AesManaged Class

Definition

Namespace:

System.Security.Cryptography

Assembly:

System.Security.Cryptography.dll

Source:

AesManaged.cs

Caution

Derived cryptographic types are obsolete. Use the Create method on the base type instead.

Provides a managed implementation of the Advanced Encryption Standard (AES) symmetric algorithm.

public ref class AesManaged sealed : System::Security::Cryptography::Aes

[System.Runtime.Versioning.UnsupportedOSPlatform("browser")]
[System.Obsolete("Derived cryptographic types are obsolete. Use the Create method on the base type instead.", DiagnosticId="SYSLIB0021", UrlFormat="https://aka.ms/dotnet-warnings/{0}")]
public sealed class AesManaged : System.Security.Cryptography.Aes

[<System.Runtime.Versioning.UnsupportedOSPlatform("browser")>]
[<System.Obsolete("Derived cryptographic types are obsolete. Use the Create method on the base type instead.", DiagnosticId="SYSLIB0021", UrlFormat="https://aka.ms/dotnet-warnings/{0}")>]
type AesManaged = class
    inherit Aes

Public NotInheritable Class AesManaged
Inherits Aes

Inheritance

Object

SymmetricAlgorithm

Aes

AesManaged

Attributes

UnsupportedOSPlatformAttribute ObsoleteAttribute

Examples

The following example demonstrates how to encrypt and decrypt sample data using the AesManaged class.

using System;
using System.IO;
using System.Security.Cryptography;

namespace Aes_Example
{
    class AesExample
    {
        public static void Main()
        {
            string original = "Here is some data to encrypt!";

            // Create a new instance of the AesManaged
            // class.  This generates a new key and initialization
            // vector (IV).
            using (AesManaged myAes = new AesManaged())
            {
                // Encrypt the string to an array of bytes.
                byte[] encrypted = EncryptStringToBytes_Aes(original, myAes.Key, myAes.IV);

                // Decrypt the bytes to a string.
                string roundtrip = DecryptStringFromBytes_Aes(encrypted, myAes.Key, myAes.IV);

                //Display the original data and the decrypted data.
                Console.WriteLine("Original:   {0}", original);
                Console.WriteLine("Round Trip: {0}", roundtrip);
            }
        }
        static byte[] EncryptStringToBytes_Aes(string plainText, byte[] Key, byte[] IV)
        {
            // Check arguments.
            if (plainText == null || plainText.Length <= 0)
                throw new ArgumentNullException("plainText");
            if (Key == null || Key.Length <= 0)
                throw new ArgumentNullException("Key");
            if (IV == null || IV.Length <= 0)
                throw new ArgumentNullException("IV");
            byte[] encrypted;

            // Create an AesManaged object
            // with the specified key and IV.
            using (AesManaged aesAlg = new AesManaged())
            {
                aesAlg.Key = Key;
                aesAlg.IV = IV;

                // Create an encryptor to perform the stream transform.
                ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);

                // Create the streams used for encryption.
                using (MemoryStream msEncrypt = new MemoryStream())
                {
                    using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                    {
                        using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                        {
                            //Write all data to the stream.
                            swEncrypt.Write(plainText);
                        }
                    }

                    encrypted = msEncrypt.ToArray();
                }
            }

            // Return the encrypted bytes from the memory stream.
            return encrypted;
        }

        static string DecryptStringFromBytes_Aes(byte[] cipherText, byte[] Key, byte[] IV)
        {
            // Check arguments.
            if (cipherText == null || cipherText.Length <= 0)
                throw new ArgumentNullException("cipherText");
            if (Key == null || Key.Length <= 0)
                throw new ArgumentNullException("Key");
            if (IV == null || IV.Length <= 0)
                throw new ArgumentNullException("IV");

            // Declare the string used to hold
            // the decrypted text.
            string plaintext = null;

            // Create an AesManaged object
            // with the specified key and IV.
            using (AesManaged aesAlg = new AesManaged())
            {
                aesAlg.Key = Key;
                aesAlg.IV = IV;

                // Create a decryptor to perform the stream transform.
                ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);

                // Create the streams used for decryption.
                using (MemoryStream msDecrypt = new MemoryStream(cipherText))
                {
                    using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                    {
                        using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                        {

                            // Read the decrypted bytes from the decrypting stream
                            // and place them in a string.
                            plaintext = srDecrypt.ReadToEnd();
                        }
                    }
                }
            }

            return plaintext;
        }
    }
}

Imports System.IO
Imports System.Security.Cryptography



Class AesExample

    Public Shared Sub Main()
        Dim original As String = "Here is some data to encrypt!"

