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The Frogbit Semi-Proprietary Scheme

The present document explains how to apply the Frogbit semi-proprietary scheme for software integrity protection. The rationale for this approach is found in a document entitled "Rationale for Using a Proprietary Algorithm for Software Integrity Protection".

The Frogbit cipher may be implemented with ten completely unrelated pseudo-random generators, either with a single secret key and a seed derivation specification for each generator, or with ten secret seeds. This creates an opportunity for a multitude of different proprietary ciphers (ciphers of which design are kept secret by commercial organizations).

It is thus possible to describe the steps for the use of the Frogbit data integrity algorithm for the creation of proprietary algorithms.

Design of ten pseudo-random generators

Starting from the many pseudo-random generator proposals reported in the specialized literature, ten unique pseudo-random generators are designed. Then, they are programmed in source code and merged with the source code for the core Frogbit algorithm.

Preparation of subprograms for data concealment and data recovery

The subprogram for data concealment comprises the steps of prefixing the cleartext data with random bits (see the document entitled "Message salting with the Frogbit algorithm"), appending some message redundancy, and feeding this expanded data stream to the encrypting part of the core Frogbit algorithm combined with the ten pseudo-random generators.

The subprogram for data recovery comprises the steps of feeding the ciphertext to the decrypting part of the core Frogbit algorithm combined with the ten pseudo-random generators, checking the message redundancy appendix, and discarding the random prefix.

Preparation of Frogbit secret key

The Frogbit secret key is a constant in the Frogbit semi-proprietary scheme. The secret key choice may be detached from the secret designs of pseudo-random generators, giving two distinct points of control for security management. A special computer utility may be required to "load" or "link" a secret key into executable programs.

Creation of data concealment utility

If the semi-proprietary scheme is used for constant software parameters, the production programs needs only the data recovery subprogram and the data concealment function should be part of a computer utility. The access to the data concealment utility gives another point of control for security management. The result of the data concealment utility may be either a scrambled configuration file or some initialization data "loaded" or "linked" into executable programs.

Creation of production programs

The production programs need to be "linked" with the data recovery subprogram, and then "loaded" with the secret key. If the semi-proprietary scheme is used for read/write data (e.g. for to store the internal state of a private random source used for cryptographic key generation), the production programs need to be "linked" with the data concealment subprogram.

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