insideNoteEx

// 'cl -DUNICODE <sourcefilename>'
#ifndef UNICODE
#define UNICODE
#endif

#include <stdio.h>
#include <windows.h>
#include <wincrypt.h>

#pragma comment(lib, "crypt32.lib") 
    
void wmain()
{
    WCHAR wszString[4096];
    DWORD cchString;

    /* test sample data (this data is nonsensical) */
    UCHAR data[] = "\xA1\x23\x1C\x56\x4f\x48\x06\x71\x01\x39\xCC\x55\xAA\x01\x02\x03\xac\xde\xff\xa9";

    /* encode */
    BYTE *pbBinary = data; 
    DWORD cbBinary = sizeof(data) - 1; // exclude termination null
    cchString = ARRAYSIZE(wszString);
    CryptBinaryToString(pbBinary,cbBinary,CRYPT_STRING_BASE64|CRYPT_STRING_NOCRLF,wszString,&cchString);

    printf("\nbase64:\n%S\n",wszString);
    
    /* decode */
    BYTE bufDecode[4096];
    DWORD cbDecode = ARRAYSIZE(bufDecode);
    CryptStringToBinary(wszString,cchString,CRYPT_STRING_BASE64,bufDecode,&cbDecode,NULL,NULL);

    /* print */
    cchString = ARRAYSIZE(wszString);
    CryptBinaryToString(bufDecode,cbDecode,CRYPT_STRING_HEXASCIIADDR,wszString,&cchString);
    
    printf("\nhex dump:\n%S\n",wszString);
}

C:\Test\code>cl -DUNICODE test.cpp

C:\Test\code>test

base64:
oSMcVk9IBnEBOcxVqgECA6ze/6k=

hex dump:
0000    a1 23 1c 56 4f 48 06 71  01 39 cc 55 aa 01 02 03   .#.VOH.q.9.U....
0010    ac de ff a9                                        ....