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4/8/2010

This function adds data to a specified hash object. This function and the CryptHashSessionKeyfunction can be called multiple times to compute the hash on long streams or on discontinuous streams.

Before calling this function, the CryptCreateHashfunction must be called to create a handle to a hash object.

Syntax 

BOOL WINAPI CryptHashData( 
  HCRYPTHASH 
hHash, 
  BYTE* 
pbData,
  DWORD 
dwDataLen, 
  DWORD 
dwFlags
);

Parameters

hHash

[in] HCRYPTHASHhandle to the hash object created by calling the CryptCreateHashfunction.

pbData

[in] Pointer to a buffer containing the data to be hashed.

dwDataLen

[in] Specifies the number of bytes of data to be hashed. This value must be zero if the CRYPT_USERDATA flag is set.

dwFlags

[in] Bitmask of flags. All Microsoft cryptographic service providers ignore this parameter. The CRYPT_USERDATA flag value is defined for other cryptographic service providers (CSPs).

If the CRYPT_USERDATA flag is set, the CSP prompts the user to input data directly and adds the data to the hash. Access directly to the hash data is not allowed; instead, applications manipulate the hash values through the hash handle. This flag allows the users to enter a personal identification number (PIN) into the system.

Return Value

TRUE indicates success. FALSE indicates failure. To get extended error information, call the GetLastErrorfunction.

The following table shows the common values for the GetLastErrorfunction. The error values prefaced by NTE are generated by the particular CSP you are using.

Value Description

ERROR_INVALID_HANDLE

One of the parameters specifies an invalid handle.

ERROR_INVALID_PARAMETER

One of the parameters contains an invalid value. This is most often an illegal pointer.

NTE_BAD_ALGID

The hHashhandle specifies an algorithm that this CSP does not support.

NTE_BAD_FLAGS

The dwFlagsparameter contains an invalid value.

NTE_BAD_HASH

The hash object specified by the hHashparameter is invalid.

NTE_BAD_HASH_STATE

An attempt was made to add data to a hash object that is already marked as finished.

NTE_BAD_KEY

A keyed hash algorithm is being used, but the session key is no longer valid. This error will be generated if the session key is destroyed before the hashing operation is complete.

NTE_BAD_LEN

The CRYPT_USERDATA flag is set and the dwDataLenparameter has a nonzero value.

NTE_BAD_UID

The CSP context that was specified when the hash object was created cannot be found.

NTE_FAIL

The function failed in some unexpected way.

NTE_NO_MEMORY

The CSP ran out of memory during the operation.

Example Code

Requirements

Header wincrypt.h
Library coredll.lib
Windows Embedded CE Windows CE 2.10 and later
Windows Mobile Windows Mobile Version 5.0 and later

See Also