HMACSHA256 Constructor (Byte[])


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

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

public HMACSHA256(
	byte[] key


Type: 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.

Exception Condition

The key parameter is null.

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
Available since 2.0
Available since 2.0
Windows Phone Silverlight
Available since 7.0
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