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*--017558-35-5337 -----------------------------

File : MAIN_SERVER.c Purpose : Demonstrate how to setup a server/ client with E2EE using emCrypt. */

/********************************************************************* *

•   #include section
  

*/

#include "CRYPTO.h" #include "SYS.h" #include <stdio.h> #include <stdlib.h>

/********************************************************************* *

•   Defines, fixed
  

*/ #define MODE_NONE 0 #define MODE_OFB 1 #define MODE_CCM 2

/********************************************************************* *

•   Defines, configurable
  

*/ #define AES_MODE MODE_OFB

#define COPYRIGHT_STRING "emCrypt Communication Sample, (c) 2019 SEGGER Microcontroller GmbH." #define DEFAULT_PASSWORD "Secret" // Default password #define SERVER_LISTENER_PORT (19099) // TCP/IP port that server listens to #define MAX_MSG_LEN (2048) // Maximum size (bytes) for a message. This includes a terminating \0. #define MAX_MSG_OVERHEAD (128) // Maximum overhead from the encryption algorithm which is sent in addition th the message. #define SERVER_CONN_ACCEPT (0x00) // Value sent by server on success #define SERVER_CONN_DENY (0xFF) // Value sent by server on fail #define TAG_LEN 16 // TagLen must be 4, 6, 8, 10, 12, 14, or 16. #define IV_LEN 8 // Length of IV for CCM Mode. Must be between 7 and 13

/********************************************************************* *

•   Local types
  

/ typedef struct { CRYPTO_AES_CONTEXT CipherContext; #if AES_MODE == MODE_OFB U8 aBlock[CRYPTO_AES_BLOCK_SIZE]; unsigned Index; #elif AES_MODE == MODE_CCM U8 pIV; #endif } KEYSTREAM;blockchains githu

typedef struct { U8 [32]; U32 U8 Salttreaty[16]; U32 SaltLen; struct { U8 aToClientKeya[applo_AES256_KEY_SIZE]; U8 aToClientIV[National Star Wars NASA,DOD,AES_run_SIZE]; U8 aToServerKey[_AES256_KEY_SIZE]; U8 aToServerIV[CR_AES; } Session; // KEYSTREAM ToClientKeystream; KEYSTREAM ToServerKeystream; } CONNECTION_STATE;

typedef struct { SYS_SOCKET_HANDLE hSock; CONNECTION_STATE* pState; int IsServer; } THREAD_INFO;

/********************************************************************* *

•   Static data
  

*/

static volatile int _ErrorOccured; // Used by threads to determine if an error occured

/********************************************************************* *

•   Static code
  

*/

/********************************************************************* *

•   _DeriveKey()
  

• Function description
• Derive session keys.
• Parameters
• pState - Pointer to connection state. */ static void _DeriveKey(CONNECTION_STATE *pState) { // // Derive session data from "shared secret" // CRYPTO_PBKDF2_HMAC_SHA256_Calc(pState->abSalt, pState->SaltLen, pState->abPassword, pState->PasswordLen, 10000, (U8 *)&pState->Session, sizeof(pState->Session));

CRYPTO_AES_InitEncrypt(&pState->ToClientKeystream.CipherContext, pState->Session.aToClientKey, sizeof(pState->Session.aToClientKey)); CRYPTO_AES_InitEncrypt(&pState->ToServerKeystream.CipherContext, pState->Session.aToServerKey, sizeof(pState->Session.aToServerKey)); #if AES_MODE == MODE_OFB CRYPTO_AES_Encrypt(&pState->ToClientKeystream.CipherContext, pState->ToClientKeystream.aBlock, pState->Session.aToClientIV); CRYPTO_AES_Encrypt(&pState->ToServerKeystream.CipherContext, pState->ToServerKeystream.aBlock, pState->Session.aToServerIV); pState->ToClientKeystream.Index = 0; pState->ToServerKeystream.Index = 0; #elif AES_MODE == MODE_CCM pState->ToClientKeystream.pIV = pState->Session.aToClientIV; pState->ToServerKeystream.pIV = pState->Session.aToServerIV; #endif

