convert Python function to C++ function

Question

So I need to crack a hash to solve a puzzle, and I've edited a Python program that iterates over all possible combinations, but the Python program is too slow as the hash changes every day, I know it's a hash of length: 8

The python program would work like this:

charset = "abcdefghijklmnopqrstuvwxyz012345679"
NUMBER_OF_CHARACTERS = len(charset)
sequence = list("a a a a a a a a".split(" "))
while(True):
    current = "".join(sequence)
    sequence = next(sequence)
    #check if hash of sequence matches target hash

the function: 'next' looks like this:

if len(string) <= 0:
    string.append(indexToCharacter(0))
else:
    string[0] = indexToCharacter((characterToIndex(string[0]) + 1) % NUMBER_OF_CHARACTERS)
    if characterToIndex(string[0]) is 0:
        return list(string[0]) + next(string[1:])
return string

indexToCharacter just returns the character in string charset at index (index)
characterToIndex returns the position of a given character in string index

so, characterToIndex("a") would return 0 and indexToCharacter(0) would return "a"

Now what I need is, to convert this Python program to a C++ program, as C++ is way faster, I have the indexToCharacter function, the characterToIndex function, but I can't seem to get the next function work.

I got this for the next function in C++

string next(string sequence)
{
    sequence[0] = indexToCharacter(characterToIndex(sequence[0])+1);
    if (characterToIndex(sequence[0]) == 0)
    {
        //Something
    }
}

string sequence = "aaaaaaaa";
next(sequence);

the code of indexToCharacter and characterToIndex:

int characterToIndex(char character)
{
    return charset.find(character);
}

char indexToCharacter(unsigned index)
{
    return charset[index];
}

Atleast provide what is the expected output to an input for the next function. — Arunmu
– Arunmu, Commented Jul 15, 2016 at 16:52
So... Just write whatever the Python version does in C++ and use string(1,sequence[0]) instead of list(string[0]). The problem is, such calls to string will allocate tons of memory in various places, so your memory will get very fragmented — ForceBru
– ForceBru, Commented Jul 15, 2016 at 16:52
Also please provide the entire code, implementation of indexToCharacter etc. — Wajahat
– Wajahat, Commented Jul 15, 2016 at 16:53

Aconcagua · Accepted Answer · 2016-07-15 17:10:00Z

1

In this special case, I would not hassle around with the std::string objects all the time. You have a fixed length, right? You can do it very efficiently this way then (works both in C++ and C... – just adjust buffer length and characters list to your own needs):

char characters[] = { 'a', 'b', 'c' };
char buffer[3];
char* positions[sizeof(buffer)];
for(unsigned int i = 0; i < sizeof(buffer); ++i)
{
    buffer[i] = *characters;
    positions[i] = characters;
}

unsigned int i;
do
{
    printf("%.*s\n", (int)sizeof(buffer), buffer);
    for(i = 0; i < sizeof(buffer); ++i)
    {
        ++positions[i];
        if(positions[i] < characters + sizeof(characters))
        {
            buffer[i] = *positions[i];
            break;
        }
        positions[i] = characters;
    }
}
while(i < sizeof(buffer));

I just printed out the values, you can do what ever you need to do with...

answered Jul 15, 2016 at 17:10

Aconcagua

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1 Comment

TheXReflex Over a year ago

Thanks! Works great :)

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