cose-rust

A Rust crate to encode and decode secured data (Signatures, Encryption or MACed) in CBOR Object Signing and Encryption (COSE) format, RFC 8152.

This crate uses the rust-openssl for the cryptographic operations and the cbor-codec for the CBOR encoding/decoding.

COSE

COSE is a concise binary data format that protects the payload of the message with a set of cryptographic operations.

A COSE structure is as follows: 1. Tag: A COSE mesage type identifier. 2. Protected header: A CBOR encoded object that contains information to be integrity protected by the cryptographic process.
3. Unprotected header: An object that contains information that is not integrity protected. 4. Content: This is specific to each type of message: 1. cose-sign1: payload and its signature. 3. cose-encrypt0: just the ciphertext. 2. cose-mac0: payload and its tag. 4. cose-sign: payload and an array of recipient buckets (each similar to cose-sign1). 5. cose-encrypt: ciphertext and an array of recipients buckets (each similar to cose-encrypt0). 6. cose-mac: payload and an array of recipients buckets (each similar to cose-mac0).

This COSE structure is than encoded in CBOR data format, resulting in a compact binary representation.

The COSE RFC 8152 specifies the following 6 types of COSE messages:

• cose-sign1: A digitally signed COSE message with a single recipient.
• cose-sign: A digitally signed COSE message with multiple recipients, each recipient has its own signature.
• cose-encrypt0: An encrypted COSE message with a single recipient.
• cose-encrypt: An encrypted COSE message with multiple recipients. In this case, for each recipient, the ciphertext is encrypted/decrypted by a shared secret between the recipient and the sender, a derived key from the shared secret or a randomly generated CEK that is derived from the shared secret (KEK).
• cose-mac0: A MAC tagged COSE message with a single recipient.
• cose-encrypt: A MAC tagged COSE message with multiple recipients. In this case, for each recipient, the tag is created/verified by a shared secret between the recipient and the sender, a derived key from the shared secret or a randomly generated CEK that is derived from the shared secret (KEK).

Usage

To import cose-rust, add the following to your Cargo.toml:

toml [dependencies] cose-rust = "0.1"

and to use it:

rust use cose;

License

This crate, cose-rust, is licensed by the MIT License.

Note

This crate is under development and it has not been tested yet.