P/Invoking CryptoAPI in .NET (VB.NET version)
Hi, welcome back,
This is a continuation of my previous post, P/Invoking CryptoAPI in .NET (C# version).
Here you have the most common P/Invoke CryptoAPI declarations I've successfully used in the past, but this time for VB.NET ( Note: I've included a couple of auxiliary functions which may be of help, too. CertContextFromCertSubject gets a certificate context from a certificate in MY/Personal certificate store, and RSACryptoServiceProviderFromCertContext creates an RSACryptoServiceProvider object from that certificate context. I don't have them in C#, but they should be easy to convert):
<SAMPLE>
Imports System.Runtime.InteropServices
Imports System.Security.Cryptography
Imports System.ComponentModel
Public Class Crypto
#Region "CONSTS"
' #define BUFSIZE 1024
Public Const BUFSIZE As Int32 = 1024
' #define AT_KEYEXCHANGE 1
Public Const AT_KEYEXCHANGE As Int32 = 1
' #define AT_SIGNATURE 2
Public Const AT_SIGNATURE As Int32 = 2
' #define CERT_STORE_PROV_SYSTEM_W ((LPCSTR) 10)
Public Const CERT_STORE_PROV_SYSTEM_W As Int32 = 10
' #define CERT_STORE_PROV_SYSTEM CERT_STORE_PROV_SYSTEM_W
Public Const CERT_STORE_PROV_SYSTEM As Int32 = CERT_STORE_PROV_SYSTEM_W
' #define CERT_SYSTEM_STORE_CURRENT_USER_ID 1
Public Const CERT_SYSTEM_STORE_CURRENT_USER_ID As Int32 = 1
' #define CERT_SYSTEM_STORE_LOCATION_SHIFT 16
Public Const CERT_SYSTEM_STORE_LOCATION_SHIFT As Int32 = 16
' #define CERT_SYSTEM_STORE_CURRENT_USER \
' (CERT_SYSTEM_STORE_CURRENT_USER_ID << CERT_SYSTEM_STORE_LOCATION_SHIFT)
Public Const CERT_SYSTEM_STORE_CURRENT_USER As Int32 = _
CERT_SYSTEM_STORE_CURRENT_USER_ID << CERT_SYSTEM_STORE_LOCATION_SHIFT
' #define CERT_PERSONAL_STORE_NAME L"My"
Public Const CERT_PERSONAL_STORE_NAME As String = "My"
' #define X509_ASN_ENCODING 0x00000001
Public Const X509_ASN_ENCODING As Int32 = &H1
' #define PKCS_7_ASN_ENCODING 0x00010000
Public Const PKCS_7_ASN_ENCODING As Int32 = &H10000
' #define MY_TYPE (PKCS_7_ASN_ENCODING | X509_ASN_ENCODING)
Public Const MY_TYPE As Int32 = PKCS_7_ASN_ENCODING + X509_ASN_ENCODING
' #define CERT_COMPARE_ANY 0
Public Const CERT_COMPARE_ANY As Int32 = 0
' #define CERT_COMPARE_SHA1_HASH 1
Public Const CERT_COMPARE_SHA1_HASH As Int32 = 1
' #define CERT_COMPARE_SHIFT 16
Public Const CERT_COMPARE_SHIFT As Int32 = 16
' #define CERT_FIND_SHA1_HASH (CERT_COMPARE_SHA1_HASH << CERT_COMPARE_SHIFT)
Public Const CERT_FIND_SHA1_HASH As Int32 = CERT_COMPARE_SHA1_HASH << CERT_COMPARE_SHIFT
' #define CERT_FIND_HASH CERT_FIND_SHA1_HASH
Public Const CERT_FIND_HASH As Int32 = CERT_FIND_SHA1_HASH
' #define CERT_FIND_ANY (CERT_COMPARE_ANY << CERT_COMPARE_SHIFT)
Public Const CERT_FIND_ANY As Int32 = CERT_COMPARE_ANY << CERT_COMPARE_SHIFT
' #define CERT_COMPARE_NAME 2
Public Const CERT_COMPARE_NAME As Int32 = 2
' #define CERT_INFO_SUBJECT_FLAG 7
Public Const CERT_INFO_SUBJECT_FLAG As Int32 = 7
' #define CERT_FIND_SUBJECT_NAME (CERT_COMPARE_NAME << CERT_COMPARE_SHIFT | CERT_INFO_SUBJECT_FLAG)
