chore: remove stew/byteutils dependencies and unneeded imports

.github/workflows/ci.yml

@@ -188,14 +188,14 @@ jobs:
         run: |
           pacman -S --needed --noconfirm mingw-w64-x86_64-gmp
           nimble refresh --verbose -y
-          nimble install --verbose -y gmp stew jsony asynctools
+          nimble install --verbose -y gmp jsony asynctools
 
       - name: Install test dependencies
         if: runner.os != 'Windows'
         shell: bash
         run: |
           nimble refresh --verbose -y
-          nimble install --verbose -y gmp stew jsony asynctools
+          nimble install --verbose -y gmp jsony asynctools
 
       - name: Run Constantine tests (UNIX with Assembly)
         if: runner.os != 'Windows' && matrix.target.BACKEND == 'ASM'

.travis.yml

@@ -81,17 +81,11 @@ addons:
   apt:
     packages:
       - libgmp-dev
-      - parallel
   homebrew:
     packages:
       - gmp
-      # Travis `bundle` bug: https://travis-ci.community/t/macos-build-fails-because-of-homebrew-bundle-unknown-command/7296/28
-      # - parallel
 
 before_install:
-  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
-      HOMEBREW_NO_AUTO_UPDATE=1 brew install parallel;
-    fi
   - |
     if [ "${CHANNEL}" = stable ]; then
       BRANCH="v$(curl https://nim-lang.org/channels/stable)"
@@ -127,7 +121,7 @@ before_script:
     - export PATH="$PWD/nim-${CHANNEL}/bin${PATH:+:$PATH}"
 script:
     - nimble refresh
-    - nimble install -y gmp stew jsony
+    - nimble install -y gmp jsony
 
     # Installing Clang9.0 or later is a pain in Travis
     # for inline assembly "flag output constraint"
@@ -137,9 +131,6 @@ script:
         nimble test_parallel_no_assembler
       else
         nimble test_parallel
-        if [[ "$ARCH" == "amd64" ]]; then
-          nimble test_parallel_no_assembler
-        fi
       fi
 branches:
   except:

README.md

@@ -15,7 +15,34 @@ with a particular focus on pairing-based cryptography as used in blockchains and
 
 The implementations are accompanied with SAGE code used as reference implementation and test vectors generators before writing highly optimized routines implemented in the [Nim language](https://nim-lang.org/)
 
-> The library is in development state and high-level wrappers or example protocols are not available yet.
+> The library is in development state and high-level wrappers or example protocols are work-in-progress.
+
+## Table of Contents
+
+<!-- TOC -->
+
+- [Constantine - Fast, compact, hardened Pairing-Based Cryptography](#constantine---fast-compact-hardened-pairing-based-cryptography)
+  - [Table of Contents](#table-of-contents)
+  - [Target audience](#target-audience)
+  - [Protocols](#protocols)
+  - [Curves supported in the backend](#curves-supported-in-the-backend)
+  - [Installation](#installation)
+  - [Dependencies](#dependencies)
+  - [Security](#security)
+    - [Disclaimer](#disclaimer)
+    - [Security disclosure](#security-disclosure)
+  - [Performance](#performance)
+    - [In blockchain](#in-blockchain)
+    - [In zero-knowledge proofs](#in-zero-knowledge-proofs)
+    - [Measuring performance](#measuring-performance)
+      - [BLS12_381 Clang + inline Assembly](#bls12_381-clang--inline-assembly)
+  - [Why Nim](#why-nim)
+  - [Compiler caveats](#compiler-caveats)
+    - [Inline assembly](#inline-assembly)
+  - [Sizes: code size, stack usage](#sizes-code-size-stack-usage)
+  - [License](#license)
+
+<!-- /TOC -->
 
 ## Target audience
 
@@ -102,6 +129,21 @@ generated incorrect add-with-carry code.
 On x86-64, inline assembly is used to workaround compilers having issues optimizing large integer arithmetic,
 and also ensure constant-time code.
 
