Encode string in base64 with UTF16BE charset in C/C++

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Hi all

I need to write a C function receive as input a string and outputs Base64 but with charset UTF16BE.

Below Base64_code function produce UTF8.

I really hope somebody can help me

Thanks all

Giovanni

What I have tried:

void Base64_code(IN const CHAR* strIn, OUT CString& strOut)
{
    const static CHAR base64ABC[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
    strOut.Empty();
    const size_t len = strlen(strIn);
    for (size_t i = 0; i < len; i += 3) 
    {
        LONG l = (((LONG)strIn[i]) << 16) | (((i + 1) < len) ? (((LONG)strIn[i + 1]) << 8) : 0) | (((i + 2) < len) ? ((LONG)strIn[i + 2]) : 0);

        strOut += base64ABC[(l >> 18) & 0x3F];
        strOut += base64ABC[(l >> 12) & 0x3F];
        if (i + 1 < len) strOut += base64ABC[(l >> 6) & 0x3F];
        if (i + 2 < len) strOut += base64ABC[(l) & 0x3F];
    }
    switch (len % 3) 
    {
    case 1:
        strOut += '=';
    case 2:
        strOut += '=';
    }
}

Posted 15-May-23 23:23pm

Drakesal

Updated 17-May-23 4:37am

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CPallini 16-May-23 6:08am

But...
Why?

3 solutions

Solution 1

Please try with the below code

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static const char base64_table[65] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

char* utf16be_base64_encode(const char* input) {
size_t input_len = strlen(input);
size_t output_len = ((input_len * 2 + 1) / 3) * 4 + 1;
char* output = (char*)malloc(output_len);
if (output == NULL) {
printf("Memory allocation failed.\n");
return NULL;
}

size_t i, j;
uint32_t val = 0;
uint8_t bytes[3];
size_t output_pos = 0;

for (i = 0; i < input_len; i += 2) {
bytes[0] = (uint8_t)input[i];
bytes[1] = (uint8_t)input[i + 1];
val = (bytes[0] << 8) | bytes[1];

for (j = 0; j < 4; ++j) {
output[output_pos++] = base64_table[(val >> 18) & 0x3F];
val <<= 6;
}
}

if (input_len % 2 != 0) {
bytes[0] = (uint8_t)input[input_len - 1];
bytes[1] = 0;
val = (bytes[0] << 8) | bytes[1];
for (j = 0; j < 3; ++j) {
output[output_pos++] = base64_table[(val >> 18) & 0x3F];
val <<= 6;
}
output[output_pos++] = '=';
}

output[output_pos] = '\0';
return output;
}

int main() {
const char* input = "Hello, world!";
char* encoded = utf16be_base64_encode(input);
if (encoded != NULL) {
printf("Base64 (UTF-16BE): %s\n", encoded);
free(encoded);
}

return 0;
}

Posted 15-May-23 23:36pm

Deepen Bedar

Comments

Drakesal 16-May-23 5:52am

For the moment thanks for the fast response :)

I tried your code and compared with site https://dencode.com/string/base64

so result for "Hello, World!" is:
site: SABlAGwAbABvACwAIABXAG8AcgBsAGQAIQA=
code: AEhlAGxsAG8sACBXAG9yAGxkACEAACE=

there is something to tune

Richard MacCutchan 16-May-23 5:54am

This code does not produce UTF16 characters.

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Richard MacCutchan · Accepted Answer · 2023-05-15T23:48:00

The issue is about encoding either an ASCCI or UTF16 string. The following code shows examples of both types, and will print the results.

C++

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

char* base64_encode(const unsigned char* strIn, int strLen)
{
    const static char* base64ABC = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
    size_t outlen = ((strLen + 3) / 3 * 4 + 1) * 2;
    char* strOut = (char*)malloc(outlen + 2);
    char* pOut = strOut;
    for (size_t i = 0; i < strLen; i += 3)
    {
        long l = (((long)strIn[i]) << 16) | (((i + 1) < strLen) ? (((long)strIn[i + 1]) << 8) : 0) | (((i + 2) < strLen) ? ((long)strIn[i + 2]) : 0);

        *pOut++ = base64ABC[(l >> 18) & 0x3F];
        *pOut++ = base64ABC[(l >> 12) & 0x3F];
        if (i + 1 < strLen) *pOut++ = base64ABC[(l >> 6) & 0x3F];
        if (i + 2 < strLen) *pOut++ = base64ABC[l & 0x3F];
    }
    switch (strLen % 3)
    {
    case 1:
        *pOut++ = '=';
    case 2:
        *pOut++ = '=';
    }
    *pOut = L'\0';

    return strOut;
}

int main() {
    const char* ascii = "Hello, world!";    // ASCII source
    char* encodedA = base64_encode((const unsigned char*)ascii, strlen(ascii));
    if (encodedA != NULL) {
        printf("Base64 ASCII: %s\n", encodedA);
        free(encodedA);
    }
    const wchar_t* utf16 = L"Hello, world!";
    int len = wcslen(utf16) * 2;
    char* encodedU = base64_encode((const unsigned char*)utf16, len);
    if (encodedU != NULL) {
        printf("Base64 UTF16: %s\n", encodedU);
        free(encodedU);
    }
    return 0;
}

Drakesal · Accepted Answer · 2023-05-17T04:37:00

Hi I have the complete solution:

bool CrypttoBase64Encode(BYTE* pbSource, DWORD dwSourceLength, CString& sBase64)
{
    bool bResult = false;
    DWORD dwDestLength = 0;
    LPTSTR psDest = NULL;
    if (CryptBinaryToString(pbSource, dwSourceLength, CRYPT_STRING_BASE64, NULL, &dwDestLength) == TRUE)
    {
        psDest = new TCHAR[dwDestLength + 1];
        if (CryptBinaryToString(pbSource, dwSourceLength, CRYPT_STRING_BASE64, psDest, &dwDestLength) == TRUE)
        {
            sBase64 = CString(psDest);
            sBase64 = sBase64.Left(sBase64.GetLength() - 2);
            bResult = true;
        }
        delete[] psDest;
    }
    return bResult;
}

int main()
{
    CString s = _T("Hello, world!");

    LPBYTE pByte = new BYTE[(s.GetLength()) * 2];
    memcpy(pByte, s, (s.GetLength()) * 2);

    CrypttoBase64Encode(pByte, (s.GetLength()) * 2, s);

    delete[] pByte;

    return 0;
}

With this you obtain a complete string encoding in UTF16 LE (unicode)

Encode string in base64 with UTF16BE charset in C/C++

3 solutions

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Solution 1

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