Improved AES GCM encryption, changed IV length to 12 bytes.

CMakeLists.txt

@@ -8,7 +8,7 @@
 #
 
 cmake_minimum_required (VERSION 2.8.12 FATAL_ERROR)
-set (SRT_VERSION 1.5.3)
+set (SRT_VERSION 1.5.4)
 
 set (CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/scripts")
 include(haiUtil) # needed for set_version_variables

haicrypt/cryspr.c

@@ -17,6 +17,10 @@ written by
 		CRYSPR/4SRT Initial implementation.
 *****************************************************************************/
 
+#ifndef _WIN32
+#include <arpa/inet.h>  /* htonl */
+#endif
+
 #include "hcrypt.h"
 #include "cryspr.h"
 
@@ -429,6 +433,8 @@ static int crysprFallback_MsEncrypt(
 
 	/* Auth tag produced by AES GCM. */
 	unsigned char tag[HAICRYPT_AUTHTAG_MAX];
+	/* Additional authenticated data used by AES-GCM. */
+	unsigned char aad[HAICRYPT_AAD_MAX];
 
 	/*
 	 * Get buffer room from the internal circular output buffer.
@@ -452,33 +458,30 @@ static int crysprFallback_MsEncrypt(
 			/* Get input packet index (in network order) */
 			hcrypt_Pki pki = hcryptMsg_GetPki(ctx->msg_info, in_data[0].pfx, 1);
 
-			/*
-			 * Compute the Initial Vector
-			 * IV (128-bit):
-			 *    0   1   2   3   4   5  6   7   8   9   10  11  12  13  14  15
-			 * +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
-			 * |                   0s                  |      pki      |  ctr  |
-			 * +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
-			 *                            XOR
-			 * +---+---+---+---+---+---+---+---+---+---+---+---+---+---+
-			 * |                         nonce                         +
-			 * +---+---+---+---+---+---+---+---+---+---+---+---+---+---+
-			 *
-			 * pki    (32-bit): packet index
-			 * ctr    (16-bit): block counter
-			 * nonce (112-bit): number used once (salt)
-			*/
-			hcrypt_SetCtrIV((unsigned char *)&pki, ctx->salt, iv);
-
 			if (ctx->mode == HCRYPT_CTX_MODE_AESGCM)
 			{
-				const int iret = cryspr_cb->cryspr->aes_gcm_cipher(true, aes_key, iv, in_data[0].pfx, pfx_len, in_data[0].payload, in_data[0].len,
+				const bool old_aead = ctx->use_gcm_153; // SRT v1.5.2 to v1.5.3.
+				if (old_aead)
+				{
+					hcrypt_SetCtrIV((unsigned char*)&pki, ctx->salt, iv);
+					memcpy(aad, in_data[0].pfx, sizeof(aad));
+				}
+				else
+				{
+					hcrypt_SetGcmIV((unsigned char*)&pki, ctx->salt, iv);
+
+					for (size_t i = 0; i < sizeof(aad) / 4; ++i)
+						*((uint32_t*)aad + i) = htonl(*((uint32_t*)in_data[0].pfx + i));
+				}
+
+				const int iret = cryspr_cb->cryspr->aes_gcm_cipher(true, aes_key, iv, aad, sizeof(aad), in_data[0].payload, in_data[0].len,
 						&out_msg[pfx_len], tag);
 				if (iret) {
 					return(iret);
 				}
 			}
 			else {
+				hcrypt_SetCtrIV((unsigned char *)&pki, ctx->salt, iv);
 #if CRYSPR_HAS_AESCTR
 				cryspr_cb->cryspr->aes_ctr_cipher(true, aes_key, iv, in_data[0].payload, in_data[0].len,
 						&out_msg[pfx_len]);
@@ -599,35 +602,34 @@ static int crysprFallback_MsDecrypt(CRYSPR_cb *cryspr_cb, hcrypt_Ctx *ctx,
 				/* Get input packet index (in network order) */
 				hcrypt_Pki pki = hcryptMsg_GetPki(ctx->msg_info, in_data[0].pfx, 1);
 