+## Dependencies
+
+Constantine has no dependencies, even on Nim standard library except:
+- for testing 
+  - jsony for parsing json test vectors
+  - the Nim standard library for unittesting, formatting and datetime.
+  - GMP for testing against GMP
+- for benchmarking
+  - The Nim standard libreary for timing and formatting
+- for Nvidia GPU backend:
+  - the LLVM runtime ("dev" version with headers is not needed)
+  - the CUDA runtime ("dev" version with headers is not needed)
+- at compile-time
+  - we need the std/macros library to generate Nim code.
+
 ## Security
 
 Hardening an implementation against all existing and upcoming attack vectors is an extremely complex task.
@@ -111,6 +153,8 @@ The library is provided as is, without any guarantees at least until:
 - formal verification of constant-time implementation is possible
 
 Defense against common attack vectors are provided on a best effort basis.
+Do note that Constantine has no external package dependencies hence it is not vulnerable to
+supply chain attacks (unless they affect a compiler or the OS).
 
 Attackers may go to great lengths to retrieve secret data including:
 - Timing the time taken to multiply on an elliptic curve
@@ -231,7 +275,7 @@ The Nim language offers the following benefits for cryptography:
   - derive constants
   - write a size-independent inline assembly code generator
 - Upcoming proof system for formal verification via Z3 ([DrNim](https://nim-lang.org/docs/drnim.html), [Correct-by-Construction RFC](https://github.com/nim-lang/RFCs/issues/222))
-### Compiler caveats
+## Compiler caveats
 
 Unfortunately compilers and in particular GCC are not very good at optimizing big integers and/or cryptographic code even when using intrinsics like `addcarry_u64`.
 

azure-pipelines.yml

@@ -268,7 +268,7 @@ steps:
   - bash: |
       echo "PATH=${PATH}"
       nimble refresh
-      nimble install -y gmp stew jsony
+      nimble install -y gmp jsony
     displayName: 'Installing package and testing dependencies'
 
   - bash: |

benchmarks/bench_ec_g1.nim

@@ -15,9 +15,7 @@ import
     ec_shortweierstrass_jacobian],
   # Helpers
   ../helpers/static_for,
-  ./bench_elliptic_template,
+  ./bench_elliptic_template
-  # Standard library
-  std/strutils
 
 # ############################################################
 #

benchmarks/bench_ec_g1_batch.nim

@@ -16,9 +16,7 @@ import
     ec_shortweierstrass_jacobian],
   # Helpers
   ../helpers/static_for,
-  ./bench_elliptic_template,
+  ./bench_elliptic_template
-  # Standard library
-  std/strutils
 
 # ############################################################
 #

benchmarks/bench_fp12.nim

@@ -12,9 +12,7 @@ import
   ../constantine/math/extension_fields,
   # Helpers
   ../helpers/static_for,
-  ./bench_fields_template,
+  ./bench_fields_template
-  # Standard library
-  std/strutils
 
 # ############################################################
 #

benchmarks/bench_fp2.nim

@@ -12,9 +12,7 @@ import
   ../constantine/math/extension_fields,
   # Helpers
   ../helpers/static_for,
-  ./bench_fields_template,
+  ./bench_fields_template
-  # Standard library
-  std/strutils
 
 # ############################################################
 #

benchmarks/bench_fp4.nim

@@ -12,9 +12,7 @@ import
   ../constantine/math/extension_fields,
   # Helpers
   ../helpers/static_for,
-  ./bench_fields_template,
+  ./bench_fields_template
-  # Standard library
-  std/strutils
 
 # ############################################################
 #

benchmarks/bench_fp6.nim

@@ -12,9 +12,7 @@ import
   ../constantine/math/extension_fields,
   # Helpers
   ../helpers/static_for,
-  ./bench_fields_template,
+  ./bench_fields_template
-  # Standard library
-  std/strutils
 
 # ############################################################
 #

benchmarks/bench_fp_double_precision.nim

@@ -22,7 +22,7 @@ import
   ../helpers/[prng_unsafe, static_for],
   ./platforms,
   # Standard library
-  std/[monotimes, times, strformat, strutils, macros]
+  std/[monotimes, times, strformat, strutils]
 
 var rng: RngState
 let seed = uint32(getTime().toUnix() and (1'i64 shl 32 - 1)) # unixTime mod 2^32

benchmarks/bench_pairing_bls12_377.nim

@@ -13,9 +13,7 @@ import
   ../constantine/math/extension_fields,
   # Helpers
   ../helpers/static_for,
-  ./bench_pairing_template,
+  ./bench_pairing_template
-  # Standard library
-  std/strutils
 
 # ############################################################
 #

benchmarks/bench_pairing_bls12_381.nim

@@ -13,9 +13,7 @@ import
   ../constantine/math/extension_fields,
   # Helpers
   ../helpers/static_for,
-  ./bench_pairing_template,
+  ./bench_pairing_template
-  # Standard library
-  std/strutils
 
