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

> @mount("ft4.evm_ signatures")
operation evm_ signatures(signers: list<byte_ array>, signatures: list< signature ?>) When it is required that an EVM signer 

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

OPERATION

# evm\_signatures

```signature
@mount("ft4.evm_signatures")
operation evm_signatures(signers: list<byte_array>, signatures: list<signature?>)
```

[Source](https://gitlab.com/chromaway/ft4-lib/-/blob/development/rell/src/lib/ft4/external/auth/operations.rell#lines-76)

When it is required that an EVM signer signs an operation, but the signer is not part of
an account auth descriptor yet, this operation must be used.

The operation must contain:

* evm\_signers
* if required, an auth operation or a strategy operation
* the operation that is being authorized

with nothing else inbetween them. Other operations may be added before and after these two.

Throws if:

* the operation that is being authorized is not whitelisted,
* there's no operation after this one, or
* there is only one operation after this one, and it's an auth or strategy operation

**Parameters**

* **signers** — The EVM addresses of signers (without `0x`)
* **signatures** — The signatures of the operation's auth message

**See Also**

* `core.auth.is_evm_signatures_authorized_operation` — for information on whitelisting operations to be able to accept EVM signatures that are not part of an auth descriptor
* [evm\_auth](https://docs.chromia.com/pages/ft4-rell/-f-t4-library/lib.ft4.external.auth/evm_auth/) — for information on how to retrieve messages and properly sign them
* `core.auth.is_auth_op` — for information on what is an auth operation
* `core.accounts.strategies.is_strategy_op` — for information on what is a strategy operation

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