-				/*
-				 * Compute the Initial Vector
-				 * IV (128-bit):
-				 *    0   1   2   3   4   5  6   7   8   9   10  11  12  13  14  15
-				 * +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
-				 * |                   0s                  |      pki      |  ctr  |
-				 * +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
-				 *                            XOR
-				 * +---+---+---+---+---+---+---+---+---+---+---+---+---+---+
-				 * |                         nonce                         +
-				 * +---+---+---+---+---+---+---+---+---+---+---+---+---+---+
-				 *
-				 * pki    (32-bit): packet index
-				 * ctr    (16-bit): block counter
-				 * nonce (112-bit): number used once (salt)
-				 */
-				hcrypt_SetCtrIV((unsigned char *)&pki, ctx->salt, iv);
-
 				if (ctx->mode == HCRYPT_CTX_MODE_AESGCM)
 				{
+					/* Additional authenticated data used by AES-GCM. */
+					unsigned char aad[HAICRYPT_AAD_MAX];
+					const bool old_aead = ctx->use_gcm_153; // SRT v1.5.2 to v1.5.3.
+					if (old_aead)
+					{
+						hcrypt_SetCtrIV((unsigned char*)&pki, ctx->salt, iv);
+						memcpy(aad, in_data[0].pfx, sizeof(aad));
+					}
+					else
+					{
+						hcrypt_SetGcmIV((unsigned char*)&pki, ctx->salt, iv);
+
+						for (size_t i = 0; i < sizeof(aad) / 4; ++i)
+							*((uint32_t*)aad + i) = htonl(*((uint32_t*)in_data[0].pfx + i));
+					}
+
 					unsigned char* tag = in_data[0].payload + in_data[0].len - HAICRYPT_AUTHTAG_MAX;
-					int liret = cryspr_cb->cryspr->aes_gcm_cipher(false, aes_key, iv, in_data[0].pfx, ctx->msg_info->pfx_len, in_data[0].payload, in_data[0].len - HAICRYPT_AUTHTAG_MAX,
+					int liret = cryspr_cb->cryspr->aes_gcm_cipher(false, aes_key, iv, aad, sizeof(aad), in_data[0].payload, in_data[0].len - HAICRYPT_AUTHTAG_MAX,
 						out_txt, tag);
 					if (liret) {
 						return(liret);
 					}
 					out_len = in_data[0].len - HAICRYPT_AUTHTAG_MAX;
 				}
 				else {
+					hcrypt_SetCtrIV((unsigned char*)&pki, ctx->salt, iv);
 #if CRYSPR_HAS_AESCTR
 					cryspr_cb->cryspr->aes_ctr_cipher(false, aes_key, iv, in_data[0].payload, in_data[0].len,
 						out_txt);

haicrypt/haicrypt.h

@@ -37,6 +37,7 @@ HaiCrypt_Cryspr HaiCryptCryspr_Get_Instance (void);     /* Return a default crys
 #define HAICRYPT_KEY_MAX_SZ         32  /* MAX key */
 #define HAICRYPT_SECRET_MAX_SZ      (HAICRYPT_PWD_MAX_SZ > HAICRYPT_KEY_MAX_SZ ? HAICRYPT_PWD_MAX_SZ : HAICRYPT_KEY_MAX_SZ)
 #define	HAICRYPT_AUTHTAG_MAX        16  /* maximum length of the auth tag (e.g. GCM) */
+#define	HAICRYPT_AAD_MAX            16  /* maximum length of the additional authenticated data (GCM mode) */
 
