Authentication Tag ignored in CCM

[philips77]

Describe the bug
CCM init allows to pass the authenticationTag as a parameter, if it's not included in the ciphertext:

CryptoSwift/Sources/CryptoSwift/BlockMode/CCM.swift

Lines 61 to 72 in e745937

	/// Initialize CCM
	///
	/// - Parameters:
	/// - iv: Initialization vector. Nonce. Valid length between 7 and 13 bytes.
	/// - tagLength: Authentication tag length, in bytes. Value of {4, 6, 8, 10, 12, 14, 16}.
	/// - messageLength: Plaintext message length (excluding tag if attached). Length have to be provided in advance.
	/// - authenticationTag: Authentication Tag value if not concatenated to ciphertext.
	/// - additionalAuthenticatedData: Additional authenticated data.
	public init(iv: Array<UInt8>, tagLength: Int, messageLength: Int, authenticationTag: Array<UInt8>, additionalAuthenticatedData: Array<UInt8>? = nil) {
	self.init(iv: iv, tagLength: tagLength, messageLength: messageLength, additionalAuthenticatedData: additionalAuthenticatedData)
	self.authenticationTag = authenticationTag
	}

However, this tag is then ignored:

CryptoSwift/Sources/CryptoSwift/BlockMode/CCM.swift

Line 105 in e745937

init(blockSize: Int, nonce: ArraySlice<UInt8>, messageLength: Int, additionalAuthenticatedData: [UInt8]?, expectedTag: Array<UInt8>? = nil, tagLength: Int, cipherOperation: @escaping CipherOperationOnBlock) {

CryptoSwift/Sources/CryptoSwift/BlockMode/CCM.swift

Lines 74 to 81 in e745937

	public func worker(blockSize: Int, cipherOperation: @escaping CipherOperationOnBlock, encryptionOperation: @escaping CipherOperationOnBlock) throws -> CipherModeWorker {
	if self.nonce.isEmpty {
	throw Error.invalidInitializationVector
	}
	return CCMModeWorker(blockSize: blockSize, nonce: self.nonce.slice, messageLength: self.messageLength, additionalAuthenticatedData: self.additionalAuthenticatedData, tagLength: self.tagLength, cipherOperation: cipherOperation)
	}
	}

where expectedTag is not used, and set to nil.

Reproduce
The following code does not decode properly:

let ccm = CCM(iv: nonce, tagLength: mic.count, messageLength: data.count,
              authenticationTag: mic,
              additionalAuthenticatedData: aad)
let aes = try AES(key: key, blockMode: ccm, padding: .noPadding)
let array = try aes.decrypt(data)
return Data(array)

however, when I concatenate data and mic, it works:

let concatenated = data + mic
let ccm = CCM(iv: nonce, tagLength: mic.count, messageLength: data.count,
              additionalAuthenticatedData: aad)
let aes = try AES(key: key, blockMode: ccm, padding: .noPadding)
let array = try aes.decrypt(concatenated)
return Data(array)

[philips77]

Ref: https://github.com/NordicSemiconductor/IOS-nRF-Mesh-Library/blob/408c08121a2e7d9bd6b40dd190030d1b453b9981/nRFMeshProvision/Classes/Crypto/Crypto.swift#L408