AesManaged Class
Provides a managed implementation of the Advanced Encryption Standard (AES) symmetric algorithm.
System.Security.Cryptography.SymmetricAlgorithm
System.Security.Cryptography.Aes
System.Security.Cryptography.AesManaged
Assembly: System.Core (in System.Core.dll)
The AesManaged type exposes the following members.
| Name | Description | |
|---|---|---|
![]() | BlockSize | Gets or sets the block size, in bits, of the cryptographic operation. (Inherited from SymmetricAlgorithm.) |
![]() | FeedbackSize | Gets or sets the number of bits to use as feedback. (Overrides SymmetricAlgorithm.FeedbackSize.) |
![]() | IV | Gets or sets the initialization vector (IV) to use for the symmetric algorithm. (Overrides SymmetricAlgorithm.IV.) |
![]() | Key | Gets or sets the secret key used for the symmetric algorithm. (Overrides SymmetricAlgorithm.Key.) |
![]() | KeySize | Gets or sets the size, in bits, of the secret key used for the symmetric algorithm. (Overrides SymmetricAlgorithm.KeySize.) |
![]() | LegalBlockSizes | Gets the block sizes, in bits, that are supported by the symmetric algorithm. (Inherited from SymmetricAlgorithm.) |
![]() | LegalKeySizes | Gets the key sizes, in bits, that are supported by the symmetric algorithm. (Inherited from SymmetricAlgorithm.) |
![]() | Mode | Gets or sets the mode for operation of the symmetric algorithm. (Overrides SymmetricAlgorithm.Mode.) |
![]() | Padding | Gets or sets the padding mode used in the symmetric algorithm. (Overrides SymmetricAlgorithm.Padding.) |
| Name | Description | |
|---|---|---|
![]() | 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). (Overrides SymmetricAlgorithm.CreateDecryptor.) |
![]() | CreateDecryptor(Byte(), Byte()) | Creates a symmetric decryptor object using the specified key and initialization vector (IV). (Overrides SymmetricAlgorithm.CreateDecryptor(Byte(), Byte()).) |
![]() | CreateEncryptor | Creates a symmetric encryptor object using the current key and initialization vector (IV). (Overrides SymmetricAlgorithm.CreateEncryptor.) |
![]() | CreateEncryptor(Byte(), Byte()) | Creates a symmetric encryptor object using the specified key and initialization vector (IV). (Overrides SymmetricAlgorithm.CreateEncryptor(Byte(), Byte()).) |
![]() | 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.) |
![]() | Equals(Object) | Determines whether the specified Object is equal to the current Object. (Inherited from Object.) |
![]() | Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
![]() | GenerateIV | Generates a random initialization vector (IV) to use for the symmetric algorithm. (Overrides SymmetricAlgorithm.GenerateIV.) |
![]() | GenerateKey | Generates a random key to use for the symmetric algorithm. (Overrides SymmetricAlgorithm.GenerateKey.) |
![]() | GetHashCode | Serves as a hash function for a particular type. (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.) |
![]() | ValidKeySize | Determines whether the specified key size is valid for the current algorithm. (Inherited from SymmetricAlgorithm.) |
| Name | Description | |
|---|---|---|
![]() | 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.) |
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. |
The following example demonstrates how to encrypt and decrypt sample data using the AesManaged class.
Imports System Imports System.IO Imports System.Security.Cryptography Class AesExample Public Shared Sub Main() Try 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 Catch e As Exception Console.WriteLine("Error: {0}", e.Message) End Try End Sub 'Main 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("Key") 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 a decrytor 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("Key") 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 decrytor 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 'AesExample
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.




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