Heatmaps

EACirc is focused on finding defects in the outputs of cryptographic functions, but does not provide any information about weaknesses in the cipher’s design that caused the defects. To provide such an information, the impact of the function’s blocks on the randomness properties of the output was inspected, so called heatmaps. These heatmaps can be interesting feedbacks to function’s designers, as they can show what causes that the ciphertext produced by their cipher cannot be considered as a random sequence.

In the branch heatmaps, selected functions (Decim, Dynamic SHA, Dynamic SHA2, Tangle, Keccak) are divided into several blocks. When the output is generated, some of these blocks can be skipped.

An exemplary configuration for Tangle function with heatmaps:

"stream-a" : {
        "type" : "sha3",
        "source" : {
        	"type" : "counter"
    	},
        "algorithm" : "Tangle",
        "round" : 24,
	"hash-bitsize" : 256,
        "heatmap" : 64511
    }

• heatmap : number (0-65535) which sets (in binary) which blocks of the function are run (1) and skipped (0). For example, 64511(10) = 1111101111111111(2) means that the function is run with all blocks, except 11^th block (counted form right side).