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

> function _ validate_ evm_ signature(op: gtx_ operation, auth_ op: gtx_ operation, flags: list<text>, account: account , auth_ descriptor: account_ auth_ de

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

FUNCTION

# \_validate\_evm\_signature

```signature
function _validate_evm_signature(op: gtx_operation, auth_op: gtx_operation, flags: list<text>, account: account, auth_descriptor: account_auth_descriptor)
```

[Source](https://gitlab.com/chromaway/ft4-lib/-/blob/development/rell/src/lib/ft4/core/auth/authentication.rell#lines-328)

Verifies that the signature found in the `evm_auth` operation is valid to authorize the
operation being called.

Throws if the signature cannot be validated. The most common reasons include:

* the auth handler for `op` is not found
* the signer is not registered in the auth descriptor
* too few signers signed the operation, in case of a multisig auth descriptor
* the signer signed the wrong message
* the auth descriptor does not give sufficient permissions for the operation that is being
  called

**Parameters**

* **op** — the operation being called
* **auth\_op** — the `evm_auth` operation that is authorizing this operation
* **flags** — the flags required by the operation
* **account** — the account the user authenticated as
* **auth\_descriptor** — the auth descriptor that is authorizing this operation

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