 # ############################################################
 #

benchmarks/bench_pairing_bn254_nogami.nim

@@ -13,9 +13,7 @@ import
   ../constantine/math/extension_fields,
   # Helpers
   ../helpers/static_for,
-  ./bench_pairing_template,
+  ./bench_pairing_template
-  # Standard library
-  std/strutils
 
 # ############################################################
 #

benchmarks/bench_pairing_bn254_snarks.nim

@@ -13,9 +13,7 @@ import
   ../constantine/math/extension_fields,
   # Helpers
   ../helpers/static_for,
-  ./bench_pairing_template,
+  ./bench_pairing_template
-  # Standard library
-  std/strutils
 
 # ############################################################
 #

benchmarks/bench_summary_bls12_377.nim

@@ -13,9 +13,7 @@ import
   ../constantine/math/extension_fields,
   # Helpers
   ../helpers/static_for,
-  ./bench_summary_template,
+  ./bench_summary_template
-  # Standard library
-  std/strutils
 
 # ############################################################
 #

benchmarks/bench_summary_bls12_381.nim

@@ -13,9 +13,7 @@ import
   ../constantine/math/extension_fields,
   # Helpers
   ../helpers/static_for,
-  ./bench_summary_template,
+  ./bench_summary_template
-  # Standard library
-  std/strutils
 
 # ############################################################
 #

benchmarks/bench_summary_bn254_nogami.nim

@@ -13,9 +13,7 @@ import
   ../constantine/math/extension_fields,
   # Helpers
   ../helpers/static_for,
-  ./bench_summary_template,
+  ./bench_summary_template
-  # Standard library
-  std/strutils
 
 # ############################################################
 #

benchmarks/bench_summary_bn254_snarks.nim

@@ -13,9 +13,7 @@ import
   ../constantine/math/extension_fields,
   # Helpers
   ../helpers/static_for,
-  ./bench_summary_template,
+  ./bench_summary_template
-  # Standard library
-  std/strutils
 
 # ############################################################
 #

benchmarks/bench_summary_pasta.nim

@@ -13,9 +13,7 @@ import
   ../constantine/math/extension_fields,
   # Helpers
   ../helpers/static_for,
-  ./bench_summary_template,
+  ./bench_summary_template
-  # Standard library
-  std/strutils
 
 # ############################################################
 #

constantine/math/arithmetic/assembly/limbs_asm_mul_mont_x86_adx_bmi2.nim

@@ -8,7 +8,7 @@
 
 import
   # Standard library
-  std/[macros, algorithm],
+  std/macros,
   # Internal
   ../../../platforms/abstractions,
   ./limbs_asm_modular_x86,

constantine/math/arithmetic/limbs_montgomery.nim

@@ -7,8 +7,6 @@
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
 import
-  # Standard library
-  std/macros,
   # Internal
   ../../platforms/abstractions,
   ./limbs, ./limbs_extmul

constantine/math/io/io_bigints.nim

@@ -291,7 +291,7 @@ func marshalBE[T](
 
   var tail = dst.len
   while tail > 0:
-    let w = if src_idx < src.len: BaseType(src[src_idx])
+    let w = if src_idx < src.len: BT(src[src_idx])
             else: 0
     inc src_idx
 
@@ -439,23 +439,20 @@ func hexToPaddedByteArray*(hexStr: string, output: var openArray[byte], order: s
     shift = (shift + 4) and 4
     dstIdx += shift shr 2
 
-func nativeEndianToHex*(bytes: openarray[byte], order: static[Endianness]): string =
+func toHex*(bytes: openarray[byte]): string =
   ## Convert a byte-array to its hex representation
-  ## Output is in lowercase and not prefixed.
+  ## Output is in lowercase and prefixed with 0x
-  ## This assumes that input is in platform native endianness
   const hexChars = "0123456789abcdef"
   result = newString(2 + 2 * bytes.len)
   result[0] = '0'
   result[1] = 'x'
   for i in 0 ..< bytes.len:
-    when order == system.cpuEndian:
     let bi = bytes[i]
     result[2 + 2*i] = hexChars.secretLookup(SecretWord bi shr 4 and 0xF)
     result[2 + 2*i+1] = hexChars.secretLookup(SecretWord bi and 0xF)
-    else:
+
-      let bmi = bytes[bytes.high - i]
+func fromHex*[N: static int](T: type array[N, byte], hex: string): T =
-      result[2 + 2*i] = hexChars.secretLookup(SecretWord bmi shr 4 and 0xF)
+  hexToPaddedByteArray(hex, result, bigEndian)
-      result[2 + 2*i+1] = hexChars.secretLookup(SecretWord bmi and 0xF)
 
