RE: Cryptography, Encryption, Decryption Help
From: kladiva (anonymous_at_discussions.microsoft.com)
Date: 03/23/04
- Next message: Maarten Struys, eMVP: "Re: eVB in .net HELP????"
- Previous message: r_z_aret_at_pen_fact.com: "Re: App Caused Pocket PC to Soft Reset on its Own?"
- Messages sorted by: [ date ] [ thread ]
Date: Tue, 23 Mar 2004 06:46:10 -0800
KRoy,
Try the following, I changed the Encrypt and Decrypt functions in the Crypto.vb class to take in strings instead of Byte arrays.
'Calling Code
Dim encryptedtext As String = Crypto.Encrypt("212a658c-2edf-46e4-b550-ebe53b91e6b3", "SomeSensitiveData#23!")
Dim cleartext As String = Crypto.Decrypt("212a658c-2edf-46e4-b550-ebe53b91e6b3", encryptedtext)
'Replace your Encrypt and Decrypt functions with the following code:
Public Shared Function Encrypt(ByVal passphrase As String, ByVal cleartext As String) As String
Dim encryptedtext As String
Dim data() As Byte
data = Encoding.Unicode.GetBytes(cleartext)
' holds encrypted data
Dim buffer As Byte() = Nothing
' crypto handles
Dim hProv As IntPtr = IntPtr.Zero
Dim hKey As IntPtr = IntPtr.Zero
Try
' get crypto provider, specify the provider (3rd argument)
' instead of using default to ensure the same provider is
' used on client and server
If Not WinApi.CryptAcquireContext(hProv, Nothing, WinApi.MS_DEF_PROV, WinApi.PROV_RSA_FULL, WinApi.CRYPT_VERIFYCONTEXT) Then
Failed("CryptAcquireContext")
End If
' generate encryption key from passphrase
hKey = GetCryptoKey(hProv, passphrase)
' determine how large of a buffer is required
' to hold the encrypted data
Dim dataLength As Integer = data.Length
Dim bufLength As Integer = data.Length
If Not WinApi.CryptEncrypt(hKey, IntPtr.Zero, True, 0, Nothing, dataLength, bufLength) Then
Failed("CryptEncrypt")
End If
' allocate and fill buffer with encrypted data
buffer = New Byte(dataLength - 1) {}
System.Buffer.BlockCopy(data, 0, buffer, 0, data.Length)
dataLength = data.Length
bufLength = buffer.Length
If Not WinApi.CryptEncrypt(hKey, IntPtr.Zero, True, 0, buffer, dataLength, bufLength) Then
Failed("CryptEncrypt")
End If
Finally
' release crypto handles
If Not hKey.Equals(IntPtr.Zero) Then
WinApi.CryptDestroyKey(hKey)
End If
If Not hProv.Equals(IntPtr.Zero) Then
WinApi.CryptReleaseContext(hProv, 0)
End If
End Try
encryptedtext = Encoding.Unicode.GetString(buffer, 0, buffer.Length)
Return encryptedtext
End Function
Public Shared Function Decrypt(ByVal passphrase As String, ByVal encryptedtext As String) As String
Dim cleartext As String
Dim data() As Byte
data = Encoding.Unicode.GetBytes(encryptedtext)
' make a copy of the encrypted data
Dim dataCopy As Byte() = CType(data.Clone(), Byte())
' holds the decrypted data
Dim buffer As Byte() = Nothing
' crypto handles
Dim hProv As IntPtr = IntPtr.Zero
Dim hKey As IntPtr = IntPtr.Zero
Try
' get crypto provider, specify the provider (3rd argument)
' instead of using default to ensure the same provider is
' used on client and server
If Not WinApi.CryptAcquireContext(hProv, Nothing, WinApi.MS_DEF_PROV, WinApi.PROV_RSA_FULL, WinApi.CRYPT_VERIFYCONTEXT) Then
Failed("CryptAcquireContext")
End If
' generate encryption key from the passphrase
hKey = GetCryptoKey(hProv, passphrase)
' decrypt the data
Dim dataLength As Integer = dataCopy.Length
If Not WinApi.CryptDecrypt(hKey, IntPtr.Zero, True, 0, dataCopy, dataLength) Then
Failed("CryptDecrypt")
End If
' copy to a buffer that is returned to the caller
' the decrypted data size might be less then
' the encrypted size
buffer = New Byte(dataLength - 1) {}
System.Buffer.BlockCopy(dataCopy, 0, buffer, 0, dataLength)
Finally
' release crypto handles
If Not hKey.Equals(IntPtr.Zero) Then
WinApi.CryptDestroyKey(hKey)
End If
If Not hProv.Equals(IntPtr.Zero) Then
WinApi.CryptReleaseContext(hProv, 0)
End If
End Try
cleartext = Encoding.Unicode.GetString(buffer, 0, buffer.Length)
Return cleartext
End Function
----- KRoy wrote: -----
I am using VS .Net 2003 to develop an VB.net Pocket PC
application which encrypts connection string information
for a SQL Server Database. I have copied the Crypto Class
code from the Pocket PC Signiture Application Sample into
my project
(http://msdn.microsoft.com/mobility/understanding/articles/
default.aspx?pull=/library/en-
us/dnnetcomp/html/ppcsignatureapp.asp).
I can not get the text I send it, to be decrypted. I
error out with an 'unhandled exception'. One thing I
notice is that I get different hProv, hHash, and hKey
values when running the CryptoSvc2.Decrypt function versus
the CryptoSvc1.Encrypt function (this may be correct, I
don't know). The following is my code:
Dim EncryptString As String
Dim DecryptString As String
Dim CodedArray() As Byte
Dim EncryptArray As Byte()
Dim DecryptArray As Byte()
Dim CryptoSvc1 As New PEdgeCF.Security.Crypto
CodedArray = System.Text.Encoding.ASCII.GetBytes("AnyText")
EncryptArray = CryptoSvc1.Encrypt("123456789", CodedArray)
EncryptString = System.Text.Encoding.ASCII.GetChars _
(EncryptArray)
MsgBox("Encrypted Data: " & EncryptString)
Dim CryptoSvc2 As New PEdgeCF.Security.Crypto
CodedArray = System.Text.Encoding.ASCII.GetBytes _
(EncryptString)
DecryptArray = CryptoSvc2.Decrypt("123456789", CodedArray)
DecryptString = System.Text.Encoding.ASCII.GetChars _
(DecryptArray)
MsgBox("Decrypted Data: " & DecryptString)
Any help would be greatly appreciated!!
- Next message: Maarten Struys, eMVP: "Re: eVB in .net HELP????"
- Previous message: r_z_aret_at_pen_fact.com: "Re: App Caused Pocket PC to Soft Reset on its Own?"
- Messages sorted by: [ date ] [ thread ]
Relevant Pages
|