Public Const CERT_FIND_SUBJECT_NAME As Int32 = (CERT_COMPARE_NAME << CERT_COMPARE_SHIFT) + CERT_INFO_SUBJECT_FLAG
' #define CERT_COMPARE_NAME_STR_W 8
Public Const CERT_COMPARE_NAME_STR_W As Int32 = 8
' #define CERT_FIND_SUBJECT_STR_W \
' (CERT_COMPARE_NAME_STR_W << CERT_COMPARE_SHIFT | CERT_INFO_SUBJECT_FLAG)
Public Const CERT_FIND_SUBJECT_STR_W As Int32 = (CERT_COMPARE_NAME_STR_W << CERT_COMPARE_SHIFT) + CERT_INFO_SUBJECT_FLAG
' #define CERT_FIND_SUBJECT_STR CERT_FIND_SUBJECT_STR_W
Public Const CERT_FIND_SUBJECT_STR As Int32 = CERT_FIND_SUBJECT_STR_W
' #define CERT_CLOSE_STORE_CHECK_FLAG 0x00000002
Public Const CERT_CLOSE_STORE_CHECK_FLAG As Int32 = &H2
' #define ALG_CLASS_HASH (4 << 13)
Public Const ALG_CLASS_HASH As Int32 = 4 << 13
' #define ALG_TYPE_ANY (0)
Public Const ALG_TYPE_ANY As Int32 = 0
' #define ALG_SID_MD5 3
Public Const ALG_SID_MD5 As Int32 = 3
' #define ALG_SID_SHA1 4
Public Const ALG_SID_SHA1 As Int32 = 4
' #define CALG_MD5 (ALG_CLASS_HASH | ALG_TYPE_ANY | ALG_SID_MD5)
Public Const CALG_MD5 As Int32 = ALG_CLASS_HASH + ALG_TYPE_ANY + ALG_SID_MD5
' #define CALG_SHA1 (ALG_CLASS_HASH | ALG_TYPE_ANY | ALG_SID_SHA1)
Public Const CALG_SHA1 As Int32 = ALG_CLASS_HASH + ALG_TYPE_ANY + ALG_SID_SHA1
' #define PP_KEYEXCHANGE_PIN 32
Public Const PP_KEYEXCHANGE_PIN As Int32 = 32
' #define PP_SIGNATURE_PIN 33
Public Const PP_SIGNATURE_PIN As Int32 = 33
' #define PROV_RSA_FULL 1
Public Const PROV_RSA_FULL As Int32 = &H1
' #define CRYPT_VERIFYCONTEXT 0xF0000000
Public Const CRYPT_VERIFYCONTEXT As Int32 = &HF0000000
' #define CERT_KEY_PROV_INFO_PROP_ID 2
Public Const CERT_KEY_PROV_INFO_PROP_ID As Int32 = 2
#End Region
#Region "STRUCTS"
' typedef struct _CRYPTOAPI_BLOB {
' DWORD cbData;
' BYTE *pbData;
' } CRYPT_HASH_BLOB, CRYPT_INTEGER_BLOB,
' CRYPT_OBJID_BLOB, CERT_NAME_BLOB;
<StructLayout(LayoutKind.Sequential)> _
Public Structure CRYPTOAPI_BLOB
Public cbData As Int32
Public pbData As IntPtr
End Structure
' typedef struct _CRYPT_ALGORITHM_IDENTIFIER {
' LPSTR pszObjId;
' CRYPT_OBJID_BLOB Parameters;
' } CRYPT_ALGORITHM_IDENTIFIER;
<StructLayout(LayoutKind.Sequential)> _
Public Structure CRYPT_ALGORITHM_IDENTIFIER
<MarshalAs(UnmanagedType.LPStr)> Public pszObjId As String
Public Parameters As CRYPTOAPI_BLOB
End Structure
' typedef struct _FILETIME {
' DWORD dwLowDateTime;
' DWORD dwHighDateTime;
' } FILETIME;
<StructLayout(LayoutKind.Sequential)> _
Public Structure FILETIME
Public dwLowDateTime As Int32
Public dwHighDateTime As Int32
End Structure
' typedef struct _CRYPT_BIT_BLOB {
' DWORD cbData;
' BYTE *pbData;
' DWORD cUnusedBits;
' } CRYPT_BIT_BLOB;
<StructLayout(LayoutKind.Sequential)> _
Public Structure CRYPT_BIT_BLOB
Public cbData As Int32
Public pbData As Byte()
Public cUnusedBits As Int32
End Structure
' typedef struct _CERT_PUBLIC_KEY_INFO {
' CRYPT_ALGORITHM_IDENTIFIER Algorithm;
' CRYPT_BIT_BLOB PublicKey;
' } CERT_PUBLIC_KEY_INFO;
