> For the complete documentation index, see [llms.txt](https://docs.griaule.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.griaule.com/gbs/en/gbds-configuration/key-validation.md).
# Key Validation
Starting with GBDS 5 new settings were added to the API
Configuration
Default Value
gbds.keyValidation.oneKeyOnly
false
gbds.keyValidation.keyFormat
false
gbds.keyValidation.inconsistentKeys
true
## Behavior
### Single key validation
The API will reject any transaction that has more than one key (enroll, update, trusted enroll and trusted update)
### Key format validation
The API will reject any transaction whose keys fail format validation.
The API will evaluate the format in the table `gbds.key_format` for each provided key ID
The API will check the following:
| Type | Validation |
| ------------ | ------------------------------------------------------------------------------- |
| CPF | Must pass the checksum validation for CPF |
| TITULO | Must pass the checksum validation for the voter registration |
| REGEX | Must pass the regex provided in the field `regex` |
| ALPHANUMERIC | Key must contain only alphanumeric characters |
| NUMERIC | Key must contain only numeric characters |
| ALPHABETIC | Key must contain only alphabetic characters |
| LENGTH | If a minimum/maximum size is configured, the key will have its length validated |
### Inconsistent Keys
When this setting is enabled, the transaction will be rejected on enroll/update/trusted when keys are potentially inconsistent when an update is performed
Cases of inconsistent keys:
* If the payload is provided with more than one key and those keys match more than one person
| IDs | Keys in the Payload | Person 1 in the Database | Person 2 in the Database |
| --------- | ------------------- | ------------------------ | ------------------------ |
| ***cpf*** | cpf-01 | cpf-01 | - |
| ***rg*** | rg-01 | - | rg-01 |
* If the payload is provided with more than one key and one key matches a person's key but that person has any other key with an ID that matches another key in the payload, but with a different value.
| IDs | Keys in the Payload | Person in the Database |
| --------- | ------------------- | ---------------------- |
| ***cpf*** | cpf-01 | cpf-01 |
| ***rg*** | rg-01 | rg-02 |
The id "rg" matches in the payload and in the person in the database, but both have different values
{% hint style="info" %}
With the setting disabled, the above transaction will raise an exception as happens in GBDS 4
{% endhint %}
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