Oh no, your girlfriend knows crypto
Your lover has a feeling you're reading her emails. Now her emails from a few of her contacts are just random letters. However, one catches your eye because the sender didn't encrypt the subject line which read "I need to see you." You could try your hand at cryptanalysis to decode the body of the message or you could figure out what cipher is being used and email him back an encrypted message to cancel those plans.
The body of the message reads: BYXTT EHDTX TRBDR RTNOC DTXRH EOLTX GFUTX NLSFI UTEPE UEFIX FTOET HYTTR HXWUR EITGA LLIES OSFRE XEIEV EMSIR DIATI MKAXH OAHXN UASNE
Also, you notice in her infinite paranoia she and this mystery person have put random bit strings at the bottom of all of their messages. This is possibly a way to verify they each are the real message authors. One person generates a random bit string and XORs it with the key then sends that bit string in the message. Then the recipient XORs that bit string and sends it back. If the message that is sent back is the original randomly generated bit string, then the original sender knows the person emailing knows their secret key. After reading two emails you know how to figure out what the key is He sends 100101100110 She sends back 001000101101 So the secret key has to be…
Thats what you get for reading her emails :P
Why not just confront her about this "mystery man"? Just say you can tell by the way she acts that you think shes seeing someone else. Its a bit better then playing cloak and dagger with her.
If you know shes fucking around then just dump her. Even if I was to lend a hand and crack the encryption it wont help the problem at all. They will just find a new way.
bdafae wrote: Homework, awesome. OP, gtfo.
If you are implying that I'm trying to dupe a community of intelligent people into doing a homework assignment then you might want to apologize to everyone for insulting their intelligence.
mkay, now that is done we can move on…
Part II of our story…
You've figured out the secret key by XORing the bit string in message one with the bit string in message two. Since the (Key xor Random) = message 1 and (message 1 xor Key) = Random Then it follows that message 1 xor message 2 (which was the random bit string) will result in the key.
Now on to the harder part…the jumbled letters. Since everyone has said to just dump her, this part is just for fun since she's long gone by now.
This cipher was part of the special forces field manual for a while. You had to be able to encrypt and decrypt in the field with just a pencil and paper without errors in five minutes. The algorithm is weak but for messages with a short life span it was good enough.
You and your partner have 2 memory words that you've exchanged securely. To encrypt the words are stripped of letters that repeat so "Popsicle" becomes "posicle" and "leethacker" becomes "lethackr" The letters of the words are given a value based on their place in the alphabet. Then the message is written under the first word and the jumbled letters are formed by writing the letters of each column in five letter pairs. Then for the second transposition the jumbled message is written under the second word and so on.
Also, you only need ten letters of the secret word to encrypt and decrypt so even if you put "The secret word is 'HellboundHackers,'" the security of the message would probably outlive the life of the message if the person who was trying to break it didn't know which cipher was used.
BAXKA LUNXG CXLTO ITNIS TIIXE NIBDE
hellboundhackers = helboundac which means the value of each column is this
6 5 7 2 9 10 8 4 1 3
But wait, if there are ten columns, why are there only 6 sets of jumbled letters? That's just a red herring to make breaking it harder. 6 sets of 5 equals 30 letters. 30 letters divided into 10 columns means they each have only 3 letters each. So "BAX" goes in the first column and "KAL" in the second and so on until you have…
6 5 7 2 9 10 8 4 1 3 I L I K E B I G B U T T S A N D I C A N N O T L I E X X X X
Sorry if this was boring, but I thought a thread on the basics would be interesting.
E-5 wrote: [quote]bdafae wrote: Homework, awesome. OP, gtfo. If you are implying that I'm trying to dupe a community of intelligent people into doing a homework assignment then you might want to apologize to everyone for insulting their intelligence.[/quote] Exactly how does the accusation that you attempted to dupe us insult out intelligence?
Sorry if this was boring, but I thought a thread on the basics would be interesting. No, it's just that you presented it in pretty much the weirdest way possible.
Ill be honest this thread is tldr.
But from scanning it, if you are talking about simple xor encryption and the one-time pad method… there's already a challenge to do this.
http://www.hellboundhackers.org/challenges/encryption/encryption_challenge_11.txt
E-5 wrote: Sorry if this was boring, but I thought a thread on the basics would be interesting.Well, it's not. At least not in the way presented. May I ask WHY you are doing this? I still can't really see the point.
