Diffie-Helman Key Exchange (PicoCTF 2022 #32 'diffie-helman')

[@pike4978]

I'm taking a cryptography class right now so this was fun for me. I actually decided to crack the message with pen and paper to test what I've learned, only took about 10 minutes. One thing I've learned about cybersecurity is that adversaries won't necessarily approach your security in the same way you designed it. In the case of a DH with p=13, there are only 12 possible shift values that Alice and Bob could have landed on. So if you wanted to approach this like a hacker then trying to decrypt their message through brute force would make it a lot easier.

[@Lodinn]

If you wanted to approach it like a hacker, you wouldn't care about the shift value at all. Brute forcing 13 values is no different from brute forcing 35.

[@OfficialSlippedHalo]

Just following along casually, reached the stuck part and I want to just write down my guess on the issue before he solves it: Im guessing the fault is that the cypher is relying on a single alphanumeric alphabet with a shift of 5, rather than separate alphabets for ascii and digits, i.e Z shifts to 0, 9 shifts to A etc Edit: feels nice that i was on the right track

[@passerby184]

this kinda feels like it'd be faster to broteforce Ciser ciper

[@ecjb1969]

If the rotation is letters and numbers, the rotation space is 26 + 10 or 36. Rotating by -5 would then be 31 I think. Maybe use ABC…Z01…9 or something similar to wrap around, not just A-Z 0-9?

[@Lodinn]

That's what half of this video was spent on. Apparently for modern people rotating 26 and 10 separately is more intuitive than lumping them together :)

[@allurbase]

[@seanvinsick]

A deque (deck) is a double ended queue. You can search, push and pop from both sides.

[@poprivest4715]

Paused it at around 23:00 and did it by hand and quickly realized how the numbers were integrated to the rotation ;) (...X,Y,Z,1,...,9,A,B,C...)

[@bladesvlogs4965]

So they ended up being 1 long string and shifted across? 👍 Glad it was you working it out 😂

[@franckchiron9848]

Took me an awful lot of time to get that one. You shouldn't feel bad, though : I think it's kind of a tunnel effect. We are so used to work on alphabet and digits separately at ASCII level that considering them as a whole is counter-intuitive. I guess that was a good one to help up keep our brain elasticity :)

[@Lodinn]

Funny how modern cryptography experts get puzzled by what people did historically ;)

[@MorningStarChrist]

You may be able to find the answer using letter frequency analysis. and some leetspeech permutations

[@lordspacecake5565]

Very informative video

[@FunkadelicFeed]

Why can't I find this? After “buffer-overflow1" it shows “forbidden paths" as the next challenge for me :/

[@verolyn8459]

I literally did what you do when decrypting it.

[@tylercoombs1]

Cyber Chef is a good place to tinker with encryption

[@Joel-gf4zl]

Exactly what I was going to suggest. Cyber Chef is great.

[@mahkhi7154]

Windows Mobile uses the Edge browser which uses Webkit/Blink.

[@JackTheDev]

i was just saying, no, no, when i saw only letters and no numbers in the shift :(

[@mohamadyakteen8710]

At 9:40 , if you continued scrolling down to ROT31 you would have found the correct Flag...

[@bhagyalakshmi1053]

How to management which one project

[@adityavsx]

Smartie

[@bhagyalakshmi1053]

Other examples rock ,sys admin moor explain deep class

[@bhagyalakshmi1053]

Scissor cyber also in farming in the class what the video

[@sandeepd6104]

Can you please make a video on RSA decryption with python

[@bhagyalakshmi1053]

Terminal open how to open

[@bhagyalakshmi1053]

How to dissolution in the 🗝️

[@mahkhi7154]

Android uses Chrome which uses Webkit/Blink.

[@ShootingUtah]

Pretty sure they intended you to use a reference alphabet of a-z1-9 all as one. I haven't worked the problem personally but that's my idea while watching you struggle.

[@flyingtiger123]

the challenge has disappeared!!: (

[@Noobiie23]

Hey I just learned about DH on CBTnuggets

[@ac1d8urn]

Literally shouting at the screen for 10 minutes ;-)

[@mahkhi7154]

The Reason the PS5 Hack worked is because the Playstation Engineers thought We couldn't Unravel their Operating system Encryption. If they thought we Could Unravel their Operating System Encryption, then they would have Blocked the Webkit Exploit. That would have made Chrome Slower and not Work on Low Powered smartphones. The Windows / Internet explorer Guys gained More of Our Windows Architecture. Internet Explorer is Faster cause of this. Chrome is Faster because of the Unchecked buffer overflow vulnerability. If they Closed that Vulnerability, Chrome would have gone slower than Internet Explorer and Not work on low end Phones. They didn't Close the hole as they Thought We Couldn't Unravel their Operating System Encryption.

[@bhagyalakshmi1053]

Video rept explain. Cvr

[@Colaholiker]

Thumbs down for not using an f-string in the end! :-P (Just kidding, I would never do that)

[@bhagyalakshmi1053]

Password 🔑

[@bhagyalakshmi1053]

Repeating repeating coming for you videos

[@vdk996]

WTF?????? are u a human ?

[@MikeDSutton]

translate is your friend: key = string.ascii_uppercase + string.digits message = "H98A9W_H6UM8W_6A_9_D6C_5ZCI9C8I_D9FF6IFD" print(message.translate(string.maketrans(key, key[-5:] + key[:-5])))

[@thepriyank121]

Really got an Idea need more learning i guess you are good in trouble shooting