Patent ID: 7639818

Claim:
A structured document signature device for attaching a digital signature to a structured document composed of a plurality of elements, the plurality of elements are hierarchized, comprising: an adaptation policy inserting unit configured to insert a value indicating an adaptation policy applied to an object element, as an attribute value of the object element, while changing the object element, the object element being any one of the plurality of elements; a hash tree constructor configured to construct a hash tree composed of a hash value of the plurality of elements by calculating the hash value of the object elements in sequence, while changing the object element from an object element lowest in the hierarchy to an object element highest in the hierarchy; a digital signature adder configured to add a digital signature which has been obtained by encrypting the hash value of the element highest in the hierarchy to the structured document, and add a digital signature which has been obtained by encrypting the value indicating the adaptation policy to the structured document; and an output configured to output the structured document to which the digital signature has been attached by the digital signature adder, wherein the hash tree constructor is configured to calculate the hash value of the object element and insert the hash value of a child element provided lower in the hierarchy than the object element as an other attribute value of the object element, and the adaptation policy indicates whether or not the child element has been permitted to be deleted.