krb5_k_verify_checksum_iov
ret = krb5_k_verify_checksum_iov(context, checksum_type, key, usage, data,
code = krb5_k_verify_checksum_iov(context, type, key, sign_usage, kiov, kiov_count, valid);
return krb5_k_verify_checksum_iov(context, cksumtype, key, usage, iov, 3,