Lightweight Cryptography for IoT: ASCON Permutation Lab

Sensor Workload

Message size 16 B

MCU clock 4 MHz

Animation speed 1.0×

Live Readout — ASCON-128

Round

0 / 0

Phase

idle

Energy used

0.0 µJ

Coin cell left

100.000 %

Energy per Message (est.)

ASCON-128

0 µJ

AES-128

0 µJ

How it works

ASCON is the NIST-selected standard (2023) for lightweight cryptography — authenticated encryption designed to run on the tiny 8/16/32-bit microcontrollers found inside battery-powered IoT sensors, where full AES-128 costs too much energy and RAM. This simulator runs the real ASCON permutation p, operating on a 320-bit state split into five 64-bit words (x0…x4), on every "Encrypt" click.

Each round r:
  x2 ^= round_constant(r)                 — add round constant
  S-box:  x0^=x4; x4^=x3; x2^=x1;
          t_i = (~x_i) & x_(i+1 mod 5);   x_i ^= t_(i-1 mod 5);
          x1^=x0; x0^=x4; x3^=x2; x2 = ~x2   — 5-bit nonlinear S-box, bit-sliced across words
  Linear layer (per word, rotate-XOR):
    x0^=ROTR(x0,19)^ROTR(x0,28)   x1^=ROTR(x1,61)^ROTR(x1,39)
    x2^=ROTR(x2, 1)^ROTR(x2, 6)   x3^=ROTR(x3,10)^ROTR(x3,17)
    x4^=ROTR(x4, 7)^ROTR(x4,41)

Initialization runs the full 12-round permutation p^a; each 8-byte (64-bit) message block absorbed into the "rate" then costs a lighter 6-round p^b before squeezing out ciphertext — exactly the sponge/duplex construction the real cipher uses. Every one of the 320 cubes in the 3D grid is one state bit, colour-coded live from the actual BigInt arithmetic — not a canned animation.

Message size — sets how many 64-bit blocks must be absorbed, which sets total rounds and total energy.
MCU clock — a faster clock finishes sooner but a real embedded MCU also draws more current per MHz, so total energy per round is treated as clock-independent here (time-to-finish scales, energy does not) — matching published lightweight-crypto benchmarking practice.
Energy comparison — per-round/per-byte energy figures (≈ 0.15 µJ/round ASCON vs ≈ 0.9 µJ/16-byte-block AES-128 on a Cortex-M-class MCU) are illustrative values drawn from published lightweight-cryptography energy benchmarks, scaled to this message's block count, to show why constrained IoT hardware needs a lighter cipher rather than reusing AES.
Coin-cell battery — models a typical 220 mAh 3 V CR2032 cell continuously running this workload, to make the energy numbers tangible.

idle

bit = 0 bit = 1 rows x0…x4 (64-bit words)

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