<StructLayout(LayoutKind.Sequential)> _
Public Structure CERT_PUBLIC_KEY_INFO
Public Algorithm As CRYPT_ALGORITHM_IDENTIFIER
Public PublicKey As CRYPT_BIT_BLOB
End Structure
' typedef struct _CERT_INFO {
' DWORD dwVersion;
' CRYPT_INTEGER_BLOB SerialNumber;
' CRYPT_ALGORITHM_IDENTIFIER SignatureAlgorithm;
' CERT_NAME_BLOB Issuer;
' FILETIME NotBefore;
' FILETIME NotAfter;
' CERT_NAME_BLOB Subject;
' CERT_PUBLIC_KEY_INFO SubjectPublicKeyInfo;
' CRYPT_BIT_BLOB IssuerUniqueId;
' CRYPT_BIT_BLOB SubjectUniqueId;
' DWORD cExtension;
' PCERT_EXTENSION rgExtension;
' } CERT_INFO;
<StructLayout(LayoutKind.Sequential)> _
Public Structure CERT_INFO
Public dwVersion As Int32
Public SerialNumber As CRYPTOAPI_BLOB
Public SignatureAlgorithm As CRYPT_ALGORITHM_IDENTIFIER
Public Issuer As CRYPTOAPI_BLOB
Public NotBefore As FILETIME
Public NotAfter As FILETIME
Public Subject As CRYPTOAPI_BLOB
Public SubjectPublicKeyInfo As CERT_PUBLIC_KEY_INFO
Public IssuerUniqueId As CRYPT_BIT_BLOB
Public SubjectUniqueId As CRYPT_BIT_BLOB
Public cExtension As Int32
Public rgExtension As IntPtr
End Structure
' typedef struct _CERT_CONTEXT {
' DWORD dwCertEncodingType;
' BYTE *pbCertEncoded;
' DWORD cbCertEncoded;
' PCERT_INFO pCertInfo;
' HCERTSTORE hCertStore;
' } CERT_CONTEXT;
<StructLayout(LayoutKind.Sequential)> _
Public Structure CERT_CONTEXT
Public dwCertEncodingType As Int32
Public pbCertEncoded As Byte()
Public cbCertEncoded As Int32
Public pCertInfo As IntPtr
Public hCertStore As IntPtr
End Structure
#End Region
#Region "FUNCTIONS (IMPORTS)"
' HCERTSTORE WINAPI CertOpenStore(
' LPCSTR lpszStoreProvider,
' DWORD dwMsgAndCertEncodingType,
' HCRYPTPROV hCryptProv,
' DWORD dwFlags,
' const void* pvPara
' );
<DllImport("Crypt32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
Public Shared Function CertOpenStore( _
ByVal lpszStoreProvider As Int32, _
ByVal dwMsgAndCertEncodingType As Int32, _
ByVal hCryptProv As IntPtr, _
ByVal dwFlags As Int32, _
ByVal pvPara As String _
) As IntPtr
End Function
' HCERTSTORE WINAPI CertOpenSystemStore(
' HCRYPTPROV hprov,
' LPTCSTR szSubsystemProtocol
');
<DllImport("Crypt32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
Public Shared Function CertOpenSystemStore( _
ByVal hprov As IntPtr, _
ByVal szSubsystemProtocol As String _
) As IntPtr
End Function
' PCCERT_CONTEXT WINAPI CertFindCertificateInStore(
' HCERTSTORE hCertStore,
' DWORD dwCertEncodingType,
' DWORD dwFindFlags,
' DWORD dwFindType,
' const void* pvFindPara,
' PCCERT_CONTEXT pPrevCertContext
' );
'<DllImport("Crypt32.dll", SetLastError:=True)> _
'Public Shared Function CertFindCertificateInStore( _
' ByVal hCertStore As IntPtr, _
' ByVal dwCertEncodingType As Int32, _
' ByVal dwFindFlags As Int32, _
' ByVal dwFindType As Int32, _
' ByRef pvFindPara As CRYPTOAPI_BLOB, _
' ByVal pPrevCertContext As IntPtr _
') As IntPtr
'End Function
<DllImport("Crypt32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
