# Cryptography

### Mod 26 \[10 pts]

> **Description**
>
> Cryptography can be easy, do you know what ROT13 is? `cvpbPGS{arkg_gvzr_V'yy_gel_2_ebhaqf_bs_ebg13_Ncualgvd}`

**Solution**

The description gives it away. I used CyberChef to solve.

**Flag: picoCTF{next\_time\_I'll\_try\_2\_rounds\_of\_rot13\_Aphnytiq}**

### Mind your Ps and Qs \[20 pts] \[Not Solved]

> **Description**
>
> In RSA, a small `e` value can be problematic, but what about `N`? Can you decrypt this? [values](https://mercury.picoctf.net/static/3cfeb09681369c26e3f19d886bc1e5d9/values)

**Solution**

a

**Flag:** 

### Easy Peasy \[40 pts] \[Not Solved]

> **Description**
>
> A one-time pad is unbreakable, but can you manage to recover the flag? (Wrap with picoCTF{}) `nc mercury.picoctf.net 36449` [otp.py](https://mercury.picoctf.net/static/2cebaadd44657a7b22ddff3d0401775f/otp.py)

**Solution**

a

**Flag:** 

### New Caesar \[60 pts] \[Not Solved]

> **Description**
>
>  We found a brand new type of encryption, can you break the secret code? (Wrap with picoCTF{}) `mlnklfnknljflfjljnjijjmmjkmljnjhmhjgjnjjjmmkjjmijhmkjhjpmkmkmljkjijnjpmhmjjgjj` [new\_caesar.py](https://mercury.picoctf.net/static/43182e6d4527ef0916b2ce43883227b7/new_caesar.py)

**Solution**

a

**Flag:** 

### Mini RSA \[70 pts] \[Not Solved]

> **Description**
>
> What happens if you have a small exponent? There is a twist though, we padded the plaintext so that (M \*\* e) is just barely larger than N. Let's decrypt this: [ciphertext](https://mercury.picoctf.net/static/e7e63a387acc347648918f419d1ae438/ciphertext)

**Solution**

a

**Flag:** 

### Dachshund Attacks \[80 pts] \[Not Solved]

> **Description**
>
> What if `d` is too small? Connect with `nc mercury.picoctf.net 41508`.

**Solution**

a

**Flag:** 

### No Padding, No Problem \[90 pts] \[Not Solved]

> **Description**
>
> Oracles can be your best friend, they will decrypt anything, except the flag's ciphertext. How will you break it? Connect with `nc mercury.picoctf.net 33780`.

**Solution**

a

**Flag:** 

### Pixelated \[100 pts] \[Not Solved]

> **Description**
>
> I have these 2 images, can you make a flag out of them? [scrambled1.png](https://mercury.picoctf.net/static/c9593d1d2ac9d850da95bffe0ac3b6c6/scrambled1.png) [scrambled2.png](https://mercury.picoctf.net/static/c9593d1d2ac9d850da95bffe0ac3b6c6/scrambled2.png)

**Solution**

a

**Flag:** 

### Play Nice \[110 pts] \[Not Solved]

> **Description**
>
> Not all ancient ciphers were so bad... The flag is not in standard format. `nc mercury.picoctf.net 33686` [playfair.py](https://mercury.picoctf.net/static/aec5fd7b1ec96307c4eda752a3353f68/playfair.py)

**Solution**

a

**Flag:** 

### Double DES \[120 pts] \[Not Solved]

> **Description**
>
> I wanted an encryption service that's more secure than regular DES, but not as slow as 3DES... The flag is not in standard format. `nc mercury.picoctf.net 3620` [ddes.py](https://mercury.picoctf.net/static/21ad728926fc3bf09205ec8df9500768/ddes.py)

**Solution**

a

**Flag:** 

### Compress and Attack \[130 pts] \[Not Solved]

> **Description**
>
> Your goal is to find the flag. [compress\_and\_attack.py](https://mercury.picoctf.net/static/894486d81cd39eb738bd3246ab3cbeb8/compress_and_attack.py) `nc mercury.picoctf.net 57393`

**Solution**

a

**Flag:** 

### Scrambled: RSA \[140 pts] \[Not Solved]

> **Description**
>
>  Hmmm I wonder if you have learned your lesson... Let's see if you understand RSA and how the encryption works. Connect with `nc mercury.picoctf.net 50075`

**Solution**

a

**Flag:** 

### It's Not My Fault 1 \[300 pts] \[Not Solved]

> **Description**
>
>  What do you mean RSA with CRT has an attack that's not a fault attack? Connect with `nc mercury.picoctf.net 56093`. [not\_my\_fault.py](https://mercury.picoctf.net/static/1901d1b2dae48da1a9326f2b90b7f1a6/not_my_fault.py)

**Solution**

a

**Flag:** 

### New Vignere \[300 pts] \[Not Solved]

> **Description**
>
>  Another slight twist on a classic, see if you can recover the flag. (Wrap with picoCTF{}) `eljodmjdjcnfcdmgbleojbgngojkkdpimebgeigpdkjpmgngpfpgelemjoglghjd` [new\_vignere.py](https://mercury.picoctf.net/static/8f3b4b39dfc1cf7b13392919f5897115/new_vignere.py)

**Solution**

a

**Flag:** 

### Clouds \[500 pts] \[Not Solved]

> **Description**
>
>  Cloud watching is a lot of fun! There are so many different shapes you see in them, and so many different types. They even inspired me to dig up an old cipher I once found to store notes about them. See if you can decrypt them! `nc mercury.picoctf.net 20974` [clouds.py](https://mercury.picoctf.net/static/0f8a58cf890170da4a9d6cbf78350e06/clouds.py)\
> The flag for this challenge does not include the standard `picoCTF{}` wrapper.

**Solution**

a

**Flag:**