 # ############################################################
 #
@@ -520,10 +517,10 @@ func appendHex*(dst: var string, big: BigInt, order: static Endianness = bigEndi
   # 1. Convert Big Int to canonical uint
   const canonLen = (big.bits + 8 - 1) div 8
   var bytes: array[canonLen, byte]
-  marshal(bytes, big, cpuEndian)
+  marshal(bytes, big, order)
 
   # 2 Convert canonical uint to hex
-  dst.add bytes.nativeEndianToHex(order)
+  dst.add bytes.toHex()
 
 func toHex*(big: BigInt, order: static Endianness = bigEndian): string =
   ## Stringify an int to hex.

constantine/platforms/gpu/ir.nim

@@ -10,8 +10,7 @@ import
   ../../math/config/[curves, precompute],
   ../../math/io/io_bigints,
   ../primitives, ../bithacks, ../endians,
-  ./llvm,
+  ./llvm
-  std/hashes
 
 # ############################################################
 #
@@ -129,10 +128,10 @@ func toHex[T](a: BigNum[T]): string =
   # 1. Convert BigInt to canonical uint
   const wordBitwidth = sizeof(T) * 8
   var bytes = newSeq[byte](byteLen(a.bits))
-  bytes.marshal(a.limbs, wordBitwidth, cpuEndian)
+  bytes.marshal(a.limbs, wordBitwidth, bigEndian)
 
   # 2 Convert canonical uint to hex
-  return bytes.nativeEndianToHex(bigEndian)
+  return bytes.toHex()
 
 # Checks
 # ------------------------------------------------
@@ -245,10 +244,6 @@ proc init*(
   result.fp.setFieldConst(ctx, wordSize, fpBits, fpMod)
   result.fr.setFieldConst(ctx, wordSize, frBits, frMod)
 
-proc hash*(curveOp: tuple[cm: CurveMetadata, op: Opcode]): Hash {.inline.} =
-  result = hash(curveOp.cm.curve) !& int(hash(curveOp.op))
-  result = !$result
-
 proc genSymbol*(cm: CurveMetadata, opcode: Opcode): string {.inline.} =
   cm.prefix & 
     (if cm.wordSize == size32: "32b_" else: "64b_") &

tests/gpu/hello_world_nvidia.nim

@@ -91,7 +91,7 @@ proc getNvvmLog(prog: NvvmProgram): string {.used.} =
     result = newString(logSize)
     check nvvmGetProgramLog(prog, result[0].addr)
 
-proc ptxCodegenViaNvidiaNvvm(module: ModuleRef, sm: tuple[major, minor: int32]): string {.used.} =
+proc ptxCodegenViaNvidiaNvvm(module: ModuleRef, sm: tuple[major, minor: int32]): string =
   ## PTX codegen via Nvidia NVVM
   
   # ######################################
@@ -118,7 +118,7 @@ proc ptxCodegenViaNvidiaNvvm(module: ModuleRef, sm: tuple[major, minor: int32]):
 
   check nvvmDestroyProgram(prog)
 
-proc ptxCodegenViaLlvmNvptx(module: ModuleRef, sm: tuple[major, minor: int32]): string {.used.} =
+proc ptxCodegenViaLlvmNvptx(module: ModuleRef, sm: tuple[major, minor: int32]): string =
   ## PTX codegen via LLVM NVPTX
   
   module.verify(AbortProcessAction)

tests/math/t_bigints_mod_vs_gmp.nim

@@ -10,7 +10,7 @@ import
   # Standard library
   std/[random, macros, times, strutils],
   # Third-party
-  gmp, stew/byteutils,
+  gmp,
   # Internal
   ../../constantine/math/io/io_bigints,
   ../../constantine/math/arithmetic,

tests/math/t_bigints_mul_high_words_vs_gmp.nim

@@ -10,7 +10,7 @@ import
   # Standard library
   std/[random, macros, times, strutils],
   # Third-party
-  gmp, stew/byteutils,
+  gmp,
   # Internal
   ../../constantine/math/io/io_bigints,
   ../../constantine/math/arithmetic,

