Initial extraction of certificate information

Closes #9

Currently only the summary and expiration date are extracted, though the door is open for futher improvements!

Sources/SwiftyProvisioningProfile/Model/DeveloperCertificate.swift

@@ -10,12 +10,14 @@ import Foundation
 public struct DeveloperCertificate: Codable, Equatable {
 
     public let data: Data
+    public let certificate: SecureCertificate?
 
     // MARK: - Codable
 
     public init(from decoder: Decoder) throws {
         let container = try decoder.singleValueContainer()
         data = try container.decode(Data.self)
+        certificate = try? SecureCertificate(base64EncodedData: data)
     }
 
     public func encode(to encoder: Encoder) throws {

Sources/SwiftyProvisioningProfile/Model/SecureCertificate.swift

@@ -0,0 +1,69 @@
+//
+//  SecureCertificate.swift
+//  SwiftyProvisioningProfile
+//
+//  Created by Sherlock, James on 13/05/2018.
+//
+
+import Foundation
+
+public struct SecureCertificate: CustomStringConvertible, Equatable {
+
+    public enum CertificateError: Error {
+        case failedToCreate
+        case failedToObtainSummary
+        case failedToObtainValues
+    }
+
+    public let summary: String
+    public let expiryDate: Date?
+
+    public init(base64EncodedData: Data) throws {
+
+        // Create Certificate
+
+        guard let certificate = SecCertificateCreateWithData(nil, base64EncodedData as CFData) else {
+            throw CertificateError.failedToCreate
+        }
+
+        // Error
+
+        var error: Unmanaged<CFError>?
+
+        func checkError() throws {
+            if let error = error {
+                throw error.takeUnretainedValue()
+            }
+        }
+
+        // Summary
+
+        guard let summary = SecCertificateCopySubjectSummary(certificate) else {
+            throw CertificateError.failedToObtainSummary
+        }
+
+        self.summary = summary as String
+
+        // Values (Expiry)
+
+        let valuesKeys = [
+            kSecOIDInvalidityDate
+        ] as CFArray
+
+        let values = SecCertificateCopyValues(certificate, valuesKeys, &error)
+        try checkError()
+
+        guard let dictionary = values as? Dictionary<CFString, Any> else {
+            throw CertificateError.failedToObtainValues
+        }
+
+        let expiryDateDictionary = dictionary[kSecOIDInvalidityDate] as? [String: Any]
+        expiryDate = expiryDateDictionary?["value"] as? Date
+
+    }
+
+    public var description: String {
+        return "\(summary), Expires: \(expiryDate?.description ?? "No Expiry Date")"
+    }
+
+}

Tests/SwiftyProvisioningProfileTests/SwiftyProvisioningProfileTests.swift

@@ -33,7 +33,7 @@ class SwiftyProvisioningProfileTests: XCTestCase {
                 let data = try Data(contentsOf: url)
                 let profile = try ProvisioningProfile.parse(from: data)
 
-                print(profile)
+                print(profile.developerCertificates.flatMap({ $0.certificate?.description }).joined(separator: "\n"))
             }
 
             // TODO: Create or find a simple & usable profile and wrtie actual tests for it