Fix a bug in the encrypt sample, that was causing the decrypt to fail (…

…#23816)

* Fix a bug in the encrypt sample, that was causing the decrypt to fail

* Apply suggestions from code review

Co-authored-by: Youssef Victor <youssefvictor00@gmail.com>

* Apply suggestions from code review

* Apply suggestions from code review

* Corrected updated names

* Addressed feedback from peer review

* Use explicit scoping of disposable implementations

Co-authored-by: Youssef Victor <youssefvictor00@gmail.com>

docs/standard/security/decrypting-data.md

@@ -1,7 +1,7 @@
 ---
 title: "Decrypting data"
 description: Learn how to decrypt data in .NET, using a symmetric algorithm or an asymmetric algorithm.
-ms.date: 03/22/2021
+ms.date: 04/19/2021
 dev_langs:
   - "csharp"
   - "vb"
@@ -21,18 +21,18 @@ Decryption is the reverse operation of encryption. For secret-key encryption, yo
 
 The decryption of data encrypted with symmetric algorithms is similar to the process used to encrypt data with symmetric algorithms. The <xref:System.Security.Cryptography.CryptoStream> class is used with symmetric cryptography classes provided by .NET to decrypt data read from any managed stream object.
 
-The following example illustrates how to create a new instance of the default implementation class for the <xref:System.Security.Cryptography.Aes> algorithm. The instance is used to perform decryption on a <xref:System.Security.Cryptography.CryptoStream> object. This example first creates a new instance of the <xref:System.Security.Cryptography.Aes> implementation class. It reads the initialization vector (IV) value from a managed stream variable, `myStream`. Next it instantiates a <xref:System.Security.Cryptography.CryptoStream> object and initializes it to the value of the `myStream` instance. The <xref:System.Security.Cryptography.SymmetricAlgorithm.CreateDecryptor%2A?displayProperty=nameWithType> method from the <xref:System.Security.Cryptography.Aes> instance is passed the IV value and the same key that was used for encryption.
+The following example illustrates how to create a new instance of the default implementation class for the <xref:System.Security.Cryptography.Aes> algorithm. The instance is used to perform decryption on a <xref:System.Security.Cryptography.CryptoStream> object. This example first creates a new instance of the <xref:System.Security.Cryptography.Aes> implementation class. It reads the initialization vector (IV) value from a managed stream variable, `fileStream`. Next it instantiates a <xref:System.Security.Cryptography.CryptoStream> object and initializes it to the value of the `fileStream` instance. The <xref:System.Security.Cryptography.SymmetricAlgorithm.CreateDecryptor%2A?displayProperty=nameWithType> method from the <xref:System.Security.Cryptography.Aes> instance is passed the IV value and the same key that was used for encryption.
 
 ```vb
 Dim aes As Aes = Aes.Create()
 Dim cryptStream As New CryptoStream(
-    myStream, aes.CreateDecryptor(key, iv), CryptoStreamMode.Read)
+    fileStream, aes.CreateDecryptor(key, iv), CryptoStreamMode.Read)
 ```
 
 ```csharp
 Aes aes = Aes.Create();
 CryptoStream cryptStream = new CryptoStream(
-    myStream, aes.CreateDecryptor(key, iv), CryptoStreamMode.Read);
+    fileStream, aes.CreateDecryptor(key, iv), CryptoStreamMode.Read);
 ```
 
 The following example shows the entire process of creating a stream, decrypting the stream, reading from the stream, and closing the streams. A file stream object is created that reads a file named *TestData.txt*. The file stream is then decrypted using the **CryptoStream** class and the **Aes** class. This example specifies key value that is used in the symmetric encryption example for [Encrypting Data](encrypting-data.md). It does not show the code needed to encrypt and transfer these values.

docs/standard/security/encrypting-data.md

@@ -1,7 +1,7 @@
 ---
 title: "Encrypting data"
 description: Learn how to encrypt data in .NET, using a symmetric algorithm or an asymmetric algorithm.
-ms.date: 03/22/2021
+ms.date: 04/16/2021
 dev_langs:
   - "csharp"
   - "vb"
@@ -21,18 +21,18 @@ Symmetric encryption and asymmetric encryption are performed using different pro
 
 The managed symmetric cryptography classes are used with a special stream class called a <xref:System.Security.Cryptography.CryptoStream> that encrypts data read into the stream. The **CryptoStream** class is initialized with a managed stream class, a class that implements the <xref:System.Security.Cryptography.ICryptoTransform> interface (created from a class that implements a cryptographic algorithm), and a <xref:System.Security.Cryptography.CryptoStreamMode> enumeration that describes the type of access permitted to the **CryptoStream**. The **CryptoStream** class can be initialized using any class that derives from the <xref:System.IO.Stream> class, including <xref:System.IO.FileStream>, <xref:System.IO.MemoryStream>, and <xref:System.Net.Sockets.NetworkStream>. Using these classes, you can perform symmetric encryption on a variety of stream objects.
 
