The LavaRnd Digital Blender algorithm consists of an n-way turn; n different SHA-1 cryptographic hash operations running in parallel, and n different xor-rotate and fold operations.

The n-way turn converts the digitized chaotic source into n sets of data. Each of the n sets are fed into a SHA-1 cryptographic hash operation to produce 20 octets of data. Each of the n sets are also fed into a xor-rotate and fold operation that also produces 20 octets of data.

The 20 octets of data produced by a given xor-rotate and fold operation is xor-ed with the 20 octets produced by the next SHA-1 cryptographic hash operation to produce 20 octets of random numbers. That is, the output from the 1st xor-rotate and fold operation is xor-ed with the output from the 2nd SHA-1 cryptographic hash operation yielding 20 octets of random numbers. The output from the 2nd xor-rotate and fold operation is xor-ed with the output from the 3rd SHA-1 cryptographic hash operation yielding 20 more octets of random numbers. This continues until the output from the final xor-rotate and fold operation is xor-ed with the output from the 1st SHA-1 cryptographic hash operation to yield the final 20 octets of random numbers.

The LavaRnd Digital Blender, in total, produces n*20 octets of random numbers.

Digital Blender choice of n

The LavaRnd Reference implementation Digital Blender determines the choice of n, with respect to the n-way turn, n SHA-1 cryptographic hash operations and n xor-rotate and fold operations, from 2 parameters:

• The amount of data read from the chaotic source
• LavaRnd output rate factor called alpha

We recommend that you choose n to be are either 1 or 5 mod 6. By avoiding multiples of 2 and 3, you will distribute pixel encodings cross multiple turns.

Lavarnd computes n from alpha as follows:

sqrt( input_length * alpha / cryptographic_hash_length ) rounded up to an integer that is 1 or 5 mod 6

Reasonable alpha rate factors typically range from 1/16 to 16, with the default rate being 1.0. The higher the alpha rate, the more output is produced from a given amount of input. High alpha rates cause the Digital Blender to use larger n values (in terms of n-way turns, SHA-1 cryptographic hash operations, and xor-rotate and fold operations).

Assuming 19200 octets of input, the following table shows the number of octets generated with respect to alpha:

Digital Blender example

Assume that 19200 octets of luminance are collected from a webcam CCD. Using an alpha rate of 1.0, the Digital Blender will operate with an n value of 17.

The 19200 octets are first fed through a 17-way turn to produce 17 output sets. Each of the 17 output sets is fed into 17 different SHA-1 cryptographic hash operations. Each of the 17 output sets is also fed into 17 different xor-rotate and fold operations.

The output of each of the 17 SHA-1 cryptographic hash operations is a 20 octet value. The output of each of the 17 xor-rotate and fold operations is also a 20 octet value. The 20 octets of a given SHA-1 cryptographic hash operation is xor-ed with the 20 octets produced by the previous xor-rotate and fold operation yielding 20 octets of random numbers.

The final set of 17 xor's are concatenated to produce 17*20 = 340 octets of random data.

What is next?

• How good is LavaRnd?
• LavaRnd Quality - Billion bit test
• LavaRnd demos - fun, statistical and other information