BlueRSA

Swift cross-platform RSA wrapper library for RSA encryption and signing. Works on supported Apple platforms (using Security framework). Linux (using OpenSSL) is working but is still somewhat of a work in progress.

Contents

• CryptorRSA: Utility functions for RSA encryption and signing. Pure Swift

Prerequisites

Swift

• Swift Open Source swift-4.0.0-RELEASE toolchain (Minimum REQUIRED for latest release)
• Swift Open Source swift-5.2-RELEASE toolchain (Recommended)
• Swift toolchain included in Xcode Version 10.0 (10A255) or higher.

macOS

• macOS 11.5.0 (Big Sur) or higher
• Xcode Version 12.0 (9A325) or higher using the included toolchain (Minimum REQUIRED for latest release).
• Xcode Version 13.4.1 (13F100) or higher using the included toolchain (Recommended).

iOS

• iOS 14.5 or higher
• Xcode Version 9.0 (9A325) or higher using the included toolchain (Minimum REQUIRED for latest release).
• Xcode Version 13.4.1 (13F100) or higher using the included toolchain (Recommended).

Linux

• Ubuntu 16.04 (or 16.10 but only tested on 16.04) and 18.04.
• One of the Swift Open Source toolchain listed above.
• OpenSSL is provided by the distribution. Note: 1.0.x, 1.1.x and later releases of OpenSSL are supported.
• The appropriate libssl-dev package is required to be installed when building.

Build

To build CryptorRSA from the command line:

% cd <path-to-clone>
% swift build

Testing

To run the supplied unit tests for CryptorRSA from the command line:

% cd <path-to-clone>
% swift build
% swift test

Using CryptorRSA

Including in your project

Swift Package Manager

To include BlueRSA into a Swift Package Manager package, add it to the dependencies attribute defined in your Package.swift file. You can select the version using the majorVersion and minor parameters. For example:

	dependencies: [
		.package(url: "https://github.com/Kitura/BlueRSA", majorVersion: <majorVersion>, minor: <minor>)
	]

Carthage

To include BlueRSA in a project using Carthage, add a line to your Cartfile with the GitHub organization and project names and version. For example:

	github "Kitura/BlueRSA" ~> <majorVersion>.<minor>

Before starting

The first you need to do is import the CryptorRSA framework. This is done by the following:

import CryptorRSA

Data Types

BlueRSA supports the following major data types:

• Key Handling

  • CryptorRSA.PublicKey - Represents an RSA Public Key.
  • CryptorRSA.PrivateKey - Represents an RSA Private Key.

• Data Handling

  • CryptorRSA.EncryptedData - Represents encrypted data.
  • CryptorRSA.PlaintextData - Represents plaintext or decrypted data.
  • CryptorRSA.SignedData - Represents signed data.

Key Handling

BlueRSA provides seven (7) functions each for creating public and private keys from data. They are as follows (where createXXXX is either createPublicKey or createPrivateKey depending on what you're trying to create):

• CryptorRSA.createXXXX(with data: Data) throws - This creates either a private or public key containing the data provided. It is assumed that the data being provided is in the proper format.
• CryptorRSA.createXXXX(withBase64 base64String: String) throws - This creates either a private or public key using the Base64 encoded String provided.
• CryptorRSA.createXXXX(withPEM pemString: String) throws - This creates either a private or public key using the PEM encoded String provided.
• CryptorRSA.createXXXX(withPEMNamed pemName: String, onPath path: String) throws - This creates either a private or public key using the PEM encoded file pointed at by the pemName and located on the path specified by path provided.
• CryptorRSA.createXXXX(withDERNamed derName: String, onPath path: String) throws - This creates either a private or public key using the DER encoded file pointed at by the derName and located on the path specified by path provided.
• CryptorRSA.createXXXX(withPEMNamed pemName: String, in bundle: Bundle = Bundle.main) throws - This creates either a private or public key using the PEM encoded file pointed at by the pemName and located in the Bundle specified by bundle provided. By default this API will look in the main bundle. Note: Apple Platforms Only
• CryptorRSA.createXXXX(withDERNamed derName: String, in bundle: Bundle = Bundle.main) throws - This creates either a private or public key using the DER encoded file pointed at by the derName and located in the Bundle specified by bundle provided. By default this API will look in the main bundle. Note: Apple Platforms Only

Additionally, there are three APIs for creating a public key by extracting the key from a PEM formatted certificate: They are:

• CryptorRSA.createPublicKey(extractingFrom data: Data) throws - This creates either a public key by extracting from the PEM encoded certificate pointed at by the data.
• CryptorRSA.createPublicKey(extractingFrom certName: String, onPath path: String) throws - This creates a public key by extracting from the PEM encoded certificate pointed at by the certName and located on the path specified by path provided.
• CryptorRSA.createPublicKey(extractingFrom certName: String, in bundle: Bundle = Bundle.main) throws - This creates a public key using the PEM encoded certificate pointed at by the derName and located in the Bundle specified by bundle provided. By default this API will look in the main bundle. Note: Apple Platforms Only

Example

The following example illustrates creating a public key given PEM encoded file located on a certain path. *Note: Exception handling omitted for brevity.

import Foundation
import CryptorRSA

...

let keyName = ...
let keyPath = ...

let publicKey = try CryptorRSA.createPublicKey(withPEMNamed: keyName, onPath: keyPath)

...

