HMACSHA1 Class

Definition

Computes a Hash-based Message Authentication Code (HMAC) using the SHA1 hash function.

public ref class HMACSHA1 : System::Security::Cryptography::HMAC
public ref class HMACSHA1 : System::Security::Cryptography::KeyedHashAlgorithm
public class HMACSHA1 : System.Security.Cryptography.HMAC
public class HMACSHA1 : System.Security.Cryptography.KeyedHashAlgorithm
[System.Runtime.InteropServices.ComVisible(true)]
public class HMACSHA1 : System.Security.Cryptography.HMAC
type HMACSHA1 = class
    inherit HMAC
type HMACSHA1 = class
    inherit KeyedHashAlgorithm
Public Class HMACSHA1
Inherits HMAC
Public Class HMACSHA1
Inherits KeyedHashAlgorithm
Inheritance
Inheritance
Attributes

Remarks

HMACSHA1 is a type of keyed hash algorithm that is constructed from the SHA1 hash function and used as an HMAC, or 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 160 bits in length.

An 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 hash value as a single message. The receiver recalculates the hash value on the received message and checks that the computed HMAC matches the transmitted HMAC.

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.

The SHA-1 (Secure Hash Algorithm, also called SHS, Secure Hash Standard) is a cryptographic hash algorithm published by the United States Government. It produces a 160-bit hash value from an arbitrary length string.

HMACSHA1 accepts keys of any size, and produces a hash sequence that is 160 bits in length.

Due to collision problems with SHA1, Microsoft recommends SHA256.

Constructors

HMACSHA1()

Initializes a new instance of the HMACSHA1 class with a randomly generated key.

HMACSHA1(Byte[])

Initializes a new instance of the HMACSHA1 class with the specified key data.

HMACSHA1(Byte[], Boolean)

Initializes a new instance of the HMACSHA1 class with the specified key data and a value that specifies whether to use the managed version of the SHA1 algorithm.

Fields

HashSizeValue

Represents the size, in bits, of the computed hash code.

(Inherited from HashAlgorithm)
HashValue

Represents the value of the computed hash code.

(Inherited from HashAlgorithm)
KeyValue

The key to use in the hash algorithm.

(Inherited from KeyedHashAlgorithm)
State

Represents the state of the hash computation.

(Inherited from HashAlgorithm)

Properties

BlockSizeValue

Gets or sets the block size to use in the hash value.

(Inherited from HMAC)
CanReuseTransform

Gets a value indicating whether the current transform can be reused.

(Inherited from HashAlgorithm)
CanTransformMultipleBlocks

When overridden in a derived class, gets a value indicating whether multiple blocks can be transformed.

(Inherited from HashAlgorithm)
Hash

Gets the value of the computed hash code.

(Inherited from HashAlgorithm)
HashName

Gets or sets the name of the hash algorithm to use for hashing.

HashName

Gets or sets the name of the hash algorithm to use for hashing.

(Inherited from HMAC)
HashSize

Gets the size, in bits, of the computed HMAC.

HashSize

Gets the size, in bits, of the computed hash code.

(Inherited from HashAlgorithm)
InputBlockSize

When overridden in a derived class, gets the input block size.

(Inherited from HashAlgorithm)
Key

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

Key

Gets or sets the key to use in the HMAC calculation.

(Inherited from HMAC)
OutputBlockSize

When overridden in a derived class, gets the output block size.

(Inherited from HashAlgorithm)

Methods

Clear()

Releases all resources used by the HashAlgorithm class.

(Inherited from HashAlgorithm)
ComputeHash(Byte[])

Computes the hash value for the specified byte array.

(Inherited from HashAlgorithm)
ComputeHash(Byte[], Int32, Int32)

Computes the hash value for the specified region of the specified byte array.

(Inherited from HashAlgorithm)
ComputeHash(Stream)

Computes the hash value for the specified Stream object.

(Inherited from HashAlgorithm)
ComputeHashAsync(Stream, CancellationToken) (Inherited from HashAlgorithm)
Dispose()

Releases all resources used by the current instance of the HashAlgorithm class.

(Inherited from HashAlgorithm)
Dispose(Boolean)

This member overrides Dispose(Boolean), and more complete documentation might be available in that topic.

Releases the unmanaged resources used by the KeyedHashAlgorithm and optionally releases the managed resources.

Dispose(Boolean)

Releases the unmanaged resources used by the HMAC class when a key change is legitimate and optionally releases the managed resources.

(Inherited from HMAC)
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.

GetHashCode()

Serves as the default hash function.

(Inherited from Object)
GetType()

Gets the Type of the current instance.

(Inherited from Object)
HashCore(Byte[], Int32, Int32)

Routes data written to the object into the SHA1 hash algorithm for computing the Hash-based Message Authentication Code (HMAC).

HashCore(Byte[], Int32, Int32)

When overridden in a derived class, routes data written to the object into the HMAC algorithm for computing the HMAC value.

(Inherited from HMAC)
HashCore(ReadOnlySpan<Byte>)

Routes data written to the object into the HMAC algorithm for computing the HMAC.

HashCore(ReadOnlySpan<Byte>)

Routes data written to the object into the HMAC algorithm for computing the HMAC.

(Inherited from HMAC)
HashCore(ReadOnlySpan<Byte>)

Routes data written to the object into the hash algorithm for computing the hash.

(Inherited from HashAlgorithm)
HashFinal()

Finalizes the HMAC computation after the last data is processed by the algorithm.

HashFinal()

When overridden in a derived class, finalizes the HMAC computation after the last data is processed by the algorithm.

(Inherited from HMAC)
Initialize()

Resets the hash algorithm to its initial state.

Initialize()

Initializes an instance of the default implementation of HMAC.

(Inherited from HMAC)
MemberwiseClone()

Creates a shallow copy of the current Object.

(Inherited from Object)
ToString()

Returns a string that represents the current object.

(Inherited from Object)
TransformBlock(Byte[], Int32, Int32, Byte[], Int32)

Computes the hash value for the specified region of the input byte array and copies the specified region of the input byte array to the specified region of the output byte array.

(Inherited from HashAlgorithm)
TransformFinalBlock(Byte[], Int32, Int32)

Computes the hash value for the specified region of the specified byte array.

(Inherited from HashAlgorithm)
TryComputeHash(ReadOnlySpan<Byte>, Span<Byte>, Int32)

Attempts to compute the hash value for the specified byte array.

(Inherited from HashAlgorithm)
TryHashFinal(Span<Byte>, Int32)

Attempts to finalize the HMAC computation after the last data is processed by the HMAC algorithm.

TryHashFinal(Span<Byte>, Int32)

Attempts to finalize the HMAC computation after the last data is processed by the HMAC algorithm.

(Inherited from HMAC)
TryHashFinal(Span<Byte>, Int32)

Attempts to finalize the hash computation after the last data is processed by the hash algorithm.

(Inherited from HashAlgorithm)

Explicit Interface Implementations

IDisposable.Dispose()

Releases the unmanaged resources used by the HashAlgorithm and optionally releases the managed resources.

(Inherited from HashAlgorithm)

Applies to

See also