extract-kem-from-nist-submission

#!/bin/bash
set -euo pipefail
shopt -s inherit_errexit

# Remove the old implementation.
rm -rf kem

archive=mceliece-20221023
archfile=$archive.tar.gz

echo -n "md5:    "; md5sum    $archfile | cut -c 1-32
echo -n "sha1:   "; sha1sum   $archfile | cut -c 1-40
echo -n "sha256: "; sha256sum $archfile | cut -c 1-64
echo

# Extract the reference implementation.
tar -xf $archfile $archive/Reference_Implementation/kem/ --strip-components=2

prepare_algorithm() {
  echo "Preparing $id"
  add_header $1
  add_gyp $1
  patch_files $1
}

add_header() {
  id=$1
  echo "#include \"kem/$id/crypto_kem_$id.h\"" >> mceliece.h
  echo "- Added $id to mceliece.h"
}

add_gyp() {
  id=$1

  variables=("CRYPTO_NAMESPACE(x)=pqcrypto_kem_${id}_##x"  \
             "_CRYPTO_NAMESPACE(x)=_pqcrypto_kem_${id}_##x")

  (
    echo "    {"
    echo "      'target_name': 'only_$id',"
    echo "      'type': 'static_library',"
    echo "      'sources': ["
    find kem/$id -maxdepth 1 -type f -name '*.c' | sort | while read source; do
      echo "        '$source',"
    done
    echo "      ],"
    echo "      'include_dirs': ["
    echo "        'kem/$id/subroutines',"
    echo "      ],"
    echo "      'defines': ["
    for def in ${variables[@]}; do
      echo "        '$def',"
    done
    echo "      ],"
    echo "      'cflags': ['-fPIC', '-Wno-unused-function']"
    echo "    },"
  ) >> binding.gyp

  echo "- Added $id to binding.gyp"
}

patch_files() {
  id=$1

  (
    # Non-source files.
    find kem/$id/ -type f ! -name '*.c' ! -name '*.h'
    # Only required for the NIST submission.
    echo kem/$id/nist
    # Irrelevant header files.
    echo kem/$id/api.h
  ) | while read f; do
    rm -r "$f"
    echo "- Removed $f"
  done

  find kem/$id -type f \( -name '*.c' -o -name '*.h' \) | while read source; do
    oldsha=$(sha1sum "$source")
    sed -i 's=<libkeccak\.a\.headers/SimpleFIPS202\.h>="../../mceliece_externals.h"=g; s="nist/rng.h"="../../mceliece_externals.h"=g' $source
    newsha=$(sha1sum "$source")
    if [ "$oldsha" != "$newsha" ]; then
      echo "- Patched $source"
    fi
  done
}

rm -f mceliece.h

implementations=`ls -1 kem | while read id; do if [ -d "kem/$id" ]; then echo $id; fi; done | sort`
(
  echo "{"
  echo "  'targets': ["
  echo "    {"
  echo "      'target_name': 'mceliece',"
  echo "      'type': 'none',"
  echo "      'dependencies': ["
  for impl in $implementations; do
    echo "        'only_$impl',"
  done
  echo "      ]"
  echo "    },"
) > binding.gyp

for id in $implementations; do
  prepare_algorithm $id
done

(
  echo "  ]"
  echo "}"
) >> binding.gyp