        ' Create a new instance of the AesManaged
        ' class.  This generates a new key and initialization 
        ' vector (IV).
        Using myAes As New AesManaged()
            ' Encrypt the string to an array of bytes.
            Dim encrypted As Byte() = EncryptStringToBytes_Aes(original, myAes.Key, myAes.IV)

            ' Decrypt the bytes to a string.
            Dim roundtrip As String = DecryptStringFromBytes_Aes(encrypted, myAes.Key, myAes.IV)

            'Display the original data and the decrypted data.
            Console.WriteLine("Original:   {0}", original)
            Console.WriteLine("Round Trip: {0}", roundtrip)
        End Using

    End Sub

    Shared Function EncryptStringToBytes_Aes(ByVal plainText As String, ByVal Key() As Byte, ByVal IV() As Byte) As Byte()
        ' Check arguments.
        If plainText Is Nothing OrElse plainText.Length <= 0 Then
            Throw New ArgumentNullException("plainText")
        End If
        If Key Is Nothing OrElse Key.Length <= 0 Then
            Throw New ArgumentNullException("Key")
        End If
        If IV Is Nothing OrElse IV.Length <= 0 Then
            Throw New ArgumentNullException("IV")
        End If
        Dim encrypted() As Byte
        
        ' Create an AesManaged object
        ' with the specified key and IV.
        Using aesAlg As New AesManaged()

            aesAlg.Key = Key
            aesAlg.IV = IV

            ' Create an encryptor to perform the stream transform.
            Dim encryptor As ICryptoTransform = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV)
            ' Create the streams used for encryption.
            Using msEncrypt As New MemoryStream()
                Using csEncrypt As New CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write)
                    Using swEncrypt As New StreamWriter(csEncrypt)
                        'Write all data to the stream.
                        swEncrypt.Write(plainText)
                    End Using
                    encrypted = msEncrypt.ToArray()
                End Using
            End Using
        End Using

        ' Return the encrypted bytes from the memory stream.
        Return encrypted

    End Function 'EncryptStringToBytes_Aes

    Shared Function DecryptStringFromBytes_Aes(ByVal cipherText() As Byte, ByVal Key() As Byte, ByVal IV() As Byte) As String
        ' Check arguments.
        If cipherText Is Nothing OrElse cipherText.Length <= 0 Then
            Throw New ArgumentNullException("cipherText")
        End If
        If Key Is Nothing OrElse Key.Length <= 0 Then
            Throw New ArgumentNullException("Key")
        End If
        If IV Is Nothing OrElse IV.Length <= 0 Then
            Throw New ArgumentNullException("IV")
        End If
        ' Declare the string used to hold
        ' the decrypted text.
        Dim plaintext As String = Nothing

        ' Create an AesManaged object
        ' with the specified key and IV.
        Using aesAlg As New AesManaged
            aesAlg.Key = Key
            aesAlg.IV = IV

            ' Create a decryptor to perform the stream transform.
            Dim decryptor As ICryptoTransform = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV)

            ' Create the streams used for decryption.
            Using msDecrypt As New MemoryStream(cipherText)

                Using csDecrypt As New CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read)

                    Using srDecrypt As New StreamReader(csDecrypt)


                        ' Read the decrypted bytes from the decrypting stream
                        ' and place them in a string.
                        plaintext = srDecrypt.ReadToEnd()
                    End Using
                End Using
            End Using
        End Using

        Return plaintext

    End Function 'DecryptStringFromBytes_Aes 
End Class

open System
open System.IO
open System.Security.Cryptography

let encryptStringToBytes_Aes (plainText: string, key : byte[], iv : byte[]) : byte[] =

    // Check arguments.
    if (isNull plainText || plainText.Length <= 0) then nullArg "plainText"
    if (isNull key || key.Length <= 0) then nullArg "key"
    if (isNull iv || iv.Length <= 0) then nullArg "iv"
    
