Diff: LoRaMacCrypto.cpp

Revision:

0:91d1a7783bb9

Child:

1:91e4e6c60d1e

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/LoRaMacCrypto.cpp	Tue Oct 20 13:21:26 2015 +0000
@@ -0,0 +1,197 @@
+/*
+ / _____)             _              | |
+( (____  _____ ____ _| |_ _____  ____| |__
+ \____ \| ___ |    (_   _) ___ |/ ___)  _ \
+ _____) ) ____| | | || |_| ____( (___| | | |
+(______/|_____)_|_|_| \__)_____)\____)_| |_|
+    (C)2013 Semtech
+
+Description: LoRa MAC layer implementation
+
+License: Revised BSD License, see LICENSE.TXT file include in the project
+
+Maintainer: Miguel Luis and Gregory Cristian
+*/
+#include "mbed.h"
+#include "board.h"
+#include "utilities.h"
+
+#include "aes.h"
+#include "cmac.h"
+
+#include "LoRaMacCrypto.h"
+
+/*!
+ * CMAC/AES Message Integrity Code (MIC) Block B0 size
+ */
+#define LORAMAC_MIC_BLOCK_B0_SIZE                   16
+
+/*!
+ * MIC field computation initial data
+ */
+static uint8_t MicBlockB0[] = { 0x49, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+                              };
+
+/*!
+ * Contains the computed MIC field.
+ *
+ * \remark Only the 4 first bytes are used
+ */
+static uint8_t Mic[16];
+
+/*!
+ * Encryption aBlock and sBlock
+ */
+static uint8_t aBlock[] = { 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+                          };
+static uint8_t sBlock[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+                            0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+                          };
+
+/*!
+ * AES computation context variable
+ */
+static aes_context AesContext;
+                   
+/*!
+ * CMAC computation context variable
+ */
+static AES_CMAC_CTX AesCmacCtx[1];
+
+/*!
+ * \brief Computes the LoRaMAC frame MIC field  
+ *
+ * \param [IN]  buffer          Data buffer
+ * \param [IN]  size            Data buffer size
+ * \param [IN]  key             AES key to be used
+ * \param [IN]  address         Frame address
+ * \param [IN]  dir             Frame direction [0: uplink, 1: downlink]
+ * \param [IN]  sequenceCounter Frame sequence counter
+ * \param [OUT] mic Computed MIC field
+ */
+void LoRaMacComputeMic( const uint8_t *buffer, uint16_t size, const uint8_t *key, uint32_t address, uint8_t dir, uint32_t sequenceCounter, uint32_t *mic )
+{
+    MicBlockB0[5] = dir;
+    
+    MicBlockB0[6] = ( address ) & 0xFF;
+    MicBlockB0[7] = ( address >> 8 ) & 0xFF;
+    MicBlockB0[8] = ( address >> 16 ) & 0xFF;
+    MicBlockB0[9] = ( address >> 24 ) & 0xFF;
+
+    MicBlockB0[10] = ( sequenceCounter ) & 0xFF;
+    MicBlockB0[11] = ( sequenceCounter >> 8 ) & 0xFF;
+    MicBlockB0[12] = ( sequenceCounter >> 16 ) & 0xFF;
+    MicBlockB0[13] = ( sequenceCounter >> 24 ) & 0xFF;
+
+    MicBlockB0[15] = size & 0xFF;
+
+    AES_CMAC_Init( AesCmacCtx );
+
+    AES_CMAC_SetKey( AesCmacCtx, key );
+
+    AES_CMAC_Update( AesCmacCtx, MicBlockB0, LORAMAC_MIC_BLOCK_B0_SIZE );
+    
+    AES_CMAC_Update( AesCmacCtx, buffer, size & 0xFF );
+    
+    AES_CMAC_Final( Mic, AesCmacCtx );
+    
+    *mic = ( uint32_t )( ( uint32_t )Mic[3] << 24 | ( uint32_t )Mic[2] << 16 | ( uint32_t )Mic[1] << 8 | ( uint32_t )Mic[0] );
