NAME

signature - Compute a Digital Signature for a Image Colormap


SYNOPSIS

ComputeMessageDigest(message_digest,input_message,message_length)

InitializeMessageDigest(message_digest)

SignatureImage(image)

TransformMessageDigest(message_digest,message)

UpdateMessageDigest(message_digest,input_message,message_length)


FUNCTION DESCRIPTIONS


ComputeMessageDigest

Function ComputeMessageDigest computes the message digest.

The format of the ComputeMessageDigest routine is:

        ComputeMessageDigest(message_digest,input_message,message_length)

A description of each parameter follows:

o message_digest:
The address of a structure of type MessageDigest.


InitializeMessageDigest

Function InitializeMessageDigest initializes the message digest structure.

The format of the InitializeMessageDigest routine is:

        InitializeMessageDigest(message_digest)

A description of each parameter follows:

o message_digest:
The address of a structure of type MessageDigest.


TransformMessageDigest

Function TransformMessageDigest updates the message digest.

The format of the TransformMessageDigest routine is:

        TransformMessageDigest(message_digest,message)

A description of each parameter follows:

o message_digest:
The address of a structure of type MessageDigest.


UpdateMessageDigest

Function UpdateMessageDigest updates the message digest.

The format of the UpdateMessageDigest routine is:

        UpdateMessageDigest(message_digest,input_message,message_length)

A description of each parameter follows:

o message_digest:
The address of a structure of type MessageDigest.


SignatureImage

Function SignatureImage computes a digital signature from an image. This signature uniquely identifies the image and is convenient for determining if the colormap of a sequence of images is identical when animating. The digital signature is from RSA Data Security MD5 Digest Algorithm described in Internet draft [MD5], July 1992.

The format of the SignatureImage routine is:

        SignatureImage(image)

A description of each parameter follows:

o image:
The address of a structure of type Image.