Add the initial files

.gitignore

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+
+# Created by https://www.gitignore.io/api/macos,swift,xcode
+# Edit at https://www.gitignore.io/?templates=macos,swift,xcode
+
+### macOS ###
+# General
+.DS_Store
+.AppleDouble
+.LSOverride
+
+# Icon must end with two \r
+Icon
+
+# Thumbnails
+._*
+
+# Files that might appear in the root of a volume
+.DocumentRevisions-V100
+.fseventsd
+.Spotlight-V100
+.TemporaryItems
+.Trashes
+.VolumeIcon.icns
+.com.apple.timemachine.donotpresent
+
+# Directories potentially created on remote AFP share
+.AppleDB
+.AppleDesktop
+Network Trash Folder
+Temporary Items
+.apdisk
+
+### Swift ###
+# Xcode
+#
+# gitignore contributors: remember to update Global/Xcode.gitignore, Objective-C.gitignore & Swift.gitignore
+
+## Build generated
+build/
+DerivedData/
+
+## Various settings
+*.pbxuser
+!default.pbxuser
+*.mode1v3
+!default.mode1v3
+*.mode2v3
+!default.mode2v3
+*.perspectivev3
+!default.perspectivev3
+xcuserdata/
+
+## Other
+*.moved-aside
+*.xccheckout
+*.xcscmblueprint
+
+## Obj-C/Swift specific
+*.hmap
+*.ipa
+*.dSYM.zip
+*.dSYM
+
+## Playgrounds
+timeline.xctimeline
+playground.xcworkspace
+
+# Swift Package Manager
+# Add this line if you want to avoid checking in source code from Swift Package Manager dependencies.
+# Packages/
+# Package.pins
+# Package.resolved
+.build/
+
+# CocoaPods
+# We recommend against adding the Pods directory to your .gitignore. However
+# you should judge for yourself, the pros and cons are mentioned at:
+# https://guides.cocoapods.org/using/using-cocoapods.html#should-i-check-the-pods-directory-into-source-control
+# Pods/
+# Add this line if you want to avoid checking in source code from the Xcode workspace
+# *.xcworkspace
+
+# Carthage
+# Add this line if you want to avoid checking in source code from Carthage dependencies.
+# Carthage/Checkouts
+
+Carthage/Build
+
+# fastlane
+# It is recommended to not store the screenshots in the git repo. Instead, use fastlane to re-generate the
+# screenshots whenever they are needed.
+# For more information about the recommended setup visit:
+# https://docs.fastlane.tools/best-practices/source-control/#source-control
+
+fastlane/report.xml
+fastlane/Preview.html
+fastlane/screenshots/**/*.png
+fastlane/test_output
+
+# Code Injection
+# After new code Injection tools there's a generated folder /iOSInjectionProject
+# https://github.com/johnno1962/injectionforxcode
+
+iOSInjectionProject/
+
+### Xcode ###
+# Xcode
+# gitignore contributors: remember to update Global/Xcode.gitignore, Objective-C.gitignore & Swift.gitignore
+
+## User settings
+
+## compatibility with Xcode 8 and earlier (ignoring not required starting Xcode 9)
+
+## compatibility with Xcode 3 and earlier (ignoring not required starting Xcode 4)
+
+### Xcode Patch ###
+*.xcodeproj/*
+!*.xcodeproj/project.pbxproj
+!*.xcodeproj/xcshareddata/
+!*.xcworkspace/contents.xcworkspacedata
+/*.gcno
+**/xcshareddata/WorkspaceSettings.xcsettings
+
+# End of https://www.gitignore.io/api/macos,swift,xcode

Cryptography & Privacy.playgroundbook/Contents/Chapters/Chapter1.playgroundchapter/Manifest.plist

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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>Name</key>
+	<string>Chapter 1</string>
+	<key>Pages</key>
+	<array>
+		<string>Introduction.cutscenepage</string>
+		<string>Cryptography Foundation.playgroundpage</string>
+		<string>Symmetric-Key Cryptography.playgroundpage</string>
+		<string>Asymmetric-Key Cryptography.playgroundpage</string>
+		<string>Practice.playgroundpage</string>
+	</array>
+</dict>
+</plist>

Cryptography & Privacy.playgroundbook/Contents/Chapters/Chapter1.playgroundchapter/Pages/Asymmetric-Key Cryptography.playgroundpage/Contents.swift

