2022-5-15 密码学刷题分享（第二部分）

由于上一次分享会没有讲，因此在做了一段时间的题目后，将下边内容补充到上一次的分享内容里。

第一题：浪里淘沙（第三页抬头）

打开题目

看到很大段文本，咋看好像杂乱无章，仔细看似乎是由很多单词组成的文本！

通过长时间的目测法，发现这段文本是

tonight
success
notice
we
example
crypto
should
backspace
learn
sublim
the
found
system
morning
user
enter

这16个单词多次重复组成，题目提示中有几个数字，也许与单词出现的次数？评率？有关！我们求一下词频，因为源文本中没有换行符或者分隔号，因此整个文本求词频用c稍显复杂（可以按首字母分类，监测到特定首字母即判断后N位是否与上述单词相同....../按长度分类？），我们用python来写求词频脚本。

f = "tonightsuccessnoticenoticewewesuccesstonightweexamplecryptoshouldwebackspacetonightbackspaceexamplelearnwesublimlearnbackspacetheshouldwelearnfoundsublimsystemexamplesublimfoundlearnshouldmorningsublimsystemuserlearnthecryptomorningexamplenoticetonightlearntonightlearntonightsublimenterusermorningfoundtonightweenterfoundnoticethecryptomorningthebackspacelearntonightlearnsublimtonightlearnfoundenterfoundsuccesstonightsuccessuserfoundmorningtonighttheshouldsublimentertonightenterbackspacelearnexamplenoticeexamplefoundsystemsuccesssublimsuccessshouldtonightcryptowelearncryptofoundshouldsublimsublimweentertonightsuccessshouldentertheentercryptouserbackspaceshouldentersystemsuccesssystementerfoundenterlearnexampletonightnoticemorningusertonightlearnmorningtonightfoundfoundsuccessnoticesystementerlearnexamplebackspaceshouldcryptocryptosublimweexampletonighttheshouldthemorningbackspacelearntonightsystemsuccesssuccessbackspacemorningnoticeuserfoundfoundtonightmorningenterenterthefoundbackspacelearnenterentershouldthesystemfounduserlearnlearnsystemnoticetonighttheshouldlearnuserbackspaceweusernoticeshouldthewefoundsystemwecryptocryptowethebackspacesystementershouldtonightsystemnoticemorningsystemweentermorningfoundsuccessusertonightsuccesstonightbackspaceshouldweenterthewesystemusernoticesystemthelearnexamplelearnfoundlearnnoticeexamplesystemthecryptocryptolearnsystemthecryptoenterlearnexamplemorningmorningweenterentersuccessexampleuserthebackspacenoticesublimenterbackspacesuccessbackspacethesublimexamplesystemtheexamplecryptolearnuserexamplelearnsystemusersuccessenterentersuccesstheuserbackspacelearnsuccessbackspacethesublimshouldwebackspaceexamplesuccesssuccesstonightweusershouldsuccessmorningcryptomorningfoundbackspacesublimshouldentershouldnoticesuccessmorningsuccessexamplelearnshouldsublimlearntonightshoulduserbackspacesublimlearncryptosuccessenternoticetonightmorningtonightwesuccessweuserbackspaceexamplewesystemnoticemorningsystemmorningcryptolearnsystemthethefoundcryptouserlearnusersystemwemorningenterexampleshouldlearncryptofoundenterbackspacelearnenterenterbackspaceshouldbackspacetheshouldthesystemshouldshouldsuccessmorningthefoundsystementersystemtonightcryptowelearnexampleexamplesystementerbackspaceshouldtheentersublimtonightfoundfoundsuccesssuccesssystemsublimcryptoshouldentersublimmorninglearnfoundtonightcryptobackspacesuccesscryptowebackspacefoundshouldnoticeshouldmorningnoticesystemcryptosystemlearnsystemnoticemorningsystementerwemorninglearnsuccessfoundwesuccesswetheusercryptousernoticebackspacesuccessshouldtonightmorningentermorninguserenternoticefoundmorningwetonightsystemthecryptotonightcryptosystemuserthefoundexampletonightusersystemcryptosublimmorninguserthefoundbackspaceshouldsuccesscryptotonightsystemnoticebackspaceusershouldenterthecryptomorningwesublimnoticesuccessnoticeusersuccesstonightlearnweuserenterfounduserexampleshouldshouldtonightwelearnthenoticethewefoundmorningexampleshouldexamplethesuccessnoticeenterfoundthecryptonoticeuserlearnuserweenterfoundmorningsystemweexamplenoticethebackspaceexamplesublimtheusermorningtonightthesuccesscryptosuccessusersuccesstonighttonightwelearnenterenterthemorningentersystemcryptobackspacemorningsystemexamplecryptouserexamplelearnsublimsuccessusersystemfoundmorningshouldcryptotonightsublimtheexamplemorningsystemuserexampleweexamplenoticesuccesssublimnoticecryptoshouldbackspaceshouldthetonightfoundsublimbackspacebackspacetonightshouldbackspacesuccesstonightbackspacesuccessmorningsystemcryptobackspaceentertonighttonightnoticelearnshoulduserfoundexamplesystemthesuccessweusertonightcryptousernoticeenternoticebackspaceusersystemfoundusernoticeshouldlearnuserfoundexampleusermorningshouldsuccessmorningmorningexampleexamplefoundsublimfoundenterbackspacenoticelearnfoundmorningcryptonoticecryptoshouldweshouldtonightcryptobackspacesublimcryptosublimenterentersublimentercryptonoticethethesublimexampleenterentershouldlearncryptoentershouldmorninglearnnoticeuserexamplesublimtonightshouldfoundtonightsuccessshouldmorningfoundtheweuserlearnsublimsystembackspacecryptotheusertonightcryptosublimmorningmorningexamplenoticetheenterlearnshouldmorningsublimfoundtonightsublimsublimexamplefounduserexamplethefoundwemorningnoticefoundcryptosuccesssublimsublimexamplethesuccessexamplenoticesuccessbackspacesublimlearnuserexamplesuccesssuccesssystemsuccessmorningmorninglearnexamplemorningtonightfoundbackspaceenternoticemorningentersuccessmorningusermorningbackspacelearncryptoenteruserenteruserthetonighttonightsuccesslearnenterfoundsuccesssystemfoundbackspaceenterlearnsystemsublimcryptoentermorningwetonightshouldlearnenterfoundcryptonoticelearnlearnshouldfoundsuccessexampletonightthesuccessfoundusertonightenterfoundsuccessshouldmorningusernoticemorningsystemsystemsuccessshouldwelearnenterfoundexamplewethefoundweshouldsystemsystemmorningmorningbackspaceshouldentersublimentertonightsuccesssystemsystemcryptousershouldsublimfoundwetonightnoticeexamplewewesuccessfoundusertonightfoundsystemexamplecryptofoundshouldshouldsuccessenterbackspaceexampletonightthelearnnoticeuserlearnsystemsublimfoundlearnsuccesssystemshouldsublimnoticelearnsystemnoticetonightexamplefoundusernoticeenterlearnnoticecryptousersystemmorningthewesystemfoundfoundshouldsystementerenterbackspacesystemsublimcryptousermorninglearnlearntonightsublimlearnenterenterbackspacesystemuserusercryptoentershouldtheusersublimnoticeexamplemorningexamplesublimsublimbackspacesystemexampleshouldsublimlearnfoundenterbackspacelearnmorningmorningfoundthetonightmorningnoticeenterlearnusersystemtonightbackspaceexamplelearntonightbackspaceweshouldcryptosuccessbackspaceexamplesuccesstheshouldmorninguserbackspacelearnthetheshouldcryptocryptotonightbackspacecryptocryptobackspacebackspacenoticeusertonightentermorningfoundweenterexampleenterfoundusersublimsystemtheexampleexamplesystemsuccessusersublimentermorningbackspacesystemfoundlearnsystemshouldsublimsublimentershouldtheusershouldexampleexampleshouldsuccesswelearnfoundsublimshoulduserweentertonightwenoticesublimsystemlearnshouldfoundsuccessuserentersuccessmorningcryptoenteruserfoundexampletonightlearnexampleexamplefoundlearnsuccesssystembackspacecryptonoticethefoundbackspacelearncryptothelearnlearnexamplesuccessnoticenoticesystemmorningcryptotonightnoticenoticeentersuccesscryptoenterbackspacesublimexampleenterfoundtonightcryptotonightsublimnoticesuccesssublimtheentertonighttheshouldthefoundsystemtonightuserbackspacesuccessshouldwebackspacenoticebackspacebackspacenoticewecryptobackspacebackspaceusertonightlearnsuccessmorningusertonightsuccessshouldbackspacecryptoenterentershouldsublimsystemexamplemorningcryptonoticethesuccessthebackspacenoticelearnsublimlearnsuccesscryptothesuccessenternoticecryptosystemsublimsuccesswebackspaceuserenterlearnuserwewemorningsuccesslearncryptobackspacewecryptosystemlearnenterenteruserexamplefoundsystemcryptousernoticefoundusersublimbackspacewesublimnoticemorningshouldexamplenoticecryptoshouldtonightmorningthefoundsystementerentersystemthecryptobackspacesublimlearnsuccessmorningsublimsystemcryptousersublimwesuccessmorningsublimbackspacecryptobackspacesublimthelearnsuccesssublimlearncryptoweweexamplecryptowenoticelearnfoundbackspacesystemsystemexampleshouldlearnsuccesssublimcryptobackspacetonightbackspacemorningmorningnoticeshouldnoticefoundthetheshouldtheshouldfoundfoundcryptosuccessbackspacesuccessshouldweenternoticeweweshouldmorningfoundusersuccessbackspacewenoticeusersuccessenterenterexamplelearnfoundwetonightusercryptothesublimsublimtonightsuccesslearnbackspacetonightentertonightthesublimnoticewefoundcryptobackspaceenterenterlearnlearntonightexamplesystementersublimnoticecryptoshoulduseruserbackspaceuserwesublimmorningwesystemshouldtonighttheusershouldnoticefoundusernoticeentersublimwethewefoundfoundlearnfoundwecryptosystemexamplemorningcryptocryptosublimtheexamplenoticefoundlearnwelearnmorningtheenterthesystemsublimtonightsuccesssystemlearnshouldenterbackspaceentersuccesssuccessbackspaceexamplenoticeentershouldsublimlearnbackspacetheshouldexamplelearnsystemusersublimbackspacebackspacesuccesswelearntonightexamplewecryptoenterwesystemsystemsublimexamplecryptolearnmorningsublimfoundsublimfoundbackspacefoundtonighttonightnoticesuccesssuccessexampleusersuccesstonightsublimcryptosystemweenterexamplesystemthethenoticesublimtonightbackspacenoticesystemexamplethesuccesstonightmorningsuccesstonightwenoticesublimtonightwelearntonightmorningsublimbackspaceenterthetonightenterwecryptofoundtheenternoticebackspacesuccesswesystemuserexamplebackspaceentersuccesstonightsublimwemorningsuccesssuccesswesublimsuccessnoticesublimfoundlearnlearnweexamplecryptonoticelearnweusershoulduserfoundcryptolearnfoundmorningtonightmorningmorningnoticewecryptowewesuccessfoundsublimweuserentershouldshouldshouldsublimbackspacetonightenterwesublimsuccessshouldfoundthethetonightwecryptoweenterfoundcryptoshouldcryptouseruserfoundentersublimsublimthelearntheshouldnoticebackspacefoundsuccessshouldtonightentermorningsystemmorningtonightwenoticelearnbackspaceexampleusershouldnoticesublimsublimexamplethesuccessnoticesystemmorningnoticecryptosystemsublimcryptosystemsuccessshouldmorningbackspaceshouldmorninglearnnoticenoticeshouldthewewesublimsublimnoticeusersuccessentersystemfoundshouldshouldcryptobackspaceusermorningsystemshouldshouldtonightwesublimuserfoundlearnbackspacethetonightmorningexampleuserthefoundbackspaceshouldtonightcryptocryptofounduserexamplenoticecryptousernoticethenoticeshouldweshouldfoundwemorningcryptosuccesslearnfoundtonightsublimnoticenoticewefoundwewesuccesssublimsublimcryptoweexampletonightsuccessfoundshouldsuccesstonightbackspacesystemshouldwesystemnoticebackspaceusersystembackspacewenoticelearnnoticenoticesuccesslearntonightuserlearnsuccessbackspacesuccesswesystemusercryptonoticethesystemusernoticewethesuccessweshouldfoundshouldcryptomorningtonightwethewesuccesslearntheshouldweexampletonightsuccessnoticenoticemorningfoundmorningfoundusersublimsystemsuccessbackspacesuccessmorninguserthefoundweexamplemorningsublimlearnfoundfoundnoticemorningshouldweuserwemorningexamplesuccesssuccessfoundthetheshouldweusershouldtheshouldexamplenoticefoundsuccesssystemfoundshouldsublimbackspacetonightshouldsystemtonightsuccesslearntonightsystemsublimsuccesscryptobackspacesystemsublimmorningmorningshouldmorninglearnsuccesslearnmorningusermorninglearnexamplecryptoshouldbackspacesublimshouldfoundbackspacesystemsystemweexamplesystemtonightsublimmorningmorninguserfoundcryptolearnbackspaceshouldbackspacenoticesublimfoundthecryptousershouldsuccesssystemsuccessshouldsystembackspacesublimshouldsublimsystembackspaceexampleshouldbackspacesublimnoticelearnsublimuserbackspaceusersublimsuccesssublimuserusernoticeshouldsuccessnoticenoticelearnexamplesystemweexamplesublimbackspacebackspacecryptoshouldusercryptosublimbackspacesublimshouldsystemnoticenoticethesuccesssuccesslearnsystemsublimwenoticelearnusersublimsystemusernoticeuserthesuccesslearnwelearnwenoticecryptolearncryptonoticenoticebackspacecryptothecryptousercryptobackspacesuccesslearnthesystemsuccessthesystemsystemcryptosuccessbackspacesublimlearnsublimcryptobackspacelearnsublimusersublimexamplecryptosublimsystemnoticecryptocryptousertheusernoticebackspacenoticenoticethecryptocryptosystembackspacesublimbackspacecryptocryptobackspacesystemuserthenoticesystemsystemsystemusernoticethecryptouserusersystemtheusercryptoexamplenoticecryptoexamplenoticetheexampleexamplethecryptotheusernoticetheexampleexamplecryptotheexampleexamplethenoticethecryptocryptoexampletheexamplecryptocryptothenoticeexamplecryptonoticetheexampleexampleexamplecryptocryptoexampleexamplethenoticethecryptothethethethethetheexampleexamplethetheexampletheexampletheexampleexampleexampleexampleexampleexampleexampleexampleexampleexampleexampleexampleexampleexampleexampleexampleexampleexampleexample"#不知道为何在此处无法使用open()命令打开文本文件并阅读；
# 因此采取下策直接把文本copy过来，有大哥懂为什么吗？求教
word = ['tonight','success','notice','example','should','crypto','backspace','learn','found','morning','we','system','sublim','the','user','enter']for s in word:print(s,f.count(s))#自带的count是在太好用了，我爱python

