Generate Hmac Sha256 Key C

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Definition

Computes a Hash-based Message Authentication Code (HMAC) by using the SHA256 hash function.

Inheritance
HMACSHA256
Attributes

Examples

The following example shows how to sign a file by using the HMACSHA256 object and then how to verify the file.

Remarks

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 (HMAC). 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.

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.

HMACSHA256 accepts keys of any size, and produces a hash sequence 256 bits in length.

Constructors

Generate Hmac Sha256 C#

HMACSHA256()

Initializes a new instance of the HMACSHA256 class with a randomly generated key.

HMACSHA256(Byte[])

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

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

Generate rsa pem key c. 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. Adobe creative suite 3 master collection key generator.

(Inherited from HashAlgorithm)
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.

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 HMAC calculation.

OutputBlockSize

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

(Inherited from HashAlgorithm)

C# Create Hmac Sha256

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)

Releases the unmanaged resources used by the HMACSHA256 and optionally releases the managed resources.

Equals(Object)

Determines whether the specified object is equal to the current object.

(Inherited from Object)
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 HMAC algorithm for computing the HMAC.

HashCore(ReadOnlySpan<Byte>)

Looking for resources to download android. Routes data written to the object into the HMAC algorithm for computing the HMAC.

HashFinal()

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

Initialize()

Resets the hash algorithm to its initial state.

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.

Generate Hmac Sha256 Key

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

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Generate Hmac Sha256 Key C
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/* hmac-sha256.c */
/*
This file is part of the AVR-Crypto-Lib.
Copyright (C) 2008 Daniel Otte (daniel.otte@rub.de)
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
*
* implementation of HMAC as described in RFC2104
* Author: Daniel Otte
* email: daniel.otte@rub.de
* License: GPLv3 or later
**/
/*
* hmac = hash ( k^opad , hash( k^ipad , msg))
*/
#include<stdint.h>
#include<string.h>
#include'config.h'
#include'sha256.h'
#include'hmac-sha256.h'
#defineIPAD0x36
#defineOPAD0x5C
#ifndef HMAC_SHA256_SHORTONLY
voidhmac_sha256_init(hmac_sha256_ctx_t *s, constvoid *key, uint16_t keylength_b){
uint8_t buffer[HMAC_SHA256_BLOCK_BYTES];
uint8_t i;
memset(buffer, 0, HMAC_SHA256_BLOCK_BYTES);
if (keylength_b > HMAC_SHA256_BLOCK_BITS){
sha256((void*)buffer, key, keylength_b);
} else {
memcpy(buffer, key, (keylength_b+7)/8);
}
for (i=0; i<HMAC_SHA256_BLOCK_BYTES; ++i){
buffer[i] ^= IPAD;
}
sha256_init(&(s->a));
sha256_nextBlock(&(s->a), buffer);
for (i=0; i<HMAC_SHA256_BLOCK_BYTES; ++i){
buffer[i] ^= IPAD^OPAD;
}
sha256_init(&(s->b));
sha256_nextBlock(&(s->b), buffer);
#if defined SECURE_WIPE_BUFFER
memset(buffer, 0, SHA256_BLOCK_BYTES);
#endif
}
voidhmac_sha256_nextBlock(hmac_sha256_ctx_t *s, constvoid *block){
sha256_nextBlock(&(s->a), block);
}
voidhmac_sha256_lastBlock(hmac_sha256_ctx_t *s, constvoid *block, uint16_t length_b){
/* while(length_b>=SHA256_BLOCK_BITS){
sha256_nextBlock(&(s->a), block);
block = (uint8_t*)block + SHA256_BLOCK_BYTES;
length_b -= SHA256_BLOCK_BITS;
}
*/sha256_lastBlock(&(s->a), block, length_b);
}
voidhmac_sha256_final(void *dest, hmac_sha256_ctx_t *s){
sha256_ctx2hash((sha256_hash_t*)dest, &(s->a));
sha256_lastBlock(&(s->b), dest, SHA256_HASH_BITS);
sha256_ctx2hash((sha256_hash_t*)dest, &(s->b));
}
#endif
/*
* keylength in bits!
* message length in bits!
*/
voidhmac_sha256(void *dest, constvoid *key, uint16_t keylength_b, constvoid *msg, uint32_t msglength_b){ /* a one-shot*/
sha256_ctx_t s;
uint8_t i;
uint8_t buffer[HMAC_SHA256_BLOCK_BYTES];
memset(buffer, 0, HMAC_SHA256_BLOCK_BYTES);
/* if key is larger than a block we have to hash it*/
if (keylength_b > SHA256_BLOCK_BITS){
sha256((void*)buffer, key, keylength_b);
} else {
memcpy(buffer, key, (keylength_b+7)/8);
}
for (i=0; i<SHA256_BLOCK_BYTES; ++i){
buffer[i] ^= IPAD;
}
sha256_init(&s);
sha256_nextBlock(&s, buffer);
while (msglength_b >= HMAC_SHA256_BLOCK_BITS){
sha256_nextBlock(&s, msg);
msg = (uint8_t*)msg + HMAC_SHA256_BLOCK_BYTES;
msglength_b -= HMAC_SHA256_BLOCK_BITS;
}
sha256_lastBlock(&s, msg, msglength_b);
/* since buffer still contains key xor ipad we can do . */
for (i=0; i<HMAC_SHA256_BLOCK_BYTES; ++i){
buffer[i] ^= IPAD ^ OPAD;
}
sha256_ctx2hash(dest, &s); /* save inner hash temporary to dest */
sha256_init(&s);
sha256_nextBlock(&s, buffer);
sha256_lastBlock(&s, dest, SHA256_HASH_BITS);
sha256_ctx2hash(dest, &s);
}
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