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+//#-hidden-code
+//
+//  See LICENSE folder for this template’s licensing information.
+//
+//  Abstract:
+//  The Swift file containing the source code edited by the user of this playground book.
+//
+
+import Foundation
+import PlaygroundSupport
+//#-end-hidden-code
+/*:
+# Asymmetric-Key Cryptography
+In asymmetric-key cryptography, we use a key-pair which contains a public key and a private key. After generating a key-pair, we usually send the public one to others, and keep the private one on the disk. As a result, anyone holding your public key can use it to send encrypted messages to you, and it can only be decrypted using the corresponding private key.
+
+This is to say, the sender doesn't need to know how to decrypt the content when encrypting, which solves the key distribution problem.
+
+> Use `generateKeyPair()` to generate a key-pair (this may take a while)
+>
+> Use `encrypt(contentData: , usingPublicKey: )` and `decrypt(contentData: , usingPrivateKey: )` to encrypt/decrypt
+>
+> For detailed usage, see help of each function
+
+- Example:
+```
+let keyPair = generateKeyPair()
+let text = "TOP SECRET"
+let textData = text.data(using: .utf8)!
+let encrypted = encrypt(contentData: textData, usingPublicKey: keyPair.publicKey)
+let decrypted = decrypt(contentData: encrypted, usingPrivateKey: keyPair.privateKey)
+print(String(data: decrypted, encoding: .utf8)!)
+// Output: "TOP SECRET"
+```
+
+- Important:
+Encrypting/Decrypting using asymmetric-key cryptography can be **way slower** than symmetric-key cryptography, and therefore is **not suitable for large files**.
+*/
+
+// Encrypt the text using a designated public key
+func encrypt(text: String, usingPublicKey publicKey: SecKey) -> Data {
+	let textData = text.data(using: .utf8)!
+	return encrypt(contentData: /*#-editable-code*/<#T##Plain Data##Data#>/*#-end-editable-code*/
+		, usingPublicKey: /*#-editable-code*/<#T##Public Key##SecKey#>/*#-end-editable-code*/
+	)
+}
+
+// Decrypt the text using a designated private key
+func decrypt(encryptedData: Data, usingPrivateKey privateKey: SecKey) -> String {
+	let decrypted = decrypt(contentData: /*#-editable-code*/<#T##Encrypted Data##Data#>/*#-end-editable-code*/, usingPrivateKey: /*#-editable-code*/<#T##Private Key##SecKey#>/*#-end-editable-code*/)
+	return String(data: decrypted, encoding: .utf8)!
+}
+
+//#-hidden-code
+let keyPair = generateKeyPair()
+let randomContent = generateRandomContent()
+let encrypted = encrypt(text: randomContent, usingPublicKey: keyPair.publicKey)
+let decrypted = decrypt(encryptedData: encrypted, usingPrivateKey: keyPair.privateKey)
+if decrypted == randomContent {
+	PlaygroundPage.current.assessmentStatus = .pass(message: """
+Congratulations, You've learnt how to use asymmetric-key cryptography!
+
+[Cryptography & Privacy in Practice: Secure Chat](@next)
+""")
+} else {
+	PlaygroundPage.current.assessmentStatus = .fail(hints: ["Please read the text above again to ensure you understand how to use asymmetric cryptography."], solution: """
+```
+func encrypt(text: String, usingPublicKey publicKey: SecKey) -> Data {
+	let textData = text.data(using: .utf8)!
+	return encrypt(contentData: textData, usingPublicKey: publicKey)
+}
+
+func decrypt(encryptedData: Data, usingPrivateKey privateKey: SecKey) -> String {
+	let decrypted = decrypt(contentData: encryptedData, usingPrivateKey: privateKey)
+	return String(data: decrypted, encoding: .utf8)!
+}
+```
+""")
+
+}
+//#-end-hidden-code

Cryptography & Privacy.playgroundbook/Contents/Chapters/Chapter1.playgroundchapter/Pages/Asymmetric-Key Cryptography.playgroundpage/LiveView.swift

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+//
+//  See LICENSE folder for this template’s licensing information.
+//
+//  Abstract:
+//  Instantiates a live view and passes it to the PlaygroundSupport framework.
+//
+
+import UIKit
+import PlaygroundSupport
+
+// Instantiate a new instance of the live view from the book's auxiliary sources and pass it to PlaygroundSupport.
+PlaygroundPage.current.liveView = instantiateLiveView()

Cryptography & Privacy.playgroundbook/Contents/Chapters/Chapter1.playgroundchapter/Pages/Asymmetric-Key Cryptography.playgroundpage/Manifest.plist

