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彩虹表：无法获得最后一个规约

c++qtcryptographyqt4rainbowtable
6
在这个密码学帖子中，它说：
“链可以无限延伸，直到达到原始输入为止。当它到达该点时，它将重复自身，并且变得无用。”
所以我的起点是12345，但我无法得到终点并进入一个无限循环，因为12345不会重复。我正在使用（lib版本：4.7.3）来实现这一点。以下是我的代码：
rainbowTable::rainbowTable(QWidget *parent) :
QWidget(parent),
ui(new Ui::rainbowTable)
{
    ui->setupUi(this);
    passwordLength = 5;
    qDebug() << getLastReduction("12345",false);
}

QString rainbowTable::hashString(QString value)
{
    QString dataToReturn =  QString(QCryptographicHash::hash((value.toAscii()),QCryptographicHash::Md5).toHex());
    return dataToReturn;
}

QString rainbowTable::reductionOfString(QString hash)
{
    QString dataToReturn = "";
    int iterator = 0;

    while ( iterator < hash.count() )
    {
        if ( hash.at(iterator) == '0' ||
             hash.at(iterator) == '1' ||
             hash.at(iterator) == '2' ||
             hash.at(iterator) == '3' || 
             hash.at(iterator) == '4' ||
             hash.at(iterator) == '5' ||
             hash.at(iterator) == '6' ||
             hash.at(iterator) == '7' ||
             hash.at(iterator) == '8' ||
             hash.at(iterator) == '9' )
        {
            dataToReturn += hash.at(iterator);
            if( dataToReturn.count() == passwordLength )
                break;
        }

        iterator++;
    }

    return dataToReturn;
}

QString rainbowTable::getLastReduction(QString value,bool isHash)
{
    int flagToAvoidImmediateExit = 0;
    if( isHash )
    {
        QString startPoint = value;
        startPoint = reductionOfString(startPoint);

        QString endPoint = "";
        QString tempPoint = startPoint;
        while( startPoint != tempPoint  || flagToAvoidImmediateExit == 0 )
        {
            flagToAvoidImmediateExit = 1;

            endPoint = tempPoint;
            tempPoint = hashString(tempPoint);
            tempPoint = reductionOfString(tempPoint);

            qDebug() << tempPoint;
        }

        return endPoint;
    }
    else
    {
        QString startPoint = value;

        QString endPoint = "";
        QString tempPoint = startPoint;

        while( startPoint != tempPoint  || flagToAvoidImmediateExit == 0 )
        {
            flagToAvoidImmediateExit = 1;

            endPoint = tempPoint;
            tempPoint = hashString(tempPoint);
            tempPoint = reductionOfString(tempPoint);

