# check_single_sig_auth · FT4 Rell API · Chromia Docs (concept)

> function check_ single_ sig_ auth(args: byte_ array, signers: list<byte_ array>, required_ flags: list<text>): validation_result Checks that the single sig

Source: https://docs.chromia.com/pages/ft4-rell/-f-t4-library/lib.ft4.core.accounts/check_single_sig_auth/

FUNCTION

# check\_single\_sig\_auth

```signature
function check_single_sig_auth(args: byte_array, signers: list<byte_array>, required_flags: list<text>): validation_result
```

[Source](https://gitlab.com/chromaway/ft4-lib/-/blob/development/rell/src/lib/ft4/core/accounts/auth_basic.rell#lines-68)

Checks that the single signature auth descriptor has all the requirements to authorize an
operation.

Can only be called from an operation.

Gives invalid result `"SIGNERS ERROR"` if `signers` has zero or more than one elements.

Gives invalid result `"MISSING SIGNATURE"` if the signer did not sign the
operation that called this function.

Gives invalid result `"MISSING FLAGS"` if the `single_sig_args` does not contain
all required flags.

**Parameters**

* **args** — The args for this auth descriptor. Expected to be a gtv encoded version of the `single_sig_args` struct.
* **signers** — The signer for this auth descriptor. Expected to be a list containing exactly one pubkey or EVM address (without `0x`)
* **required\_flags** — The flags it must have for the operation that needs to be authorized.

**Returns**

`utils.VALID` if valid, `utils.invalid` otherwise.

[View this page on docs.chromia.com](https://docs.chromia.com/pages/ft4-rell/-f-t4%20-library/lib.ft4.core.accounts/check_single_sig_auth.html)Generated API reference, mirrored from the live docs