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A Python implementation of Sign-In with Ethereum (EIP-4361).

Project description

with Ethereum

This package provides a Python implementation of EIP-4361: Sign In With Ethereum.


SIWE can be easily installed in any Python project with pip:

pip install siwe


SIWE provides a SiweMessage class which implements EIP-4361.

Parsing a SIWE Message

Parsing is done by initializing a SiweMessage object with an EIP-4361 formatted string:

from siwe import SiweMessage
message: SiweMessage = SiweMessage(message=eip_4361_string)

Alternatively, initialization of a SiweMessage object can be done with a dictionary containing expected attributes:

message: SiweMessage = SiweMessage(message={"domain": "", "address": "0x1234...", ...})

Verifying and Authenticating a SIWE Message

Verification and authentication is performed via EIP-191, using the address field of the SiweMessage as the expected signer. The validate method checks message structural integrity, signature address validity, and time-based validity attributes.

    # You can also specify other checks (e.g. the nonce or domain expected).
except siwe.ValidationError:
    # Invalid

Serialization of a SIWE Message

SiweMessage instances can also be serialized as their EIP-4361 string representations via the prepare_message method:



Parsing and verifying a SiweMessage is easy:

    message: SiweMessage = SiweMessage(message=eip_4361_string)
    message.verify(signature, nonce="abcdef", domain=""):
except siwe.ValueError:
    # Invalid message
    print("Authentication attempt rejected.")
except siwe.ExpiredMessage:
    print("Authentication attempt rejected.")
except siwe.DomainMismatch:
    print("Authentication attempt rejected.")
except siwe.NonceMismatch:
    print("Authentication attempt rejected.")
except siwe.MalformedSession as e:
    # e.missing_fields contains the missing information needed for validation
    print("Authentication attempt rejected.")
except siwe.InvalidSignature:
    print("Authentication attempt rejected.")

# Message has been verified. Authentication complete. Continue with authorization/other.


poetry install
git submodule update --init
poetry run pytest

See Also


Our Python library for Sign-In with Ethereum has not yet undergone a formal security audit. We welcome continued feedback on the usability, architecture, and security of this implementation.

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