+}
+
+void LoRaMacPayloadEncrypt( const uint8_t *buffer, uint16_t size, const uint8_t *key, uint32_t address, uint8_t dir, uint32_t sequenceCounter, uint8_t *encBuffer )
+{
+    uint16_t i;
+    uint8_t bufferIndex = 0;
+    uint16_t ctr = 1;
+
+    memset1( AesContext.ksch, '\0', 240 );
+    aes_set_key( key, 16, &AesContext );
+
+    aBlock[5] = dir;
+
+    aBlock[6] = ( address ) & 0xFF;
+    aBlock[7] = ( address >> 8 ) & 0xFF;
+    aBlock[8] = ( address >> 16 ) & 0xFF;
+    aBlock[9] = ( address >> 24 ) & 0xFF;
+
+    aBlock[10] = ( sequenceCounter ) & 0xFF;
+    aBlock[11] = ( sequenceCounter >> 8 ) & 0xFF;
+    aBlock[12] = ( sequenceCounter >> 16 ) & 0xFF;
+    aBlock[13] = ( sequenceCounter >> 24 ) & 0xFF;
+
+    while( size >= 16 )
+    {
+        aBlock[15] = ( ( ctr ) & 0xFF );
+        ctr++;
+        aes_encrypt( aBlock, sBlock, &AesContext );
+        for( i = 0; i < 16; i++ )
+        {
+            encBuffer[bufferIndex + i] = buffer[bufferIndex + i] ^ sBlock[i];
+        }
+        size -= 16;
+        bufferIndex += 16;
+    }
+
+    if( size > 0 )
+    {
+        aBlock[15] = ( ( ctr ) & 0xFF );
+        aes_encrypt( aBlock, sBlock, &AesContext );
+        for( i = 0; i < size; i++ )
+        {
+            encBuffer[bufferIndex + i] = buffer[bufferIndex + i] ^ sBlock[i];
+        }
+    }
+}
+
+void LoRaMacPayloadDecrypt( const uint8_t *buffer, uint16_t size, const uint8_t *key, uint32_t address, uint8_t dir, uint32_t sequenceCounter, uint8_t *decBuffer )
+{
+    LoRaMacPayloadEncrypt( buffer, size, key, address, dir, sequenceCounter, decBuffer );
+}
+
+void LoRaMacJoinComputeMic( const uint8_t *buffer, uint16_t size, const uint8_t *key, uint32_t *mic )
+{
+    AES_CMAC_Init( AesCmacCtx );
+
+    AES_CMAC_SetKey( AesCmacCtx, key );
+
+    AES_CMAC_Update( AesCmacCtx, buffer, size & 0xFF );
+
+    AES_CMAC_Final( Mic, AesCmacCtx );
+
+    *mic = ( uint32_t )( ( uint32_t )Mic[3] << 24 | ( uint32_t )Mic[2] << 16 | ( uint32_t )Mic[1] << 8 | ( uint32_t )Mic[0] );
+}
+
+void LoRaMacJoinDecrypt( const uint8_t *buffer, uint16_t size, const uint8_t *key, uint8_t *decBuffer )
+{
+    memset1( AesContext.ksch, '\0', 240 );
+    aes_set_key( key, 16, &AesContext );
+    aes_encrypt( buffer, decBuffer, &AesContext );
+    // Check if optional CFList is included
+    if( size >= 16 )
+    {
+        aes_encrypt( buffer + 16, decBuffer + 16, &AesContext );
+    }
+}
+
+void LoRaMacJoinComputeSKeys( const uint8_t *key, const uint8_t *appNonce, uint16_t devNonce, uint8_t *nwkSKey, uint8_t *appSKey )
+{
+    uint8_t nonce[16];
+    uint8_t *pDevNonce = ( uint8_t * )&devNonce;
+    
+    memset1( AesContext.ksch, '\0', 240 );
+    aes_set_key( key, 16, &AesContext );
+
+    memset1( nonce, 0, sizeof( nonce ) );
+    nonce[0] = 0x01;
+    LoRaMacMemCpy( appNonce, nonce + 1, 6 );
+    LoRaMacMemCpy( pDevNonce, nonce + 7, 2 );
+    aes_encrypt( nonce, nwkSKey, &AesContext );
+
+    memset1( nonce, 0, sizeof( nonce ) );
+    nonce[0] = 0x02;
+    LoRaMacMemCpy( appNonce, nonce + 1, 6 );
+    LoRaMacMemCpy( pDevNonce, nonce + 7, 2 );
+    aes_encrypt( nonce, appSKey, &AesContext );
+}