verify signature from cab using RSACryptoServiceProvider ?

[jwei]

windows ce 5, cf v3.5

i try to verify the signature of a signed cab-file (with certificate)
programmatically

i would use these steps :

1) build a signed cab with vs2008
2) get the cab into device
3) my app verifies the signature of the cab using a certificate (calc the
hash of the cab and compare with signature)

my questions:
- how i get the signature for verify from the signed cab file (not the hash) ?
- which additionaly packages i have to include in my os design (platform
builder) since i get an unknown error with function
RSACryptoServiceProvider.ImportCspBlob(pubkey); (i get pubkey byte[] from
cert.GetPublicKey(); already reduced by len=12 bytes) ?

thanks

 

[jwei]

this is the error i get on ImportCspBlob:

....
RSACryptoServiceProvider csp = new RSACryptoServiceProvider();
csp.ImportCspBlob(publicKeyData);
....

Unknown Error '8000700F'.