AppStoreReceiptDecoder:解码Apple App Store收据中解密的有效载荷数据

## App Store Receipt Decoder The Apple App Store receipt is a PKCS7 container signed with Apple's private key and needs to be decrypted with Apple's public key to obtain the contained payload data. The payload data is in ASN.1 DER format. This project helps in decoding that format. ### Usage To try it, run `./run.sh` To use it in your Swift project, add `AppStoreReceipt.swift` to the project and use it like this: ~~~ Swift let data: NSData // data output from PKCS7_verify var bundleId: String? var bundleIdData: NSData? let receipt = AppStoreReceipt(payloadData: data) receipt.enumerateReceiptAttributes { (type, version, value) in switch (type) { case 2: // Bundle id bundleId = AppStoreReceipt.decodeASN1String(value) bundleIdData = value ... default: break } } ~~~ To use it in your Objective-C project, add `AppStoreReceipt.swift` to the project, add the `@objc` attribute to the `AppStoreReceipt` Swift class, import the Swift header (see 'Using Swift from Objective-C' in [_Using Swift with Cocoa and Objective-C_][swift-cocoa-book]), and use it like this: [swift-cocoa-book]: https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/BuildingCocoaApps/ ~~~ Objective-C NSData* data; // data output from PKCS7_verify __block NSString* bundleId; __block NSData* bundleIdData; AppStoreReceipt *receipt = [AppStoreReceipt receiptWithPayloadData: data]; [receipt enumerateReceiptAttributes:^(NSInteger type, NSInteger version, NSData * __nonnull value) { switch (type) { case 2: bundleId = [AppStoreReceipt decodeASN1String:value]; bundleIdData = value; break; ... default: break; } }]; ~~~ See `main.swift` for a more detailed example. ### Why Integrating the [ASN.1 compiler][asn1c]-generated code with an iOS project introduces multiple source files and warnings, and is not Swift 1.2-friendly because of the use of function pointers. This project provides a clean one-file receipt decoder in Swift. [asn1c]: https://github.com/vlm/asn1c