Implemented encryption algorithm used for a number of RPC buffers.

(actually, decryption only currently because I need to get some sleep).

Basically another Microsoft twist on DES; the "master key" is the user's
NT hash MD4'd and subsets of this are chosen as the 56-bit DES keys.
(This used to be commit f09388fa6f41a13ca035b5b2ff40be804608f619)

2 files changed, 46 insertions, 1 deletions

diff --git a/source3/libsmb/smbdes.c b/source3/libsmb/smbdes.c
index d0e1c6e85f..08bc929f01 100644
--- a/source3/libsmb/smbdes.c
+++ b/source3/libsmb/smbdes.c
@@ -277,7 +277,7 @@ static void str_to_key(unsigned char *str,unsigned char *key)
 }
 
 
-static void smbhash(unsigned char *out, unsigned char *in, unsigned char *key, int forw)
+void smbhash(unsigned char *out, unsigned char *in, unsigned char *key, int forw)
 {
 	int i;
 	char outb[64];
diff --git a/source3/libsmb/smbencrypt.c b/source3/libsmb/smbencrypt.c
index e35cccd734..3835c99815 100644
--- a/source3/libsmb/smbencrypt.c
+++ b/source3/libsmb/smbencrypt.c
@@ -226,3 +226,48 @@ BOOL make_oem_passwd_hash(char data[516], const char *passwd, uchar old_pw_hash[
 	return True;
 }
 
+int nt_decrypt_string2(STRING2 *out, STRING2 *in, char nt_hash[16])
+{
+	uchar bufhdr[8];
+	int datalen;
+
+	uchar key[16];
+	uchar *keyptr = key;
+	uchar *keyend = key + sizeof(key);
+
+	uchar *outbuf = (uchar *)out->buffer;
+	uchar *inbuf = (uchar *)in->buffer;
+	uchar *inbufend;
+
+
+	mdfour(key, nt_hash, 16);
+
+	smbhash(bufhdr, inbuf, keyptr, 0);
+	datalen = IVAL(bufhdr, 0);
+
+	if ((datalen > in->str_str_len) || (datalen > MAX_STRINGLEN))
+	{
+		DEBUG(0, ("nt_decrypt_string2: failed\n"));
+		return False;
+	}
+
+	out->str_max_len = out->str_str_len = datalen;
+	inbuf += 8;
+	inbufend = inbuf + datalen;
+
+	while (inbuf < inbufend)
+	{
+		keyptr += 7;
+		if (keyptr + 7 > keyend)
+		{
+			keyptr = (keyend - keyptr) + key;
+		}
+
+		smbhash(outbuf, inbuf, keyptr, 0);
+
+		inbuf += 8;
+		outbuf += 8;
+	}
+
+	return True;
+}