algrid

import UIKit

class ViewController: UIViewController {

    let fullWidth = UIScreen.main.bounds.width
    let tableView = UITableView()
    
    let headerView: UIView = {
        let v = Header()
        v.backgroundColor = .red

algrid

    guard let publicKey = SecKeyCopyPublicKey(key!) else {
        UIAlertController.showSimple(title: "Can't verify signature",
                                     text: "Can't get public key",
                                     from: self)
        return
    }

    let algorithm: SecKeyAlgorithm = .ecdsaSignatureMessageX962SHA256
    guard SecKeyIsAlgorithmSupported(publicKey, .verify, algorithm) else {
        UIAlertController.showSimple(title: "Can't verify signature",

algrid

    let clearTextData = clearText.data(using: .utf8)!
    
    // Signing the original message
    sign(algorithm: .ecdsaSignatureMessageX962SHA256, data: clearTextData)

    // Signing precalculated sha256 hash of the original message (produces the same result)
    sign(algorithm: .ecdsaSignatureDigestX962SHA256, data: sha256(data: clearTextData))

algrid

    private func sign(algorithm: SecKeyAlgorithm, data: Data) {
        
        guard SecKeyIsAlgorithmSupported(key!, .sign, algorithm) else {
            UIAlertController.showSimple(title: "Can't sign",
                                         text: "Algorith not supported",
                                         from: self)
            return
        }
        
        // SecKeyCreateSignature call is blocking when the used key

algrid

    // cipherTextData is our encrypted data

    let algorithm: SecKeyAlgorithm = .eciesEncryptionCofactorVariableIVX963SHA256AESGCM
    guard SecKeyIsAlgorithmSupported(self.key!, .decrypt, algorithm) else {
        UIAlertController.showSimple(title: "Can't decrypt",
                                     text: "Algorith not supported", from: self)
        return
    }

    // SecKeyCreateDecryptedData call is blocking when the used key

algrid

    let clearText = "Hello"

    let algorithm: SecKeyAlgorithm = .eciesEncryptionCofactorVariableIVX963SHA256AESGCM
    guard SecKeyIsAlgorithmSupported(publicKey, .encrypt, algorithm) else {
        UIAlertController.showSimple(title: "Can't encrypt",
                                     text: "Algorith not supported", from: self)
        return
    }
    var error: Unmanaged<CFError>?
    let clearTextData = clearText.data(using: .utf8)!

algrid

    guard let publicKey = SecKeyCopyPublicKey(key) else {
        // Can't get public key
        return
    }
    let algorithm: SecKeyAlgorithm = .eciesEncryptionCofactorVariableIVX963SHA256AESGCM
    guard SecKeyIsAlgorithmSupported(publicKey, .encrypt, algorithm) else {
        // Algorith not supported
        return
    }
    // Now we're ready to encrypt data using publicKey

algrid

    static func loadKey(name: String) -> SecKey? {
        let tag = name.data(using: .utf8)!
        let query: [String: Any] = [
            kSecClass as String                 : kSecClassKey,
            kSecAttrApplicationTag as String    : tag,
            kSecAttrKeyType as String           : kSecAttrKeyTypeEC,
            kSecReturnRef as String             : true
        ]
        
        var item: CFTypeRef?

algrid

    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

algrid

    checkBiometryState { success in
        guard success else {
            // Biometric authentication is not available
            return
        }
        let authContext = LAContext()
        let accessControl = KeychainHelper.getBioSecAccessControl()
        authContext.evaluateAccessControl(accessControl,
                                          operation: .useItem,
                                          localizedReason: "Access sample keychain entry") {