# Cryptography ### The Numbers \[50 pts] > **Description** > > The [numbers](https://jupiter.challenges.picoctf.org/static/f209a32253affb6f547a585649ba4fda/the_numbers.png)... what do they mean? **Solution** Given *16 9 3 15 3 20 6 { = picoCTF* \[given that is the format]\ 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26\ a b c d e f g h i j k l m n o p q r s t u v w x y z\ Thus *20 8 5 14 21 13 2 5 18 19 13 1 19 15 14 } = thenumbersmason}* **Flag: PICOCTF{THENUMBERSMASON}** ### Easy1 \[100 pts] \[Not Solved] > **Description** > > The one time pad can be cryptographically secure, but not when you know the key. Can you solve this? We've given you the encrypted flag, key, and a table to help `UFJKXQZQUNB` with the key of `SOLVECRYPTO`. Can you use this [table](https://jupiter.challenges.picoctf.org/static/1fd21547c154c678d2dab145c29f1d79/table.txt) to solve it?. **Solution** a **Flag:** ### 13 \[100 pts] > **Description** > > Cryptography can be easy, do you know what ROT13 is? `cvpbPGS{abg_gbb_onq_bs_n_ceboyrz}` **Solution** I could just go to an online converter, BUT I decided to write the code myself. ``` enc_message = 'cvpbPGS{abg_gbb_onq_bs_n_ceboyrz}' message = "" rot = 13 alphabet = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ' for c in enc_message: try: index = alphabet.index(c) new_letter = alphabet[(index + rot )% len(alphabet)] if index < 26: # Fix mismatched casing message += new_letter.lower() elif index > 26: message += new_letter.upper() except: # Doesn't exist in alphabet message += c continue print(message) ``` **Flag: picoCTF{not\_too\_bad\_of\_a\_problem}** ### caesar \[100 pts] > **Description** > > Decrypt this [message](https://jupiter.challenges.picoctf.org/static/6385b895dcb30c74dbd1f0ea271e3563/ciphertext). **Solution** Reusing the code from earlier with a little modification because we need to try all possibilities to get to this point I made this code ```python enc_message = '{dspttjohuifsvcjdpoabrkttds}' alphabet = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ' for shift in range(0, 26): # Shift 1 to 25 letters (26 would be no shift) message = '' for c in enc_message: try: index = alphabet.index(c) new_letter = alphabet[(index + shift)% len(alphabet)] if index < 26: # Fix mismatched casing message += new_letter.lower() elif index > 26: message += new_letter.upper() except: # Doesn't exist in alphabet message += c continue print(str(shift) + " " + message) ``` **Flag: picoCTF{crossingtherubiconzaqjsscr}** ### la cifra de \[200 pts] \[Not Solved] > **Description** > > I found this cipher in an old book. Can you figure out what it says? Connect with `nc jupiter.challenges.picoctf.org 32411`. **Solution** When type in the command it returns > Encrypted message: Ne iy nytkwpsznyg nth it mtsztcy vjzprj zfzjy rkhpibj nrkitt ltc tnnygy ysee itd tte cxjltk > > Ifrosr tnj noawde uk siyyzre, yse Bnretèwp Cousex mls hjpn xjtnbjytki xatd eisjd > > Iz bls lfwskqj azycihzeej yz Brftsk ip Volpnèxj ls oy hay tcimnyarqj dkxnrogpd os 1553 my Mnzvgs Mazytszf Merqlsu ny hox moup Wa inqrg ipl. Ynr. Gotgat Gltzndtg Gplrfdo > > Ltc tnj tmvqpmkseaznzn uk ehox nivmpr g ylbrj ts ltcmki my yqtdosr tnj wocjc hgqq ol fy oxitngwj arusahje fuw ln guaaxjytrd catizm tzxbkw zf vqlckx hizm ceyupcz yz tnj fpvjc hgqqpohzCZK{m311a50\_0x\_a1rn3x3\_h1ah3x7g996649} > > Ehk ktryy herq-ooizxetypd jjdcxnatoty