermissionFlags.Sign);
if (target == null)
{
if (canEncrypt == false && canDecrypt == false && canSign == false)
{
return(true);
}
else
{
return(false);
}
}
if (!target.GetType().Equals(this.GetType()))
{
throw new ArgumentException(Resource.ResourceManager[Resource.MessageKey.CryptographicPermissionArgumentException]);
}
// Cast the target to an EncryptionPermission.
CryptographicPermission targetPerm = (CryptographicPermission)target;
canTargetEncrypt = (targetPerm._permFlag & CryptographicPermissionFlags.Encrypt).Equals(CryptographicPermissionFlags.Encrypt);
canTargetDecrypt = (targetPerm._permFlag & CryptographicPermissionFlags.Decrypt).Equals(CryptographicPermissionFlags.Decrypt);
canTargetSignature = (targetPerm._permFlag & CryptographicPermissionFlags.Sign).Equals(CryptographicPermissionFlags.Sign);
// Every value set (true) in this permission must be in the target.
// The following code checks to see if the current permission is a subset
// of the target. If the current permission has something that the target
// does not have, it cannot be a subset.
if (canEncrypt == true && canTargetEncrypt == false)
{
return(false);
}
if (canDecrypt == true && canTargetDecrypt == false)
{
return(false);
}
if (canSign == true && canTargetSignature == false)
{
return(false);
}
return(true);
}
/// <summary>
/// Implement <see cref="IPermission.Union"/>. This returns a permission object that is the result
/// of the set union between the current permission and the supplied permission.
/// </summary>
/// <param name="target">See <see cref="IPermission"/>.</param>
/// <returns></returns>
public override IPermission Union(IPermission target)
{
if (target == null)
{
return(Copy());
}
if (!target.GetType().Equals(this.GetType()))
{
throw new ArgumentException(Resource.ResourceManager[Resource.MessageKey.CryptographicPermissionArgumentException]);
}
// Cast the target to an CryptographicPermission.
CryptographicPermission targetPerm = (CryptographicPermission)target;
CryptographicPermissionFlags unionPerm = this._permFlag | targetPerm._permFlag;
return(new CryptographicPermission(unionPerm));
}
/// <summary>
/// Implement <see cref="IPermission.Intersect"/>. This returns a permission object that is the
/// result of the set intersection between the current permission and the supplied permission.
/// </summary>
/// <param name="target">See <see cref="IPermission"/>.</param>
/// <returns></returns>
public override IPermission Intersect(IPermission target)
{
// An input of null indicates a permission with no state.
// There can be no common state, so the method returns null.
if (target == null)
{
return(null);
}
if (!target.GetType().Equals(this.GetType()))
{
throw new ArgumentException(Resource.ResourceManager[Resource.MessageKey.CryptographicPermissionArgumentException]);
}
// Cast target to an CryptographicPermission.
CryptographicPermission targetPerm = (CryptographicPermission)target;
CryptographicPermissionFlags intersectPerm = this._permFlag & targetPerm._permFlag;
return(new CryptographicPermission(intersectPerm));
}