# Master License for iOS

Master license is the offline license that allows using Mobile SDKs with any `bundle_id`, unlike the regular licenses. To get a master license, create a pair of keys as shown below. Email us the public key, and we will email you the master license shortly after that.\
Your application needs to sign its `bundle_id` with the private key, and the Mobile SDK checks the signature using the public key from the master license. Master licenses are time-limited.

## Generating Keys

This section describes the process of creating your private and public keys.

### Creating a Private Key

To create a private key, run the commands below one by one.

```bash
openssl genpkey -algorithm RSA -outform DER -out privateKey.der -pkeyopt rsa_keygen_bits:2048
# for MacOS
base64 -i privateKey.der -o privateKey.txt
# for Linux 
base64 -w 0 privateKey.der > privateKey.txt
```

You will get these files:

* *privateKey.der* is a private .der key;
* *privateKey.txt* is *privateKey.der* encoded by *base64*. This key containing will be used as the host app *bundle\_id* signature.

The OpenSSL command specification: <https://www.openssl.org/docs/man1.1.1/man1/openssl-pkcs8.html>

### Creating a Public Key

To create a public key, run this command.

```sh
openssl rsa -pubout -in privateKey.der -out publicKey.pub
```

You will get the public key file: *publicKey.pub*. To get a license, please email us this file. We will email you the license.

## SDK Integration

SDK initialization:

```swift
OZSDK(licenseSources: [LicenseSource], masterLicenseSignature: String? = nil, completion: @escaping ((LicenseData?, LicenseError?) -> Void))
```

License setting:

```swift
setLicense(licenseSource: LicenseSource, masterLicenseSignature: String? = nil)
```

Prior to the SDK initializing, create a base64-encoded signature for the host app `bundle_id` using the private key.

Signature creation example:

```swift
private func getSignature() -> String? {
    let privateKeyBase64String = "the string copied from the privateKey.txt file"
    // with key example:
    // let privateKeyBase64String = "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"
    guard let data = Data(base64Encoded: privateKeyBase64String, options: [.ignoreUnknownCharacters]) else {
      return nil
    }
     
    let sizeInBits = data.count * 8
    let keyDict: [CFString: Any] = [
      kSecAttrKeyType: kSecAttrKeyTypeRSA,
      kSecAttrKeyClass: kSecAttrKeyClassPrivate,
      kSecAttrKeySizeInBits: NSNumber(value: sizeInBits)
    ]
     
    var error: Unmanaged<CFError>?
    guard let secKey = SecKeyCreateWithData(data as CFData, keyDict as CFDictionary, &error) else {
      return nil
    }
     
    guard let bundleID = Bundle.main.bundleIdentifier else {
      return nil
    }
    guard let signature = SecKeyCreateSignature(secKey,
                          .rsaSignatureMessagePKCS1v15SHA512,
                          Data(bundleID.utf8) as CFData,
                          &error) else {
      return nil
    }
    return (signature as Data).base64EncodedString()
  }
```

Pass the signature as the `masterLicenseSignature` parameter either during the SDK initialization or license setting.

If the signature is invalid, the initialization continues as usual: the SDK checks the list of `bundle_id` included into the license like it does it by default without a master license.


---

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