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

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

BOOL WINAPI CryptHashData( 
  BYTE* pbData,
  DWORD dwDataLen, 
  DWORD dwFlags


[in] HCRYPTHASH handle to the hash object created by calling the CryptCreateHash function.


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


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


[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.

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

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

Value Description


One of the parameters specifies an invalid handle.


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


The hHash handle specifies an algorithm that this CSP does not support.


The dwFlags parameter contains an invalid value.


The hash object specified by the hHash parameter is invalid.


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


A keyed hash algorithm is being used, but the session key is no longer valid.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.


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


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


The function failed in some unexpected way.


The CSP ran out of memory during the operation.

Windows Embedded CEWindows CE 2.10 and later
Windows MobileWindows Mobile Version 5.0 and later

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