Add a couple of new helper functions to BER_Decoder:

decode_and_check takes an expected value; if the decoded value does
not match, a Decoding_Error with a specified string is thrown. Useful
for checking embedded version codes.

decode_octet_string_bigint is for decoding INTEGER values that are
stored as OCTET STRINGs. Totally obnoxious and useless, but common
especially in the ECC standards.

1 files changed, 1 insertions, 6 deletions

diff --git a/src/pubkey/pkcs8.cpp b/src/pubkey/pkcs8.cpp
index 400fdbb48..35ff7f206 100644
--- a/src/pubkey/pkcs8.cpp
+++ b/src/pubkey/pkcs8.cpp
@@ -105,19 +105,14 @@ SecureVector<byte> PKCS8_decode(DataSource& source, const User_Interface& ui,
             key = decryptor.read_all();
             }
 
-         u32bit version;
-
          BER_Decoder(key)
             .start_cons(SEQUENCE)
-               .decode(version)
+               .decode_and_check<u32bit>(0, "Unknown PKCS #8 version number")
                .decode(pk_alg_id)
                .decode(key, OCTET_STRING)
                .discard_remaining()
             .end_cons();
 
-         if(version != 0)
-            throw Decoding_Error("PKCS #8: Unknown version number");
-
          break;
          }
       catch(Decoding_Error)