COSEMessage

The COSEMessage class encapsulates the structure and functionality of COSE messages within the Uniot project. It leverages the CBORObject class for handling CBOR-encoded data and integrates with cryptographic libraries (such as Ed25519) to provide robust signing and verification mechanisms. The class supports the creation, manipulation, signing, and verification of COSE_Sign1 messages, ensuring data integrity and authenticity in communications.

Constructor and Destructor:

  • COSEMessage() Constructs an empty COSEMessage instance. Initializes a new COSE_Sign1 message, setting up protected and unprotected headers, payload, and signature fields.

  • COSEMessage(Bytes buf) Constructs a COSEMessage instance from a given byte buffer. Parses the provided byte buffer to populate the COSE_Sign1 message fields. Sets the read success flag based on the parsing outcome.

  • virtual ~COSEMessage() Destructor that cleans up the COSE message. Frees allocated resources and resets internal pointers to prevent memory leaks.

Message Handling:

  • bool read(const Bytes &buf) Decodes the byte buffer and extracts the protected header, unprotected header, payload, and signature fields. Validates the structure and content of the COSE message.

  • bool wasReadSuccessful() const Checks if the last read operation was successful.

Header Manipulation:

  • Bytes getProtectedHeader() Extracts the protected header portion of the COSE message for inspection or modification.

  • CBORObject getUnprotectedHeader() Provides access to the unprotected headers, allowing for the addition or modification of header fields.

  • Bytes getUnprotectedKid() Extracts the Key Identifier (kid) used for identifying the key associated with the COSE message.

Payload and Signature:

  • Bytes getPayload() Retrieves the payload of the COSE message.

  • Bytes getSignature() Retrieves the signature of the COSE message.

Signing and Verification:

  • void sign(const ICOSESigner &signer, const Bytes &external = Bytes()) Signs the COSE message using the provided signer.

    • signer (const ICOSESigner &): The signer object implementing the ICOSESigner interface.

    • external (const Bytes &, optional): External Additional Authenticated Data (AAD) to include in the signature.

  • bool verify(const Bytes &publicKey) Verifies the signature of the COSE message using the provided public key.

Serialization:

  • Bytes build() const Serializes the COSEMessage into a byte buffer.

State Management:

  • bool isSigned() Checks if the COSE message has been signed.

  • void clean() Resets the COSEMessage to its initial state.

Private Methods:

  • bool _read(const Bytes &buf) Internal method to parse a byte buffer and populate the COSE message fields.

  • void _create() Initializes the internal CBOR structure for a new COSE_Sign1 message.

  • void _clean() Cleans up the internal CBOR structure and resets pointers.

  • bool _setProtectedHeader(const CBORObject &pHeader) Sets the protected header of the COSE message.

  • bool _setSignature(const Bytes &signature) Sets the signature of the COSE message.

  • Bytes _toBeSigned(const Bytes &external = Bytes()) Builds the Sig_structure as defined in the COSE specification, which includes the context, protected header, external AAD, and payload. This sequence is what the signer uses to generate the signature.

    • external (const Bytes &, optional): External Additional Authenticated Data (AAD) to include in the signature.

PreviousCOSENextICOSESigner

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