    // Create an AesManaged object
    // with the specified key and IV.
    use aesAlg = new AesManaged()
    aesAlg.Key <- key
    aesAlg.IV <- iv

    // Create an encryptor to perform the stream transform.
    let encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV)

    // Create the streams used for encryption.
    use msEncrypt = new MemoryStream()
    use csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write)
    use swEncrypt = new StreamWriter(csEncrypt)
    
    //Write all data to the stream.
    swEncrypt.Write(plainText)
    swEncrypt.Flush()
    
    // Return the encrypted bytes from the memory stream.
    msEncrypt.ToArray()

let decryptStringFromBytes_Aes (cipherText : byte[], key : byte[], iv : byte[]) : string =

    // Check arguments.
    if (isNull cipherText || cipherText.Length <= 0) then nullArg "cipherText"
    if (isNull key || key.Length <= 0) then nullArg "key"
    if (isNull iv || iv.Length <= 0) then nullArg "iv"

    // Create an AesManaged object
    // with the specified key and IV.
    use aesAlg = new AesManaged()
    aesAlg.Key <- key
    aesAlg.IV <- iv

    // Create a decryptor to perform the stream transform.
    let decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV)

    // Create the streams used for decryption.
    use msDecrypt = new MemoryStream(cipherText)
    use csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read)
    use srDecrypt = new StreamReader(csDecrypt)

    // Read the decrypted bytes from the decrypting stream
    // and return the resulting string.
    srDecrypt.ReadToEnd()

[<EntryPoint>]
let main argv = 

    let original = "Here is some data to encrypt!"

    // Create a new instance of the AesManaged
    // class.  This generates a new key and initialization 
    // vector (IV).
    use myAes = new AesManaged()

    // Encrypt the string to an array of bytes.
    let encrypted = encryptStringToBytes_Aes(original, myAes.Key, myAes.IV)

    // Decrypt the bytes to a string.
    let roundtrip = decryptStringFromBytes_Aes(encrypted, myAes.Key, myAes.IV)

    //Display the original data and the decrypted data.
    Console.WriteLine("Original:   {0}", original)
    Console.WriteLine("Round Trip: {0}", roundtrip)
    0

Remarks

The AES algorithm is essentially the Rijndael symmetric algorithm with a fixed block size and iteration count. This class functions the same way as the RijndaelManaged class but limits blocks to 128 bits and does not allow feedback modes.

Note

If the Windows security policy setting for Federal Information Processing Standards (FIPS)-compliant algorithms is enabled, using this algorithm throws a CryptographicException.

Note

Microsoft believes that it's no longer safe to decrypt data encrypted with the Cipher-Block-Chaining (CBC) mode of symmetric encryption (which is the default value of the Mode property) when verifiable padding has been applied without first ensuring the integrity of the ciphertext, except for very specific circumstances. For more information, see Timing vulnerabilities with CBC-mode symmetric decryption using padding.

Constructors

AesManaged()

Initializes a new instance of the AesManaged class.

Fields

BlockSizeValue	Represents the block size, in bits, of the cryptographic operation. (Inherited from SymmetricAlgorithm)
FeedbackSizeValue	Represents the feedback size, in bits, of the cryptographic operation. (Inherited from SymmetricAlgorithm)
IVValue	Represents the initialization vector (IV) for the symmetric algorithm. (Inherited from SymmetricAlgorithm)
KeySizeValue	Represents the size, in bits, of the secret key used by the symmetric algorithm. (Inherited from SymmetricAlgorithm)
KeyValue	Represents the secret key for the symmetric algorithm. (Inherited from SymmetricAlgorithm)
LegalBlockSizesValue	Specifies the block sizes, in bits, that are supported by the symmetric algorithm. (Inherited from SymmetricAlgorithm)
LegalKeySizesValue	Specifies the key sizes, in bits, that are supported by the symmetric algorithm. (Inherited from SymmetricAlgorithm)
ModeValue	Represents the cipher mode used in the symmetric algorithm. (Inherited from SymmetricAlgorithm)
PaddingValue	Represents the padding mode used in the symmetric algorithm. (Inherited from SymmetricAlgorithm)

Properties

BlockSize	Gets or sets the block size, in bits, of the cryptographic operation.
FeedbackSize	Gets or sets the number of bits to use as feedback.
IV	Gets or sets the initialization vector (IV) to use for the symmetric algorithm.
Key	Gets or sets the secret key used for the symmetric algorithm.
KeySize	Gets or sets the size, in bits, of the secret key used for the symmetric algorithm.
LegalBlockSizes	Gets the block sizes, in bits, that are supported by the symmetric algorithm.
LegalKeySizes	Gets the key sizes, in bits, that are supported by the symmetric algorithm.
Mode	Gets or sets the mode for operation of the symmetric algorithm.
Padding	Gets or sets the padding mode used in the symmetric algorithm.

