Sign1

Sign1Message messages are used when there is a single signature attached to the basic COSE structure, consisting of headers and payload. Receivers must implicitly know the public key to verify the message since no additional key information is transported.

The payload can either be included in the message or remain detached. Detached payloads must be provided as detached_payload argument during signing and verification.

../../_images/sign1.png
class pycose.messages.sign1message.Sign1Message(phdr=None, uhdr=None, payload=None, external_aad=b'', key=None, *args, **kwargs)
encode(tag=True, sign=True, detached_payload=None, *args, **kwargs)

Encodes the message into a CBOR array with or without a CBOR tag.

compute_signature(detached_payload=None, *args, **kwargs)

Computes the signature over a COSE message.

Returns:

the signature

classmethod decode(received, *args, **kwargs)

Decode received COSE message based on the CBOR tag.

If called on CoseMessage, this function can decode any supported message type. Otherwise, if called on a sub-class of CoseMessage, only messages of that type will be allowed to be decoded.

Parameters:

received – COSE messages encoded as bytes

Raises:

  • AttributeError – When the COSE message, it cannot be decoded properly

  • ValueError – The received parameter must be bytes

  • KeyError – thrown when the CBOR tag, identifying the COSE message is unrecognized

  • TypeError – thrown when the messages cannot be decoded properly

  • TypeError – The message’s tag does not match the expected type.

Returns:

An initialized CoseMessage

get_attr(attribute, default=None)

Fetches an header attribute from the COSE header buckets.

Parameters:

  • attribute – A header parameter to fetch from the buckets.

  • default – A default return value in case the attribute was not found

Raises:

CoseException – When the same attribute is found in both the protected and unprotected header.

Returns:

If found returns a header attribute else ‘None’ or the default value

property phdr_encoded

Encode the protected header.

Returns:

Returns the encoded protected header.

property uhdr_encoded

Encode the unprotected header.

Returns:

Returns the encoded unprotected header.

verify_signature(detached_payload=None, *args, **kwargs)

Verifies the signature of a received COSE message.

Returns:

True for a valid signature or False for an invalid signature