lib: Add per-message encryption with OpenSSL

This adds a per-message symmetric encryption using the OpenSSL
library. At flow allocation, an Elliptic Curve Diffie-Hellman exchange
is performed to derive a shared secret, which is then hashed using
SHA3-256 to be used as a key for symmetric AES-256 encryption. Each
message on an encrypted flow adds a small crypto header that includes
a random 128-bit Initialization Vector (IV). If the server does not
have OpenSSL enabled, the flow allocation will fail with an -ECRYPT
error.

Future optimizations are to piggyback the public keys on the flow
allocation message, and to enable per-flow encryption that maintains
the context of the encryption over multiple packets and doesn't
require sending IVs.

Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>

3 files changed, 75 insertions, 12 deletions

diff --git a/include/ouroboros/errno.h b/include/ouroboros/errno.h
index 27b21e82..20049751 100644
--- a/include/ouroboros/errno.h
+++ b/include/ouroboros/errno.h
@@ -25,11 +25,12 @@
 
 #include <errno.h>
 
-#define ENOTALLOC    1000 /* Flow is not allocated */
-#define EIPCPTYPE    1001 /* Unknown IPCP type */
+#define ENOTALLOC    1000 /* Flow is not allocated           */
+#define EIPCPTYPE    1001 /* Unknown IPCP type               */
 #define EIRMD        1002 /* Failed to communicate with IRMD */
 #define EIPCP        1003 /* Failed to communicate with IPCP */
-#define EIPCPSTATE   1004 /* Target in wrong state */
-#define EFLOWDOWN    1005 /* Flow is down */
+#define EIPCPSTATE   1004 /* Target in wrong state           */
+#define EFLOWDOWN    1005 /* Flow is down                    */
+#define ECRYPT       1006 /* Encryption error                */
 
 #endif /* OUROBOROS_ERRNO_H */
diff --git a/include/ouroboros/qos.h b/include/ouroboros/qos.h
index 0e4518f4..f5becaa6 100644
--- a/include/ouroboros/qos.h
+++ b/include/ouroboros/qos.h
@@ -34,6 +34,7 @@ typedef struct qos_spec {
         uint32_t ber;           /* Bit error rate, errors per billion bits */
         uint8_t  in_order;      /* In-order delivery, enables FRCT */
         uint32_t max_gap;       /* In ms */
+        uint32_t cypher_s;      /* Cypher strength, 0 = no encryption */
 } qosspec_t;
 
 static const qosspec_t qos_raw = {
@@ -43,7 +44,8 @@ static const qosspec_t qos_raw = {
         .loss         = 1,
         .ber          = 1,
         .in_order     = 0,
-        .max_gap      = UINT32_MAX
+        .max_gap      = UINT32_MAX,
+        .cypher_s     = 0
 };
 
 static const qosspec_t qos_raw_no_errors = {
@@ -53,7 +55,19 @@ static const qosspec_t qos_raw_no_errors = {
         .loss         = 1,
         .ber          = 0,
         .in_order     = 0,
-        .max_gap      = UINT32_MAX
+        .max_gap      = UINT32_MAX,
+        .cypher_s     = 0
+};
+
+static const qosspec_t qos_raw_crypt = {
+        .delay        = UINT32_MAX,
+        .bandwidth    = 0,
+        .availability = 0,
+        .loss         = 1,
+        .ber          = 0,
+        .in_order     = 0,
+        .max_gap      = UINT32_MAX,
+        .cypher_s     = 256
 };
 
 static const qosspec_t qos_best_effort = {
@@ -63,7 +77,19 @@ static const qosspec_t qos_best_effort = {
         .loss         = 1,
         .ber          = 0,
         .in_order     = 1,
-        .max_gap      = UINT32_MAX
+        .max_gap      = UINT32_MAX,
+        .cypher_s     = 0
+};
+
+static const qosspec_t qos_best_effort_crypt = {
+        .delay        = UINT32_MAX,
+        .bandwidth    = 0,
+        .availability = 0,
+        .loss         = 1,
+        .ber          = 0,
+        .in_order     = 1,
+        .max_gap      = UINT32_MAX,
+        .cypher_s     = 256
 };
 
 static const qosspec_t qos_video   = {
@@ -73,7 +99,19 @@ static const qosspec_t qos_video   = {
         .loss         = 1,
         .ber          = 0,
         .in_order     = 1,
-        .max_gap      = 100
+        .max_gap      = 100,
+        .cypher_s     = 0
+};
+
+static const qosspec_t qos_video_crypt   = {
+        .delay        = 100,
+        .bandwidth    = UINT64_MAX,
+        .availability = 3,
+        .loss         = 1,
+        .ber          = 0,
+        .in_order     = 1,
+        .max_gap      = 100,
+        .cypher_s     = 256
 };
 
 static const qosspec_t qos_voice = {
@@ -83,7 +121,19 @@ static const qosspec_t qos_voice = {
         .loss         = 1,
         .ber          = 0,
         .in_order     = 1,
-        .max_gap      = 50
+        .max_gap      = 50,
+        .cypher_s     = 0
+};
+
+static const qosspec_t qos_voice_crypt = {
+        .delay        = 50,
+        .bandwidth    = 100000,
+        .availability = 5,
+        .loss         = 1,
+        .ber          = 0,
+        .in_order     = 1,
+        .max_gap      = 50,
+        .cypher_s     = 256
 };
 
 static const qosspec_t qos_data = {
@@ -93,7 +143,19 @@ static const qosspec_t qos_data = {
         .loss         = 0,
         .ber          = 0,
         .in_order     = 1,
-        .max_gap      = 2000
+        .max_gap      = 2000,
+        .cypher_s     = 0
+};
+
+static const qosspec_t qos_data_crypt = {
+        .delay        = 1000,
+        .bandwidth    = 0,
+        .availability = 0,
+        .loss         = 0,
+        .ber          = 0,
+        .in_order     = 1,
+        .max_gap      = 2000,
+        .cypher_s     = 256
 };
 
 #endif /* OUROBOROS_QOS_H */
diff --git a/include/ouroboros/sockets.h.in b/include/ouroboros/sockets.h.in
index 1e9dc9ca..4f03ca46 100644
--- a/include/ouroboros/sockets.h.in
+++ b/include/ouroboros/sockets.h.in
@@ -60,8 +60,8 @@ irm_msg_t * send_recv_irm_msg(irm_msg_t * msg);
 
 
 /* qos message conversion needed in different components */
-qosspec_msg_t spec_to_msg(qosspec_t * qs);
+qosspec_msg_t spec_to_msg(const qosspec_t * qs);
 
-qosspec_t     msg_to_spec(qosspec_msg_t * msg);
+qosspec_t     msg_to_spec(const qosspec_msg_t * msg);
 
 #endif