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CryptSetKeyParam (Windows CE 5.0)

Windows CE 5.0
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This function customizes various aspects of a key's operations. The values set by this function are not persisted to memory and are used only within a single session.

The Microsoft cryptographic service providers (CSPs) do not allow setting the values for key exchange or signature keys; however, custom providers may define parameters that can be set on these keys.

BOOL WINAPI CryptSetKeyParam( 
  HCRYPTKEY hKey, 
  DWORD dwParam, 
  BYTE* pbData, 
  DWORD dwFlags
);

Parameters

hKey
[in] HCRYPTKEY handle to the key on which to set parameters.
dwParam
[in] Key parameter type.

The following table shows the available key types.

Key typeDescriptionpbData content
KP_ALGIDKey algorithmALG_ID identifier for the algorithm specified when the key was created. Note that when key specifications AT_KEYEXCHANGE and AT_SIGNATURE are used, the algorithm identifiers that are used to generate the key depend on the provider. As a result, the values returned from CryptGetKeyParam for these key specifications when the KP_ALGID value is specified depend on the provider used. To determine the algorithm identifier that the different providers use for the key specifications AT_KEYEXCHANGE and AT_SIGNATURE, see ALG_ID.
KP_BLOCKLENSession key or public/private key pair specified by hKeyDWORD value indicating the block length. For stream ciphers, this value is always zero.

If session key is specified by hKey, the pbData parameter contains the key cipher's block length, in bits.

If a public/private key pair is specified by hKey, pbData contains a BLOB with the key pair's encryption granularity, in bits.

KP_CERTIFICATECertificateA buffer containing the DER-encoded X.509 certificate. The public key in the certificate must match the corresponding signature or exchange key.
KP_EFFECTIVE_KEYLENhKey specifies block cipher session keyDWORD value equal to the effective key length.
KP_GhKey specifies a DSS keyPrime Q from the DSS key BLOB. The length of the data is returned in the pdwDataLen parameter.
KP_IVInitialization vector. The hkey parameter specifies a block cipher session keyBYTE array indicating the current initialization vector. This array contains block_length/8 elements. For example, if the block length is sixty-four bits, the initialization vector consists of eight bytes.
KP_KEYEXCHANGE_PINPassword to unlock a smart cardA null-terminated ASCII string that sets the password used to enable the private key for the key exchange.
KP_KEYLENDWORD value, in bits, used to get the actual length of the keyThis value can be used to get the length of any key type. Microsoft CSPs return a key length of 64 bits for CALG_DES, 128 bits for CALG_3DES_112, and 192 bits for CALG_3DES. These lengths are different from the lengths returned when enumerating algorithms with the dwParam value of CryptGetProvParam set to PP_ENUMALGS. The length returned by this call is the actual size of the key including the parity bits included in the key.

Microsoft CSPs that support the ALG_ID CALG_CYLINK_MEK return 64-four bits for that algorithm. CALG_CYLINK_MEK is a 64 key but has parity and zeroed key bits to make the key length 64 bits.

KP_MODEhkey specifies a block cipher session keyDWORD value indicating the mode of the cipher. For a list of valid cipher modes, see the table in the Remarks section.
KP_MODE_BITSNumber of bits to feed back; the hkey parameter specifies a block cipher session keyDWORD value indicating the number of bits that are processed per cycle when the OFB or CFB cipher mode is used.
KP_PhKey specifies a DSS keyPrime modulus P from the DSS key BLOB. The length of the data is returned in the pdwDataLen parameter.
KP_PADDINGPadding mode. The hkey parameter specifies a block cipher session keyDWORD value indicating the padding method used by the cipher. The padding method currently defined is PKCS5_PADDING — PKCS 5 (sec 6.2).
KP_PERMISSIONSKey permissionsDWORD value with zero or more bit permission flags set.
KP_QhKey specifies a DSS keyGenerator G from the key BLOB. The length of the data is returned in the pdwDataLen parameter.
KP_SALTSalt valueBYTE array indicating the current salt value. The size of the salt value varies depending on the CSP and algorithm being used. Salt values do not apply to public/private key pairs.
KP_SALT_EXSalt valueThe CRYPT_DATA_BLOB that specifies the variable size salt value.
KP_SIGNATURE_PINPassword to unlock a smart cardA null-terminated ASCII string that sets the password used to enable the signature private key.
KP_XhKey specifies a DSS keyAfter the P, Q, and G values have been set, a call can be made to CryptSetKeyParam to specify the KP_X value for dwParam and NULL for the pbData parameter. This causes the X and Y values to be generated.
pbData
[in] Pointer to the data buffer. The value in this buffer must be set before calling the CryptSetKeyParam function. The form of this data varies depending on the parameter value.
dwFlags
[in] Reserved for future use and must be set to zero.

Return Values

TRUE indicates success. FALSE indicates failure. To get extended error information, call the GetLastError function.

The following table shows the common values for the GetLastError function. The error values prefaced by NTE are generated by the particular CSP you are using.

ValueDescription
ERROR_BUSYThe CSP context is currently being used by another process.
ERROR_INVALID_HANDLEOne of the parameters specifies an invalid handle.
ERROR_INVALID_PARAMETEROne of the parameters contains an invalid value. This is most often an illegal pointer.
NTE_BAD_DATAEither the algorithm that works with the public key you are trying to import is not supported by this CSP, or an attempt was made to import a session key that was encrypted with something other than one of your public keys.
NTE_BAD_FLAGSThe dwFlags parameter is nonzero or the pbData buffer contains an invalid value.
NTE_BAD_KEYThe hKey parameter does not contain a valid handle to a key.
NTE_BAD_TYPEThe dwParam parameter specifies an unknown parameter.
NTE_BAD_UIDThe CSP context that was specified when the hKey key was created cannot be found.
NTE_FAILThe function failed in some unexpected way.

Example Code

#include <wincrypt.h>

HCRYPTPROV hProv = 0;
HCRYPTKEY hKey = 0;
DWORD dwMode;
BYTE pbData[16];
DWORD dwCount;
DWORD i;

// Get a handle to the user default provider using CryptAcquireContext.
// For sample code, see CryptAcquireContext.
...
...

// Create a random block cipher session key.
if(!CryptGenKey(hProv, CALG_RC2, CRYPT_EXPORTABLE, &hKey)) {
 printf("Error %x during CryptGenKey!\n", GetLastError());
 goto done;
}

// Set the cipher mode.
dwMode = CRYPT_MODE_ECB;
if(!CryptSetKeyParam(hKey, KP_MODE, &dwMode, 0)) {
 printf("Error %x during CryptSetKeyParam!\n", GetLastError());
 goto done;
}

// Generate a random initialization vector.
if(!CryptGenRandom(hProv, 8, pbData)) {
 printf("Error %x during CryptGenRandom!\n", GetLastError());
 goto done;
}

// Set the initialization vector.
if(!CryptSetKeyParam(hKey, KP_IV, pbData, 0)) {
 printf("Error %x during CryptSetKeyParam!\n", GetLastError());
 goto done;
}

// Use 'hKey' to encrypt a message.
...

done:

// Destroy the session key.
if(hKey != 0) CryptDestroyKey(hKey);

// Free the provider handle.
if(hProv != 0) CryptReleaseContext(hProv, 0);

Requirements

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

See Also

CryptGenKey | CryptGetKeyParam


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