See Also
 Important: |
|---|
| This is retired content. This content is outdated and is no longer being maintained. It is provided as a courtesy for individuals who are still using these technologies. This content may contain URLs that were valid when originally published, but now link to sites or pages that no longer exist. |
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.
Syntax
BOOL WINAPI CryptSetKeyParam( HCRYPTKEY hKey, DWORD dwParam, BYTE* pbData, DWORD dwFlags ); |
Parameters
- hKey
-
[in] HCRYPTKEYhandle to the key on which to set parameters.
- dwParam
-
[in] Key parameter type.
The following table shows the available key types.
Key type Description pbDatacontent KP_ALGID
Key algorithm
ALG_IDidentifier 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 CryptGetKeyParamfor 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_BLOCKLEN
Session key or public/private key pair specified by hKey
DWORDvalue indicating the block length. For stream ciphers, this value is always zero.
If session key is specified by hKey, the pbDataparameter contains the key cipher's block length, in bits.
If a public/private key pair is specified by hKey, pbDatacontains a BLOB with the key pair's encryption granularity, in bits.
KP_CERTIFICATE
Certificate
A buffer containing the DER-encoded X.509 certificate. The public key in the certificate must match the corresponding signature or exchange key.
KP_EFFECTIVE_KEYLEN
hKeyspecifies block cipher session key
DWORDvalue equal to the effective key length.
KP_G
hKeyspecifies a DSS key
Prime Q from the DSS key BLOB. The length of the data is returned in the pdwDataLenparameter.
KP_IV
Initialization vector. The hkeyparameter specifies a block cipher session key
BYTEarray 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_PIN
Password to unlock a smart card
A null-terminated ASCII string that sets the password used to enable the private key for the key exchange.
KP_KEYLEN
DWORDvalue, in bits, used to get the actual length of the key
This 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 dwParamvalue of CryptGetProvParamset 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_MODE
hkeyspecifies a block cipher session key
DWORDvalue indicating the mode of the cipher. For a list of valid cipher modes, see the table in the Remarks section.
KP_MODE_BITS
Number of bits to feed back; the hkeyparameter specifies a block cipher session key
DWORDvalue indicating the number of bits that are processed per cycle when the OFB or CFB cipher mode is used.
KP_P
hKeyspecifies a DSS key
Prime modulus P from the DSS key BLOB. The length of the data is returned in the pdwDataLenparameter.
KP_PADDING
Padding mode. The hkeyparameter specifies a block cipher session key
DWORDvalue indicating the padding method used by the cipher. The padding method currently defined is PKCS5_PADDING — PKCS 5 (sec 6.2).
KP_PERMISSIONS
Key permissions
DWORDvalue with zero or more bit permission flags set.
KP_Q
hKeyspecifies a DSS key
Generator G from the key BLOB. The length of the data is returned in the pdwDataLenparameter.
KP_SALT
Salt value
BYTE 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_EX
Salt value
The CRYPT_DATA_BLOB that specifies the variable size salt value.
KP_SIGNATURE_PIN
Password to unlock a smart card
A null-terminated ASCII string that sets the password used to enable the signature private key.
KP_X
hKeyspecifies a DSS key
After the P, Q, and G values have been set, a call can be made to CryptSetKeyParamto specify the KP_X value for dwParamand NULL for the pbDataparameter. 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 CryptSetKeyParamfunction. The form of this data varies depending on the parameter value.
- dwFlags
-
[in] Reserved for future use and must be set to zero.
Return Value
TRUE indicates success. FALSE indicates failure. To get extended error information, call the GetLastErrorfunction.
The following table shows the common values for the GetLastErrorfunction. The error values prefaced by NTE are generated by the particular CSP you are using.
| Value | Description |
|---|---|
|
ERROR_BUSY |
The CSP context is currently being used by another process. |
|
ERROR_INVALID_HANDLE |
One of the parameters specifies an invalid handle. |
|
ERROR_INVALID_PARAMETER |
One of the parameters contains an invalid value. This is most often an illegal pointer. |
|
NTE_BAD_DATA |
Either 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_FLAGS |
The dwFlagsparameter is nonzero or the pbDatabuffer contains an invalid value. |
|
NTE_BAD_KEY |
The hKeyparameter does not contain a valid handle to a key. |
|
NTE_BAD_TYPE |
The dwParamparameter specifies an unknown parameter. |
|
NTE_BAD_UID |
The CSP context that was specified when the hKeykey was created cannot be found. |
|
NTE_FAIL |
The function failed in some unexpected way. |
Example Code
 Copy 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 <A
HREF="wce50lrfcryptacquirecontext.htm">CryptAcquireContext</A>.
...
...
// 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
| Header | wincrypt.h |
| Library | coredll.lib |
| Windows Embedded CE | Windows CE 2.10 and later |
| Windows Mobile | Windows Mobile Version 5.0 and later |