Security and Performance
It is assumed that the Humber Cipher algorithm is in the public domain. Therefore, the security of encryption depends entirely on the security of its register keys. Each index register has 22048 possible initial settings and each shift register has 22048 possible initial settings. Therefore the probability of selecting the correct initial settings for Humber as a whole is 1 in 28192. Providing the confidentiality of the keys remains intact, the most likely attack would be on the PRNG processes. The MTNG requires eight seeds. Each seed has 264 possible values, so the probability of selecting the correct set of 8 initial key generation seeds is 1 in 2512.
Because there are no pre-defined seeds for the PRNG processes, it is not possible to identify them and reproduce the generation of the keys. Once all the seed values have been captured, the keys are generated. At the end of the whole process, the values of the seeds are discarded so they can never be discovered to allow the rollback generation of the key files.