-The following example illustrates how to create a new instance of the default implementation class for the <xref:System.Security.Cryptography.Aes> algorithm. The instance is used to perform encryption on a **CryptoStream** class. In this example, the **CryptoStream** is initialized with a stream object called `myStream` that can be any type of managed stream. The **CreateEncryptor** method from the **Aes** class is passed the key and IV that are used for encryption. In this case, the default key and IV generated from `aes` are used.
+The following example illustrates how to create a new instance of the default implementation class for the <xref:System.Security.Cryptography.Aes> algorithm. The instance is used to perform encryption on a **CryptoStream** class. In this example, the **CryptoStream** is initialized with a stream object called `fileStream` that can be any type of managed stream. The **CreateEncryptor** method from the **Aes** class is passed the key and IV that are used for encryption. In this case, the default key and IV generated from `aes` are used.
 
 ```vb
 Dim aes As Aes = Aes.Create()
 Dim cryptStream As New CryptoStream(
-    myStream, aes.CreateEncryptor(key, iv), CryptoStreamMode.Write)
+    fileStream, aes.CreateEncryptor(key, iv), CryptoStreamMode.Write)
 ```
 
 ```csharp
 Aes aes = Aes.Create();
 CryptoStream cryptStream = new CryptoStream(
-    myStream, aes.CreateEncryptor(key, iv), CryptoStreamMode.Write);
+    fileStream, aes.CreateEncryptor(key, iv), CryptoStreamMode.Write);
 ```
 
 After this code is executed, any data written to the **CryptoStream** object is encrypted using the AES algorithm.

docs/standard/security/snippets/decrypting-data/csharp/aes-decrypt.cs

@@ -2,43 +2,45 @@
 using System.IO;
 using System.Security.Cryptography;
 
-public class DecryptExample
+try
 {
-    public static void Main(string[] args)
+    using (FileStream fileStream = new("TestData.txt", FileMode.Open))
     {
-        //Decryption key must be the same value that was used
-        //to encrypt the stream.
-        byte[] key = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16 };
-
-        try
+        using (Aes aes = Aes.Create())
         {
-            //Create a file stream.
-            using FileStream myStream = new FileStream("TestData.txt", FileMode.Open);
-
-            //Create a new instance of the default Aes implementation class
-            using Aes aes = Aes.Create();
-
-            //Reads IV value from beginning of the file.
             byte[] iv = new byte[aes.IV.Length];
-            myStream.Read(iv, 0, iv.Length);
+            int numBytesToRead = aes.IV.Length;
+            int numBytesRead = 0;
+            while (numBytesToRead > 0)
+            {
+                int n = fileStream.Read(iv, numBytesRead, numBytesToRead);
+                if (n == 0) break;
 
-            //Create a CryptoStream, pass it the file stream, and decrypt
-            //it with the Aes class using the key and IV.
-            using CryptoStream cryptStream = new CryptoStream(
-               myStream,
-               aes.CreateDecryptor(key, iv),
-               CryptoStreamMode.Read);
+                numBytesRead += n;
+                numBytesToRead -= n;
+            }
 
-            //Read the stream.
-            using StreamReader sReader = new StreamReader(cryptStream);
+            byte[] key =
+            {
+                0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
+                0x09, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16
+            };
 
-            //Display the message.
-            Console.WriteLine("The decrypted original message: {0}", sReader.ReadToEnd());
-        }
-        catch
-        {
-            Console.WriteLine("The decryption failed.");
-            throw;
+            using (CryptoStream cryptoStream = new(
+               fileStream,
+               aes.CreateDecryptor(key, iv),
+               CryptoStreamMode.Read))
+            {
+                using (StreamReader decryptReader = new(cryptoStream))
+                {
+                    string decryptedMessage = await decryptReader.ReadToEndAsync();
+                    Console.WriteLine($"The decrypted original message: {decryptedMessage}");
+                }
+            }
         }
     }
 }
+catch (Exception ex)
+{
+    Console.WriteLine($"The decryption failed. {ex}");
+}

docs/standard/security/snippets/decrypting-data/csharp/aesdecrypt.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net5.0</TargetFramework>
   </PropertyGroup>
 
