Random keys and their quality

OTP (One-Time-Pad) encryption requires true random numbers if it is to be truly undecryptable. Encrypter-X takes this into account and generates byte sequences with real random numbers, which are then used by the application not only as one key but as a key bundle.

This is the extension of the OTP method to the MOTP method (Multi-One-Time-Pad) and the idea behind this is that if they are true random numbers, the sequence of numbers starting at a position A in this key bundle is completely uncorrelated from the sequence starting at position B, because this sequence could also have been generated independently, by chance, when it was regenerated.

Thus, a byte sequence of length 1000 provides us with 1000 virtual independent keys and to satisfy the undecryptability condition of the OTP method, Encrypter-X manages the allocation of start positions into a key and ensures that no start position is used a second time. This is equivalent to destroying the key used to encrypt a file/message after it has been used.

To analyze how well Encrypter-X generates the random numbers for the key bundles, some statistical tests were performed with relatively large keys. In addition to the equal distribution of the numerical values, the occurrence of the same patterns in between the key bundles was also examined.

The uniform distribution of the numerical values between 1 and 255 is exceptionally good for all key bundle sizes. The analysis is strikingly good when searching for the same patterns in different keys. It has been shown that all patterns with a length of three bytes of a key bundle occur at most once in another key bundle, patterns with a length of four bytes often occur only once and larger patterns do not occur at all.