1 files changed, 49 insertions, 0 deletions
diff --git a/krebs/5pkgs/simple/syncthing-device-id.nix b/krebs/5pkgs/simple/syncthing-device-id.nix
new file mode 100644
index 000000000..9533800fd
--- /dev/null
+++ b/krebs/5pkgs/simple/syncthing-device-id.nix
@@ -0,0 +1,49 @@
+{ openssl, writePython2Bin }:
+
+writePython2Bin "syncthing-device-id" {
+  flakeIgnore = [
+    "E226"
+    "E302"
+    "E305"
+    "E501"
+    "F401"
+  ];
+} /* python */ ''
+  import base64
+  import hashlib
+  import subprocess
+  import sys
+
+  B32ALPHABET = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567'
+
+  def luhn_checksum(data, alphabet=B32ALPHABET):
+      n = len(alphabet)
+      number = tuple(alphabet.index(i) for i in reversed(data))
+      result = (sum(number[::2]) +
+                sum(sum(divmod(i * 2, n)) for i in number[1::2])) % n
+      return alphabet[-result]
+
+  def main(incert):
+      der_data = subprocess.check_output([
+          '${openssl}/bin/openssl',
+          'x509',
+          '-outform',
+          'DER',
+      ], stdin=incert)
+      data_hash = hashlib.sha256(der_data)
+      b32_hash = base64.b32encode(data_hash.digest()).decode('ascii')
+
+      result = b32_hash.upper().rstrip('=')
+      blocks = [result[pos:pos+13] for pos in range(0, len(result), 13)]
+      result = '''.join(block + luhn_checksum(block) for block in blocks)
+
+      blocks = [result[pos:pos+7] for pos in range(0, len(result), 7)]
+      print('-'.join(blocks))
+
+  if __name__ == '__main__':
+      import argparse
+      parser = argparse.ArgumentParser(description='Generate syncthing ID from certificate')
+      parser.add_argument('incert', type=argparse.FileType('rb'), help='Certificate path')
+      args = parser.parse_args()
+      main(**vars(args))
+''