A security system is configured to use a variable length encoding of a security identifier for segments of protected content material. In this system, a distinction is made between a "zero" information bit, and the "absence" of the information bit in a shorter information item. A conventional N-bit information encoding is encoded as a variable bit encoding, wherein the information encoding ranges from N-k bits to N+k bits. By distinguishing "zero" bits from "absent" bits, this variable bit encoding allows for 2^N-k+2^N-(k-1) . . . +2^N . . . +2^N+(k-1)+2^N+k possible unique information values. Preferably, the number of bits used for each encoding of a segment of a data set is a random value, further adding to the complexity of creating a dictionary mapping for protected content material.