 #define HAICRYPT_SALT_SZ            16
 
@@ -96,6 +97,7 @@ typedef struct hcrypt_Session_str* HaiCrypt_Handle;
 int  HaiCrypt_SetLogLevel(int level, int logfa);
 
 int  HaiCrypt_Create(const HaiCrypt_Cfg *cfg, HaiCrypt_Handle *phhc);
+int  HaiCrypt_UpdateGcm153(HaiCrypt_Handle hhc, unsigned use_gcm_153);
 int  HaiCrypt_Clone(HaiCrypt_Handle hhcSrc, HaiCrypt_CryptoDir tx, HaiCrypt_Handle *phhc);
 int  HaiCrypt_Close(HaiCrypt_Handle hhc);
 int  HaiCrypt_Tx_GetBuf(HaiCrypt_Handle hhc, size_t data_len, unsigned char **in_p);

haicrypt/hcrypt.c

@@ -178,6 +178,18 @@ int HaiCrypt_Create(const HaiCrypt_Cfg *cfg, HaiCrypt_Handle *phhc)
     return(0);
 }
 
+int HaiCrypt_UpdateGcm153(HaiCrypt_Handle hhc, unsigned use_gcm_153)
+{
+    ASSERT(hhc != NULL);
+    hcrypt_Session* crypto = hhc;
+    if (!crypto)
+        return (-1);
+
+    crypto->ctx_pair[0].use_gcm_153 = use_gcm_153;
+    crypto->ctx_pair[1].use_gcm_153 = use_gcm_153;
+    return (0);
+}
+
 int HaiCrypt_ExtractConfig(HaiCrypt_Handle hhcSrc, HaiCrypt_Cfg* pcfg)
 {
     hcrypt_Session *crypto = (hcrypt_Session *)hhcSrc;

haicrypt/hcrypt.h

@@ -135,6 +135,25 @@ typedef struct hcrypt_Session_str {
             hcrypt_XorStream(&(iv)[0], (nonce), 112/8); \
         } while(0)
 
+/* HaiCrypt-TP GCM mode IV (96-bit) - SRT 1.5.4:
+ *    0   1   2   3   4   5  6   7   8   9   10  11 
+ * +---+---+---+---+---+---+---+---+---+---+---+---+
+ * |                   0s          |      pki      |
+ * +---+---+---+---+---+---+---+---+---+---+---+---+
+ *                         XOR                   
+ * +---+---+---+---+---+---+---+---+---+---+---+---+
+ * |                      nonce                    +
+ * +---+---+---+---+---+---+---+---+---+---+---+---+
+ *
+ * pki   (32-bit): packet index
+ * nonce (96-bit): number used once (salt)
+ */
+#define hcrypt_SetGcmIV(pki, nonce, iv) do { \
+            memset(&(iv)[0], 0, 96/8); \
+            memcpy(&(iv)[8], (pki), HCRYPT_PKI_SZ); \
+            hcrypt_XorStream(&(iv)[0], (nonce), 96/8); \
+        } while(0)
+
 #define hcrypt_XorStream(dst, strm, len) do { \
             int __XORSTREAMi; \
             for (__XORSTREAMi = 0 \

haicrypt/hcrypt_ctx.h

@@ -70,6 +70,7 @@ typedef struct tag_hcrypt_Ctx {
 #define HCRYPT_CTX_MODE_AESCBC  3   /* Cipher-block chaining mode */
 #define HCRYPT_CTX_MODE_AESGCM  4   /* AES GCM authenticated encryption */
         unsigned         mode;
+        bool             use_gcm_153; /* AES-GCM compatibility mode (SRT v1.5.3 and earlier) */
 
         struct {
             size_t       key_len;

haicrypt/hcrypt_ctx_rx.c

@@ -28,8 +28,8 @@ int hcryptCtx_Rx_Init(hcrypt_Session *crypto, hcrypt_Ctx *ctx, const HaiCrypt_Cf
 		ctx->mode = (cfg->flags & HAICRYPT_CFG_F_GCM) ? HCRYPT_CTX_MODE_AESGCM : HCRYPT_CTX_MODE_AESCTR;
 	}
 	ctx->status = HCRYPT_CTX_S_INIT;
-
 	ctx->msg_info = crypto->msg_info;
+	ctx->use_gcm_153 = false; // Default initialization.
 
