krb5_k_verify_checksum
krb5_k_verify_checksum(NULL, key, 0, &block, &sum, &val);
ret = krb5_k_verify_checksum(context, key, usage, data, cksum, valid);
code = krb5_k_verify_checksum(context, subkey,
code = krb5_k_verify_checksum(context, key, KRB5_KEYUSAGE_FINISHED, conv,
ret = krb5_k_verify_checksum(context, key,
ret = krb5_k_verify_checksum(context, key, KRB5_KEYUSAGE_KRB_SAFE_CKSUM,