tests/math/t_bigints_mul_vs_gmp.nim

@@ -10,7 +10,7 @@ import
   # Standard library
   std/[random, macros, times, strutils],
   # Third-party
-  gmp, stew/byteutils,
+  gmp,
   # Internal
   ../../constantine/math/io/io_bigints,
   ../../constantine/math/arithmetic,

tests/math/t_ec_shortw_prj_edge_cases.nim

@@ -14,17 +14,14 @@
 
 import
   # Standard library
-  std/[unittest, times],
+  std/unittest,
   # Internals
   ../../constantine/platforms/abstractions,
   ../../constantine/math/config/curves,
   ../../constantine/math/arithmetic,
   ../../constantine/math/extension_fields,
-  ../../constantine/math/io/[io_bigints, io_fields, io_extfields, io_ec],
+  ../../constantine/math/io/[io_bigints, io_fields, io_extfields],
-  ../../constantine/math/elliptic/[ec_shortweierstrass_projective, ec_scalar_mul],
+  ../../constantine/math/elliptic/ec_shortweierstrass_projective
-  # Test utilities
-  ../../helpers/prng_unsafe,
-  ./support/ec_reference_scalar_mult
 
 func testAddAssociativity[EC](a, b, c: EC) =
   var tmp1{.noInit.}, tmp2{.noInit.}: ECP_ShortW_Prj[Fp2[BLS12_381], G2]

tests/math/t_ec_shortw_prj_g1_mul_sanity.nim

@@ -10,9 +10,8 @@ import
   # Standard library
   std/[unittest, times],
   # Internals
-  ../../constantine/math/config/[common, curves],
+  ../../constantine/math/config/curves,
-  ../../constantine/math/[arithmetic, primitives],
+  ../../constantine/math/io/io_fields,
-  ../../constantine/math/io/[io_bigints, io_fields, io_ec],
   ../../constantine/math/elliptic/[ec_shortweierstrass_affine, ec_shortweierstrass_projective, ec_scalar_mul],
   # Test utilities
   ../../helpers/prng_unsafe,

tests/math/t_finite_fields_vs_gmp.nim

@@ -8,9 +8,9 @@
 
 import
   # Standard library
-  std/[random, macros, times, strutils],
+  std/[random, macros, times],
   # Third-party
-  gmp, stew/byteutils,
+  gmp,
   # Internal
   ../../constantine/platforms/abstractions,
   ../../constantine/math/io/[io_bigints, io_fields],

tests/math/t_pairing_bls12_377_line_functions.nim

@@ -8,7 +8,7 @@
 
 import
   # Standard library
-  std/[tables, unittest, times],
+  std/[unittest, times],
   # Internals
   ../../constantine/platforms/abstractions,
   ../../constantine/math/arithmetic,
@@ -21,7 +21,7 @@ import
     ec_scalar_mul],
   ../../constantine/math/pairing/lines_eval,
   # Test utilities
-  ../helpers/[prng_unsafe, static_for]
+  ../../helpers/[prng_unsafe, static_for]
 
 const
   Iters = 4

tests/math/t_pairing_bls12_381_line_functions.nim

@@ -8,7 +8,7 @@
 
 import
   # Standard library
-  std/[tables, unittest, times],
+  std/[unittest, times],
   # Internals
   ../../constantine/platforms/abstractions,
   ../../constantine/math/arithmetic,
@@ -17,11 +17,10 @@ import
   ../../constantine/math/io/io_extfields,
   ../../constantine/math/elliptic/[
     ec_shortweierstrass_affine,
-    ec_shortweierstrass_projective,
+    ec_shortweierstrass_projective],
-    ec_scalar_mul],
   ../../constantine/math/pairing/lines_eval,
   # Test utilities
-  ../helpers/[prng_unsafe, static_for]
+  ../../helpers/[prng_unsafe, static_for]
 
 const
   Iters = 4

tests/math/t_pairing_cyclotomic_subgroup.nim

@@ -8,7 +8,7 @@
 
 import
   # Standard library
-  std/[tables, unittest, times],
+  std/[unittest, times],
   # Internals
   ../../constantine/platforms/abstractions,
   ../../constantine/math/arithmetic,

