彩虹表：无法获得最后一次减少
[英]Rainbow Table: Unable to get last reduction
问题描述
In this cryptography post it says 
在这个密码学的帖子中说
The chain can go as long as you want, until it hits the original input.
So my starting point is 12345 but I can't get the end point and having an endless loop because 12345 doesn't repeat. 所以我的起点是12345但我无法得到终点并且无限循环因为12345不重复。 I'm using qt4.7 (lib version: 4.7.3) to achieve this. 我正在使用qt4.7 （lib版本：4.7.3）来实现这一目标。 Here is my code 这是我的代码
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;
}
}
Here is the debug ouput for a few seconds: 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"
As you see 12345 doesn't repeat but other numbers are repeated and having endless loop. 如你所见12345不重复，但其他数字重复并有无限循环。 Is my starting point wrong? 我的出发点是错的吗？
1 个解决方案
解决方案1
24 已采纳 2014-07-09 07:39:09
The chain is not guaranteed to ever hit the initial value again. 该链条不能保证再次达到初始值。 More often than not you'll probably find it entering a loop like this: 通常情况下，你可能会发现它进入这样的循环：
If the input is larger than the hash output, it is impossible by definition to ever hit the initial input value again. 如果输入大于散列输出，则根据定义不可能再次达到初始输入值。 However, even if the input has an equal length to the output, it is not guaranteed that the hash will cover every single possible value in the output space before looping around. 但是，即使输入与输出的长度相等，也不能保证散列将在循环之前覆盖输出空间中的每个可能值。 This actually depends on the characteristics and quality of the hash. 这实际上取决于哈希的特征和质量。 A hash may have one big cycle, covering every single possible output value in its loop. 散列可能有一个大循环，覆盖其循环中的每个可能的输出值。 Other hashes may enter a number of different possible loops, each covering a different subset of the output space. 其他散列可以进入许多不同的可能循环，每个循环覆盖输出空间的不同子集。 Other hashes may not ever cover every possible output value. 其他哈希值可能无法涵盖所有可能的输出值。
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