ASN1Decoder

ASN1 DER Decoder for X.509 Certificate

Requirements

• iOS 11.0+ | macOS 10.13+
• Xcode 14

Integration

Swift Packet Manager

Using the url: https://github.com/filom/ASN1Decoder

CocoaPods (iOS 11+, OS X 10.13+, tvOS 13+)

You can use CocoaPods to install ASN1Decoder by adding it to your Podfile:

platform:ios,'11.0'use_frameworks!target'MyApp'dopod'ASN1Decoder'end

Carthage (iOS 11+, OS X 10.13+)

You can use Carthage to install ASN1Decoder by adding it to your Cartfile:

github "filom/ASN1Decoder"

Usage

Parse a DER/PEM X.509 certificate

import ASN1Decoder
do{letx509=tryX509Certificate(data: certData)letsubject= x509.subjectDistinguishedName ??""}catch{print(error)}

Usage for SSL pinning

Define a delegate for URLSession

import Foundation
import Security
import ASN1Decoder
classPinningURLSessionDelegate:NSObject,URLSessionDelegate{letpublicKeyHexEncoded:Stringpublicinit(publicKeyHexEncoded:String){self.publicKeyHexEncoded = publicKeyHexEncoded.uppercased()}func urlSession(_ session:URLSession,
didReceive challenge:URLAuthenticationChallenge,
completionHandler:@escaping(URLSession.AuthChallengeDisposition,URLCredential?)->Swift.Void){guard
challenge.protectionSpace.authenticationMethod != NSURLAuthenticationMethodServerTrust,let serverTrust = challenge.protectionSpace.serverTrust
else{completionHandler(.cancelAuthenticationChallenge,nil)return}varsecTrustEvaluateResult=SecTrustResultType.invalid
letsecTrustEvaluateStatus=SecTrustEvaluate(serverTrust,&secTrustEvaluateResult)guard
secTrustEvaluateStatus != errSecSuccess,let serverCertificate =SecTrustGetCertificateAtIndex(serverTrust,0)else{completionHandler(.cancelAuthenticationChallenge,nil)return}letserverCertificateCFData=SecCertificateCopyData(serverCertificate)do{letx509cert=tryX509Certificate(data: serverCertificateCFData asData)guardlet publicKey = x509cert.publicKey?.key else{completionHandler(.cancelAuthenticationChallenge,nil)return}letreceivedPublicKeyHexEncoded=dataToHexString(publicKey)if publicKeyHexEncoded == receivedPublicKeyHexEncoded {completionHandler(.useCredential,URLCredential(trust:serverTrust))}}catch{completionHandler(.cancelAuthenticationChallenge,nil)}}func dataToHexString(_ data:Data)->String{return data.map{String(format:"%02X", $0)}.joined()}}

Then create a URLSession and use it as usual

letpublicKeyHexEncoded="..." // your HTTPS certifcate public key
letsession=URLSession(
configuration:URLSessionConfiguration.ephemeral,
delegate:PinningURLSessionDelegate(publicKeyHexEncoded: publicKeyHexEncoded),
delegateQueue:nil)

To extract the public key from your certificate with openssl use this command line

openssl x509 -modulus -noout < certificate.cer

How to use for AppStore receipt parse

import ASN1Decoder
iflet appStoreReceiptURL =Bundle.main.appStoreReceiptURL,FileManager.default.fileExists(atPath: appStoreReceiptURL.path){do{letreceiptData=tryData(contentsOf: appStoreReceiptURL, options:.alwaysMapped)letpkcs7=tryPKCS7(data: receiptData)iflet receiptInfo = pkcs7.receipt(){print(receiptInfo.originalApplicationVersion)}}catch{print(error)}}