 	if (cfg && hcryptCtx_SetSecret(crypto, ctx, &cfg->secret)) {
 		return(-1);

haicrypt/hcrypt_ctx_tx.c

@@ -35,7 +35,7 @@ int hcryptCtx_Tx_Init(hcrypt_Session *crypto, hcrypt_Ctx *ctx, const HaiCrypt_Cf
 
 	ctx->mode = (cfg->flags & HAICRYPT_CFG_F_GCM) ? HCRYPT_CTX_MODE_AESGCM : HCRYPT_CTX_MODE_AESCTR;
 	ctx->status = HCRYPT_CTX_S_INIT;
-
+	ctx->use_gcm_153 = false; // Default initialization.
 	ctx->msg_info = crypto->msg_info;
 
 	if (hcryptCtx_SetSecret(crypto, ctx, &cfg->secret)) {
@@ -184,7 +184,6 @@ int hcryptCtx_Tx_Refresh(hcrypt_Session *crypto)
 	ASSERT(HCRYPT_CTX_S_SARDY <= new_ctx->status);
 
 	/* Keep same KEK, configuration, and salt */
-//	memcpy(&new_ctx->aes_kek, &ctx->aes_kek, sizeof(new_ctx->aes_kek));
 	memcpy(&new_ctx->cfg, &ctx->cfg, sizeof(new_ctx->cfg));
 
 	new_ctx->salt_len = ctx->salt_len;

srtcore/core.cpp

@@ -2020,7 +2020,7 @@ bool srt::CUDT::processSrtMsg(const CPacket *ctrlpkt)
         {
             uint32_t srtdata_out[SRTDATA_MAXSIZE];
             size_t   len_out = 0;
-            res = m_pCryptoControl->processSrtMsg_KMREQ(srtdata, len, CUDT::HS_VERSION_UDT4,
+            res = m_pCryptoControl->processSrtMsg_KMREQ(srtdata, len, CUDT::HS_VERSION_UDT4, m_uPeerSrtVersion,
                     (srtdata_out), (len_out));
             if (res == SRT_CMD_KMRSP)
             {
@@ -2057,7 +2057,7 @@ bool srt::CUDT::processSrtMsg(const CPacket *ctrlpkt)
     case SRT_CMD_KMRSP:
     {
         // KMRSP doesn't expect any following action
-        m_pCryptoControl->processSrtMsg_KMRSP(srtdata, len, CUDT::HS_VERSION_UDT4);
+        m_pCryptoControl->processSrtMsg_KMRSP(srtdata, len, m_uPeerSrtVersion);
         return true; // nothing to do
     }
 
@@ -2646,7 +2646,7 @@ bool srt::CUDT::interpretSrtHandshake(const CHandShake& hs,
                     return false;
                 }
 
-                int res = m_pCryptoControl->processSrtMsg_KMREQ(begin + 1, bytelen, HS_VERSION_SRT1,
+                int res = m_pCryptoControl->processSrtMsg_KMREQ(begin + 1, bytelen, HS_VERSION_SRT1, m_uPeerSrtVersion,
                             (out_data), (*pw_len));
                 if (res != SRT_CMD_KMRSP)
                 {
@@ -2693,7 +2693,7 @@ bool srt::CUDT::interpretSrtHandshake(const CHandShake& hs,
             }
             else if (cmd == SRT_CMD_KMRSP)
             {
-                int res = m_pCryptoControl->processSrtMsg_KMRSP(begin + 1, bytelen, HS_VERSION_SRT1);
+                int res = m_pCryptoControl->processSrtMsg_KMRSP(begin + 1, bytelen, m_uPeerSrtVersion);
                 if (m_config.bEnforcedEnc && res == -1)
                 {
                     if (m_pCryptoControl->m_SndKmState == SRT_KM_S_BADSECRET)
@@ -6022,13 +6022,15 @@ bool srt::CUDT::createCrypter(HandshakeSide side, bool bidirectional)
     // they have outdated values.
     m_pCryptoControl->setCryptoSecret(m_config.CryptoSecret);
 
