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CryptHashPublicKeyInfo function

Important  This API is deprecated. New and existing software should start using Cryptography Next Generation APIs. Microsoft may remove this API in future releases.

The CryptHashPublicKeyInfo function encodes the public key information in a CERT_PUBLIC_KEY_INFO structure and computes the hash of the encoded bytes. The hash created is used with key identifier functions.


BOOL WINAPI CryptHashPublicKeyInfo(
  _In_    HCRYPTPROV_LEGACY     hCryptProv,
  _In_    ALG_ID                Algid,
  _In_    DWORD                 dwFlags,
  _In_    DWORD                 dwCertEncodingType,
  _Out_   BYTE                  *pbComputedHash,
  _Inout_ DWORD                 *pcbComputedHash


hCryptProv [in]

This parameter is not used and should be set to NULL.

Windows Server 2003 and Windows XP:  A handle of the cryptographic service provider (CSP) to use to compute the hash.

This parameter's data type is HCRYPTPROV.

Unless there is a strong reason for passing in a specific cryptographic provider in hCryptProv, zero is passed in. Passing in zero causes the default RSA or Digital Signature Standard (DSS) provider to be acquired before doing hash, signature verification, or recipient encryption operations.

Algid [in]

An ALG_ID structure that specifies the CryptoAPI hash algorithm to use. If Algid is zero, the default hash algorithm, SHA1, is used.

dwFlags [in]

Values to be passed on to CryptCreateHash.

dwCertEncodingType [in]

Specifies the encoding type used. It is always acceptable to specify both the certificate and message encoding types by combining them with a bitwise-OR operation as shown in the following example:


Currently defined encoding types are:

pInfo [in]

A pointer to a CERT_PUBLIC_KEY_INFO structure that contains the public key information to be encoded and hashed.

pbComputedHash [out]

A pointer to a buffer to receive the computed hash.

To set the size of this information for memory allocation purposes, this parameter can be NULL. For more information, see Retrieving Data of Unknown Length.

pcbComputedHash [in, out]

A pointer to a DWORD that contains the size, in bytes, of the buffer pointed to by the pbComputedHash parameter. When the function returns, the DWORD contains the number of bytes stored in the buffer.

Note  When processing the data returned in the buffer, applications need to 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 (TRUE).

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

Note  Errors from the called functions CryptCreateHash, CryptGetHashParam, and CryptHashData can be propagated to this function. This function has the following error codes.
Return codeDescription

If the buffer specified by the pbComputedHash 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 pcbComputedHash.


Invalid certificate encoding type. Currently only X509_ASN_ENCODING is supported.


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.


Minimum supported client

Windows XP [desktop apps | UWP apps]

Minimum supported server

Windows Server 2003 [desktop apps | UWP apps]







See also

Data Management Functions