Public Shared Function CertFindCertificateInStore( _
ByVal hCertStore As IntPtr, _
ByVal dwCertEncodingType As Int32, _
ByVal dwFindFlags As Int32, _
ByVal dwFindType As Int32, _
ByVal pvFindPara As String, _
ByVal pPrevCertContext As IntPtr _
) As IntPtr
End Function
' BOOL WINAPI CryptAcquireCertificatePrivateKey(
' PCCERT_CONTEXT pCert,
' DWORD dwFlags,
' void* pvReserved,
' HCRYPTPROV* phCryptProv,
' DWORD* pdwKeySpec,
' BOOL* pfCallerFreeProv
' );
<DllImport("Crypt32.dll", SetLastError:=True)> _
Public Shared Function CryptAcquireCertificatePrivateKey( _
ByVal pCert As IntPtr, _
ByVal dwFlags As Int32, _
ByVal pvReserverd As IntPtr, _
ByRef phCryptProv As IntPtr, _
ByRef pdwKeySpec As Int32, _
ByRef pfCallerFreeProv As Boolean _
) As Boolean
End Function
' BOOL WINAPI CertCloseStore(
' HCERTSTORE hCertStore,
' DWORD dwFlags
' );
<DllImport("Crypt32.dll", SetLastError:=True)> _
Public Shared Function CertCloseStore( _
ByVal hCertStore As IntPtr, _
ByVal dwFlags As Int32 _
) As Boolean
End Function
' BOOL WINAPI CryptReleaseContext(
' HCRYPTPROV hProv,
' DWORD dwFlags
' );
<DllImport("Advapi32.dll", SetLastError:=True)> _
Public Shared Function CryptReleaseContext( _
ByVal hProv As IntPtr, _
ByVal dwFlags As Int32 _
) As Boolean
End Function
' BOOL WINAPI CryptCreateHash(
' HCRYPTPROV hProv,
' ALG_ID Algid,
' HCRYPTKEY hKey,
' DWORD dwFlags,
' HCRYPTHASH* phHash
' );
<DllImport("advapi32.dll", SetLastError:=True)> _
Public Shared Function CryptCreateHash( _
ByVal hProv As IntPtr, _
ByVal Algid As Int32, _
ByVal hKey As IntPtr, _
ByVal dwFlags As Int32, _
ByRef phHash As IntPtr _
) As Boolean
End Function
' BOOL WINAPI CryptDestroyHash(
' HCRYPTHASH hHash
' );
<DllImport("advapi32.dll", SetLastError:=True)> _
Public Shared Function CryptDestroyHash( _
ByVal hHash As IntPtr _
) As Boolean
End Function
' BOOL WINAPI CryptSetProvParam(
' HCRYPTPROV hProv,
' DWORD dwParam,
' BYTE* pbData,
' DWORD dwFlags
' );
<DllImport("advapi32.dll", SetLastError:=True)> _
Public Shared Function CryptSetProvParam( _
ByVal hProv As IntPtr, _
ByVal dwParam As Int32, _
ByVal pbData As Byte(), _
ByVal dwFlags As Int32 _
) As Boolean
End Function
' BOOL WINAPI CryptHashData(
' HCRYPTHASH hHash,
' BYTE* pbData,
' DWORD dwDataLen,
' DWORD dwFlags
' );
<DllImport("advapi32.dll", SetLastError:=True)> _
Public Shared Function CryptHashData( _
ByVal hHash As IntPtr, _
ByVal pbData As Byte(), _
ByVal dwDataLen As Int32, _
ByVal dwFlags As Int32 _
) As Boolean
End Function
' BOOL WINAPI CryptSignHash(
' HCRYPTHASH hHash,
' DWORD dwKeySpec,
' LPCTSTR sDescription,
' DWORD dwFlags,
' BYTE* pbSignature,
' DWORD* pdwSigLen
' );
<DllImport("advapi32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
Public Shared Function CryptSignHash( _
ByVal hHash As IntPtr, _
ByVal dwKeySpec As Int32, _
ByVal sDescription As String, _
ByVal dwFlags As Int32, _
ByVal pbSignature As Byte(), _
ByRef pdwSigLen As Int32 _
) As Boolean
End Function
