Rc4 stream cipher

[jjnicola]

Add functions to open a cipher handler, the function to encrypt stream data using the cipher handle,
and the function to close a handler.
Currently, encrypt_stream_data only supports GCRY_CIPHER_ARCFOUR algorithm.

$ cat rc4.nasl
include("dump.inc");

display("\n\nComplet 1");
iv = raw_string(0x01, 0x00);
key = raw_string(0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf1, 0xf1, 0xf1, 0xf1, 0xf1, 0xf1, 0xf1, 0xf1);
data = raw_string(0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0xbb, 0xaa);

enc = rc4_encrypt(key: key, data: data);
display(hexstr(enc));
display(hexdump(ddata: enc));

display("\n\nComplet 2");
iv = raw_string(0x01, 0x00);
key = raw_string(0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf1, 0xf1, 0xf1, 0xf1, 0xf1, 0xf1, 0xf1, 0xf1);
data = raw_string(0x23, 0x01, 0x34, 0x03, 0x45, 0x32, 0xac, 0xac, 0x08, 0x09, 0x0a, 0x0b, 0x3c, 0x0d, 0x0e, 0x0f, 0xba, 0x1a);

enc = rc4_encrypt(key: key, data: data);
display(hexstr(enc));
display(hexdump(ddata: enc));

display("\n\nPart 1.1");
key = raw_string(0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf1, 0xf1, 0xf1, 0xf1, 0xf1, 0xf1, 0xf1, 0xf1);
data = raw_string(0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f);
hd = open_rc4_cipher(key: key);
display("nasl hd: ", hd);
enc =rc4_encrypt(data: data, hd: hd);
display(hexstr(enc));
display(hexdump(ddata: enc));

display("\n\nPart 2.1");
key = raw_string(0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf1, 0xf1, 0xf1, 0xf1, 0xf1, 0xf1, 0xf1, 0xf1);
data = raw_string(0x23, 0x01, 0x34, 0x03, 0x45, 0x32, 0xac, 0xac, 0x08, 0x09, 0x0a, 0x0b, 0x3c, 0x0d);
hd1 = open_rc4_cipher(key: key);
display("nasl hd: ", hd1);
enc = rc4_encrypt(data: data, hd: hd1);
display(hexstr(enc));
display(hexdump(ddata: enc));

display("\n\nPart 1.2");
data = raw_string(0xbb, 0xaa);
enc = rc4_encrypt(data: data, hd: hd);
display(hexstr(enc));
display(hexdump(ddata: enc));

display("\n\nPart 2.2");
data = raw_string(0x0e, 0x0f, 0xba, 0x1a);
enc = rc4_encrypt(data: data, hd: hd1);
display(hexstr(enc));
display(hexdump(ddata: enc));

close_stream_cipher(hd: hd1);
close_stream_cipher(hd: hd);`
```