add encryption and decryption methods

Package.swift

@@ -11,7 +11,7 @@ let package = Package(
     ],
     dependencies: [
         .package(url: "https://github.com/johnnzhou/lcl-k1.git", branch: "main"),
-        .package(url: "https://github.com/johnnzhou/swift-crypto.git", branch: "main"),
+        .package(url: "https://github.com/johnnzhou/swift-crypto.git", branch: "main")
     ],
     targets: [
         // Targets are the basic building blocks of a package, defining a module or a test suite.

Sources/LCLPingAuth/Auth/Authenticate.swift

@@ -60,6 +60,6 @@ public func validate(credential: Data) throws -> ValidationResult {
 
     h_pkr = digest(data: outputData, algorithm: .SHA256)
     outputData.removeAll()
-    
+
     return ValidationResult(R: r, skT: skT, hPKR: h_pkr)
 }

Sources/LCLPingAuth/Cryptography/ECDSA.swift

@@ -92,7 +92,6 @@ public class ECDSA {
     }
 }
 
-
 extension K1.ECDSA.Signature {
     /// The data representation of signature in bytes
     var toData: Data {
@@ -104,4 +103,3 @@ extension K1.ECDSA.Signature {
         return Data(byteBuffer)
     }
 }
-

Sources/LCLPingAuth/Models.swift

@@ -17,12 +17,6 @@ struct Keys: Decodable {
     var sigmaT: String
     var skT: String
     var pk_a: String
-
-    init(sigmaT: String, skT: String, pk_a: String) {
-        self.sigmaT = sigmaT
-        self.skT = skT
-        self.pk_a = pk_a
-    }
 }
 
 extension Keys {

Sources/LCLPingAuth/Utils/Data+LCLPingAuth.swift

@@ -31,7 +31,7 @@ private func htoi(_ value: UInt8) throws -> UInt8 {
 }
 
 extension Data {
-    
+
     /// Initialize the `Data` from the hex string value
     init(hexString: String) throws {
         self.init()
@@ -52,15 +52,15 @@ extension Data {
 }
 
 extension ByteArray {
-    
+
     /// The  `Data` representation of the byte array
     var toData: Data {
         return Data(self)
     }
 }
 
 extension Data {
-    
+
     /// The hex String representation of the given `Data`
     var hex: String {
         reduce("") { $0 + String(format: "%02hhx", $1) }

Sources/LCLPingAuth/Utils/Security+LCLPingAuth.swift

@@ -44,21 +44,21 @@ public func generateSecureRandomBytes(count: Int) -> Result<Data, LCLPingAuthErr
     let res = withUnsafeMutableBytes(of: &bytes) { buffer in
         return getentropy(buffer.baseAddress, count)
     }
-    
+
     if res == -1 {
         // TODO: check errno for detailed error
         return .failure(.keyGenerationFailed)
     }
-    
+
     return .success(Data(bytes))
     #endif
 }
 
 extension Digest {
-    
+
     /// the bytes representation of the `Digest` data
     var bytes: [UInt8] { Array(makeIterator()) }
-    
+
     /// the `Data` representation of the `Digest` data
     var data: Data { Data(bytes) }
 }
@@ -89,3 +89,29 @@ public func digest(data: Data, algorithm: HashAlgorithm) -> Data {
     }
 }
 
+/**
+    Encrypt the plaintext using the given symmetric key
+
+    - Parameters:
+        - plainText: the plaintext data to be encrypted
+        - key: the symmetric key that will be used for encryption
+
+    - Returns: the encrypted data
+*/
+public func encrypt(plainText: Data, key: SymmetricKey) throws -> Data {
+    let box = try AES.GCM.seal(plainText, using: key)
+    return box.combined!
+}
+
+/**
+    Decrypt the cipher data using the given symmetric key
+
+    - Parameters:
+        - cipher: the cipher text to be decrypted
+        - key: the symmetric key that will be used for decryption
+    - Returns: the decrypted data
+*/
+public func decrypt(cipher: Data, key: SymmetricKey) throws -> Data {
+    let box = try AES.GCM.SealedBox(combined: cipher)
+    return try AES.GCM.open(box, using: key)
+}