BCryptHashData function (bcrypt.h)

The BCryptHashData function appends data to an ongoing cryptographic hash or Message Authentication Code (MAC) computation.

Syntax

NTSTATUS BCryptHashData(
  [in, out] BCRYPT_HASH_HANDLE hHash,
  [in]      PUCHAR             pbInput,
  [in]      ULONG              cbInput,
  [in]      ULONG              dwFlags
);

Parameters

[in, out] hHash

The handle of the hash or MAC object to use to perform the operation. This handle is obtained by calling the BCryptCreateHash or BCryptDuplicateHash functions.

[in] pbInput

A pointer to a buffer that contains the data to process. The cbInput parameter contains the number of bytes in this buffer. This function does not modify the contents of this buffer.

[in] cbInput

The size, in bytes, of the pbInput buffer.

[in] dwFlags

A set of flags that modify the behavior of this function. No flags are currently defined, so this parameter should be zero.

Return value

Returns a status code that indicates the success or failure of the function.

Possible return codes include, but are not limited to, the following.

Remarks

To combine more than one buffer into the hash or MAC, you can call this function multiple times, passing a different buffer each time. This is functionally equivalent to concatenating these buffers into a single buffer and doing a single hash or MAC call, but is more often more convenient when the data is not naturally contiguous in memory.

To obtain the hash or MAC value, call the BCryptFinishHash function. After the BCryptFinishHash function has been called, the hHash handle cannot be reused, unless it was created with the BCRYPT_HASH_REUSABLE_FLAG flag.

When using a supported algorithm provider, BCryptHashData can be called either from user mode or kernel mode. Kernel mode callers can execute either at PASSIVE_LEVEL IRQL or DISPATCH_LEVEL IRQL. If the current IRQL level is DISPATCH_LEVEL, the handle provided in the hAlgorithm parameter must have been opened by using the BCRYPT_PROV_DISPATCH flag, and any pointers passed to the BCryptHashData function must refer to nonpaged (or locked) memory.

To call this function in kernel mode, use Cng.lib, which is part of the Driver Development Kit (DDK). Windows Server 2008 and Windows Vista: To call this function in kernel mode, use Ksecdd.lib.

Requirements

See also

BCryptCreateHash

BCryptFinishHash

BCryptDestroyHash