https://play.picoctf.org/practice/challenge/31?category=2&page=4&search=
jadi ada gambar bendera
Awalnya gue ngira ada manipulasi biner di gambar ini, jadi gue coba buka binary filenya.
eh ga ketemu.
terus coba nyari solusi di online. ternyata ini pake ICS (international Code Signal)
| Letter / radio name |
Flag | Blazon | ICS meaning as single flag | Meaning when used with numeric complements |
|---|---|---|---|---|
| A Alfa |
 |
Swallowtailed, per pale argent and azure | “I have a diver down; keep well clear at slow speed.” | Azimuth or bearing |
| B Bravo |
 |
Swallowtailed, gules | “I am taking in or discharging or carrying dangerous goods.” (Originally used by the Royal Navy specifically for military explosives.) | |
| C Charlie |
 |
Azure, a fess gules fimbriated argent | “Affirmative.”[a][b] | Magnetic bearing |
| D Delta |
 |
Or, a Spanish fess azure | “Keep clear of me; I am maneuvering with difficulty.”[b] | Date |
| E Echo |
 |
Per fess azure and gules | “I am altering my course to starboard.”[b] | |
| F Foxtrot |
 |
Argent, a lozenge throughout gules | “I am disabled; communicate with me.”[c] | |
| G Golf |
 |
Paly of six or and azure | “I require a pilot.”
By fishing vessels near fishing grounds: “I am hauling nets.” |
Longitude (The first 2 or 3 digits denote degrees; the last 2 denote minutes.) |
| H Hotel |
 |
Per pale argent and gules | “I have a pilot on board.”[b] | |
| I India |
 |
Or, a pellet | “I am altering my course to port.”[b] | |
| J Juliett |
 |
Azure, a fess argent | “I am on fire and have dangerous cargo on board: keep well clear of me.”
or “I am leaking dangerous cargo.” |
|
| K Kilo |
 |
Per pale or and azure | “I wish to communicate with you.” | “I wish to communicate with you by…”:
1) Morse signaling by hand-flags or arms; 2) Loud hailer (megaphone); 3) Morse signaling lamp; 4) Sound signals. |
| L Lima |
 |
Quarterly or and sable | “Stop immediately.” | Latitude (the first 2 digits denote degrees; the last 2 denote minutes.) |
| M Mike |
 |
Azure, a saltire argent | “My vessel is stopped and making no way through the water.”[b] | |
| N November |
 |
Chequy of sixteen azure and argent | “Negative.”[a] | |
| O Oscar |
 |
Per bend gules and or | “Man overboard.”[b] (often attached to the man overboard pole on boats).
With a sinister hoist, the semaphore flag. |
|
| P Papa |
 |
Azure, an inescutcheon argent | The blue Peter.
In harbour: All persons should report on board as the vessel is about to proceed to sea. At sea: It may be used by fishing vessels to mean: “My nets have come fast upon an obstruction.” |
|
| Q Quebec |
 |
Or | “My vessel is ‘healthy’ and I request free pratique.” | |
| R Romeo |
 |
Gules, a cross or | No ICS meaning as single flag.Prior to 1969: “The way is off my ship; you may feel your way past me.” | Distance (range) in nautical miles. |
| S Sierra |
 |
Argent, an inescutcheon azure | “I am operating astern propulsion.”[b] | Speed (velocity) in knots |
| T Tango |
 |
Tierced in pale gules, argent and azure | “Keep clear of me.”[b]
Fishing boats: “Keep clear of me; I am engaged in pair trawling.” |
Local time. (The first 2 digits denote hours; the last 2 denote minutes.) |
| U Uniform |
 |
Quarterly gules and argent | “You are running into danger.”[d] | |
| V Victor |
 |
Argent, a saltire gules | “I require assistance.” | Velocity in kilometres per hour. |
| W Whiskey |
 |
Azure, an inescutcheon gules fimbriated argent | “I require medical assistance.” | |
| X Xray |
 |
Argent, a cross azure | “Stop carrying out your intentions and watch for my signals.” | |
| Y Yankee |
 |
Bendy sinister of ten or and gules | “I am dragging my anchor.” | |
| Z Zulu |
 |
Per saltire or, sable, gules and azure | “I require a tug.”
By fishing vessels near fishing grounds: “I am shooting nets.”[e] |
Time (UTC). (The first 2 digits denote hours; the last 2 denote minutes.) |
| Number | NATO flag | ICS flag | Blazons |
|---|---|---|---|
| 0 Zero |
 |
 |
NATO: Argent, five crosses hummetty azure in saltire ICS: Or, a pale gules |
| 1 One |
 |
 |
NATO: Gules, a fess or ICS: Argent, a torteau |
| 2 Two |
 |
 |
NATO: Or, a fess gules ICS: Azure, a plate |
| 3 Three |
 |
 |
NATO: Azure, a fess gules ICS: Tierced in pale gules, argent and azure |
| 4 Four |
 |
 |
NATO: Gules, a saltire argent ICS: Gules, a cross of Saint Philip argent |
| 5 Five |
 |
 |
NATO: Or, a saltire azure ICS: Per pale or and azure |
| 6 Six |
 |
 |
NATO: Bendy sinister of seven argent and azure ICS: Per fess sable and argent |
| 7 Seven |
 |
 |
NATO: Gules, a pale argent ICS: Per fess or and gules |
| 8 Eight |
 |
 |
NATO: Or, a pale azure ICS: Argent, a cross of Saint Philip gules |
| 9 Nine |
 |
 |
NATO: Azure, a pale argent ICS: Quarterly argent, sable, gules and or |
https://en.wikipedia.org/wiki/International_maritime_signal_flags
jadi decode nya adalah
PICOCTF{F1AG5AND5TUFF}