prepared header encryption

CMakeLists.txt

@@ -61,8 +61,12 @@ add_library(n2n n2n.c
                 transform_null.c
                 transform_tf.c
                 transform_aes.c
+		transform_cc20.c
+		transform_speck.c
+		speck.c
 		random_numbers.c
 		pearson.c
+		header_encryption.c
                 tuntap_freebsd.c
                 tuntap_netbsd.c
                 tuntap_linux.c

Makefile.in

@@ -51,7 +51,7 @@ N2N_LIB=libn2n.a
 N2N_OBJS=n2n.o wire.o minilzo.o twofish.o speck.o \
 	 edge_utils.o sn_utils.o \
          transform_null.o transform_tf.o transform_aes.o transform_cc20.o transform_speck.o \
-	 pearson.o \
+	 header_encryption.o pearson.o \
          tuntap_freebsd.o tuntap_netbsd.o tuntap_linux.o random_numbers.o \
 	 tuntap_osx.o
 LIBS_EDGE+=$(LIBS_EDGE_OPT)

header_encryption.c

@@ -1,35 +1,38 @@
-#include <stdio.h>
+#include "header_encryption.h"
-#include <stdint.h>
+
+#include <string.h>
 
-// #include "n2n_wire.h"	// n2n_community_t
 #include "n2n.h"
-#include "speck.h"
+#include "random_numbers.h"
+#include "pearson.h"
 #include "portable_endian.h"
 
 
-uint32_t decryt_packet_header (uint8_t packet[], uint8_t packet_len,
+#include <stdio.h>
-			       char * community_name, speck_ctx * ctx) {
+
+
+uint32_t packet_header_decrypt (uint8_t packet[], uint8_t packet_len,
+			        char * community_name, he_context_t * ctx) {
 
 	// assemble IV
 	// the last four are ASCII "n2n!" and do not get overwritten
 	uint8_t iv[16] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 			   0x00, 0x00, 0x00, 0x00, 0x6E, 0x32, 0x6E, 0x21 };
-	// the first 96 bits of the packet are used padded with ASCII "n2n!"
+	// the first 96 bits of the packet get padded with ASCII "n2n!"
 	// to full 128 bit IV
-	memcopy (iv, packet, 12);
+	memcpy (iv, packet, 12);
-
+	// alternatively, consider: pearson_hash_128 (iv, packet, 12);
-	// alternatively, consider: pearson_hash_128 (iv, packet, 12)
 
 	// try community name as possible key and check for magic bytes
 	uint32_t magic = 0x6E326E00; // ="n2n_"
 	uint32_t test_magic;
 	// check for magic bytes and resonable value in header len field
-	speck_he ((uint8_t*)&test_magic, &packet[12], 4, iv, ctx);
+	speck_he ((uint8_t*)&test_magic, &packet[12], 4, iv, (speck_context_t*)ctx);
 	test_magic = be32toh (test_magic);
 	if ( ((test_magic <<  8) == magic)
 	  && ((test_magic >> 24) <= packet_len) // (test_masgic >> 24) is header_len
 	   ) {
-		speck_he (&packet[12], &packet[12], (test_magic >> 24) - 12, iv, ctx);
+		speck_he (&packet[12], &packet[12], (test_magic >> 24) - 12, iv, (speck_context_t*)ctx);
 		// restore original packet order
 		memcpy (&packet[0], &packet[16], 4);
 		memcpy (&packet[4], community_name, N2N_COMMUNITY_SIZE);
@@ -39,7 +42,7 @@ uint32_t decryt_packet_header (uint8_t packet[], uint8_t packet_len,
 }
 
 
-int32_t decryt_packet_header_if_required (uint8_t packet[], uint16_t packet_len,
+int32_t packet_header_decrypt_if_required (uint8_t packet[], uint16_t packet_len,
 					   struct sn_community *communities) {
 
 	if (packet_len < 20)
@@ -58,8 +61,12 @@ int32_t decryt_packet_header_if_required (uint8_t packet[], uint16_t packet_len,
 	   ) {
 
 		// most probably unencrypted
-		return (1);
 
+		// TODO:
+		// !!! make sure, no downgrading happens here !!!
+		// NOT FOR DEFINETLY ENCRYPTED COMMUNITIES / NO DOWNGRADE, NO INJECTION
+
+		return (HEADER_ENCRYPTION_NONE);
 	} else {
 