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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>Name</key>
+	<string>Asymmetric-Key Cryptography</string>
+	<key>LiveViewEdgeToEdge</key>
+	<true/>
+	<key>LiveViewMode</key>
+	<string>VisibleByDefault</string>
+</dict>
+</plist>

Cryptography & Privacy.playgroundbook/Contents/Chapters/Chapter1.playgroundchapter/Pages/Cryptography Foundation.playgroundpage/Contents.swift

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+//#-hidden-code
+//
+//  See LICENSE folder for this template’s licensing information.
+//
+//  Abstract:
+//  The Swift file containing the source code edited by the user of this playground book.
+//
+//#-end-hidden-code
+/*:
+# Cryptography Foundation
+## What's Cryptography?
+In software development, we use cryptography to do a lot of things that are related to security, for example, encrypting and decrypting.
+## What Will We Learn
+In this playground book, we'll learn two of the most basic cryptography concepts so that you can secure the app:
+### Symmetric-Key Cryptography
+In symmetric-key cryptography, we use a key (just a password) which is shared between the sender and the receiver. Anyone holding the key can decrypt the content.
+### Asymmetric-Key Cryptography
+By contrast, in asymmetric-key cryptography, we use key-pairs. A key-pair is made up of a public key and a private key. After generating a key-pair, we keep the private one on our disk and share the public one to others. Anyone can encrypt a message using the public key, and only the holder of the corresponding private key can decrypt it.
+
+> A bit confused, or TL;DR? Don't be afraid! You'll understand how to use them in the following part with ease.
+
+[Let's Go!](@next)
+*/
+//#-hidden-code
+import PlaygroundSupport
+PlaygroundPage.current.assessmentStatus = .pass(message: "[Let's go!](@next)")
+//#-end-hidden-code

Cryptography & Privacy.playgroundbook/Contents/Chapters/Chapter1.playgroundchapter/Pages/Cryptography Foundation.playgroundpage/LiveView.swift

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+//
+//  See LICENSE folder for this template’s licensing information.
+//
+//  Abstract:
+//  Instantiates a live view and passes it to the PlaygroundSupport framework.
+//
+
+import UIKit
+import PlaygroundSupport
+
+// Instantiate a new instance of the live view from the book's auxiliary sources and pass it to PlaygroundSupport.
+PlaygroundPage.current.liveView = instantiateLiveView()

Cryptography & Privacy.playgroundbook/Contents/Chapters/Chapter1.playgroundchapter/Pages/Cryptography Foundation.playgroundpage/Manifest.plist

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>Name</key>
+	<string>Cryptography Foundation</string>
+	<key>LiveViewEdgeToEdge</key>
+	<true/>
+	<key>LiveViewMode</key>
+	<string>VisibleByDefault</string>
+</dict>
+</plist>

Cryptography & Privacy.playgroundbook/Contents/Chapters/Chapter1.playgroundchapter/Pages/Introduction.cutscenepage/Manifest.plist

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>CutsceneReference</key>
+	<string>WWDC19 Cutscene1.html</string>
+	<key>Name</key>
+	<string>Introduction</string>
+</dict>
+</plist>

Cryptography & Privacy.playgroundbook/Contents/Chapters/Chapter1.playgroundchapter/Pages/Introduction.cutscenepage/PrivateResources/WWDC19 Cutscene1.html

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+<!DOCTYPE html>
+<html>
+  <head>
+	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
+	<meta http-equiv="X-UA-Compatible" content="chrome=1,IE=edge" />
+	<title>WWDC19 Cutscene1</title>
+	<style>
+		html {
+			height:100%;
+		}
+		body {
+			background-color:#FFFFFF;
+			margin:0;
+			height:100%;
+		}
+	</style>
+	<!-- copy these lines to your document head: -->
+
+	<meta name="viewport" content="user-scalable=no, width=device-height" />
+
+	<!-- end copy -->
+  </head>
+  <body>
+	<!-- copy these lines to your document: -->
+
+	<div id="wwdc19cutscene1_hype_container" style="margin:auto;position:relative;width:2732px;height:2048px;overflow:hidden;">
+		<script type="text/javascript" charset="utf-8" src="WWDC19%20Cutscene1.hyperesources/wwdc19cutscene1_hype_generated_script.js?12474"></script>
+	</div>
+
+	<!-- end copy -->
+  </body>
+</html>