            qDebug() << tempPoint;
        }

        return endPoint;
    }
}

这是几秒钟的调试输出：
"38064" 
"37923" 
"59636" 
"14842" 
"81105" 
"83011" 
"84978" 
"72903" 
"28301" 
"59067" 
"94222" 
"35329" 
"75907" 
"52980" 
"64297" 
"36654" 
"12207" 
"83738" 
"03523" 
"79083" 
"15597" 
"32652" 
"13934" 
"88497" 
"75435" 
"79791" 
"58265" 
"09856" 
"18041" 
"43966" 
"65978" 
"64242" 
"52739" 
"55704" 
"56811" 
"58183" 
"68597" 
"84064" 
"85717" 
"46438" 
"18042" 
"71321" 
"88067" 
"70648" 
"83580" 
"11878" 
"32297" 
"52376" 
"41289" 
"07909" 
"50439" 
"03819" 
"50325" 
"82736" 
"41621" 
"05497" 
"15546" 
"64017" 
"90503" 
"13150" 
"30287" 
"01749" 
"81308" 
"12036" 
"37241" 
"35850" 
"97225" 
"80539" 
"17472" 
"63098" 
"85818" 
"18438" 
"26139" 
"09545" 
"97042" 
"63672" 
"37406" 
"41180" 
"14910" 
"28900" 
"29729" 
"56861" 
"16208" 
"83565" 
"30912" 
"95541" 
"08468" 
"29539" 
"93679" 
"42487" 
"95833" 
"42793" 
"97064" 
"18087" 
"75623" 
"13910" 
"60404" 
"52557" 
"95932" 
"65477" 
"28304" 
"08456" 
"27849" 
"11429" 
"38896" 
"08634" 
"97107" 
"96385" 
"44159" 
"32875" 
"17063" 
"86213" 
"85052" 
"46852" 
"97541" 
"81412" 
"31199" 
"96618" 
"16178" 
"56100" 
"50394" 
"42087" 
"90552" 
"51966" 
"13598" 
"28757" 
"38715" 
"71025" 
"61334" 
"43686" 
"74633" 
"50360" 
"99883" 
"01361" 
"49662" 
"62929" 
"07280" 
"59161" 
"32509" 
"93670" 
"95649" 
"15206" 
"99927" 
"93692" 
"37748" 
"23350" 
"74680" 
"68259" 
"04819" 
"26627" 
"65968" 
"06919" 
"09194" 
"50084" 
"74452" 
"23763" 
"17953" 
"35026" 
"86691" 
"67542" 
"95634" 
"00793" 
"20270" 
"24386" 
"35606" 
"76055" 
"00010" 
"00798" 
"30867" 
"20697" 
"02143" 
"12044" 
"05098" 
"52828" 
"98446" 
"54039" 
"08778" 
"98405" 
"92267" 
"71783" 
"61953" 
"87447" 
"66505" 
"66535" 
"01776" 
"90120" 
"51497" 
"56082" 
"18253" 
"15222" 
"74769" 
"19614" 
"86376" 
"65391" 
"43365" 
"90484" 
"32717" 
"75052" 
"16186" 
"89444" 
"15439" 
"65166" 
"75785" 
"72462" 
"75920" 
"91383" 
"41678" 
"94123" 
"61751" 
"47976" 
"67798" 
"59438" 
"10180" 
"65854" 
"40218" 
"77990" 
"44843" 
"84554" 
"52350" 
"73347" 
"51901" 
"61155" 
"30316" 
"83096" 
"64946" 
"05985" 
"24208" 
"28718" 
"02241" 
"22303" 
"23331" 
"18410" 
"54868" 
"51723" 
"06401" 
"49554" 
"65577" 
"28105" 
"42319" 
"34167" 
"85036" 
"98679" 
"08594" 
"31075" 
"80514" 
"11517" 
"66780" 
"33411" 
"83180" 
"61910" 
"70423" 
"16885" 
"09107" 
"83702" 
"81842" 
"88430" 
"59146" 
"29140" 
"47236" 
"29625" 
"03078" 
"26540" 
"79321" 
"41649" 
"10210" 
"75702" 
"12020" 
"36877" 
"57307" 
"03222" 
"46603" 
"58449" 
"94709" 
"01436" 
"84975" 
"39385" 
"15952" 
"67607" 
"91666" 
"34456" 
"53385" 
"21512" 
"06712" 
"42073" 
"61343" 
"66825" 
"70199" 
"73203" 
"60216" 
"39469" 
"84324" 
"47850" 
"84825" 
"52471" 
"92397" 
"86051" 
"33676" 
"04221" 
"79740" 
"11573" 
"26304" 
"52510" 
"12679" 
"05930" 
"49607" 
"10880" 
"99174" 
"53967" 
"06397" 
"25700" 
"96721" 
"94694" 
"96566" 
"31746" 
"57359" 
"84870" 
"06236" 
"10673" 
"45914" 
"19209" 
"32478" 
"38824" 
"71178" 
"22983" 
"36320" 
"46594" 
"66538" 
"80495" 
"35645" 
"38064" 
"37923" 
"59636" 
"14842" 
"81105" 
"83011" 
"84978" 
"72903" 
"28301" 
"59067" 
"94222" 
"35329" 
"75907" 
"52980" 
"64297" 
"36654" 
"12207" 
"83738" 
"03523" 
"79083" 
"15597" 
"32652" 
"13934" 
"88497" 
"75435" 
"79791" 
"58265" 
"09856" 
"18041" 
"43966" 
"65978" 
"64242" 
"52739" 
"55704" 
"56811" 
"58183" 
"68597" 
"84064" 
"85717" 
"46438" 
"18042" 
"71321" 
"88067" 
"70648" 
"83580" 
"11878" 
"32297" 
"52376" 
"41289" 
"07909" 
"50439" 
"03819" 
"50325" 
"82736" 
"41621" 
"05497" 
"15546" 
"64017" 
"90503" 
"13150" 
"30287" 
"01749" 
"81308" 
"12036" 
"37241" 
"35850" 
"97225" 
"80539" 
"17472" 
"63098" 
"85818" 
"18438" 
"26139" 
"09545" 
"97042" 
"63672" 
"37406" 
"41180" 
"14910" 
"28900" 
"29729" 
"56861" 
"16208" 
"83565" 
"30912" 
"95541" 
"08468" 
"29539" 
"93679" 
"42487" 
"95833" 
"42793" 
"97064" 
"18087" 
"75623" 
"13910" 
"60404" 
"52557" 
"95932" 
"65477" 
"28304" 
"08456" 
"27849" 
"11429" 
"38896" 
"08634" 
"97107" 
"96385" 
"44159" 
"32875" 
"17063" 
"86213" 
"85052" 
"46852" 
"97541" 
"81412" 
"31199" 
"96618" 
"16178" 
"56100" 
"50394" 
"42087" 
"90552" 
"51966" 
"13598" 
"28757" 
"38715" 
"71025" 
"61334" 
"43686" 
"74633" 
"50360" 
"99883" 
"01361" 
"49662" 
"62929" 
"07280" 
"59161" 
"32509" 
"93670" 
"95649" 
"15206" 
"99927" 
"93692" 
"37748" 
"23350" 
"74680" 
"68259" 
"04819" 
"26627" 
"65968" 
"06919" 
"09194" 
"50084" 
"74452" 
"23763" 
"17953" 
"35026" 
"86691" 
"67542" 
"95634" 
"00793" 
"20270" 
"24386" 
"35606" 
"76055" 
"00010" 
"00798" 
"30867" 
"20697" 
"02143" 
"12044" 
"05098" 
"52828" 
"98446" 
"54039" 
"08778" 
"98405" 
"92267" 
"71783" 
"61953" 
"87447" 
"66505" 
"66535" 
"01776" 
"90120" 
"51497" 
"56082" 
"18253" 
"15222" 
"74769" 
"19614" 
"86376" 
"65391" 
"43365" 
"90484"

