- Support signature verification with SubjectPublicKeyInfo formatted keys

since, although rare, they are RFC 6376 specified (LP: #1851862)

ChangeLog

@@ -3,6 +3,8 @@ Version 1.0.0
     - Add new timeout parameter to enable DNS lookup timeouts to be adjusted
     - Add new DKIM.present function to allow applications to test if a DKIM
       signature is present without doing validation (LP: #1851141)
+    - Support signature verification with SubjectPublicKeyInfo formatted keys
+      since, although rare, they are RFC 6376 specified (LP: #1851862)
     - Drop usage of pymilter Milter.dns in dnsplug since it doesn't support
       havine a timeout passed to it
 

dkim/crypto.py

@@ -118,8 +118,11 @@ def parse_public_key(data):
         # Not sure why the [1:] is necessary to skip a byte.
         x = asn1_parse(ASN1_Object, data)
         pkd = asn1_parse(ASN1_RSAPublicKey, x[0][1][1:])
-    except ASN1FormatError as e:
-        raise UnparsableKeyError('Unparsable public key: ' + str(e))
+    except ASN1FormatError as e_spki:
+        try:
+            pkd = asn1_parse(ASN1_RSAPublicKey, data)
+        except ASN1FormatError as e_rsa:
+            raise UnparsableKeyError('Unparsable public key; SubjectPublicKeyInfo: ' + str(e_spki) + '; RSAPublicKey: ' + str(e_rsa))
     pk = {
         'modulus': pkd[0][0],
         'publicExponent': pkd[0][1],