 </Project>

docs/standard/security/snippets/decrypting-data/vb/aes-decrypt.vb

@@ -4,30 +4,40 @@ Imports System.Security.Cryptography
 
 Module Module1
     Sub Main()
-        'Decryption key must be the same value that was used
-        'to encrypt the stream.
+        ' Decryption key must be the same value that was used
+        ' to encrypt the stream.
         Dim key As Byte() = {&H1, &H2, &H3, &H4, &H5, &H6, &H7, &H8, &H9, &H10, &H11, &H12, &H13, &H14, &H15, &H16}
 
         Try
-            'Create a file stream.
-            Using myStream As FileStream = New FileStream("TestData.txt", FileMode.Open)
+            ' Create a file stream.
+            Using fileStream As New FileStream("TestData.txt", FileMode.Open)
 
-                'Create a new instance of the default Aes implementation class
+                ' Create a new instance of the default Aes implementation class
                 Using aes As Aes = Aes.Create()
 
-                    'Reads IV value from beginning of the file.
+                    ' Reads IV value from beginning of the file.
                     Dim iv As Byte() = New Byte(aes.IV.Length - 1) {}
-                    myStream.Read(iv, 0, iv.Length)
+                    Dim numBytesToRead As Integer = CType(aes.IV.Length, Integer)
+                    Dim numBytesRead As Integer = 0
 
-                    'Create an instance of the CryptoStream class, pass it the file stream, and decrypt
-                    'it with the Rijndael class using the key and IV.
-                    Using cryptStream As New CryptoStream(myStream, aes.CreateDecryptor(key, iv), CryptoStreamMode.Read)
+                    While (numBytesToRead > 0)
+                        Dim n As Integer = fileStream.Read(iv, numBytesRead, numBytesToRead)
+                        If n = 0 Then
+                            Exit While
+                        End If
+                        numBytesRead += n
+                        numBytesToRead -= n
+                    End While
 
-                        'Read the stream.
-                        Using sReader As New StreamReader(cryptStream)
+                    ' Create an instance of the CryptoStream class, pass it the file stream, and decrypt
+                    ' it with the Rijndael class using the key and IV.
+                    Using cryptoStream As New CryptoStream(fileStream, aes.CreateDecryptor(key, iv), CryptoStreamMode.Read)
 
-                            'Display the message.
-                            Console.WriteLine("The decrypted original message: {0}", sReader.ReadToEnd())
+                        ' Read the stream.
+                        Using decryptReader As New StreamReader(cryptoStream)
+
+                            ' Display the message.
+                            Console.WriteLine($"The decrypted original message: {decryptReader.ReadToEnd()}")
                         End Using
                     End Using
                 End Using

docs/standard/security/snippets/decrypting-data/vb/aesdecrypt.vbproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net5.0</TargetFramework>
   </PropertyGroup>
 
 </Project>

docs/standard/security/snippets/encrypting-data/csharp/aes-encrypt.cs

@@ -2,54 +2,38 @@
 using System.IO;
 using System.Security.Cryptography;
 
-public class EncryptExample
+try
 {
-    public static void Main(string[] args)
+    using (FileStream fileStream = new("TestData.txt", FileMode.OpenOrCreate))
     {
-        //Encryption key used to encrypt the stream.
-        //The same value must be used to encrypt and decrypt the stream.
-        byte[] key = { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16 };
-
-        try
+        using (Aes aes = Aes.Create())
         {
-            //Create a file stream
-            using FileStream myStream = new FileStream("TestData.txt", FileMode.OpenOrCreate);
-
-            //Create a new instance of the default Aes implementation class  
-            // and configure encryption key.  
-            using Aes aes = Aes.Create();
+            byte[] key =
+            {
+                0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
+                0x09, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16
+            };
             aes.Key = key;
 
-            //Stores IV at the beginning of the file.
-            //This information will be used for decryption.
             byte[] iv = aes.IV;
-            myStream.Write(iv, 0, iv.Length);
+            fileStream.Write(iv, 0, iv.Length);
 
