Write a decoder program in C++, using struct { }; Write a decoder program in C++

Question

Write a decoder program in C++, using struct { };

Write a decoder program in C++, using struct { }; Locate the output file from running the executable: ''decodeme .jiw''. You will need to use this file as your input file for the program you write. Design your program using struct to ''decode'' the message in the ''decodeme.jiw'' file: -Read the content from the ''decodeme.jiw'' file -Reverse the process as shown in this program, to ''decode'' the message from the contents read from the ''decodeme.jiw'' file. - Display the message to the console. This message should match with the string s that is shown in this program.

Explanation / Answer

#include #include #include #include #pragma comment(lib, "crypt32.lib") // Link with the Crypt32.lib file. #pragma comment (lib, "Crypt32") #define MY_ENCODING_TYPE (PKCS_7_ASN_ENCODING | X509_ASN_ENCODING) #define MAX_NAME 256 #define ENCODED_FILE_NAME L"testStream.p7s" //------------------------------------------------------------------- // Define function MyHandleError. void MyHandleError(LPTSTR psz) { _ftprintf(stderr, TEXT("An error occurred in the program. ")); _ftprintf(stderr, TEXT("%s "), psz); _ftprintf(stderr, TEXT("Error number %x. "), GetLastError()); _ftprintf(stderr, TEXT("Program terminating. ")); exit(1); } // End of MyHandleError. //+---------------------------------------------- // Callback function used for streamed Signing. //----------------------------------------------- BOOL WINAPI EncodeCallback( const void *pvArg, BYTE *pbData, DWORD cbData, BOOL fFinal) { DWORD dwWrittenBytes = 0; HANDLE hFileToWrite = INVALID_HANDLE_VALUE; hFileToWrite = *((HANDLE *)pvArg); if ( !WriteFile( hFileToWrite, pbData, cbData, &dwWrittenBytes, NULL) || (dwWrittenBytes != cbData)) { return FALSE; } return TRUE; } //+---------------------------------------------- // Callback function used for decoding streamed Signing. //----------------------------------------------- BOOL WINAPI DecodeCallback( const void *pvArg, BYTE *pbData, DWORD cbData, BOOL fFinal) { if (pbData != NULL && cbData > 0) { *(pbData+cbData) = 0; printf("%s", (char*)pbData); } return TRUE; } void EncodeMessageWithStream(LPWSTR pwszSignerName) { //--------------------------------------------------------------- // Declare and initialize variables. This includes declaring and // initializing a pointer to message content to be countersigned // and encoded. Usually, the message content will exist somewhere // and a pointer to it is passed to the application. BYTE* pbContent1 = (BYTE*)"First sentence. "; DWORD cbContent1 = lstrlenA((char *)pbContent1); BYTE* pbContent2 = (BYTE*)"Second sentence. "; DWORD cbContent2 = lstrlenA((char *)pbContent2); HCRYPTPROV hCryptProv; // CSP handle HCERTSTORE hStoreHandle; // store handle PCCERT_CONTEXT pSignerCert; // signer certificate CMSG_SIGNER_ENCODE_INFO SignerEncodeInfo; CMSG_SIGNER_ENCODE_INFO SignerEncodeInfoArray[1]; CERT_BLOB SignerCertBlob; CERT_BLOB SignerCertBlobArray[1]; CMSG_SIGNED_ENCODE_INFO SignedMsgEncodeInfo; HCRYPTMSG hMsg; LPWSTR pszNameString; DWORD dwKeySpec; //--------------------------------------------------------------- // Open the My system certificate store. if(!(hStoreHandle = CertOpenStore( // The system store will be a virtual store. CERT_STORE_PROV_SYSTEM, // Encoding type not needed with this PROV. 0, // Accept the default HCRYPTPROV. NULL, CERT_SYSTEM_STORE_CURRENT_USER, // Set the system store location in the registry. Other // predefined system stores could have been used, including // trust, Ca, or root. L"MY"))) { MyHandleError(L"Could not open the MY system store."); } //--------------------------------------------------------------- // Get a pointer to a signer's signature certificate. if(pSignerCert = CertFindCertificateInStore( hStoreHandle, MY_ENCODING_TYPE, 0, CERT_FIND_SUBJECT_STR, pwszSignerName, NULL)) { //----------------------------------------------------------- // A certificate was found. Get and print the name of the // subject of the certificate. if(CertGetNameString( pSignerCert, CERT_NAME_SIMPLE_DISPLAY_TYPE, 0, NULL, pszNameString, MAX_NAME) > 1) { printf("The message signer is %s ",pszNameString); } else { MyHandleError(L"CertGetNameString failed. "); } } else { MyHandleError(L"Cert not found. "); } //--------------------------------------------------------------- // Initialize the CMSG_SIGNER_ENCODE_INFO structure. //--------------------------------------------------------------- // Get a handle to a cryptographic provider. if(!