 		// most probably encrypted
@@ -67,24 +74,23 @@ int32_t decryt_packet_header_if_required (uint8_t packet[], uint16_t packet_len,
 		int32_t ret;
 		struct sn_community *c, *tmp;
 		HASH_ITER (hh, communities, c, tmp) {
-			// check if this is an encrypted community
+			// skip the definitely unencrypted communities
-			if ( ret = decrypt_packet_header (packet, packet_len, c->community, c-> ctx) ) {
+			if (c->header_encryption == HEADER_ENCRYPTION_NONE)
-				// no upgrade from unencrypted to encrypted
+				continue;
-				if (c->header_encryption == 1)
+			if ( (ret = packet_header_decrypt (packet, packet_len, c->community, &(c->header_encryption_ctx))) ) {
-					return (-2);
 				// set to 'encrypted'
-				 c->header_encryption = 2;
+				 c->header_encryption = HEADER_ENCRYPTION_ENABLED;
 				// no need to test any further
-				return (2);
+				return (HEADER_ENCRYPTION_ENABLED);
 			}
 		}
-		// no match
+		// no matching key/community
 		return (-3);
 	}
 }
 
 
-int32_t encryt_packet_header (uint8_t packet[], uint8_t header_len, speck_ctx * ctx) {
+int32_t packet_header_encrypt (uint8_t packet[], uint8_t header_len, he_context_t * ctx) {
 
 	if (header_len < 20)
 		return (-1);
@@ -100,5 +106,16 @@ int32_t encryt_packet_header (uint8_t packet[], uint8_t header_len, speck_ctx *
 
 	iv[12] = header_len;
 
-	speck_he (&packet[12], &packet[12], header_len - 12, iv, ctx);
+	speck_he (&packet[12], &packet[12], header_len - 12, iv, (speck_context_t*)ctx);
+
+	return (0);
+}
+
+
+void packet_header_setup_key (char * community_name, he_context_t * ctx) {
+
+	uint8_t key[16];
+	pearson_hash_128 (key, (uint8_t*)community_name, N2N_COMMUNITY_SIZE);
+
+	speck_expand_key_he (key, ctx);
 }

header_encryption.h

@@ -0,0 +1,17 @@
+#include <stdint.h>
+
+#include "speck.h"
+typedef speck_context_t he_context_t;
+
+
+#define HEADER_ENCRYPTION_UNKNOWN       0
+#define HEADER_ENCRYPTION_NONE          1
+#define HEADER_ENCRYPTION_ENABLED       2
+
+
+uint32_t decrypt_packet_header (uint8_t packet[], uint8_t packet_len,
+                                char * community_name, he_context_t * ctx);
+
+int32_t encryt_packet_header (uint8_t packet[], uint8_t header_len, he_context_t * ctx);
+
+int32_t encryt_packet_header (uint8_t packet[], uint8_t header_len, he_context_t * ctx);

n2n.h

@@ -111,6 +111,7 @@ typedef struct ether_hdr ether_hdr_t;
 #include <openssl/opensslv.h>
 #include <openssl/crypto.h>
 #include "minilzo.h"
+#include "header_encryption.h"
 
 #define closesocket(a) close(a)
 #endif /* #ifndef WIN32 */
@@ -160,6 +161,7 @@ typedef struct tuntap_dev {
 #define MSG_TYPE_FEDERATION             8
 #define MSG_TYPE_PEER_INFO              9
 #define MSG_TYPE_QUERY_PEER            10
+#define MSG_TYPE_MAX_TYPE	       10
 
 /* N2N compression indicators. */
 /* Compression is disabled by default for outgoing packets if no cli
@@ -225,6 +227,8 @@ typedef struct n2n_edge_conf {
   n2n_sn_name_t       sn_ip_array[N2N_EDGE_NUM_SUPERNODES];
   n2n_route_t	      *routes;		      /**< Networks to route through n2n */
   n2n_community_t     community_name;         /**< The community. 16 full octets. */
+  uint8_t	      header_encryption;      /**< Header encryption indicator. */
+  he_context_t	      header_encryption_ctx;  /**< Header encryption cipher context. */
   n2n_transform_t     transop_id;             /**< The transop to use. */
   uint16_t	      compression;	      /**< Compress outgoing data packets before encryption */
   uint16_t	      num_routes;	      /**< Number of routes in routes */
@@ -270,7 +274,9 @@ typedef struct sn_stats
  struct sn_community
 {
     char community[N2N_COMMUNITY_SIZE];
-    struct peer_info *edges; /* Link list of registered edges. */
+    uint8_t	      header_encryption;      /* Header encryption indicator. */
+    he_context_t      header_encryption_ctx;  /* Header encryption cipher context. */
+    struct peer_info *edges; 		      /* Link list of registered edges. */
 