-            //Create a CryptoStream, pass it the FileStream, and encrypt
-            //it with the Aes class.  
-            using CryptoStream cryptStream = new CryptoStream(
-                myStream, 
+            using (CryptoStream cryptoStream = new(
+                fileStream,
                 aes.CreateEncryptor(),
-                CryptoStreamMode.Write);
-
-            //Create a StreamWriter for easy writing to the
-            //file stream.  
-            using StreamWriter sWriter = new StreamWriter(cryptStream);
-
-            //Write to the stream.  
-            sWriter.WriteLine("Hello World!");
-
-            cryptStream.FlushFinalBlock();
-
-            //Inform the user that the message was written  
-            //to the stream.  
-            Console.WriteLine("The file was encrypted.");
-        }
-        catch
-        {
-            //Inform the user that an exception was raised.  
-            Console.WriteLine("The encryption failed.");
-            throw;
+                CryptoStreamMode.Write))
+            {
+                using (StreamWriter encryptWriter = new(cryptoStream))
+                {
+                    encryptWriter.WriteLine("Hello World!");
+                }
+            }
         }
     }
+
+    Console.WriteLine("The file was encrypted.");
+}
+catch (Exception ex)
+{
+    Console.WriteLine($"The encryption failed. {ex}");
 }

docs/standard/security/snippets/encrypting-data/csharp/aesencrypt.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net5.0</TargetFramework>
   </PropertyGroup>
 
 </Project>

docs/standard/security/snippets/encrypting-data/vb/aes-encrypt.vb

@@ -4,33 +4,36 @@ Imports System.Security.Cryptography
 
 Module Module1
     Sub Main()
-        'Encryption key used to encrypt the stream.
-        'The same value must be used to encrypt and decrypt the stream.
-        Dim key As Byte() = {&H1, &H2, &H3, &H4, &H5, &H6, &H7, &H8, &H9, &H10, &H11, &H12, &H13, &H14, &H15, &H16}
-
         Try
-            'Create a file stream
-            Using myStream As FileStream = New FileStream("TestData.txt", FileMode.OpenOrCreate)
+            ' Create a file stream
+            Using fileStream As New FileStream("TestData.txt", FileMode.OpenOrCreate)
 
-                'Create a new instance of the default Aes implementation class  
-                ' and configure encryption key.  
+                ' Create a new instance of the default Aes implementation class  
+                ' and configure encryption key.
                 Using aes As Aes = Aes.Create()
+                    'Encryption key used to encrypt the stream.
+                    'The same value must be used to encrypt and decrypt the stream.
+                    Dim key As Byte() = {
+                        &H1, &H2, &H3, &H4, &H5, &H6, &H7, &H8,
+                        &H9, &H10, &H11, &H12, &H13, &H14, &H15, &H16
+                    }
+
                     aes.Key = key
 
-                    'Stores IV at the beginning of the file.
-                    'This information will be used for decryption.
+                    ' Stores IV at the beginning of the file.
+                    ' This information will be used for decryption.
                     Dim iv As Byte() = aes.IV
-                    myStream.Write(iv, 0, iv.Length)
+                    fileStream.Write(iv, 0, iv.Length)
 
-                    'Create a CryptoStream, pass it the FileStream, and encrypt
-                    'it with the Aes class.  
-                    Using cryptStream As New CryptoStream(myStream, aes.CreateEncryptor(), CryptoStreamMode.Write)
+                    ' Create a CryptoStream, pass it the FileStream, and encrypt
+                    ' it with the Aes class.
+                    Using cryptoStream As New CryptoStream(fileStream, aes.CreateEncryptor(), CryptoStreamMode.Write)
 
-                        'Create a StreamWriter for easy writing to the
-                        'file stream.  
-                        Using sWriter As New StreamWriter(cryptStream)
+                        ' Create a StreamWriter for easy writing to the
+                        ' file stream.
+                        Using sWriter As New StreamWriter(cryptoStream)
 
-                            'Write to the stream.  
+                            'Write to the stream.
                             sWriter.WriteLine("Hello World!")
                         End Using
                     End Using

docs/standard/security/snippets/encrypting-data/vb/aesencrypt.vbproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp3.1</TargetFramework>
+    <TargetFramework>net5.0</TargetFramework>
   </PropertyGroup>
 
 </Project>