Methods

Clear()	Releases all resources used by the SymmetricAlgorithm class. (Inherited from SymmetricAlgorithm)
CreateDecryptor()	Creates a symmetric decryptor object using the current key and initialization vector (IV).
CreateDecryptor(Byte[], Byte[])	Creates a symmetric decryptor object using the specified key and initialization vector (IV).
CreateEncryptor()	Creates a symmetric encryptor object using the current key and initialization vector (IV).
CreateEncryptor(Byte[], Byte[])	Creates a symmetric encryptor object using the specified key and initialization vector (IV).
DecryptCbc(Byte[], Byte[], PaddingMode)	Decrypts data using CBC mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
DecryptCbc(ReadOnlySpan<Byte>, ReadOnlySpan<Byte>, PaddingMode)	Decrypts data using CBC mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
DecryptCbc(ReadOnlySpan<Byte>, ReadOnlySpan<Byte>, Span<Byte>, PaddingMode)	Decrypts data into the specified buffer, using CBC mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
DecryptCfb(Byte[], Byte[], PaddingMode, Int32)	Decrypts data using CFB mode with the specified padding mode and feedback size. (Inherited from SymmetricAlgorithm)
DecryptCfb(ReadOnlySpan<Byte>, ReadOnlySpan<Byte>, PaddingMode, Int32)	Decrypts data using CFB mode with the specified padding mode and feedback size. (Inherited from SymmetricAlgorithm)
DecryptCfb(ReadOnlySpan<Byte>, ReadOnlySpan<Byte>, Span<Byte>, PaddingMode, Int32)	Decrypts data into the specified buffer, using CFB mode with the specified padding mode and feedback size. (Inherited from SymmetricAlgorithm)
DecryptEcb(Byte[], PaddingMode)	Decrypts data using ECB mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
DecryptEcb(ReadOnlySpan<Byte>, PaddingMode)	Decrypts data using ECB mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
DecryptEcb(ReadOnlySpan<Byte>, Span<Byte>, PaddingMode)	Decrypts data into the specified buffer, using ECB mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
Dispose()	Releases all resources used by the current instance of the SymmetricAlgorithm class. (Inherited from SymmetricAlgorithm)
Dispose(Boolean)	Releases the unmanaged resources used by the SymmetricAlgorithm and optionally releases the managed resources. (Inherited from SymmetricAlgorithm)
EncryptCbc(Byte[], Byte[], PaddingMode)	Encrypts data using CBC mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
EncryptCbc(ReadOnlySpan<Byte>, ReadOnlySpan<Byte>, PaddingMode)	Encrypts data using CBC mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
EncryptCbc(ReadOnlySpan<Byte>, ReadOnlySpan<Byte>, Span<Byte>, PaddingMode)	Encrypts data into the specified buffer, using CBC mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
EncryptCfb(Byte[], Byte[], PaddingMode, Int32)	Encrypts data using CFB mode with the specified padding mode and feedback size. (Inherited from SymmetricAlgorithm)
EncryptCfb(ReadOnlySpan<Byte>, ReadOnlySpan<Byte>, PaddingMode, Int32)	Encrypts data using CFB mode with the specified padding mode and feedback size. (Inherited from SymmetricAlgorithm)
EncryptCfb(ReadOnlySpan<Byte>, ReadOnlySpan<Byte>, Span<Byte>, PaddingMode, Int32)	Encrypts data into the specified buffer, using CFB mode with the specified padding mode and feedback size. (Inherited from SymmetricAlgorithm)
EncryptEcb(Byte[], PaddingMode)	Encrypts data using ECB mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
EncryptEcb(ReadOnlySpan<Byte>, PaddingMode)	Encrypts data using ECB mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
EncryptEcb(ReadOnlySpan<Byte>, Span<Byte>, PaddingMode)	Encrypts data into the specified buffer, using ECB mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
GenerateIV()	Generates a random initialization vector (IV) to use for the symmetric algorithm.
GenerateKey()	Generates a random key to use for the symmetric algorithm.
GetCiphertextLengthCbc(Int32, PaddingMode)	Gets the length of a ciphertext with a given padding mode and plaintext length in CBC mode. (Inherited from SymmetricAlgorithm)
GetCiphertextLengthCfb(Int32, PaddingMode, Int32)	Gets the length of a ciphertext with a given padding mode and plaintext length in CFB mode. (Inherited from SymmetricAlgorithm)
GetCiphertextLengthEcb(Int32, PaddingMode)	Gets the length of a ciphertext with a given padding mode and plaintext length in ECB mode. (Inherited from SymmetricAlgorithm)
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetType()	Gets the Type of the current instance. (Inherited from Object)
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
ToString()	Returns a string that represents the current object. (Inherited from Object)
TryDecryptCbc(ReadOnlySpan<Byte>, ReadOnlySpan<Byte>, Span<Byte>, Int32, PaddingMode)	Attempts to decrypt data into the specified buffer, using CBC mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
TryDecryptCbcCore(ReadOnlySpan<Byte>, ReadOnlySpan<Byte>, Span<Byte>, PaddingMode, Int32)	When overridden in a derived class, attempts to decrypt data into the specified buffer, using CBC mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
TryDecryptCfb(ReadOnlySpan<Byte>, ReadOnlySpan<Byte>, Span<Byte>, Int32, PaddingMode, Int32)	Attempts to decrypt data into the specified buffer, using CFB mode with the specified padding mode and feedback size. (Inherited from SymmetricAlgorithm)
TryDecryptCfbCore(ReadOnlySpan<Byte>, ReadOnlySpan<Byte>, Span<Byte>, PaddingMode, Int32, Int32)	When overridden in a derived class, attempts to decrypt data into the specified buffer, using CFB mode with the specified padding mode and feedback size. (Inherited from SymmetricAlgorithm)
TryDecryptEcb(ReadOnlySpan<Byte>, Span<Byte>, PaddingMode, Int32)	Attempts to decrypt data into the specified buffer, using ECB mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
TryDecryptEcbCore(ReadOnlySpan<Byte>, Span<Byte>, PaddingMode, Int32)	When overridden in a derived class, attempts to decrypt data into the specified buffer, using ECB mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
TryEncryptCbc(ReadOnlySpan<Byte>, ReadOnlySpan<Byte>, Span<Byte>, Int32, PaddingMode)	Attempts to encrypt data into the specified buffer, using CBC mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
TryEncryptCbcCore(ReadOnlySpan<Byte>, ReadOnlySpan<Byte>, Span<Byte>, PaddingMode, Int32)	When overridden in a derived class, attempts to encrypt data into the specified buffer, using CBC mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
TryEncryptCfb(ReadOnlySpan<Byte>, ReadOnlySpan<Byte>, Span<Byte>, Int32, PaddingMode, Int32)	Attempts to encrypt data into the specified buffer, using CFB mode with the specified padding mode and feedback size. (Inherited from SymmetricAlgorithm)
TryEncryptCfbCore(ReadOnlySpan<Byte>, ReadOnlySpan<Byte>, Span<Byte>, PaddingMode, Int32, Int32)	When overridden in a derived class, attempts to encrypt data into the specified buffer, using CFB mode with the specified padding mode and feedback size. (Inherited from SymmetricAlgorithm)
TryEncryptEcb(ReadOnlySpan<Byte>, Span<Byte>, PaddingMode, Int32)	Attempts to encrypt data into the specified buffer, using ECB mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
TryEncryptEcbCore(ReadOnlySpan<Byte>, Span<Byte>, PaddingMode, Int32)	When overridden in a derived class, attempts to encrypt data into the specified buffer, using ECB mode with the specified padding mode. (Inherited from SymmetricAlgorithm)
ValidKeySize(Int32)	Determines whether the specified key size is valid for the current algorithm. (Inherited from SymmetricAlgorithm)