pinvoke, how to marshal "unsigned char *"

[runner]

I'm trying to call some functions from OpenSSL library but I'm a bit confused when I have to use pinvoke.

first function should create key from some input data, it's declared :

void BF_set_key(BF_KEY *key, int len, const unsigned char *data);

I've translated it as

public static extern IntPtr BF_set_key (IntPtr key, int len, [In] byte[] data)

and I try to call it this way:

      byte[] data = 
      { 
        0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 
        0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68 
      };
IntPtr key = Marshal.AllocHGlobal( 4168 );  // 4168 is size BF_KEY struct
key = BlowFish . BF_set_key (key, data.Length, data);

next function should encrypt/decypt input block an write the result to ouput one, it is declared :

void BF_ecb_encrypt(const unsigned char *in, unsigned char *out, BF_KEY *key, int enc);

my managed wrapper:

public static extern void BF_ecb_encrypt
([In] byte[] input, [Out] byte[] output, IntPtr key, int enc);

calling it:

byte[] input = { 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68 };
byte[] output = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
byte[] output2 = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
BF_ecb_encrypt (input, output, key, 1); // encrypt
BlowFish . BF_ecb_encrypt (output, output2, key, 0); // decrypt

I suppose that output2 will contains the same data as input after the last line executes but the results are strange - ecnryption returns some data but I'm afraid not the encrypted form of input, output2 returns some random data.

I'm pretty sure I do something wrong (probably several somethings:)) - please can you tell me, what ?

[rednael]

Please read the following article:
http://blog.rednael.com/2008/08/29/M...DLLsInNET.aspx

It's an in depth article about marshalling between native code and managed code. It shows which types are interoperable, how to import a DLL, how to pass strings, how to pass structures and how to de-reference pointers.

Code examples in C# are included.

[auralcircuitry]

Was searching for exactly this, your link saved me! thank you