kingpin-apps/swift-cose

Platform support

| Platform | Status | |---|---| | iOS / macOS / watchOS / tvOS / visionOS | ✓ | | Linux | ✓ | | Android | ✓ | | WebAssembly (WASI) | ✗ — blocked upstream |

WASM is blocked by apple/swift-crypto's _CryptoExtras module (pulled in transitively via swift-certificates/X509): Sources/_CryptoExtras/Util/ThreadSpecific/ThreadSpecific.swift references a ThreadOpsSystem typealias that has no WASI implementation. Upstream itself is not green for WASM — see the swift-crypto build matrix. We'll revisit when upstream lands WASI support.

Usage

To add SwiftCOSE as dependency to your Xcode project, select File > Swift Packages > Add Package Dependency, enter its repository URL: https://github.com/Kingpin-Apps/swift-cose.git and import SwiftCOSE.

``swift dependencies: [ .package(url: "https://github.com/Kingpin-Apps/swift-cose.git", from: "0.0.1") ] ``

Then, to use it in your source code, add:

import SwiftCOSE

What is COSE ?

CBOR Encoded Message Syntax (COSE) is a data format for concise representation of small messages RFC 8152. COSE is optimized for low power devices. The messages can be encrypted, MAC'ed and signed. There are 6 different types of COSE messages:

• Encrypt0: An encrypted COSE message with a single recipient. The payload and AAD are protected by a shared CEK (Content Encryption Keys)
• Encrypt: An encrypted COSE message can have multiple recipients. For each recipient the CEK is encrypted with a KEK (Key Encryption Key) - using AES key wrap - and added to the message.
• MAC0: An authenticated COSE message with one recipient.
• MAC: An authenticated COSE message that can have multiple recipients. For each recipient, the authentication key is encrypted with a KEK and added to the message.
• Sign1: A signed COSE message with a single signature.
• Sign: A COSE message that has been signed by multiple entities (each signature is carried in a COSE signature structure, added to the message).

A basic COSE message consists of 2 information buckets and the payload:

• Protected header: This message field contains information that needs to be protected. This information is taken into account during the encryption, calculation of the MAC or the signature.
• Unprotected header: The information contained in the unprotected header is not protected by the cryptographic algorithms.
• Payload: Contains the payload of the message, protected (mac'ed, signed or encrypted) by the cryptographic algorithms.

Additionally, based on the message type, other message fields can be added:

• MAC or signature (for MAC0 or Sign1 messages)
• COSE recipients or COSE signatures (for MAC, Encrypt, and Sign messages)

Examples

Encoding

import SwiftCOSE

// Create a COSE Encrypt0 Message
let msg = Enc0Message(
    phdr: [
        Algorithm(): A128GCM(),
        IV(): Data([0x01, 0x02, 0x03, 0x04])
    ],
    uhdr: [
        KID(): Data("test.guy@example.com".utf8)
    ],
    payload: Data("A secret message".utf8)
)

// Create a COSE Symmetric Key
let coseKey = SymmetricKey.generateKey(keyLength: 32)
msg.key = coseKey

// Performs encryption and CBOR serialization
msg.encode()

Decoding

import SwiftCOSE

// message bytes (CBOR encoded)
let msg = Data([0xd8, 0x3d, 0x85, 0x01, 0x01, 0xa0, 0x01, 0x02, 0x03, 0x04, 0x58, 0x14, 0x54, 0x65, 0x73, 0x74, 0x20, 0x6d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65])

let coseMsg = Enc0Message.decode(from: msg)

// Create a COSE Symmetric Key
let coseKey = SymmetricKey.generateKey(keyLength: 32)
msg.key = coseKey

msg.decrypt()

Package Metadata

Repository: kingpin-apps/swift-cose

Default branch: main

README: README.md