From c00d8b7fd277441232af65aa87da89b27ef2e7f0 Mon Sep 17 00:00:00 2001
From: divverent <divverent@d7cf8633-e32d-0410-b094-e92efae38249>
Date: Thu, 9 Apr 2009 06:23:27 +0000
Subject: [PATCH] Add my own HMAC implementation (verified using the test
 vectors). Planning to use HMAC-MD4 for an alternate rcon authentication.

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@8884 d7cf8633-e32d-0410-b094-e92efae38249
---
 hmac.c       | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 hmac.h       | 14 +++++++++++++
 makefile.inc |  1 +
 3 files changed, 72 insertions(+)
 create mode 100644 hmac.c
 create mode 100644 hmac.h

diff --git a/hmac.c b/hmac.c
new file mode 100644
index 00000000..eb254e21
--- /dev/null
+++ b/hmac.c
@@ -0,0 +1,57 @@
+#include "quakedef.h"
+#include "hmac.h"
+
+void hmac(
+	hashfunc_t hfunc, int hlen, int hblock,
+	unsigned char *out,
+	unsigned char *in, int n,
+	unsigned char *key, int k
+)
+{
+	unsigned char hashbuf[32];
+	unsigned char k_xor_ipad[128];
+	unsigned char k_xor_opad[128];
+	unsigned char catbuf[256];
+	int i;
+
+	if(sizeof(hashbuf) < (size_t) hlen)
+		Host_Error("Invalid hash function used for HMAC - too long hash length");
+	if(sizeof(k_xor_ipad) < (size_t) hblock)
+		Host_Error("Invalid hash function used for HMAC - too long hash block length");
+	if(sizeof(catbuf) < (size_t) hblock + (size_t) hlen)
+		Host_Error("Invalid hash function used for HMAC - too long hash block length");
+	if(sizeof(catbuf) < (size_t) hblock + (size_t) n)
+		Host_Error("Invalid hash function used for HMAC - too long message length");
+
+	if(k > hblock)
+	{
+		// hash the key if it is too long
+		// NO! that makes it too short if hblock != hlen
+		// just shorten it, then
+		// hfunc(hashbuf, key, k);
+		// key = hashbuf;
+		k = hblock;
+	}
+	else if(k < hblock)
+	{
+		// zero pad the key if it is too short
+		memcpy(k_xor_opad, key, k);
+		for(i = k; i < hblock; ++i)
+			k_xor_opad[i] = 0;
+		key = k_xor_opad;
+		k = hblock;
+	}
+
+	for(i = 0; i < hblock; ++i)
+	{
+		k_xor_ipad[i] = key[i] ^ 0x36;
+		k_xor_opad[i] = key[i] ^ 0x5c;
+	}
+
+	memcpy(catbuf, k_xor_ipad, hblock);
+	memcpy(catbuf + hblock, in, n);
+	hfunc(hashbuf, catbuf, hblock + n);
+	memcpy(catbuf, k_xor_opad, hblock);
+	memcpy(catbuf + hblock, hashbuf, hlen);
+	hfunc(out, catbuf, hblock + hlen);
+}
diff --git a/hmac.h b/hmac.h
new file mode 100644
index 00000000..d2a327b6
--- /dev/null
+++ b/hmac.h
@@ -0,0 +1,14 @@
+#ifndef HMAC_H
+#define HMAC_H
+
+typedef void (*hashfunc_t) (unsigned char *out, unsigned char *in, int n);
+void hmac(
+	hashfunc_t hfunc, int hlen, int hblock,
+	unsigned char *out,
+	unsigned char *in, int n,
+	unsigned char *key, int k
+);
+
+#define HMAC_MDFOUR_16BYTES(out, in, n, key, k) hmac(mdfour, 16, 64, out, in, n, key, k)
+
+#endif
diff --git a/makefile.inc b/makefile.inc
index 5bd7de85..f5e3e628 100644
--- a/makefile.inc
+++ b/makefile.inc
@@ -107,6 +107,7 @@ OBJ_COMMON= \
 	gl_rmain.o \
 	gl_rsurf.o \
 	gl_textures.o \
+	hmac.o \
 	host.o \
 	host_cmd.o \
 	image.o \
-- 
2.39.2