(CryptAcquireCertificatePrivateKey( pSignerCert, 0, NULL, &hCryptProv, &dwKeySpec, NULL))) { DWORD dwError = GetLastError(); if(NTE_BAD_PUBLIC_KEY == dwError) { printf("NTE_BAD_PUBLIC_KEY "); } MyHandleError(L"CryptAcquireContext failed"); } memset(&SignerEncodeInfo, 0, sizeof(CMSG_SIGNER_ENCODE_INFO)); SignerEncodeInfo.cbSize = sizeof(CMSG_SIGNER_ENCODE_INFO); SignerEncodeInfo.pCertInfo = pSignerCert->pCertInfo; SignerEncodeInfo.hCryptProv = hCryptProv; SignerEncodeInfo.dwKeySpec = dwKeySpec; SignerEncodeInfo.HashAlgorithm.pszObjId = szOID_RSA_MD5; SignerEncodeInfo.pvHashAuxInfo = NULL; //--------------------------------------------------------------- // Initialize the first element of an array of signers. // Note: Currently, there is only one signer. SignerEncodeInfoArray[0] = SignerEncodeInfo; //--------------------------------------------------------------- // Initialize the CMSG_SIGNED_ENCODE_INFO structure. SignerCertBlob.cbData = pSignerCert->cbCertEncoded; SignerCertBlob.pbData = pSignerCert->pbCertEncoded; //--------------------------------------------------------------- // Initialize the first element of an array of signer BLOBs. // Note: In this program, there is only one signer BLOB used. SignerCertBlobArray[0] = SignerCertBlob; memset(&SignedMsgEncodeInfo, 0, sizeof(CMSG_SIGNED_ENCODE_INFO)); SignedMsgEncodeInfo.cbSize = sizeof(CMSG_SIGNED_ENCODE_INFO); SignedMsgEncodeInfo.cSigners = 1; SignedMsgEncodeInfo.rgSigners = SignerEncodeInfoArray; SignedMsgEncodeInfo.cCertEncoded = 1; SignedMsgEncodeInfo.rgCertEncoded = SignerCertBlobArray; // Fill the CMSG_STREAM_INFO structure. CMSG_STREAM_INFO stStreamInfo; // BER_ENCODING stStreamInfo.cbContent = 0xffffffff; // DER_ENCODING // stStreamInfo.cbContent = cbContent; stStreamInfo.pfnStreamOutput = EncodeCallback; HANDLE hOutMsgFile = INVALID_HANDLE_VALUE; hOutMsgFile = CreateFile( ENCODED_FILE_NAME, GENERIC_WRITE, FILE_SHARE_WRITE, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL); if (INVALID_HANDLE_VALUE == hOutMsgFile) { MyHandleError(L"CreateFile (OUT MSG)"); } stStreamInfo.pvArg = &hOutMsgFile; //--------------------------------------------------------------- // Open a message to encode. if(!(hMsg = CryptMsgOpenToEncode( MY_ENCODING_TYPE, // encoding type 0, // flags CMSG_SIGNED, // message type &SignedMsgEncodeInfo, // pointer to structure NULL, // inner content OID &stStreamInfo))) // stream information { MyHandleError(L"OpenToEncode failed"); } //--------------------------------------------------------------- // Update the message with the data. if(!(CryptMsgUpdate( hMsg, // handle to the message pbContent1, // pointer to the content cbContent1, // size of the content FALSE))) // first call { MyHandleError(L"MsgUpdate failed"); } if(!(CryptMsgUpdate( hMsg, // handle to the message pbContent2, // pointer to the content cbContent2, // size of the content TRUE))) // last call { MyHandleError(L"MsgUpdate failed"); } //--------------------------------------------------------------- // The message is signed and encoded. // Close the message handle and the certificate store. CryptMsgClose(hMsg); CertCloseStore(hStoreHandle, CERT_CLOSE_STORE_FORCE_FLAG); CryptReleaseContext(hCryptProv,0); CloseHandle(hOutMsgFile); } void DecodeMessageWithStream() { //--------------------------------------------------------------- // Open the message for decoding. HCRYPTMSG hMsg; // Fill the CMSG_STREAM_INFO structure. CMSG_STREAM_INFO stStreamInfo2; // BER_ENCODING stStreamInfo2.cbContent = 0xffffffff; stStreamInfo2.pfnStreamOutput = DecodeCallback; if(!(hMsg = CryptMsgOpenToDecode( MY_ENCODING_TYPE, // encoding type 0, // flags 0, // message type (get from message) NULL, // cryptographic provider // use NULL for the default provider NULL, // recipient information &stStreamInfo2))) // stream information { MyHandleError(L"OpenToDecode failed."); } HANDLE hInMsgFile = INVALID_HANDLE_VALUE; hInMsgFile = CreateFile( ENCODED_FILE_NAME, GENERIC_READ, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL); if (INVALID_HANDLE_VALUE == hInMsgFile) { MyHandleError(L"CreateFile (IN MSG)"); } const DWORD cbBytesToRead = 256; byte pbEncodedBlob[cbBytesToRead]; DWORD cbBytesRead; BOOL lastCall = FALSE; while (ReadFile( hInMsgFile, pbEncodedBlob, cbBytesToRead, &cbBytesRead, NULL)) { if (cbBytesRead

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