# Constantine
# Copyright (c) 2018-2019    Status Research & Development GmbH
# Copyright (c) 2020-Present Mamy André-Ratsimbazafy
# Licensed and distributed under either of
#   * MIT license (license terms in the root directory or at http://opensource.org/licenses/MIT).
#   * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
# at your option. This file may not be copied, modified, or distributed except according to those terms.

# ############################################################
#
#           Benchmark of modular exponentiation
#
# ############################################################

# 2 implementations are available
# - 1 is constant time
# - 1 exposes the exponent bits to:
#   timing attack,
#   memory access analysis,
#   power analysis (i.e. oscilloscopes on embedded)
#   It is suitable for public exponents for example
#   to compute modular inversion via the Fermat method

import
  ../constantine/config/[common, curves],
  ../constantine/arithmetic/[bigints_checked, finite_fields],
  ../constantine/io/[io_bigints, io_fields],
  random, std/monotimes, times, strformat,
  ./timers

const Iters = 1_000_000

randomize(1234)

echo "\n⚠️ Measurements are approximate and use the CPU nominal clock: Turbo-Boost and overclocking will skew them."
echo "==========================================================================================================\n"

proc addBench() =
  var r, x, y: Fp[BLS12_381]
  # BN254 field modulus
  x.fromHex("0x30644e72e131a029b85045b68181585d97816a916871ca8d3c208c16d87cfd47")
  # BLS12-381 prime - 2
  y.fromHex("0x1a0111ea397fe69a4b1ba7b6434bacd764774b84f38512bf6730d2a0f6b0f6241eabfffeb153ffffb9feffffffffaaa9")

  let start = getMonotime()
  let startClk = getTicks()
  for _ in 0 ..< Iters:
    x += y
  let stopClk = getTicks()
  let stop = getMonotime()

  echo &"Time for {Iters} additions in 𝔽p (constant-time 381-bit): {inMilliseconds(stop-start)} ms"
  echo &"Time for 1 addition in 𝔽p ==> {inNanoseconds((stop-start) div Iters)} ns"
  echo &"Cycles per addition 𝔽p ==> {(stopClk - startClk) div Iters} cycles"

addBench()

proc mulBench() =
  var r, x, y: Fp[BLS12_381]
  # BN254 field modulus
  x.fromHex("0x30644e72e131a029b85045b68181585d97816a916871ca8d3c208c16d87cfd47")
  # BLS12-381 prime - 2
  y.fromHex("0x1a0111ea397fe69a4b1ba7b6434bacd764774b84f38512bf6730d2a0f6b0f6241eabfffeb153ffffb9feffffffffaaa9")

  let start = getMonotime()
  let startClk = getTicks()
  for _ in 0 ..< Iters:
    r.prod(x, y)
  let stopClk = getTicks()
  let stop = getMonotime()

  echo &"Time for {Iters} multiplications 𝔽p (constant-time 381-bit): {inMilliseconds(stop-start)} ms"
  echo &"Time for 1 multiplication 𝔽p ==> {inNanoseconds((stop-start) div Iters)} ns"
  echo &"Cycles per multiplication 𝔽p ==> {(stopClk - startClk) div Iters} cycles"

mulBench()