<Do something with the key...>

Data Encryption and Decryption Handling

BlueRSA provides functions for the creation of each of the three (3) data handling types:

Plaintext Data Handling and Signing

There are two class level functions for creating a PlaintextData object. These are:

• CryptorRSA.createPlaintext(with data: Data) -> PlaintextData - This function creates a PlaintextData containing the specified data.
• CryptorRSA.createPlaintext(with string: String, using encoding: String.Encoding) throws -> PlaintextData - This function creates a PlaintextData object using the string encoded with the specified encoding as the data.

Once the PlaintextData object is created, there are two instance functions that can be used to manipulate the contained data. These are:

• encrypted(with key: PublicKey, algorithm: Data.Algorithm) throws -> EncryptedData? - This function allows you to encrypt containing data using the public key and algorithm specified. This function returns an optional EncryptedData object containing the encryped data.
• signed(with key: PrivateKey, algorithm: Data.Algorithm) throws -> SignedData? - This function allows you to sign the contained data using the private key and algorithm specified. This function returns an optional SignedData object containing the signature of the signed data.

Example

• Encryption: Note: Exception handling omitted for brevity.

import Foundation
import CryptorRSA

...

let keyName = ...
let keyPath = ...

let myData: Data = <... Data to be encrypted ...>

let publicKey = try CryptorRSA.createPublicKey(withPEMNamed: keyName, onPath: keyPath)
let myPlaintext = CryptorRSA.createPlaintext(with: myData)
let encryptedData = try myPlaintext.encrypted(with: publicKey, algorithm: .sha1)

...

< Do something with the encrypted data...>

• Signing: Note: Exception handling omitted for brevity.

import Foundation
import CryptorRSA

...

let keyName = ...
let keyPath = ...

let myData: Data = <... Data to be signed ...>

let privateKey = try CryptorRSA.createPrivateKey(withPEMNamed: keyName, onPath: keyPath)
let myPlaintext = CryptorRSA.createPlaintext(with: myData)
let signedData = try myPlaintext.signed(with: privateKey, algorithm: .sha1)

...

< Do something with the signed data...>

Encrypted Data Handling

There are two class level functions for creating a EncryptedData object. These are:

• CryptorRSA.createEncrypted(with data: Data) -> EncryptedData - This function creates a EncryptedData containing the specified encrypted data.
• CryptorRSA.createEncrypted(with base64String: String) throws -> EncryptedData - This function creates a EncrpytedData using the Base64 representation of already encrypted data.

Once the EncryptedData object is created, there is an instance function that can be used to decrypt the enclosed data:

• decrypted(with key: PrivateKey, algorithm: Data.Algorithm) throws -> DecryptedData? - This function allows you to decrypt containing data using the public key and algorithm specified. This function returns an optional DecryptedData object containing the encryped data.

BlueRSA currently supports OAEP padding, which is the recommended padding algorithm.

Example

• Decryption: Note: Exception handling omitted for brevity.

import Foundation
import CryptorRSA

...

let keyName = ...
let keyPath = ...
let publicKey = try CryptorRSA.createPublicKey(withPEMNamed: keyName, onPath: keyPath)

let pkeyName = ...
let pkeyPath = ...
let privateKey = try CryptorRSA.createPrivateKey(withPEMNamed: pkeyName, onPath: pkeyPath)

let myData: Data = <... Data to be encrypted ...>

let myPlaintext = CryptorRSA.createPlaintext(with: myData)
let encryptedData = try myPlaintext.encrypted(with: publicKey, algorithm: .sha1)

let decryptedData = try encryptedData.decrypted(with: privateKey, algorithm: .sha1)

...

< Do something with the decrypted data...>

Signature Verification Handling

There is a single class level function that can be used to create a SignedData object. It is:

• CryptorRSA.createSigned(with data: Data) -> SignedData - This function creates a SignedData containing the specified signed data.

Once created or obtained PlaintextData and SignedData, there is an instance function which can be used to verify the signature contained therein:

• verify(with key: PublicKey, signature: SignedData, algorithm: Data.Algorithm) throws -> Bool - This function is used to verify, using the public key and algorithm, the signature. Returns true if the signature is valid, false otherwise.

• Verifying: Note: Exception handling omitted for brevity.

import Foundation
import CryptorRSA

...

let keyName = ...
let keyPath = ...
let publicKey = try CryptorRSA.createPublicKey(withPEMNamed: keyName, onPath: keyPath)

let pkeyName = ...
let pkeyPath = ...
let privateKey = try CryptorRSA.createPrivateKey(withPEMNamed: pkeyName, onPath: pkeyPath)

let myData: Data = <... Data to be signed ...>

let myPlaintext = CryptorRSA.createPlaintext(with: myData)
let signedData = try myPlaintext.signed(with: privateKey, algorithm: .sha1)

if try myPlaintext.verify(with: publicKey, signature: signedData, algorithm: .sha1) {

	print("Signature verified")

} else {

	print("Signature Verification Failed")
}

Data Type Utility Functions

All three of the data handling types have two common utility instance functions. These are:

• digest(using algorithm: Data.Algorithm) throws -> Data - This function returns a Data object containing a digest constructed using the specified algorithm.
• string(using encoding: String.Encoding) throws -> String - This functions returns a String representation of the data using the specified encoding.

Community

We love to talk server-side Swift and Kitura. Join our Slack to meet the team!

License

This library is licensed under Apache 2.0. Full license text is available in LICENSE.