      UT_hash_handle hh; /* makes this structure hashable */
 };

pearson.c

@@ -157,3 +157,59 @@ void pearson_hash_256 (uint8_t *out, const uint8_t *in, size_t len) {
 	o = (uint64_t*)&out[24];
 	*o = lower_hash;
 }
+
+
+void pearson_hash_128 (uint8_t *out, const uint8_t *in, size_t len) {
+
+	/* initial values -  astonishingly, assembling using SHIFTs and ORs (in register)
+         * works faster on well pipelined CPUs than loading the 64-bit value from memory.
+         * however, there is one advantage to loading from memory: as we also store back to
+         * memory at the end, we do not need to care about endianess! */
+	uint8_t upper[8] = { 0x0F, 0x0E, 0x0D, 0x0C, 0x0B, 0x0A, 0x09, 0x08 };
+	uint8_t lower[8] = { 0x07, 0x06, 0x05, 0x04, 0x03, 0x02, 0x01, 0x00 };
+
+	uint64_t upper_hash_mask = *(uint64_t*)&upper;
+	uint64_t lower_hash_mask = *(uint64_t*)&lower;
+
+	uint64_t upper_hash = 0;
+	uint64_t lower_hash = 0;
+
+	for (size_t i = 0; i < len; i++) {
+		// broadcast the character, xor into hash, make them different permutations
+		uint64_t c = (uint8_t)in[i];
+		c |= c <<  8;
+		c |= c << 16;
+		c |= c << 32;
+		upper_hash ^= c ^ upper_hash_mask;
+		lower_hash ^= c ^ lower_hash_mask;
+		// table lookup
+		uint8_t x;
+		uint64_t h = 0;
+		x = upper_hash; x = t[x]; upper_hash >>= 8; h |= x; h=ROR64(h,8);
+		x = upper_hash; x = t[x]; upper_hash >>= 8; h |= x; h=ROR64(h,8);
+		x = upper_hash; x = t[x]; upper_hash >>= 8; h |= x; h=ROR64(h,8);
+		x = upper_hash; x = t[x]; upper_hash >>= 8; h |= x; h=ROR64(h,8);
+		x = upper_hash; x = t[x]; upper_hash >>= 8; h |= x; h=ROR64(h,8);
+		x = upper_hash; x = t[x]; upper_hash >>= 8; h |= x; h=ROR64(h,8);
+		x = upper_hash; x = t[x]; upper_hash >>= 8; h |= x; h=ROR64(h,8);
+		x = upper_hash; x = t[x]; upper_hash >>= 8; h |= x; h=ROR64(h,8);
+ 		upper_hash = h;
+
+		h = 0;
+		x = lower_hash; x = t[x]; lower_hash >>= 8; h |= x; h=ROR64(h,8);
+		x = lower_hash; x = t[x]; lower_hash >>= 8; h |= x; h=ROR64(h,8);
+		x = lower_hash; x = t[x]; lower_hash >>= 8; h |= x; h=ROR64(h,8);
+		x = lower_hash; x = t[x]; lower_hash >>= 8; h |= x; h=ROR64(h,8);
+		x = lower_hash; x = t[x]; lower_hash >>= 8; h |= x; h=ROR64(h,8);
+		x = lower_hash; x = t[x]; lower_hash >>= 8; h |= x; h=ROR64(h,8);
+		x = lower_hash; x = t[x]; lower_hash >>= 8; h |= x; h=ROR64(h,8);
+		x = lower_hash; x = t[x]; lower_hash >>= 8; h |= x; h=ROR64(h,8);
+		lower_hash = h;
+	}
+	// store output
+	uint64_t *o;
+	o = (uint64_t*)&out[0];
+	*o = upper_hash;
+	o = (uint64_t*)&out[8];
+	*o = lower_hash;
+}

pearson.h

@@ -17,3 +17,5 @@
  */
 
 void pearson_hash_256 (uint8_t *out, const uint8_t *in, size_t len);
+
+void pearson_hash_128 (uint8_t *out, const uint8_t *in, size_t len);

speck.h

@@ -2,6 +2,10 @@
 // taken from (and modified: removed pure crypto-stream generation and seperated key expansion)
 // https://github.com/nsacyber/simon-speck-supercop/blob/master/crypto_stream/speck128256ctr/
 
+
+#ifndef SPECK_H
+#define SPECK_H
+
 #define u32 uint32_t
 #define u64 uint64_t
 
@@ -61,3 +65,6 @@ int speck_he (unsigned char *out, const unsigned char *in, unsigned long long in
 
 
 int speck_expand_key_he (const unsigned char *k, speck_context_t *ctx);
+
+
+#endif