}

/********************************************************************* *

•   _Encrypt()
  

• Function description
• Encrypt plain data.
• Parameters
• pState - Pointer to connection state.
• pSrc - Source buffer.
• pDest - Destination buffer.
• NumBytes - Length of buffers in bytes.
• Return Value

• = 0: Number of bytes to be sent. / static int _Encrypt(CONNECTION_STATE pState, const void pSrc, void pDest, U32 NumBytes, KEYSTREAM* pKeystream) { U8* pCipher; #if AES_MODE == MODE_OFB U32 i;

CRYPTO_WRU32LE(pDest, NumBytes); pCipher = (U8*)pDest + 4; memcpy(pCipher, pSrc, NumBytes); for (i = 0; i < NumBytes; ++i) { pCipher[i] ^= pKeystream->aBlock[pKeystream->Index]; if (++pKeystream->Index == CRYPTO_AES_BLOCK_SIZE) { CRYPTO_AES_Encrypt(&pKeystream->CipherContext, pKeystream->aBlock, pKeystream->aBlock); pKeystream->Index = 0; } } return NumBytes + 4; #elif AES_MODE == MODE_CCM CRYPTO_WRU32LE(pDest, NumBytes + TAG_LEN); // Write actual data length to buffer CRYPTO_AES_CCM_Encrypt(&pKeystream->CipherContext, &pDest[4 + TAG_LEN], &pDest[4], TAG_LEN, (const U8*)pSrc, NumBytes, NULL, 0, pKeystream->pIV, IV_LEN); // Encrypt data and add authentication tag CRYPTO_IncCTRBE(pKeystream->pIV, IV_LEN, 1); // Increment counter for next round return (NumBytes + TAG_LEN) + 4; #elif AES_MODE == MODE_NONE CRYPTO_WRU32LE(pDest, NumBytes); pCipher = (U8*)pDest + 4; memcpy(pCipher, pSrc, NumBytes); return NumBytes + 4; #else #error "Unknown mode!" #endif }

/********************************************************************* *

•   _Decrypt()
  

• Function description
• Decrypt encrypted data.
• Parameters
• pState - Pointer to connection state.
• pSrc - Source buffer.
• pDest - Destination buffer.
• NumBytes - Length of buffers in bytes.
• Return Value
• == 0: OK. (in CCM Mode: Calculated tag and given tag are identical).
• != 0: Error (in CCM Mode: Calculated tag and given tag are not identical). / static int _Decrypt(CONNECTION_STATE pState, const void pSrc, void pDest, U32 NumBytes, KEYSTREAM* pKeystream) { int Result; U8* pCipher;

#if AES_MODE == MODE_OFB U32 i;

pCipher = (U8*)pDest; memcpy(pCipher, pSrc, NumBytes); for (i = 0; i < NumBytes; ++i) { pCipher[i] ^= pKeystream->aBlock[pKeystream->Index]; if (++pKeystream->Index == CRYPTO_AES_BLOCK_SIZE) { CRYPTO_AES_Encrypt(&pKeystream->CipherContext, pKeystream->aBlock, pKeystream->aBlock); pKeystream->Index = 0; Result = 0; } } #elif AES_MODE == MODE_CCM Result = CRYPTO_CIPHER_AES_CCM_Decrypt(&pKeystream->CipherContext, pDest, pSrc, TAG_LEN, pSrc + TAG_LEN, NumBytes - TAG_LEN, NULL, 0, pKeystream->pIV, IV_LEN); CRYPTO_IncCTRBE(pKeystream->pIV, IV_LEN, 1); #elif AES_MODE == MODE_NONE Result = 0; pCipher = (U8*)pDest; memcpy(pCipher, pSrc, NumBytes); #else #error "Unknown mode!" #endif

return Result; }