openssl genrsa -out root.key 2048

openssl req -x509 -new -key root.key -out root.crt

openssl genpkey -algorithm RSA -out private.pem -aes256

penssl genpkey -algorithm RSA -out private.pem

openssl req -new -key private.pem -out certificate.csr

openssl x509 -req -in certificate.csr -CA root.crt -CAkey root.key -CAcreateserial -out certificate.crt

openssl pkcs12 -export -in certificate.crt -inkey private.pem -out certificate.p12

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSData *p12Data = [NSData dataWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"certificate" ofType:@"p12"]];
        NSDictionary *options = @{(__bridge id)kSecImportExportPassphrase: @"123456"};
        CFArrayRef items = NULL;
        OSStatus status = SecPKCS12Import((__bridge CFDataRef)p12Data, (__bridge CFDictionaryRef)options, &items);
        if (status == errSecSuccess) {
            CFDictionaryRef identityDict = CFArrayGetValueAtIndex(items, 0);
            SecIdentityRef identity = (SecIdentityRef)CFDictionaryGetValue(identityDict, kSecImportItemIdentity);
            SecCertificateRef certificate = NULL;
            SecIdentityCopyCertificate(identity, &certificate);
            // Получить закрытый ключ
            SecKeyRef privateKey = NULL;
            SecIdentityCopyPrivateKey(identity, &privateKey);
            // Получить открытый ключ
            SecPolicyRef policy = SecPolicyCreateBasicX509();
            SecTrustRef trust;
            SecTrustCreateWithCertificates(certificate, policy, &trust);
            SecTrustResultType trustResult;
            SecTrustEvaluate(trust, &trustResult);
            SecKeyRef publicKey = SecTrustCopyPublicKey(trust);
            
            NSString *testBase64 = @"Cy4JAEFCQ0QjMTIzNA4uBwAAAAEBAAABCi4gAJjruIAtnUTW0IkHex7/gCKJUb+927IrBoD40CP+nZjdCS4uAHpoYW5nMyZKREpoSkRFd0pFcGpaVGc0V0ZsSE9HZHpkRWcyZWtGeVFXRnZMbVUNLggAAAABAAAAAQAMLkEABHTznz0bpFsvbiYz7gwwVwZEBU2hcRHEwKNDdyGCfKc1IktkBlDqUogUnfqJPUrnkKQCDaEU91zB2aQrBqoAvUo=";
            NSData *signData = [[NSData alloc] initWithBase64EncodedString:testBase64 options:0];
            SecKeyAlgorithm algorithm = kSecKeyAlgorithmRSASignatureMessagePKCS1v15SHA256;
            CFErrorRef error = NULL;
            NSData *signature = (NSData *)CFBridgingRelease(SecKeyCreateSignature(privateKey, algorithm, (__bridge CFDataRef)signData, &error));

            if (error == NULL) {
                // Подписано успешно, используйте signature Следовать за
                SecKeyAlgorithm algorithm = kSecKeyAlgorithmRSASignatureMessagePKCS1v15SHA256;
                BOOL result = SecKeyVerifySignature(publicKey, algorithm, (__bridge CFDataRef)signData, (__bridge CFDataRef)signature, NULL);

                if (result) {
                    // Проверка подписи прошла успешно
                    NSLog(@"Используйте p12 для добавления подписи, Проверка подписи прошла успешно");

                } else {
                    // Проверка подписи не удалась
                }
            } else {
                // Не удалось добавить подпись, ошибка обработки.
            }
            // свободная память
            if (identity) CFRelease(identity);
            if (certificate) CFRelease(certificate);
            if (privateKey) CFRelease(privateKey);
            if (publicKey) CFRelease(publicKey);
        }
        
    });