运行结果：

/Users/yuwenao/PycharmProjects/pythonProject8/venv/bin/python /Users/yuwenao/PycharmProjects/pythonProject8/main.py
tonight 117
success 138
notice 136
example 139
should 131
crypto 141
backspace 129
learn 134
found 125
morning 113
we 124
system 130
sublim 132
the 140
user 133
enter 120进程已结束，退出代码为 0

count的用法

count()函数

描述：统计字符串里某个字符出现的次数，可以选择字符串索引的起始位置和结束位置。

语法：str.count("char", start,end) 或 str.count("char")

返回值：整型

参数说明：

str —— 要统计的字符(可以是单字符，也可以是多字符)

star —— 索引字符串的起始位置，默认参数为0

end —— 索引字符串的结束位置，默认参数为字符串长度即len(str)

似乎都是100多的数量，和4、8、11等等没有关系，是否是数量排名？

试一下，由小到大第四号：we ；第八号：should ;第11号：learn ;第15号：the;第十六号：crypto

组合一下就是：weshouldlearnthecrypto

第二题：一张碟报

打开题目

猜测为替换密码。因此着重寻找替换规则。我们看到左边的文章似乎是易于阅读的，判定为明文，而右上角的文章看起来与左边的文章一样，但是某些东西被替换了，判断为密文，被替换的即为替换规则，然后右下角还有一条用奇奇怪怪的文字写的文本，判断为本题需要解密的密文，于是乎我们写个脚本，在比较前两篇文章得到代还规律的同时，解密右下角的文本。


