Examples of org.foray.ps.filter.EexecDecodeFilter

• org.foray.ps.filter.EexecDecodeFilter
  Handles the PostScript encryption used in the "eexec" operator, usually used in Type1 fonts to encrypt the actual glyph-drawing data and the /Private dictionary. Please note that although this is a true filter, it should not be used directly in PostScript or PDF output. It is used by PostScript interpreters to decode contents processed by the "eexec" operator, and is used by font writing or embedding programs that need to encrypt code to be used by that operator. It is not (to our knowledge) available as a standard filter. This filter is designed to allow chunks of data to be encoded or decoded at a time. In other words, the entire set of data does not have to be encoded or decoded as the same time, but can be done in pieces. (This was done to save memory). However, the encoding and decoding used by this filter are dependent on data previously processed. Therefore, you must process the data starting at its beginning to be able to encode or decode subsequent data. Both the encode and decode methods are stateful, i.e. they are highly dependent on keeping track of their state from one chunk to the next. Of course, there is nothing wrong with encoding or decoding your entire input in one chunk, if you wish to do so. Type1 fonts actually use a double layer of encryption, whereby the glyph definitions are encrypted using this algorithm, then a large chunk of the font file, which includes the glyph definitions, is encrypted again, also using this algorithm (although with different seeding and constants). This situation can be handled by using two instances of this class, one for the inside encryption and one for the outside. The definition of the algorithms implemented in this class can be found in Chapter 7 of the Adobe Type 1 Font Format Specification. The PostScript Language Reference Manual (2nd Edition) cites this document as the authoritative reference on the topic (see the "eexec" operator).

Related Classes of org.foray.ps.filter.EexecDecodeFilter