The MsiGetFileSignatureInformation function takes the path to a file that has been digitally signed and returns the file's signer certificate and hash. MsiGetFileSignatureInformation may be called to obtain the signer certificate and hash needed to populate the MsiDigitalCertificate, MsiPatchCertificate, and MsiDigitalSignature tables.

Windows Installer 3.0 and later:  Beginning with Windows Installer 3.0, the Windows Installer can verify the digital signatures of patches (.msp files) by using the MsiPatchCertificate and MsiDigitalCertificate tables. For more information see Guidelines for Authoring Secure Installations and User Account Control (UAC) Patching.

Windows Installer 2.0:  Digital signatures of patches is not supported. Windows Installer 2.0 uses digital signatures as a means to detect corrupted resources, and can only verify the digital signatures of external cabinets, and only by the use of the MsiDigitalSignature and MsiDigitalCertificate tables.

Syntax

C++HRESULT MsiGetFileSignatureInformation(
  __in     LPCTSTR szSignedObjectPath,
  __in     DWORD dwFlags,
  __out    PCCERT_CONTEXT *ppcCertContext,
  __out    BYTE *pbHashData,
  __inout  DWORD *pcbHashData
);

Parameters

szSignedObjectPath [in]

Pointer to a null-terminated string specifying the full path to the file that contains the digital signature.

dwFlags [in]

Special error case flags.

Flag	Meaning
MSI_INVALID_HASH_IS_FATAL 0x1	Without this flag set, and when requesting only the certificate context, an invalid hash in the digital signature does not cause MsiGetFileSignatureInformation to return a fatal error. To return a fatal error for an invalid hash, set the MSI_INVALID_HASH_IS_FATAL flag.

 

ppcCertContext [out]

Returned signer certificate context

pbHashData [out]

Returned hash buffer. This parameter can be null if the hash data is not being requested.

pcbHashData [in, out]

Pointer to a variable that specifies the size, in bytes, of the buffer pointed to by the pbHashData parameter. This parameter cannot be null if pbHashData is non-Null. If ERROR_MORE_DATA is returned, pbHashData gives the size of the buffer required to hold the hash data. If ERROR_SUCCESS is returned, it gives the number of bytes written to the hash buffer. The pcbHashData parameter is ignored if pbHashData is null.

Return Value

MsiGetFileSignatureInformation also returns all the Win32 error values mapped to their equivalent HRESULT data type by HRESULT_FROM_WIN32.

Remarks

When requesting only the certificate context, an invalid hash in the digital signature does not cause MsiGetFileSignatureInformation to return a fatal error. To return a fatal error for an invalid hash, set the MSI_INVALID_HASH_IS_FATAL flag in the dwFlags parameter.

The certificate context and hash information is extracted from the file by a call to WinVerifyTrust. The ppcCertContext parameter is a duplicate of the signer certificate context from the signature. It is the responsibility of the caller to call CertFreeCertificateContext to free the certificate context when finished.

Note that MsiGetFileSignatureInformation requires the presence of the Wintrust.dll file on the system.

Requirements

See Also

MsiDigitalCertificate table

MsiDigitalSignature table

Digital Signatures and Windows Installer

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Build date: 8/13/2009