正如您所看到的，12345不重复，但其他数字重复并且具有无限循环。我的起始点错了吗？

1个回答
24

这个哈希链不一定会再次回到初始值。通常情况下，你可能会发现它进入像这样的循环：

1 -> 2 -> 3 -> 4 -> 2 -> 3 -> 4 -> 2 -> ...

如果输入大于哈希输出，则无法再次命中初始输入值。然而，即使输入长度与输出相等，也不能保证哈希在循环之前覆盖输出空间中的每个可能值。这实际上取决于哈希的特性和质量。一个哈希可能有一个大循环，在其循环中涵盖了每一个可能的输出值。其他哈希可能进入多个不同的可能循环，每个循环涵盖输出空间的不同子集。其他哈希可能永远不会覆盖每个可能的输出值。

1
这张图片是从这里获取的，这个更好吗？http://security.stackexchange.com/a/10661 - deceze
4
这句话的意思是你的缩减函数不能将结果平均分配到整个可能的范围内，你需要使用不同的哈希 / 缩减函数。我不是该领域的专家，无法建议您任何特定的函数，这可能需要另一个问题来解决。 - deceze
1
哈希函数具有特定的输出范围。在您的情况下，输出可以是 00000、00001 或 00002 等，直到 99999。这是 10000 种可能的输出值。您期望的是在这些输出值中循环。当您输入 00000 时，它将输出 00001。当您输入 00001 时，它将输出 00002，以此类推，直到您完全绕回到 99999 → 00000（实际上，您期望路径看起来比这更随机，但原理相同）。 （继续...） - deceze
1
嗯，那不会发生。它正在进行 00000 → 00001 → 00002 → 00001 → 00002... 当您输入 00002 时，它不会进入下一个“预期”的步骤 00003，而是循环回到 00001，从那里显然会进入无限循环。您必须更改减少函数的基本特性，以确保它能够完全循环并不遗漏任何值。这不是关于某些偏移量问题，而是关于没有任何东西在您的减少函数中保证完整循环的基本原则。 - deceze
2
@abi 哎呀，打错了一个 0... 你是本周的挑剔者奖得主。 ;) - deceze
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