+    const bool useGcm153 = m_uPeerSrtVersion <= SrtVersion(1, 5, 3);
+
     if (bidirectional || m_config.bDataSender)
     {
         HLOGC(rslog.Debug, log << CONID() << "createCrypter: setting RCV/SND KeyLen=" << m_config.iSndCryptoKeyLen);
         m_pCryptoControl->setCryptoKeylen(m_config.iSndCryptoKeyLen);
     }
 
-    return m_pCryptoControl->init(side, m_config, bidirectional);
+    return m_pCryptoControl->init(side, m_config, bidirectional, useGcm153);
 }
 
 SRT_REJECT_REASON srt::CUDT::setupCC()
@@ -7762,7 +7764,7 @@ bool srt::CUDT::updateCC(ETransmissionEvent evt, const EventVariant arg)
         // - m_dCWndSize
         m_tdSendInterval    = microseconds_from((int64_t)m_CongCtl->pktSndPeriod_us());
         const double cgwindow = m_CongCtl->cgWindowSize();
-        m_iCongestionWindow = cgwindow;
+        m_iCongestionWindow = (int) cgwindow;
 #if ENABLE_HEAVY_LOGGING
         HLOGC(rslog.Debug,
               log << CONID() << "updateCC: updated values from congctl: interval=" << FormatDuration<DUNIT_US>(m_tdSendInterval)

srtcore/crypto.cpp

@@ -138,7 +138,7 @@ void srt::CCryptoControl::createFakeSndContext()
 int srt::CCryptoControl::processSrtMsg_KMREQ(
         const uint32_t* srtdata SRT_ATR_UNUSED,
         size_t bytelen SRT_ATR_UNUSED,
-        int hsv SRT_ATR_UNUSED,
+        int hsv SRT_ATR_UNUSED, unsigned srtv SRT_ATR_UNUSED,
         uint32_t pw_srtdata_out[], size_t& w_srtlen)
 {
     //Receiver
@@ -172,6 +172,8 @@ int srt::CCryptoControl::processSrtMsg_KMREQ(
         (m_iCryptoMode == CSrtConfig::CIPHER_MODE_AUTO && kmdata[HCRYPT_MSG_KM_OFS_CIPHER] == HCRYPT_CIPHER_AES_GCM) ||
         (m_iCryptoMode == CSrtConfig::CIPHER_MODE_AES_GCM);
 
+    m_bUseGcm153 = srtv <= SrtVersion(1, 5, 3);
+
     // What we have to do:
     // If encryption is on (we know that by having m_KmSecret nonempty), create
     // the crypto context (if bidirectional, create for both sending and receiving).
@@ -331,6 +333,13 @@ int srt::CCryptoControl::processSrtMsg_KMREQ(
         HLOGC(cnlog.Debug, log << "processSrtMsg_KMREQ: NOT REPLAYING the key update to TX CRYPTO CTX.");
     }
 
+#ifdef SRT_ENABLE_ENCRYPTION
+    if (m_hRcvCrypto != NULL)
+        HaiCrypt_UpdateGcm153(m_hRcvCrypto, m_bUseGcm153);
+    if (m_hSndCrypto != NULL)
+        HaiCrypt_UpdateGcm153(m_hSndCrypto, m_bUseGcm153);
+#endif
+
     return SRT_CMD_KMRSP;
 
 HSv4_ErrorReport:
@@ -359,7 +368,7 @@ int srt::CCryptoControl::processSrtMsg_KMREQ(
     return SRT_CMD_KMRSP;
 }
 