tests/t_blssig_pop_on_bls12381_g2.nim

@@ -7,8 +7,8 @@
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
 import
-  std/[json, os, unittest, strutils],
+  std/[os, unittest, strutils],
-  pkg/[jsony, stew/byteutils],
+  pkg/jsony,
   ../constantine/blssig_pop_on_bls12381_g2,
   ../constantine/math/io/io_bigints
 

tests/t_ethereum_evm_precompiles.nim

@@ -9,8 +9,6 @@
 import
   # Standard library
   std/[times, os, strutils, macros],
-  # Status
-  pkg/stew/byteutils,
   # 3rd party
   pkg/jsony,
   # Internals

tests/t_hash_sha256_vs_openssl.nim

@@ -1,10 +1,9 @@
 import
   # Internals
   ../constantine/hashes,
+  ../constantine/math/io/io_bigints,
   # Helpers
-  ../helpers/prng_unsafe,
+  ../helpers/prng_unsafe
-  # Third-party
-  stew/byteutils
 
 # Deal with platform mess
 # --------------------------------------------------------------------
@@ -65,7 +64,7 @@ proc sanityABC =
   var bufCt: array[32, byte]
   let msg = "abc"
 
-  let hashed = hexToByteArray[32](
+  let hashed = array[32, byte].fromHex(
     "BA7816BF8F01CFEA414140DE5DAE2223" &
     "B00361A396177A9CB410FF61F20015AD")
 
@@ -77,7 +76,7 @@ proc sanityABC2 =
   var bufCt: array[32, byte]
   let msg = "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq"
 
-  let hashed = hexToByteArray[32](
+  let hashed = array[32, byte].fromHex(
     "248D6A61D20638B8E5C026930C3E6039" &
     "A33CE45964FF2167F6ECEDD419DB06C1")
 

tests/t_hash_to_curve.nim

@@ -8,7 +8,7 @@
 
 import
   # Standard library
-  std/[unittest, times, os, strutils, macros],
+  std/[unittest, times, os, strutils],
   # 3rd party
   pkg/jsony,
   # Internals

tests/t_hash_to_curve_random.nim

@@ -8,7 +8,7 @@
 
 import
   # Standard library
-  std/[unittest, times, os, strutils],
+  std/[unittest, times],
   # Internals
   ../constantine/math/config/curves,
   ../constantine/math/extension_fields,

tests/t_hash_to_field.nim

@@ -11,10 +11,7 @@ import
   ../constantine/hash_to_curve/h2c_hash_to_field,
   ../constantine/math/config/[curves_declaration, type_ff],
   ../constantine/math/extension_fields/towers,
-  ../constantine/math/io/[io_fields, io_extfields],
+  ../constantine/math/io/[io_bigints, io_fields, io_extfields]
-
-  # Third-party
-  stew/byteutils
 
 # Test vectors for expandMessageXMD
 # ----------------------------------------------------------------------
@@ -47,19 +44,19 @@ testExpandMessageXMD(1):
   let msg = ""
   const expected = "f659819a6473c1835b25ea59e3d38914c98b374f0970b7e4c92181df928fca88"
   const len_in_bytes = expected.len div 2
-  const expectedBytes = hexToByteArray[len_in_bytes](expected)
+  const expectedBytes = array[len_in_bytes, byte].fromHex(expected)
 
 testExpandMessageXMD(2):
   let msg = "abc"
   const expected = "1c38f7c211ef233367b2420d04798fa4698080a8901021a795a1151775fe4da7"
   const len_in_bytes = expected.len div 2
-  const expectedBytes = hexToByteArray[len_in_bytes](expected)
+  const expectedBytes = array[len_in_bytes, byte].fromHex(expected)
 
 testExpandMessageXMD(3):
   let msg = "abcdef0123456789"
   const expected = "8f7e7b66791f0da0dbb5ec7c22ec637f79758c0a48170bfb7c4611bd304ece89"
   const len_in_bytes = expected.len div 2
-  const expectedBytes = hexToByteArray[len_in_bytes](expected)
+  const expectedBytes = array[len_in_bytes, byte].fromHex(expected)
 
 testExpandMessageXMD(4):
   let msg = "q128_qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq" &
@@ -67,7 +64,7 @@ testExpandMessageXMD(4):
             "qqqqqqqqqqqqqqqqqqqqqqqqq"
   const expected = "72d5aa5ec810370d1f0013c0df2f1d65699494ee2a39f72e1716b1b964e1c642"
   const len_in_bytes = expected.len div 2
-  const expectedBytes = hexToByteArray[len_in_bytes](expected)
+  const expectedBytes = array[len_in_bytes, byte].fromHex(expected)
 
