Rien à signaler
all files in resources/ were provided.
Description
J'ai chiffré le flag avec le cryptosystème à clé publique bien connu RSA.
Challenge
We are hinted that this is RSA, we can see in rien-a-signaler.py that this is indeed some sort of manual RSA.
We can use RsaCtfTool as we are given enough important info in output.txt:
RsaCtfTool -e 14939086586092777407540803168471412724086958884607893995687327163153290580760558837291728666456222816453459253012875608081140912518401828609726644228963594136502689596910372270878975142615041204855876795840250744447608791110019817832312337476046798491861483950133453478764973611286365531244274907864964200118887980416350639882907479248120503190137345205402154450552803826178574159801186219948543406588724442253188994068292704744044422267282898105644719291000793491804938648328829611223993162601906075018324472156338267348355427156047595434154590931416765750047893661286247274247632521858558403416012123883148428323057 -n 15796942747309728499758004731551695370913663306666035509299434642801916886496898004446545897149657535285268305926374338100837909963511256277964036962044387829939281166102731090331978991280163210213940391251452338553405036351243486418991475381065523778778374159216111211039724992140348798301914302441933569705494577465736752087544176074475722982600742085989140379907623574747713824460161103249270448563714176784913386788071348191510218812659925461534747629228752452045853041012162619056264262054391967199115369336548943331022933845667724296738334370747384492830658154258526863726939357154899976616849634493499797766299 --decrypt 8974868290281688737233990325600894780715849339628541493919631966007477856153771121147897587192029426714635875587384109624607194486211852465796766441066196469272988076202321557112300294463883797708163984188107199926745938577562219282934551167072277621808474131345695591468145868455419473050498493285402336637848596791275101533878984692539165395918338275186762268105380646876795842765910627488934075701761752437069042340873474933889573307306539126206460702731582652544213958040586038088129224761895431978602343177304095553828090049657631935349611981192723124744317395844933142968117051307548448128268941861109853064071
# private argument is not set, the private key will not be displayed, even if recovered.
# ['/var/folders/rk/y9r70jbj2dlbfqsk5h7xly6r0000gn/T/tmpbb5p0h_5']
# [*] Testing key /var/folders/rk/y9r70jbj2dlbfqsk5h7xly6r0000gn/T/tmpbb5p0h_5.
# attack initialized...
# attack initialized...
# [*] Performing lucas_gcd attack on /var/folders/rk/y9r70jbj2dlbfqsk5h7xly6r0000gn/T/tmpbb5p0h_5.
# 100%|█████████████████████████████████████████████| 9999/9999 [00:00<00:00, 75256.33it/s]
# [+] Time elapsed: 0.1454 sec.
# [*] Performing pastctfprimes attack on /var/folders/rk/y9r70jbj2dlbfqsk5h7xly6r0000gn/T/tmpbb5p0h_5.
# [+] Time elapsed: 0.0004 sec.
# [*] Performing system_primes_gcd attack on /var/folders/rk/y9r70jbj2dlbfqsk5h7xly6r0000gn/T/tmpbb5p0h_5.
# 100%|████████████████████████████████████████████| 7007/7007 [00:00<00:00, 670656.02it/s]
# [+] Time elapsed: 0.0321 sec.
# [*] Performing factordb attack on /var/folders/rk/y9r70jbj2dlbfqsk5h7xly6r0000gn/T/tmpbb5p0h_5.
# [!] Composite not in factordb, couldn't factorize...
# [+] Time elapsed: 0.3659 sec.
# [*] Performing fibonacci_gcd attack on /var/folders/rk/y9r70jbj2dlbfqsk5h7xly6r0000gn/T/tmpbb5p0h_5.
# 100%|█████████████████████████████████████████████| 9999/9999 [00:00<00:00, 70016.75it/s]
# [+] Time elapsed: 0.1434 sec.
# [*] Performing smallq attack on /var/folders/rk/y9r70jbj2dlbfqsk5h7xly6r0000gn/T/tmpbb5p0h_5.
# [+] Time elapsed: 0.2543 sec.
# [*] Performing rapid7primes attack on /var/folders/rk/y9r70jbj2dlbfqsk5h7xly6r0000gn/T/tmpbb5p0h_5.
# [+] Time elapsed: 0.0003 sec.
# [*] Performing mersenne_primes attack on /var/folders/rk/y9r70jbj2dlbfqsk5h7xly6r0000gn/T/tmpbb5p0h_5.
# 29%|██████████████ | 15/51 [00:00<00:00, 403298.46it/s]
# [+] Time elapsed: 0.0004 sec.
# [*] Performing nonRSA attack on /var/folders/rk/y9r70jbj2dlbfqsk5h7xly6r0000gn/T/tmpbb5p0h_5.
# [+] Time elapsed: 0.0040 sec.
# [*] Performing wiener attack on /var/folders/rk/y9r70jbj2dlbfqsk5h7xly6r0000gn/T/tmpbb5p0h_5.
# 2%|▉ | 14/662 [00:00<00:00, 191896.26it/s]
# [*] Attack success with wiener method !
# [+] Total time elapsed min,max,avg: 0.0003/0.3659/0.1051 sec.
# Results for /var/folders/rk/y9r70jbj2dlbfqsk5h7xly6r0000gn/T/tmpbb5p0h_5:
# Decrypted data :
# HEX : 0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000464353437b373236346264326462376661653737653063346532343435653435656438396662653938663763316263386537373936313131653332363534663161643166307d0a
# INT (big endian) : 265169881291524521370308814528191034527231017917910727657776537717468439921407976331684441342334048130410807713023469141294350672366119990280271349405563492132947753991434
# INT (little endian) : 1324116075642765741877637990346911409784786796748184424983624176541982966162649340208074462017938732984057544588223959710742530188154972269400206927922494510423262500292439841402780584834171209515015583208634737702310357304214152909406419546046262706698088931376649054722365855517431410458306767063737926917005726683961251605364155733774022481987394503063927421530733101258532116620169398302920543868838679594398467278322744462606965287102199766734249732448181514771725259683809943903005345942745478018921250507670284527606599730525529096240274042433601425172320067362379936285692212048280210223103820214624273301504
# utf-8 : FCSC{<redacted>}
# utf-16 : 䘀千筃㈷㐶摢搲㝢慦㝥攷挰攴㐲㔴㑥攵㡤昹敢㠹㝦ㅣ换攸㜷㘹ㄱ攱㈳㔶昴愱ㅤて
# STR : b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00FCSC{<redacted>}\n'