Main.cpp

void encodeVignère_Legacy(char* input, const char* key) {
    uint32 lenInput = strlen(input);
    uint32 lenKey = strlen(key);

    for(uint32 i = 0; i < max(lenInput, lenKey); ++i) {
        if(i < lenInput)
        {
            char value = input[i];
            if(!((value >= 'A' && value <= 'Z') || (value >= 'a' && value <= 'z')))
                throw std::exception("Invalid input provided!");
        }
        if(i < lenKey)
        {
            char value = key[i];
            if(!((value >= 'A' && value <= 'Z') || (value >= 'a' && value <= 'z')))
                throw std::exception("Invalid key provided!");
        }
    }

    for(uint32 i = 0, keyIndex = 0; i < lenInput; ++i, ++keyIndex) {
        char& ref = input[i];
        const char& keyChar = key[keyIndex % lenKey];
        uint32 keyOffset = 0;

        if(keyChar >= 'A' && keyChar <= 'Z')
            keyOffset = (uint32)(keyChar - 'A');
        else
            keyOffset = (uint32)(keyChar - 'z');

        bool isUpperCase = (ref >= 'A' && ref <= 'Z');
        char minChar = isUpperCase ? 'A' : 'a';

        uint32 newKey = (uint32)ref + keyOffset;
        newKey -= minChar;
        newKey %= 26;
        newKey += minChar;

        ref = (char)newKey;
    }
}

void decodeVignère_Legacy(char* input, const char* key) {
    uint32 lenInput = strlen(input);
    uint32 lenKey = strlen(key);

    for(uint32 i = 0; i < max(lenInput, lenKey); ++i) {
        if(i < lenInput)
        {
            char value = input[i];
            if(!((value >= 'A' && value <= 'Z') || (value >= 'a' && value <= 'z')))
                throw std::exception("Invalid input provided!");
        }
        if(i < lenKey)
        {
            char value = key[i];
            if(!((value >= 'A' && value <= 'Z') || (value >= 'a' && value <= 'z')))
                throw std::exception("Invalid key provided!");
        }
    }

    for(uint32 i = 0, keyIndex = 0; i < lenInput; ++i, ++keyIndex) {
        char& ref = input[i];
        const char& keyChar = key[keyIndex % lenKey];
        uint32 keyOffset = 0;

        if(keyChar >= 'A' && keyChar <= 'Z')
            keyOffset = (uint32)(keyChar - 'A');
        else
            keyOffset = (uint32)(keyChar - 'z');

        bool isUpperCase = (ref >= 'A' && ref <= 'Z');
        char minChar = isUpperCase ? 'A' : 'a';

        int32 newKey = (int32)ref - keyOffset;
        newKey -= minChar;
        if(newKey < 0)
            newKey = 26 + newKey;

        newKey += minChar;

        ref = (char)newKey;
    }
}