WriteProtection.AlgorithmIdExtensibility Property

Definition

Namespace:

DocumentFormat.OpenXml.Wordprocessing

Assembly:

DocumentFormat.OpenXml.dll

Package:

DocumentFormat.OpenXml v3.0.1

Cryptographic Algorithm Extensibility

Represents the following attribute in the schema: w:algIdExt

public DocumentFormat.OpenXml.HexBinaryValue? AlgorithmIdExtensibility { get; set; }

member this.AlgorithmIdExtensibility : DocumentFormat.OpenXml.HexBinaryValue with get, set

Public Property AlgorithmIdExtensibility As HexBinaryValue

Property Value

HexBinaryValue

Returns StringValue.

Remarks

The following information from the ECMA International Standard ECMA-376 can be useful when working with this class.

Specifies that a cryptographic algorithm which was not defined by the Office Open XML Standard has been used to generate the hash value stored with this document.

This value, when present, shall be interpreted based on the value of the algIdExtSource attribute in order to determine the algorithm used, which shall be application defined. This extensibility affords the fact that with exponentially increasing computing power, documents created in the future will likely need to use as yet undefined hashing algorithms in order to remain secure.

If this value is present, the cryptAlgorithmClass, cryptAlgorithmType, and cryptAlgorithmSid attribute values shall be ignored in favor of the algorithm defined by this attribute.

Consider a WordprocessingML document with the following information stored in one of its protection elements:

<w:… w:algIdExt="0000000A"   
  w:algIdExtSource="Contoso"  
  w:hash="9oN7nWkCAyEZib1RomSJTjmPpCY=" />  

The algIdExt attribute value of 0000000A specifies that the algorithm with hex code A shall be used as defined by the Contoso application.

The possible values for this attribute are defined by the ST_LongHexNumber simple type.