Creating a cryptographic key stored in Secure Enclave

KeychainSE.swift

    static func makeAndStoreKey(name: String,
                                requiresBiometry: Bool = false) throws -> SecKey {

        let flags: SecAccessControlCreateFlags
        if #available(iOS 11.3, *) {
            flags = requiresBiometry ?
                [.privateKeyUsage, .biometryCurrentSet] : .privateKeyUsage
        } else {
            flags = requiresBiometry ?
                [.privateKeyUsage, .touchIDCurrentSet] : .privateKeyUsage
        }
        let access =
            SecAccessControlCreateWithFlags(kCFAllocatorDefault,
                                            kSecAttrAccessibleWhenUnlockedThisDeviceOnly,
                                            flags,
                                            nil)!
        let tag = name.data(using: .utf8)!
        let attributes: [String: Any] = [
            kSecAttrKeyType as String           : kSecAttrKeyTypeEC,
            kSecAttrKeySizeInBits as String     : 256,
            kSecAttrTokenID as String           : kSecAttrTokenIDSecureEnclave,
            kSecPrivateKeyAttrs as String : [
                kSecAttrIsPermanent as String       : true,
                kSecAttrApplicationTag as String    : tag,
                kSecAttrAccessControl as String     : access
            ]
        ]
        
        var error: Unmanaged<CFError>?
        guard let privateKey = SecKeyCreateRandomKey(attributes as CFDictionary, &error) else {
            throw error!.takeRetainedValue() as Error
        }
        
        return privateKey
    }