commit cf4bf3da46ea3ed65b1f2355c5373232dd0d2d20
Author: Pierre-Olivier Mercier <nemunaire@nemunai.re>
Date:   Sun May 30 17:40:01 2021 +0200

    Initial commit

diff --git a/Dockerfile b/Dockerfile
new file mode 100644
index 0000000..fa04c88
--- /dev/null
+++ b/Dockerfile
@@ -0,0 +1,6 @@
+FROM alpine
+
+RUN apk add --no-cache openssl xxd zip
+COPY crxmake.sh /usr/bin/crxmake
+
+CMD ["crxmake.sh"]
\ No newline at end of file
diff --git a/crxmake.sh b/crxmake.sh
new file mode 100755
index 0000000..b182b21
--- /dev/null
+++ b/crxmake.sh
@@ -0,0 +1,59 @@
+# Purpose: Pack a Chromium extension directory into crx format
+
+if test $# -ne 1; then
+  echo "Usage: crxmake.sh <extension dir>"
+  exit 1
+fi
+
+dir=$1
+name=$(basename "$dir")
+crx="$name.crx"
+pub="$name.pub"
+sig="$name.sig"
+zip="$name.zip"
+tosign="$name.presig"
+binary_crx_id="$name.crxid"
+trap 'rm -f "$pub" "$sig" "$zip" "$tosign" "$binary_crx_id"' EXIT
+
+
+# zip up the crx dir
+cwd=$(pwd -P)
+(cd "$dir" && zip -qr -9 -X "$cwd/$zip" .)
+
+echo "${EXTENSION_CRX_KEY}" > /tmp/extension.pem
+cat /tmp/extension.pem
+
+#extract crx id
+openssl rsa -in /tmp/extension.pem -pubout -outform der | openssl dgst -sha256 -binary -out "$binary_crx_id"
+truncate -s 16 "$binary_crx_id"
+
+#generate file to sign
+(
+  # echo "$crmagic_hex $version_hex $header_length $pub_len_hex $sig_len_hex"
+  printf "CRX3 SignedData"
+  echo "00 12 00 00 00 0A 10" | xxd -r -p
+  cat "$binary_crx_id" "$zip"
+) > "$tosign"
+
+# signature
+openssl dgst -sha256 -binary -sign /tmp/extension.pem < "$tosign" > "$sig"
+
+# public key
+openssl rsa -pubout -outform DER < /tmp/extension.pem > "$pub" 2>/dev/null
+
+
+crmagic_hex="43 72 32 34" # Cr24
+version_hex="03 00 00 00" # 3
+header_length="45 02 00 00"
+header_chunk_1="12 AC 04 0A A6 02"
+header_chunk_2="12 80 02"
+header_chunk_3="82 F1 04 12 0A 10"
+(
+  echo "$crmagic_hex $version_hex $header_length $header_chunk_1" | xxd -r -p
+  cat "$pub"
+  echo "$header_chunk_2" | xxd -r -p
+  cat "$sig"
+  echo "$header_chunk_3" | xxd -r -p
+  cat "$binary_crx_id" "$zip"
+) > "$crx"
+echo "Wrote $crx"