str1='今天上午，朝歌区梆子公司决定，在每天三更天不亮免费在各大小区门口设卡为全城提供二次震耳欲聋的敲更提醒，' \'呼吁大家早睡早起，不要因为贪睡断送大好人生，时代的符号是前进。为此，全区老人都蹲在该公司东边树丛合力抵制，' \'不给公司人员放行，场面混乱。李罗鹰住进朝歌区五十年了，人称老鹰头，几年孙子李虎南刚从东北当猎户回来，每月还寄回来几块鼹鼠干。' \'李罗鹰当年遇到的老婆是朝歌一枝花，所以李南虎是长得非常秀气的一个汉子。李罗鹰表示：无论梆子公司做的对错，反正不能打扰他孙子睡觉，' \'子曰：‘睡觉乃人之常情’。梆子公司这是连菩萨睡觉都不放过啊。李南虎表示：梆子公司智商捉急，小心居民猴急跳墙！这三伏天都不给睡觉，这不扯淡么！' \'到了中午人群仍未离散，更有人提议要烧掉这个公司，公司高层似乎恨不得找个洞钻进去。直到治安人员出现才疏散人群归家，但是李南虎仍旧表示爷爷年纪大了，睡不好对身体不好。'str2='喵天上午，汪歌区哞叽公司决定，在每天八哇天不全免费在各大小区门脑设卡为全城提供双次震耳欲聋的敲哇提醒，' \'呼吁大家早睡早起，不要因为贪睡断送大好人生，时代的编号是前进。为此，全区眠人都足在该公司流边草丛合力抵制，' \'不给公司人员放行，场面混乱。李罗鸟住进汪歌区五十年了，人称眠鸟顶，几年孙叽李熬值刚从流北当屁户回来，每月还寄回来几块报信干。' \'李罗鸟当年遇到的眠婆是汪歌一枝花，所以李值熬是长得非常秀气的一个汉叽。李罗鸟表示：无论哞叽公司做的对错，反正不能打扰他孙叽睡觉，' \'叽叶：‘睡觉乃人之常情’。哞叽公司这是连衣服睡觉都不放过啊。李值熬表示：哞叽公司智商捉急，小心居民猴急跳墙！这八伏天都不给睡觉，这不扯淡么！'\'到了中午人群仍未离散，哇有人提议要烧掉这个公司，公司高层似乎恨不得找个洞钻进去。直到治安人员出现才疏散人群归家，但是李值熬仍旧表示爷爷年纪大了，睡不好对身体不好。'str3='喵汪哞叽双哇顶，眠鸟足屁流脑，八哇报信断流脑全叽，眠鸟进北脑上草，八枝遇孙叽，孙叽对熬编叶：值天衣服放鸟捉猴顶。鸟对：北汪罗汉伏熬乱天门。' \'合编放行，卡编扯呼。人离烧草，报信归洞，孙叽找爷爷。'ans='' #存放解出来的明文for i in range(len(str3)):for j in range(len(str2)):if str3[i] == str2[j]:ans+=str1[j]breakprint(ans)

原理很简单，运行一下得结果

/Users/yuwenao/PycharmProjects/BUUCTF-GBLaoWang/venv/bin/python /Users/yuwenao/PycharmProjects/BUUCTF-GBLaoWang/main.py
今朝梆子二更头，老鹰蹲猎东口，三更鼹鼠断东口亮子，老鹰进北口上树，三枝遇孙子，孙子对虎符曰：南天菩萨放鹰捉猴头。鹰对：北朝罗汉伏虎乱天门。合符放行，卡符扯呼。人离烧树，鼹鼠归洞，孙子找爷爷。进程已结束，退出代码为 0

第三道题：Keyboard

很有意思，一开始想不到后来手机输入法点错了，才得到解题灵感（无技术力）

都是数字，但排除数制转化。没有与26个字母顺序对应的关系。好像看不出明显的密码类型。

看回题"Keyboard"，键盘？小写字母？我看着笔记本上的键盘沉默了。直到上网冲浪的时候，手机点到九宫格输入法，我才发现九宫格里数字和字母有相关性，那么6是否意味着点一次“6”键，而复数的“6”则意味着点多次呢？（九宫格通过次数决定具体字母？）我们不妨试试

得到flag='mobilephond' （一个一个看）