heimdal and OS X 10.3

Hello, the current version of heimdal (1.0.1) does not build on OS X 10.3:

ks_keychain.c: In function `set_private_key': ks_keychain.c:226: error: `kSecKeyKeySizeInBits' undeclared (first use in this function) ks_keychain.c:226: error: (Each undeclared identifier is reported only once ks_keychain.c:226: error: for each function it appears in.) ks_keychain.c: In function `keychain_iter': ks_keychain.c:458: error: `kSecKeyLabel' undeclared (first use in this function) make[3]: *** [libhx509_la-ks_keychain.lo] Error 1

These constants are only available from 10.4 (according to http://developer.apple.com/documentation/Security/Reference/SecurityRefUpdat...). Is there any recommendation on what to do on 10.3 systems? Thanks, A.