Crypto (cryptography) test record
1. Railfence (fence password)
Let’s take a look at the title description first:
the content of the title attachment is:
ccehgyaefnpeoobe{lcirg}epriec_ora_g
The information we can get from the title Railfence (fence password) and the title description is that this question is a fence password, and then it is mentioned in the title description A farmer’s woman feeds 5 chicks in the fence. From this we can infer that the number of columns in the fence password should be 5. But after decrypting, we found that the number of columns was set to 5 incorrectly. Then we tried other numbers and found that all It was not the correct answer. After being confused for a long time, I asked my classmates before I realized that there is another form of fence password: W-shaped fence password. Knowing that this question is a W-shaped fence password, so I searched for related content on the Internet to get a general understanding of the so-called W-shaped password. Below, I will provide you with two blogs about W-shaped fence passwords for your convenience. To understand.
Link: link .
Link: link .
After knowing the existence of the W-shaped fence password, we will start to decrypt this question. Above we have inferred that the number of columns in the fence password should be 5. Now let’s try Check whether the number of columns is 5 is correct. After decryption, it is found that the number of columns is 5 is correct.
I found the decryption tool for the W-shaped fence password when looking at the blog of the big guy in the link above. Here is a link for everyone.
Link: link .
2、Rabbit
The Rabbit stream cipher is designed by Cryptoco (http://www.cryptico.com). The key length is 128 bits. The maximum encrypted message length is 264 Bytes, which is 16 TB. If the message exceeds this length, the key needs to be replaced. Process the remaining messages.
Attachment content: U2FsdGVkX1/+ydnDPowGbjjJXhZxm2MP2AgI This topic
is a Rabbit stream password, we can check the Rabbit stream password online decryption tool on the Internet to decrypt it, and finally the flag package obtained after decryption can be submitted with flag{ }.
3. Not just Morse
First look at the title description:
the content of the title attachment is:
–/.-/-.–/…–.-/-…/./…–.-/…/.-/…-/./…–. -/.-/-./—/-/…/./.-./…–.-/-…/./-.-./—/-…/./…/…/…/…/ .-/.-/.-/.-/.-/-…/.-/.-/-…/-…/-…/.-/.-/-…/-…/.-/.- /.-/.-/.-/.-/.-/.-/-…/.-/.-/-…/.-/-…/.-/.-/.-/.-/. -/.-/.-/-…/-…/.-/-…/.-/.-/.-/-…/-…/.-/.-/.-/-…/-…/ .-/.-/-…/.-/.-/.-/.-/-…/.-/-…/.-/.-/-…/.-/.-/.-/-… /-…/.-/-…/.-/.-/.-/-…/.-/.-/.-/-…/.-/.-/-…/.-/-…/- …/.-/.-/-…/-…/-…/.-/-…/.-/.-/.-/-…/.-/-…/.-/-…/-…/ .-/.-/.-/-…/-…/.-/-…/.-/.-/.-/-…/.-/.-/-…/.-/.-/-… /.-/.-/.-/.-/-…/-…/.-/-…/-…/.-/.-/-…/-…/.-/.-/-…/. -/.-/-…/.-/.-/.-/-…/.-/.-/-…/.-/.-/-…/.-/.-/-…/.-/ -…/.-/.-/-…/-…/.-/-…/.-/.-/.-/.-/-…/-…/.-/-…/.-/.- /-…/-…/.-
Seeing the title "More than Morse", the first thing we thought of was the Morse code. After opening the title attachment, it was indeed the Morse code, and then we could decrypt it with the Morse code. Later, I found that the result did not seem right, as shown in the following figure:
Take a closer look at the small section "MAY_ BE_ HAVE ANOTHER DECODEHHHH" at the front of the result after decrypting with Morse code, which means that there may be another type of code, and then we will return to the title description, and then take a good look at the title and find the last Two people said in unison: "I thought about it!" A kind of food. A kind of food? Isn't this deciphering, how did it involve the food? Oh~ I also thought, "Password, food", there is indeed one password related to food, hehe, everyone knows it is the Bacon password, let’s look at the following section of the result after decrypting with Morse password , It does meet the characteristics of the Bacon password. So, let's use the Bacon cipher to decrypt it. After decryption, we found that we got the correct answer, as shown in the figure below. The last thing to note is that the answer format required by the title is cyberpeace{}, and the answer inside the braces should be lowercase.
4. [BJDCTF 2nd] The old illiterate
Attachment to the title: 罼雧 眔眔灏Zhe 匶襫軼瀬瀬莶軄鶛 Jiao 鳓哵眔鞟鰝
Seeing this string of incomprehensible Chinese characters in the attachment is really confused, and then I went to Baidu to find Chinese character conversion It is a pinyin decryption tool, and after decrypting this string of unintelligible Chinese characters, it is found that its pinyin is a bit interesting. The corresponding pinyin meaning of the Chinese character above is: "BJD braces, this is the flag, just hand in braces".
So the final flag is: BJD {Zhejiang 襫黼瀬鎶貶軄鶛娇鳓哵}
5. Mixed coding
Seeing the mixed code of the question, you know that this question must use several passwords to solve the answer, so let's decrypt it slowly.
The content of the subject attachment is as follows:
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 ==
Seeing this string of passwords in the attachment, and adding "==" as the suffix at the end of the password, we first thought of the Base64 password, so let's solve it.
After decrypting with the Base64 password, we got a string of passwords that resembled the ASCII code, but after decrypting it was found that it was not an ASCII code, so we checked the information on the Internet and found that this string of passwords should be Unicode codes, then we use a Unicode decryption tool Let's decrypt a secret, and get the following result after decryption.
Hey, after decrypting with Unicode, it seems to return to Base64 password. In this case, we will use Base64 to decrypt it again.
After decryption, I found a string of numbers, and careful observation found that it was an ASCII code, so in the end we only need to compare the ASCII code table to convert this string of numbers into letters.
The final flag is: cyberpeace{welcometoattackanddefenceworld}