CryptHashMessage (Compact 2013)

3/28/2014

This function creates a hash of the message.

Syntax

BOOL WINAPI CryptHashMessage(
      __in PCRYPT_HASH_MESSAGE_PARA pHashPara,
      __in BOOL fDetachedHash,
      __in DWORD cToBeHashed,
      __in const BYTE* rgpbToBeHashed[],
      __in DWORD rgcbToBeHashed[],
      __out BYTE* pbHashedBlob,
      __inout DWORD* pcbHashedBlob,
      __out_opt BYTE* pbComputedHash,
      __inout_opt DWORD* pcbComputedHash
);

Parameters

• pHashPara
  [in] Pointer to a CRYPT_HASH_MESSAGE_PARA structure that contains the hash parameters.

• fDetachedHash
  [in] If this parameter is set to TRUE, only pbComputedHash is encoded in pbHashedBlob. Otherwise, both rgpbToBeHashed and pbComputedHash are encoded.

• cToBeHashed
  [in] Number of array elements in rgpbToBeHashed and rgcbToBeHashed. This parameter can only be 1 unless fDetachedHash is set to TRUE.

• rgpbToBeHashed
  [in] Array of pointers to buffers that contain the contents to be hashed.

• rgcbToBeHashed
  [in] Array of sizes, in bytes, of the buffers that are pointed to by rgpbToBeHashed.

• pbHashedBlob
  [out] Pointer to a buffer to receive the hashed message that is encoded for transmission.

  This parameter can be set to NULL if the hashed message is not needed for additional processing, or it can be set to NULL to set the size of the hashed message for memory allocation purposes. A hashed message will not be returned if this parameter is NULL. For more information, see Retrieving Data of Unknown Length.

• pcbHashedBlob
  [in, out] Pointer to a DWORD that specifies the size, in bytes, of the buffer pointed to by the pbHashedBlob parameter. When the function returns, this variable contains the size, in bytes, of the decrypted message copied to pbHashedBlob. This parameter must be the address of a DWORD and not NULL or the length of the buffer will not be returned.

  Note

  When processing the data that is returned, applications must use the actual size of the data returned. The actual size can be slightly smaller than the size of the buffer specified on input. On input, buffer sizes are usually specified so they are large enough to ensure that the largest possible output data will fit in the buffer. On output, the variable pointed to by this parameter is updated to reflect the actual size of the data copied to the buffer.

• pbComputedHash
  [out, optional] Pointer to a buffer to receive the newly created hash value. This parameter can be set to NULL if the newly created hash is not needed for additional processing, or it can be set to NULL to set the size of the hash for memory allocation purposes. For more information, see Retrieving Data of Unknown Length.

• pcbComputedHash
  [in, out, optional] Pointer to a DWORD that specifies the size, in bytes, of the buffer pointed to by the pbComputedHash parameter. When the function returns, this DWORD contains the size, in bytes, of the newly created hash that was copied to pbComputedHash.

  Note

  When processing the data that is returned, applications must use the actual size of the data that is returned. The actual size can be slightly smaller than the size of the buffer specified on input. On input, buffer sizes are usually specified so they are large enough to ensure that the largest possible output data will fit in the buffer. On output, the variable pointed to by this parameter is updated to reflect the actual size of the data copied to the buffer.

Return Value

Returns true (nonzero) if function succeeds; otherwise, false (zero). To retrieve extended error information, call GetLastError.

Note

Errors from the called functions CryptCreateHash, CryptHashData, and CryptGetHashParam might be propagated to this function.

The following error codes are most commonly returned by the GetLastError function.

Value	Description
E_INVALIDARG	The message encoding type is not valid. Currently only PKCS_7_ASN_ENCODING is supported. The cbSize in *pHashPara is not valid.
ERROR_MORE_DATA	If the buffer specified by the pbHashedBlob parameter is not large enough to hold the returned data, the function sets the ERROR_MORE_DATA code and stores the required buffer size, in bytes, into the variable pointed to by pbHashedBlob.

If the function fails, GetLastError may return an Abstract Syntax Notation One (ASN.1) encoding/decoding error. For information about these errors, see ASN.1 Encoding/Decoding Return Values.

Requirements

Header	wincrypt.h
Library	crypt32.lib

See Also

Reference

Certificates Functions