CryptImportKey

This function transfers a cryptographic key from a key binary large object (BLOB) to the cryptographic service provider (CSP). This function can be used to import an Schannel session key, regular session key, public key, or public/private key pair. For all but the public key, the key or key pair is encrypted.

BOOL WINAPI CryptImportKey( HCRYPTPROVhProv,BYTE* pbData,DWORDdwDataLen,HCRYPTKEYhPubKey, DWORDdwFlags,HCRYPTKEY* phKey);

Parameters

• hProv
  [in] HCRYPTPROV handle to a CSP created by a call to the CryptAcquireContext function.

• pbData
  [in] Pointer to the buffer containing the key BLOB. This key BLOB was generated by the CryptExportKey function, either by this application or by another application running on a different computer.

  This key BLOB consists of a standard header followed by the encrypted key.

• dwDataLen
  [in] Specifies the length, in bytes, of the key BLOB.

• hPubKey
  [in] The meaning of this parameter differs, depending on the CSP type and the type of key BLOB being imported.

  If a signed key BLOB is being imported, this key is used to validate the signature of the key BLOB. In this case, this parameter contains a handle to the key exchange public key of the party that created the key BLOB.

  If the key BLOB is encrypted with the key exchange key pair, for example, a SIMPLEBLOB, this parameter contains the handle to the key exchange key.

  If the key BLOB is encrypted with a session key, for example, an encrypted PRIVATEKEYBLOB, this parameter contains a handle to this session key.

  If the key BLOB is not encrypted, for example, a PUBLICKEYBLOB, this parameter is not used and must be set zero.

  If the key BLOB is encrypted with a session key in an Schannel CSP, for example, an encrypted OPAQUEKEYBLOB, this parameter is not used and must be set to zero.

• dwFlags
  [in] Currently used only when a public/private key pair in the form of a PRIVATEKEYBLOB is imported into the CSP.

  The following table shows defined flag values.

  Value	Description
  CRYPT_EXPORTABLE	The key being imported is eventually to be re-exported. If this flag is not used, then calls to CryptExportKey with the key handle fail.
  CRYPT_NO_SALT	Specifies that a no-salt value gets allocated for a 40-bit symmetric key.

• phKey
  [out] Pointer to the HCRYPTKEY handle to the key that was imported.

Return Values

TRUE indicates success. FALSE indicates failure. To get extended error information, call the GetLastError function. The following table shows common values for the GetLastError function. The error values prefaced by NTE are generated by the particular CSP you are using.

Example Code

#include <wincrypt.h>

FILE *hSourceFile = NULL;
HCRYPTPROV hProv = 0;
HCRYPTKEY hKey = 0;
BYTE *pbKeyBlob = NULL;
DWORD dwBlobLen;

// Open the file, getting the file handle 'hSourceFile'.
...

// Get a handle to the default provider.
if(!CryptAcquireContext(&hProv, NULL, NULL, PROV_RSA_FULL, 0)) {
 printf("Error %x during CryptAcquireContext!\n", GetLastError());
 goto done;
}

// Read the key BLOB length from the file and allocate memory.
fread(&dwBlobLen, sizeof(DWORD), 1, hSourceFile);
pbKeyBlob = malloc(dwBlobLen);

// Read the key BLOB from the file.
fread(pbKeyBlob, 1, dwBlobLen, hSourceFile);

// Import the key BLOB into the CSP.
if(!CryptImportKey(hProv, pbKeyBlob, dwBlobLen, 0, 0, &hKey)) {
 printf("Error %x during CryptImportKey!\n", GetLastError());
 free(pbKeyBlob);
 goto done;
}

// Free memory.
free(pbKeyBlob);

// Use 'hKey' to perform cryptographic operations.
...

done:

// Destroy the session key.
if(hKey) CryptDestroyKey(hKey);

// Release the provider handle.
if(hProv) CryptReleaseContext(hProv, 0);
 

Requirements

OS Versions: Windows CE 2.10 and later.
Header: Wincrypt.h.
Link Library: Coredll.lib.

See Also

CryptAcquireContext | CryptDestroyKey | CryptExportKey

 Last updated on Thursday, April 08, 2004

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