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HMAC.Key Property

Gets or sets the key to use in the hash algorithm.

Namespace: System.Security.Cryptography
Assembly: mscorlib (in mscorlib.dll)

'Declaration
Public Overrides Property Key As Byte()
'Usage
Dim instance As HMAC
Dim value As Byte()

value = instance.Key

instance.Key = value
/** @property */
public byte[] get_Key ()

/** @property */
public void set_Key (byte[] value)

public override function get Key () : byte[]

public override function set Key (value : byte[])

Not applicable.

Property Value

The key to use in the hash algorithm.

Exception typeCondition

CryptographicException

An attempt is made to change the Key property after hashing has begun.

This property is the key for the keyed hash algorithm.

A Hash-based Message Authentication Code (HMAC) can be used to determine whether a message sent over an insecure channel has been tampered with, provided that the sender and receiver share a secret key. The sender computes the hash value for the original data and sends both the original data and the HMAC as a single message. The receiver recomputes the hash value on the received message and checks that the computed hash value matches the transmitted hash value.

HMAC can be used with any iterative cryptographic hash function, such as MD5 or SHA-1, in combination with a secret shared key. The cryptographic strength of HMAC depends on the properties of the underlying hash function.

Any change to the data or the hash value results in a mismatch, because knowledge of the secret key is required to change the message and reproduce the correct hash value. Therefore, if the original and computed hash values match, the message is authenticated.

Windows 98, Windows Server 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

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