more precise detection of key description

Author: thestinger

src/main/java/app/attestation/server/AttestationProtocol.java

@@ -1235,12 +1235,12 @@ private static Verified verifyStateless(final Certificate[] certificates,
             }
 
             attestKey = true;
-        } catch (final CertificateParsingException e) {}
+        } catch (final Attestation.KeyDescriptionMissingException e) {}
 
         for (int i = 2; i < certificates.length; i++) {
             try {
                 new Attestation((X509Certificate) certificates[i]);
-            } catch (final CertificateParsingException e) {
+            } catch (final Attestation.KeyDescriptionMissingException e) {
                 continue;
             }
             throw new GeneralSecurityException("only initial key and attest key should have attestation extension");

src/main/java/app/attestation/server/attestation/Attestation.java

@@ -174,11 +174,17 @@ public String toString() {
         return s.toString();
     }
 
+    public class KeyDescriptionMissingException extends CertificateParsingException {
+        private KeyDescriptionMissingException(final String message) {
+            super(message);
+        }
+    }
+
     private ASN1Sequence getAttestationSequence(X509Certificate x509Cert)
             throws CertificateParsingException {
         byte[] attestationExtensionBytes = x509Cert.getExtensionValue(KEY_DESCRIPTION_OID);
         if (attestationExtensionBytes == null || attestationExtensionBytes.length == 0) {
-            throw new CertificateParsingException(
+            throw new KeyDescriptionMissingException(
                     "Did not find extension with OID " + KEY_DESCRIPTION_OID);
         }
         return Asn1Utils.getAsn1SequenceFromBytes(attestationExtensionBytes);