' BOOL WINAPI CertFreeCertificateContext(
' PCCERT_CONTEXT pCertContext
' );
<DllImport("Crypt32.dll", SetLastError:=True)> _
Public Shared Function CertFreeCertificateContext( _
ByVal pCertContext As IntPtr _
) As Boolean
End Function
' BOOL WINAPI CryptAcquireContext(
' HCRYPTPROV* phProv,
' LPCTSTR pszContainer,
' LPCTSTR pszProvider,
' DWORD dwProvType,
' DWORD dwFlags
' );
<DllImport("advapi32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
Public Shared Function CryptAcquireContext( _
ByRef hProv As IntPtr, _
ByVal pszContainer As String, _
ByVal pszProvider As String, _
ByVal dwProvType As Int32, _
ByVal dwFlags As Int32 _
) As Boolean
End Function
' BOOL WINAPI CryptImportPublicKeyInfo(
' HCRYPTPROV hCryptProv,
' DWORD dwCertEncodingType,
' PCERT_PUBLIC_KEY_INFO pInfo,
' HCRYPTKEY* phKey
' );
<DllImport("crypt32.dll", SetLastError:=True)> _
Public Shared Function CryptImportPublicKeyInfo( _
ByVal hCryptProv As IntPtr, _
ByVal dwCertEncodingType As Int32, _
ByVal pInfo As IntPtr, _
ByRef phKey As IntPtr _
) As Boolean
End Function
' BOOL WINAPI CryptVerifySignature(
' HCRYPTHASH hHash,
' BYTE* pbSignature,
' DWORD dwSigLen,
' HCRYPTKEY hPubKey,
' LPCTSTR sDescription,
' DWORD dwFlags
' );
<DllImport("advapi32.dll", CharSet:=CharSet.Auto, SetLastError:=True)> _
Public Shared Function CryptVerifySignature( _
ByVal hHash As IntPtr, _
ByVal pbSignature As Byte(), _
ByVal dwSigLen As Int32, _
ByVal hPubKey As IntPtr, _
ByVal sDescription As String, _
ByVal dwFlags As Int32 _
) As Boolean
End Function
' BOOL WINAPI CryptDestroyKey(
' HCRYPTKEY hKey
' );
<DllImport("advapi32.dll", SetLastError:=True)> _
Public Shared Function CryptDestroyKey( _
ByVal hKey As IntPtr _
) As Boolean
End Function
' BOOL WINAPI CertGetCertificateContextProperty(
' PCCERT_CONTEXT pCertContext,
' DWORD dwPropId,
' void* pvData,
' DWORD* pcbData
' );
<DllImport("crypt32.dll", SetLastError:=True)> _
Public Shared Function CertGetCertificateContextProperty( _
ByVal pCertContext As IntPtr, _
ByVal dwPropId As Int32, _
ByVal pvData As IntPtr, _
ByRef pcbData As Int32 _
) As Boolean
End Function
' PCCERT_CONTEXT WINAPI CertEnumCertificatesInStore(
' HCERTSTORE hCertStore,
' PCCERT_CONTEXT pPrevCertContext
');
<DllImport("crypt32.dll", SetLastError:=True)> _
Public Shared Function CertEnumCertificatesInStore( _
ByVal hCertStore As IntPtr, _
ByVal pPrevCertContext As IntPtr _
) As IntPtr
End Function
' PCCERT_CONTEXT WINAPI CertDuplicateCertificateContext(
' PCCERT_CONTEXT pCertContext
');
<DllImport("crypt32.dll", SetLastError:=True)> _
Public Shared Function CertDuplicateCertificateContext( _
ByVal pCertContext As IntPtr _
) As IntPtr
End Function
#End Region
#Region "FUNCTIONS"
Public Shared Function CertContextFromCertSubject(ByVal subject As String) As IntPtr
' Variables
'
Dim bResult As Boolean = False
Dim hStoreHandle As IntPtr = IntPtr.Zero
Dim pCertContext As IntPtr = IntPtr.Zero
Try
' Open the certificate store.