ol f aordllvmlbkytc inahkw socjgex, bls sfoe gwzuti 1467 my Rjzn Hfetoxea Gqmexyt. > > Tnj Gimjyèrk Htpnjc iy ysexjqoxj dosjeisjd cgqwej yse Gqmexyt Doxn ox Fwbkwei Inahkw. > > Tn 1508, Ptsatsps Zwttnjxiax tnbjytki ehk xz-cgqwej ylbaql rkhea (g rltxni ol xsilypd gqahggpty) ysaz bzuri wazjc bk f nroytcgq nosuznkse ol yse Bnretèwp Cousex. > > Gplrfdo’y xpcuso butvlky lpvjlrki tn 1555 gx l cuseitzltoty ol yse lncsz. Yse rthex mllbjd ol yse gqahggpty fce tth snnqtki cemzwaxqj, bay ehk fwpnfmezx lnj yse osoed qptzjcs gwp mocpd hd xegsd ol f xnkrznoh vee usrgxp, wnnnh ify bk itfljcety hizm paim noxwpsvtydkse. **Flag:** ### Tapping \[200 pts] > **Description** > > Theres tapping coming in from the wires. What's it saying `nc jupiter.challenges.picoctf.org 21610`. **Solution** Hmmm, let me just guess Morse code maybe. Connecting it gives an easy impression with \ .--. .. -.-. --- -.-. - ..-. { -- ----- .-. ... ...-- -.-. ----- -.. ...-- .---- ... ..-. ..- -. ...-- ----. ----- ..--- ----- .---- ----. ..... .---- ----. }\ Which put into [Cyber Chef](https://gchq.github.io/CyberChef/#recipe=From_Morse_Code\('Space','Line%20feed'\)) comes out the flag. (Note to do this you have to remove the {}) **Flag: PICOCTF{M0RS3C0D31SFUN3902019519}** ### Flags \[200 pts] \[Not Solved] > **Description** > > What do the [flags](https://jupiter.challenges.picoctf.org/static/fbeb5f9040d62b18878d199cdda2d253/flag.png) mean? **Solution** a **Flag:** ### Mr-Worldwide \[200 pts] \[Not Solved] > **Description** > > A musician left us a [message](https://jupiter.challenges.picoctf.org/static/d5570d48262dbba2a31f2a940409ad9d/message.txt). What's it mean? **Solution** a **Flag:** ### rsa-pop-quiz \[200 pts] \[Not Solved] > **Description** > > Class, take your seats! It's PRIME-time for a quiz... `nc jupiter.challenges.picoctf.org 58617` **Solution** a **Flag:** ### waves over lambda \[300 pts] \[Not Solved] > **Description** > > We made a lot of substitutions to encrypt this. Can you decrypt it? Connect with `nc jupiter.challenges.picoctf.org 43522`. **Solution** a **Flag:** ### miniRSA \[300 pts] \[Not Solved] > **Description** > > Let's decrypt this: [ciphertext](https://jupiter.challenges.picoctf.org/static/d21037ad23ed84cfff20a84768a0f2b2/ciphertext)? Something seems a bit small. **Solution** a **Flag:** ### b00tl3gRSA2 \[400 pts] \[Not Solved] > **Description** > > In RSA d is a lot bigger than e, why don't we use d to encrypt instead of e? Connect with `nc jupiter.challenges.picoctf.org 19566`. **Solution** a **Flag:** ### AES-ABC \[400 pts] \[Not Solved] > **Description** > > AES-ECB is bad, so I rolled my own cipher block chaining mechanism - Addition Block Chaining! You can find the source here: [aes-abc.py](https://jupiter.challenges.picoctf.org/static/1b1beb0a49c958d0f2423800eaff58a7/aes-abc.py). The AES-ABC flag is [body.enc.ppm](https://jupiter.challenges.picoctf.org/static/1b1beb0a49c958d0f2423800eaff58a7/body.enc.ppm) **Solution** a **Flag:** ### b00tl3gRSA3 \[450 pts] \[Not Solved] > **Description** > > Why use p and q when I can use more? Connect with `nc jupiter.challenges.picoctf.org 4557`. **Solution** a **Flag:** ### john\_pollard \[500 pts] \[Not Solved] > **Description** > > Sometimes RSA [certificates](https://jupiter.challenges.picoctf.org/static/c882787a19ed5d627eea50f318d87ac5/cert) are breakable **Solution** a **Flag:**