-int srt::CCryptoControl::processSrtMsg_KMRSP(const uint32_t* srtdata, size_t len, int /* XXX unused? hsv*/)
+int srt::CCryptoControl::processSrtMsg_KMRSP(const uint32_t* srtdata, size_t len, unsigned srtv)
 {
     /* All 32-bit msg fields (if present) swapped on reception
      * But HaiCrypt expect network order message
@@ -371,9 +380,6 @@ int srt::CCryptoControl::processSrtMsg_KMRSP(const uint32_t* srtdata, size_t len
 
     int retstatus = -1;
 
-    // Unused?
-    //bool bidirectional = hsv > CUDT::HS_VERSION_UDT4;
-
     // Since now, when CCryptoControl::decrypt() encounters an error, it will print it, ONCE,
     // until the next KMREQ is received as a key regeneration.
     m_bErrorReported = false;
@@ -459,6 +465,14 @@ int srt::CCryptoControl::processSrtMsg_KMRSP(const uint32_t* srtdata, size_t len
         }
         HLOGC(cnlog.Debug, log << "processSrtMsg_KMRSP: key[0]: len=" << m_SndKmMsg[0].MsgLen << " retry=" << m_SndKmMsg[0].iPeerRetry
             << "; key[1]: len=" << m_SndKmMsg[1].MsgLen << " retry=" << m_SndKmMsg[1].iPeerRetry);
+
+        m_bUseGcm153 = srtv <= SrtVersion(1, 5, 3);
+#ifdef SRT_ENABLE_ENCRYPTION
+        if (m_hRcvCrypto != NULL)
+            HaiCrypt_UpdateGcm153(m_hRcvCrypto, m_bUseGcm153);
+        if (m_hSndCrypto != NULL)
+            HaiCrypt_UpdateGcm153(m_hSndCrypto, m_bUseGcm153);
+#endif
     }
 
     LOGP(cnlog.Note, FormatKmMessage("processSrtMsg_KMRSP", SRT_CMD_KMRSP, len));
@@ -593,6 +607,7 @@ srt::CCryptoControl::CCryptoControl(SRTSOCKET id)
     , m_KmRefreshRatePkt(0)
     , m_KmPreAnnouncePkt(0)
     , m_iCryptoMode(CSrtConfig::CIPHER_MODE_AUTO)
+    , m_bUseGcm153(false)
     , m_bErrorReported(false)
 {
     m_KmSecret.len = 0;
@@ -606,7 +621,7 @@ srt::CCryptoControl::CCryptoControl(SRTSOCKET id)
     m_hRcvCrypto = NULL;
 }
 
-bool srt::CCryptoControl::init(HandshakeSide side, const CSrtConfig& cfg, bool bidirectional SRT_ATR_UNUSED)
+bool srt::CCryptoControl::init(HandshakeSide side, const CSrtConfig& cfg, bool bidirectional SRT_ATR_UNUSED, bool bUseGcm153 SRT_ATR_UNUSED)
 {
     // NOTE: initiator creates m_hSndCrypto. When bidirectional,
     // it creates also m_hRcvCrypto with the same key length.
@@ -620,6 +635,7 @@ bool srt::CCryptoControl::init(HandshakeSide side, const CSrtConfig& cfg, bool b
     // Set UNSECURED state as default
     m_RcvKmState = SRT_KM_S_UNSECURED;
     m_iCryptoMode = cfg.iCryptoMode;
+    m_bUseGcm153 = bUseGcm153;
 
 #ifdef SRT_ENABLE_ENCRYPTION
     if (!cfg.bTSBPD && m_iCryptoMode == CSrtConfig::CIPHER_MODE_AUTO)
@@ -807,7 +823,7 @@ srt::EncryptionStatus srt::CCryptoControl::encrypt(CPacket& w_packet SRT_ATR_UNU
     {
         return ENCS_FAILED;
     }
-    else if ( rc > 0 )
+    else if (rc > 0)
     {
         // XXX what happens if the encryption is said to be "succeeded",
         // but the length is 0? Shouldn't this be treated as unwanted?