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HMACSHA256 Constructor (array<Byte>)

Initializes a new instance of the HMACSHA256 class with the specified key data.

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

public:
HMACSHA256(
	array<unsigned char>^ key
)

Parameters

key
Type: array<System::Byte>

The secret key for HMACSHA256 encryption. The key can be any length. However, the recommended size is 64 bytes. If the key is more than 64 bytes long, it is hashed (using SHA-256) to derive a 64-byte key. If it is less than 64 bytes long, it is padded to 64 bytes.

ExceptionCondition
ArgumentNullException

The key parameter is nullptr.

HMACSHA256 is a type of keyed hash algorithm that is constructed from the SHA-256 hash function and used as a Hash-based Message Authentication Code. The HMAC process mixes a secret key with the message data, hashes the result with the hash function, mixes that hash value with the secret key again, and then applies the hash function a second time. The output hash is 256 bits in length.

For an example of how to use this constructor, see the HMACSHA256 class.

.NET Framework

Supported in: 4.5.3, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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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