Windows CE 3.0

This function computes the hash of the encoded content from a signed and encoded certificate. The hash is performed on only the "to be signed" encoded content and its signature.

BOOL WINAPI CryptHashToBeSigned(
DWORD dwCertEncodingType,
const BYTE *pbEncoded,
DWORD cbEncoded,
BYTE *pbComputedHash,
DWORD *pcbComputedHash


[in] Handle of the CSP used to compute the hash.

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

[in] Specifies the encoding type used. Currently, only X509_ASN_ENCODING is used; however, additional encoding types may be added in the future.
[in] Address of a buffer containing the content to be hashed. This is the encoded form of a CERT_SIGNED_CONTENT_INFO.
[in] Size, in bytes, of the buffer.
[out] Pointer to a buffer to receive the computed hash.

This parameter can be NULL to set the size of this information for memory allocation purposes.

[in/out] 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 Values

If the function succeeds, the return value is nonzero (TRUE).

If the function fails, the return value is zero (FALSE).

For extended error information, call the GetLastError function.

Note   Errors from the called CryptCreateHash, CryptGetHashParam, and CryptHashData functions might be propagated to this function. The following table shows the error codes for this function.
Error code Description
ERROR_MORE_DATA 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, into the variable pointed to by the pcbComputedHash parameter.
ERROR_FILE_NOT_FOUND Invalid certificate encoding type. Currently only X509_ASN_ENCODING is supported.
NTE_BAD_ALGID The signature algorithm's object identifier doesn't map to a known or supported hash algorithm.


The desktop platform supports the PKCS_7_ASN_ENCODING flag, but Windows CE does not. Windows CE ignores the flag when it is specified.


Runs on Versions Defined in Include Link to
Windows CE OS 3.0 or later Wincrypt.h   Crypt32.lib
Note   This API is part of the complete Windows CE OS package as provided by Microsoft. The functionality of a particular platform is determined by the original equipment manufacturer (OEM) and some devices may not support this API.

See Also

CryptCreateHash, CryptGetHashParam, CryptHashCertificate, CryptHashData, CryptHashPublicKeyInfo

 Last updated on Tuesday, July 13, 2004

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