CryptVerifyMessageSignatureWithKey function (wincrypt.h)

The CryptVerifyMessageSignatureWithKey function verifies a signed message's signature by using specified public key information.


BOOL CryptVerifyMessageSignatureWithKey(
  [in]      PCERT_PUBLIC_KEY_INFO          pPublicKeyInfo,
  [in]      const BYTE                     *pbSignedBlob,
  [in]      DWORD                          cbSignedBlob,
  [out]     BYTE                           *pbDecoded,
  [in, out] DWORD                          *pcbDecoded


[in] pVerifyPara

A pointer to a CRYPT_KEY_VERIFY_MESSAGE_PARA structure that contains verification parameters.

[in] pPublicKeyInfo

A pointer to a CERT_PUBLIC_KEY_INFO structure that contains the public key that is used to verify the signed message. If NULL, the signature is not verified.

[in] pbSignedBlob

A pointer to a buffer that contains the signed message.

[in] cbSignedBlob

The size, in bytes, of the signed message buffer.

[out] pbDecoded

A pointer to a buffer to receive the decoded message.

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

[in, out] pcbDecoded

A pointer to a DWORD value that specifies the size, in bytes, of the pbDecoded buffer. When the function returns, this DWORD contains the size, in bytes, of the decoded message. The decoded message will not be returned if this parameter is NULL.

Note  When processing the data 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 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

If the function succeeds, the function returns nonzero.

If the function fails, it returns zero. For extended error information, call GetLastError.

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

Return code Description
If the buffer specified by the pbDecoded 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, in the variable pointed to by pcbDecoded.
Invalid message and certificate encoding types. Currently only PKCS_7_ASN_ENCODING and X509_ASN_ENCODING_TYPE are supported. Invalid cbSize in *pVerifyPara.
Not a signed cryptographic message.
The message does not have any signers or a signer for the specified dwSignerIndex.
The message was hashed and signed by using an unknown or unsupported algorithm.
The message's signature was not verified.


Requirement Value
Minimum supported client Windows XP [desktop apps only]
Minimum supported server Windows Server 2003 [desktop apps only]
Target Platform Windows
Header wincrypt.h
Library Crypt32.lib
DLL Crypt32.dll