초록 ▼

Techniques for protecting the security of digital representations, and of analog forms made from them. The techniques include authentication techniques that can authenticate both a digital representation and an analog form produced from the digital representation, an active watermark that contains p

Techniques for protecting the security of digital representations, and of analog forms made from them. The techniques include authentication techniques that can authenticate both a digital representation and an analog form produced from the digital representation, an active watermark that contains program code that may be executed when the watermark is read, and a watermark agent that reads watermarks and sends messages with information concerning the digital representations that contain the watermarks. The authentication techniques use semantic information to produce authentication information. Both the semantic information and the authentication information survive when an analog form is produced from the digital representation. In one embodiment, the semantic information is alphanumeric characters and the authentication information is either contained in a watermark embedded in the digital representation or expressed as a bar code. With the active watermark, the watermark includes program code. When a watermark reader reads the watermark, it may cause the program code to be executed. One application of active watermarks is making documents that send messages when they are operated on. A watermark agent may be either a permanent resident of a node in a network or of a device such as a copier or it may move from one network node to another. In the device or node, the watermark agent executes code which examines digital representations residing in the node or device for watermarked digital representations that are of interest to the watermark agent. The watermark agent then sends messages which report the results of its examination of the digital representations. If the watermarks are active, the agent and the active watermark may cooperate an the agent may cause some or all of the code than an active watermark contains to be executed.

대표청구항 ▼

[ What is claimed is:] [1.]1. Apparatus which authenticates a digital representation from which an analog form may be made, the apparatus comprising:an authenticator which uses semantic information in the digital representation that will be present in the analog form to produce first authentication

[ What is claimed is:] [1.]1. Apparatus which authenticates a digital representation from which an analog form may be made, the apparatus comprising:an authenticator which uses semantic information in the digital representation that will be present in the analog form to produce first authentication information; andan incorporator which incorporates the first authentication information into the digital representation such that the first authentication information is preserved in the analog form and the semantic information remains useful in the analog form to produce second authentication information which is comparable to the first authentication information, reby the first authentication information may be retrieved from the analog form and compared with the second authentication information produced from the semantic information in the analog form to determine authenticity of the analog form.