If you created your own encryption challenge and wanted us to try to break it, then the whole story about the girlfriend and such should be left out. It's completely irrelevant here.
crypto fanfic FTL
Although it isn't really fiction since this was based off of an assignment I had a few months ago combined with an interesting request I got from a friend who was asking me how to keep her emails secret.
But my assignment was pretty straight forward, encrypt with two transpositions and explain how to decrypt, I did it, got an A whooppee. And my friend's eyes glazed over when I started explaining digital signatures and encryption so she obviously didn't do as the person in my scenario did.
So those two things were pretty boring in and of themselves, but I thought it would be interesting to see what would happen if they did and view it from the boyfriend's point of view.
I think everyone learned a valuable lesson about the power of knowledge.
This wasn't a "crypto challenge" at all. Those are pretty straight up and down, there's a cipher…break it. This challenge was about whether you should break it or not. For this challenge everyone who said, "just dump the cheatin <explicative expletive>" gets 1 point. Admins, make it happen. For all those that said "TLDR" +5, but only if you're reading this.
E-5 wrote: I think everyone learned a valuable lesson about the power of knowledge.
I didn't learn anything. Not from this anyway.
This challenge was about whether you should break it or not. For this challenge everyone who said, "just dump the cheatin <explicative expletive>" gets 1 point. Admins, make it happen. For all those that said "TLDR" +5, but only if you're reading this.
I usually hate when people say this, but this time I think it's warranted: GTFO.
E-5 Replied:
This wasn't a "crypto challenge" at all. Those are pretty straight up and down, there's a cipher…break it. This challenge was about whether you should break it or not. For this challenge everyone who said, "just dump the cheatin <explicative expletive>" gets 1 point. Admins, make it happen. For all those that said "TLDR" +5, but only if you're reading this.
I'm thinking NO!
yet.
Personally, I don't see what the big deal is- he was trying to elicit a response to a problem; to get the community working as a team towards a common goal rather than individually on random challenges. Sure, it was presented weird and the idea itself may have been a tad flawed, but I'm having trouble seeing anything that warrants a GTFO… Sure that last paragraph was moronic, but I sense that was his intent. Our responses were moronic, why shouldn't he follow suit?
My last paragraph was using the Bacon Cipher so the pattern of the words would be more relevant than the actual words themselves.
I can't believe I posted in a crypto thread and everyone was focused on the content and not the pattern.
I guess if I would've posted, "hey guys check this out, 01100010 01101001 01101110 01100001 01110010 01111001 01100110 01101111 01110010 01110100 01101000 01100101 01110111 01101001 01101110"
The response would've been " awww GTFO, random ones and zeros?! are you serious? what the… what is that about?!"
It's fine though, this thread has deteriorated to a level I never thought possible. I've never been so ashamed to call myself an OP of a thread in all my life.
I do think it warranted a GTFO. So I want everyone to know that today I bought a whole bag of onions and as everyone has suggested I will "Grill Ten Fresh Onions."
yum
E-5 wrote: I guess if I would've posted, "hey guys check this out, 01100010 01101001 01101110 01100001 01110010 01111001 01100110 01101111 01110010 01110100 01101000 01100101 01110111 01101001 01101110"
The response would've been " awww GTFO, random ones and zeros?! are you serious? what the… what is that about?!"
No, the response would have been "So?". What you did was take some random encryption challenge and create a silly little story to go with it and then you posted it with no explanation of the purpose.
And then when people got confused and questioned the purpose, you started giving weird responses like "And now we've all learned the value of knowledge". This is why people got annoyed with you. Only a few of us can read minds, be considerate of those who can't.
Apophis wrote: [quote]E-5 wrote: I guess if I would've posted, "hey guys check this out, 01100010 01101001 01101110 01100001 01110010 01111001 01100110 01101111 01110010 01110100 01101000 01100101 01110111 01101001 01101110"
The response would've been " awww GTFO, random ones and zeros?! are you serious? what the… what is that about?!"
No, the response would have been "So?". What you did was take some random encryption challenge and create a silly little story to go with it and then you posted it with no explanation of the purpose.
And then when people got confused and questioned the purpose, you started giving weird responses like "And now we've all learned the value of knowledge". This is why people got annoyed with you. Only a few of us can read minds, be considerate of those who can't.[/quote]
Exactly, If you want to post a challenge for the community, do so. This whole thread is a waste. Lock.