System and methods for embedding additional data in compressed data streams

An encoder for compressing data is described, including a history buffer having multiple storage locations for storing target data units. The encoder is configured to input a target data string including multiple target data units, and additional data (e.g., security data associated with the target data string). In the event the history buffer contains multiple matching strings that match the target data string, the encoder is configured to select a displacement value of one of the matching strings dependent on a portion of the additional data, and to produce a copy pointer corresponding to the target data string and including the selected displacement. The selected displacement value in the copy pointer conveys the portion of the additional data. A decoder for decompressing data is also described, including a history buffer having multiple storage locations for storing data units. The decoder is configured to input a copy pointer including a displacement value indicative of a location of a first data unit of a data string in the history buffer, to use the displacement value to determine the data string, and to use the displacement value to determine a value of a quantity of additional data conveyed by the displacement value in the event multiple copies of the data string exist in the history buffer. A system is described including the encoder and the decoder, as are methods for compressing and decompressing data.