 testExpandMessageXMD(5):
   let msg = "a512_aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" &
@@ -82,7 +79,7 @@ testExpandMessageXMD(5):
             "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
   const expected = "3b8e704fc48336aca4c2a12195b720882f2162a4b7b13a9c350db46f429b771b"
   const len_in_bytes = expected.len div 2
-  const expectedBytes = hexToByteArray[len_in_bytes](expected)
+  const expectedBytes = array[len_in_bytes, byte].fromHex(expected)
 
 testExpandMessageXMD(6):
   let msg = ""
@@ -92,7 +89,7 @@ testExpandMessageXMD(6):
                     "fc5d9d8d77e2071b86ab114a9f34150954a7531da568a1ea8c7608" &
                     "61c0cde2005afc2c114042ee7b5848f5303f0611cf297f"
   const len_in_bytes = expected.len div 2
-  const expectedBytes = hexToByteArray[len_in_bytes](expected)
+  const expectedBytes = array[len_in_bytes, byte].fromHex(expected)
 
 testExpandMessageXMD(7):
   let msg = "abc"
@@ -102,7 +99,7 @@ testExpandMessageXMD(7):
                     "98619c0aa0c6c51fca15520789925e813dcfd318b542f879944127" &
                     "1f4db9ee3b8092a7a2e8d5b75b73e28fb1ab6b4573c192"
   const len_in_bytes = expected.len div 2
-  const expectedBytes = hexToByteArray[len_in_bytes](expected)
+  const expectedBytes = array[len_in_bytes, byte].fromHex(expected)
 
 testExpandMessageXMD(8):
   let msg = "abcdef0123456789"
@@ -112,7 +109,7 @@ testExpandMessageXMD(8):
                     "4b9535a819b445814890b7029b5de805bf62b33a4dc7e24acdf2c9" &
                     "24e9fe50d55a6b832c8c84c7f82474b34e48c6d43867be"
   const len_in_bytes = expected.len div 2
-  const expectedBytes = hexToByteArray[len_in_bytes](expected)
+  const expectedBytes = array[len_in_bytes, byte].fromHex(expected)
 
 testExpandMessageXMD(9):
   let msg = "q128_qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq" &
@@ -124,7 +121,7 @@ testExpandMessageXMD(9):
                     "720fe96ba53db947842120a068816ac05c159bb5266c63658b4f00" &
                     "0cbf87b1209a225def8ef1dca917bcda79a1e42acd8069"
   const len_in_bytes = expected.len div 2
-  const expectedBytes = hexToByteArray[len_in_bytes](expected)
+  const expectedBytes = array[len_in_bytes, byte].fromHex(expected)
 
 testExpandMessageXMD(10):
   let msg = "a512_aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" &
@@ -143,7 +140,7 @@ testExpandMessageXMD(10):
                     "42a0807bb148b77c2ef82ed4b6c9f7fcb732e7f94466c8b51e52bf" &
                     "378fba044a31f5cb44583a892f5969dcd73b3fa128816e"
   const len_in_bytes = expected.len div 2
-  const expectedBytes = hexToByteArray[len_in_bytes](expected)
+  const expectedBytes = array[len_in_bytes, byte].fromHex(expected)
 
 template testHashToField(id, constants: untyped) =
   # Section "Expand test vectors {#expand-testvectors}"

tests/t_kdf_hkdf.nim

@@ -7,11 +7,19 @@
 # at your option. This file may not be copied, modified, or distributed except according to those terms.
 
 import
-  stew/byteutils,
+  ../constantine/math/io/io_bigints,
   ../constantine/[hashes, mac/mac_hmac, kdf/kdf_hkdf]
 
 proc hexToBytes(s: string): seq[byte] =
-  if s.len != 0: return hexToSeqByte(s)
+  if s.len > 0:
+    var skip = 0
+    if s.len >= 2:
+      skip = 2*(
+        int(s[0] == '0') and
+        (int(s[1] == 'x') or int(s[1] == 'X'))
+      )
+    result.setLen((s.len - skip) div 2)
+    s.hexToPaddedByteArray(result, bigEndian)
 
 template test(id, constants: untyped) =
   proc `test _ id`() =