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HMAC Class

Represents the abstract class from which all implementations of Hash-based Message Authentication Code (HMAC) must derive.

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

[ComVisibleAttribute(true)]
public abstract class HMAC : KeyedHashAlgorithm

The HMAC type exposes the following members.

  NameDescription
Protected methodSupported by Silverlight for Windows PhoneHMACInitializes a new instance of the HMAC class.
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  NameDescription
Protected propertySupported by Silverlight for Windows PhoneBlockSizeValueGets or sets the block size to use in the hash value.
Public propertySupported by Silverlight for Windows PhoneCanReuseTransformGets a value indicating whether the current transform can be reused. (Inherited from HashAlgorithm.)
Public propertySupported by Silverlight for Windows PhoneCanTransformMultipleBlocksWhen overridden in a derived class, gets a value indicating whether multiple blocks can be transformed. (Inherited from HashAlgorithm.)
Public propertySupported by Silverlight for Windows PhoneHashGets the value of the computed hash code. (Inherited from HashAlgorithm.)
Public propertySupported by Silverlight for Windows PhoneHashNameGets or sets the name of the hash algorithm to use for hashing.
Public propertySupported by Silverlight for Windows PhoneHashSizeGets the size, in bits, of the computed hash code. (Inherited from HashAlgorithm.)
Public propertySupported by Silverlight for Windows PhoneInputBlockSizeWhen overridden in a derived class, gets the input block size. (Inherited from HashAlgorithm.)
Public propertySupported by Silverlight for Windows PhoneKeyGets or sets the key to use in the hash algorithm. (Overrides KeyedHashAlgorithm.Key.)
Public propertySupported by Silverlight for Windows PhoneOutputBlockSizeWhen overridden in a derived class, gets the output block size. (Inherited from HashAlgorithm.)
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  NameDescription
Public methodSupported by Silverlight for Windows PhoneClearReleases all resources used by the HashAlgorithm class. (Inherited from HashAlgorithm.)
Public methodSupported by Silverlight for Windows PhoneComputeHash(Byte[])Computes the hash value for the specified byte array. (Inherited from HashAlgorithm.)
Public methodSupported by Silverlight for Windows PhoneComputeHash(Stream)Computes the hash value for the specified Stream object. (Inherited from HashAlgorithm.)
Public methodSupported by Silverlight for Windows PhoneComputeHash(Byte[], Int32, Int32)Computes the hash value for the specified region of the specified byte array. (Inherited from HashAlgorithm.)
Protected methodSupported by Silverlight for Windows PhoneDisposeReleases the unmanaged resources used by the HMAC class when a key change is legitimate and optionally releases the managed resources. (Overrides KeyedHashAlgorithm.Dispose(Boolean).)
Public methodSupported by Silverlight for Windows PhoneEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodSupported by Silverlight for Windows PhoneFinalizeAllows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
Public methodSupported by Silverlight for Windows PhoneGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodSupported by Silverlight for Windows PhoneGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodSupported by Silverlight for Windows PhoneHashCoreWhen overridden in a derived class, routes data written to the object into the default HMAC hash algorithm for computing the hash value. (Overrides HashAlgorithm.HashCore(Byte[], Int32, Int32).)
Protected methodSupported by Silverlight for Windows PhoneHashFinalWhen overridden in a derived class, finalizes the hash computation after the last data is processed by the cryptographic stream object. (Overrides HashAlgorithm.HashFinal().)
Public methodSupported by Silverlight for Windows PhoneInitializeInitializes an instance of the default implementation of HMAC. (Overrides HashAlgorithm.Initialize().)
Protected methodSupported by Silverlight for Windows PhoneMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodSupported by Silverlight for Windows PhoneToStringReturns a string that represents the current object. (Inherited from Object.)
Public methodSupported by Silverlight for Windows PhoneTransformBlockComputes the hash value for the specified region of the input byte array and copies the resulting hash value to the specified region of the output byte array. (Inherited from HashAlgorithm.)
Public methodSupported by Silverlight for Windows PhoneTransformFinalBlockComputes the hash value for the specified region of the specified byte array. (Inherited from HashAlgorithm.)
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  NameDescription
Protected fieldSupported by Silverlight for Windows PhoneHashSizeValueRepresents the size, in bits, of the computed hash code. (Inherited from HashAlgorithm.)
Protected fieldSupported by Silverlight for Windows PhoneHashValueRepresents the value of the computed hash code. (Inherited from HashAlgorithm.)
Protected fieldSupported by Silverlight for Windows PhoneKeyValueThe key to use in the hash algorithm. (Inherited from KeyedHashAlgorithm.)
Protected fieldSupported by Silverlight for Windows PhoneStateRepresents the state of the hash computation. (Inherited from HashAlgorithm.)
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  NameDescription
Explicit interface implemetationPrivate methodSupported by Silverlight for Windows PhoneIDisposable.DisposeReleases the unmanaged resources used by the HashAlgorithm and optionally releases the managed resources. (Inherited from HashAlgorithm.)
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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.

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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