'
hStoreHandle = CertOpenSystemStore( _
0, _
CERT_PERSONAL_STORE_NAME _
)
If (hStoreHandle.Equals(IntPtr.Zero)) Then
Throw New Exception("CertOpenStore error", New Win32Exception(Marshal.GetLastWin32Error()))
End If
' Get a certificate that matches the search criteria.
'
pCertContext = CertFindCertificateInStore( _
hStoreHandle, _
MY_TYPE, _
0, _
CERT_FIND_SUBJECT_STR, _
subject, _
IntPtr.Zero _
)
If (pCertContext.Equals(IntPtr.Zero)) Then
Throw New Exception("CertFindCertificateInStore error", New Win32Exception(Marshal.GetLastWin32Error()))
End If
Return pCertContext
Catch ex As Exception
' Any errors? Show them.
'
If (ex.InnerException Is Nothing) Then
MessageBox.Show(ex.Message)
Else
MessageBox.Show(ex.Message + " --> " + ex.InnerException.Message)
End If
Finally
' Clean up and free memory.
'
If (Not hStoreHandle.Equals(IntPtr.Zero)) Then
bResult = CertCloseStore( _
hStoreHandle, _
CERT_CLOSE_STORE_CHECK_FLAG _
)
End If
End Try
Return Nothing
End Function
' Converted to VB.NET from KB article 320602
'
Public Shared Function RSACryptoServiceProviderFromCertContext(ByVal pCertContext As IntPtr) As RSACryptoServiceProvider
'Determine the size of the buffer that you need to allocate.
'
Dim cbData As Int32 = 0
Dim fStatus As Boolean = CertGetCertificateContextProperty( _
pCertContext, _
CERT_KEY_PROV_INFO_PROP_ID, _
0, _
cbData)
If (Not fStatus) Then
MessageBox.Show("CertGetCertificateContextProperty error --> " + Marshal.GetLastWin32Error().ToString())
' Get the CERT_KEY_PROV_HANDLE_PROP_ID value and the HCRYPTPROV value.
'
cbData = 4
Dim pCryptKeyProvInfo As IntPtr = Marshal.AllocHGlobal(New IntPtr(cbData))
fStatus = CertGetCertificateContextProperty( _
pCertContext, _
CERT_KEY_PROV_INFO_PROP_ID, _
pCryptKeyProvInfo, _
cbData)
If (Not fStatus) Then
MessageBox.Show("CertGetCertificateContextProperty error --> " + Marshal.GetLastWin32Error().ToString())
End If
Return Nothing
End If
If (Not cbData = 0) Then
' Allocate an unmanaged buffer to store the CRYPT_KEY_PROV_INFO structure.
'
Dim pCryptKeyProvInfo As IntPtr = Marshal.AllocHGlobal(cbData)
' Get the CRYPT_KEY_PROV_INFO structure.
'
fStatus = CertGetCertificateContextProperty( _
pCertContext, _
CERT_KEY_PROV_INFO_PROP_ID, _
pCryptKeyProvInfo, _
cbData)
If (Not fStatus) Then
MessageBox.Show("CertGetCertificateContextProperty failed: " + Marshal.GetLastWin32Error().ToString())
Marshal.FreeHGlobal(pCryptKeyProvInfo)
Else
' Build a CspParameters object with the provider type, the provider name,
' and the container name from the CRYPT_KEY_PROV_INFO structure.
' The pointer to the container name is the first DWORD in the CRYPT_KEY_PROV_INFO
' structure, the pointer to the provider name is the second DWORD, and
' the provider type is the third DWORD.
'
Try
Dim CspParams As CspParameters = New CspParameters( _
Marshal.ReadInt32(New IntPtr(pCryptKeyProvInfo.ToInt32 + 8)), _
Marshal.PtrToStringUni(New IntPtr(Marshal.ReadInt32(New IntPtr(pCryptKeyProvInfo.ToInt32 + 4)))), _
Marshal.PtrToStringUni(New IntPtr(Marshal.ReadInt32(pCryptKeyProvInfo))))
' Free the unmanaged CRYPT_KEY_PROV_INFO buffer.
'
Marshal.FreeHGlobal(pCryptKeyProvInfo)
Return New RSACryptoServiceProvider(CspParams)
Catch ex As Exception
MessageBox.Show(ex.Message)
End Try
End If
End If
Return Nothing
End Function
#End Region
End Class
</SAMPLE>
I hope this helps.
Cheers,
Alex (Alejandro Campos Magencio)