#StackBounty: #block-cipher #randomness Randomness Testing of Block Ciphers with 256-bit Block/ Key length

Bounty: 100

NIST explained the process of "Randomness Testing of the AES Candidate Algorithms" in the document.

The document explains the generation of 9 datasets for AES candidates with 128-bit block length and 128-key length. The document also state the number of streams and length of each stream that were set in NIST Statistical Test Suite for randomness testing.

However, the document does not state the process for 192-bit and 256-bit key lengths. Whereas AES candidates also support these two key settings.

From details of each test, one can generate all 9 data sets for 192 and 256 bit keys. But then what should be the stream length and number of streams to be tested, specially for the following tests where number of blocks to be generated is dependent on the key length.

  1. Key Avalanche
  2. Low Density Keys
  3. High Density Keys

Generating above three datasets for 256-bit key, results in much longer bit stream as compared to the one generated by 128-bit key length. So in order to analyze the complete bit stream, one should increase the "number of streams" parameter in NIST or "length of stream" parameter? If both the parameters to be increased, then what should be their value?

Going further, what should be the value of these two parameters for all 9 data sets for block ciphers with 256-bit block and key length?


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