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Challenge "Music Code — Part 1"

Challenge "Music Code — Part 1"  

  By: admin on March 23, 2011, 2:02 p.m.

A piece of music is given as mp3 file and in music notation. The notes represent a secret message, which was encrypted with two classic methods. In part 1 of this challenge you have to solve the first of these methods. Thereafter, you can set out to solve part 2 (which is in level 2).
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 Last edited by: admin on Oct. 31, 2021, 2:54 a.m., edited 1 time in total.

Re: Challenge "Music Code"  

  By: Sven-from-de on April 27, 2011, 1:59 a.m.

Auf S. 10 des Aufgabentextes steht: "Die Anordnung der Klartextzeichen ist dabei allerdings eine andere als beim MTC3-Jingle."

Bedeutet das, dass man die Substitutionstabelle von S. 3 des Aufgabentextes nicht nutzen kann?
Wenn ja, dann hätte man, selbst wenn man die Musiknoten richtig abgelesen und die Transposition gelöst hätte, noch immer eine monoalphabetische Substitution zu lösen.
Das ist bei einer so kurzen Textlänge (105) Zeichen und einem Alphabet von 36 Zeichen doch relativ schwierig, oder?

MfG Sven

Re: Challenge "Music Code - Part 1"  

  By: be on May 25, 2011, 1:01 a.m.

Informationen / Deutsch:
Wir haben die bisherige Challenge "Musik-Code" aus Level 1 entfernt und in zwei Teile aufgesplittet, da die Gesamtlösung für Level 1 zu schwer war. Somit gibt es nun "Music Code - Teil 1" in Level 1 und "Music Code - Teil 2" in Level 2.

Damit kann man auch leichter herausfinden, ob man auf dem richtigen Weg ist.

Für Teil 1 muss man die Noten lesen und die Rück-Transposition durchführen. Für Teil 2 ist danach noch die Rück-Substitution durchzuführen.[/list:u]

Information / English: The former challenge "Music Code" from level 1 was split up into two parts, because performing the whole solution was too heavy as a level 1 challenge. So, now there is "Music Code - Part 1" in level 1 and "Music Code - Part 2" in level 2.

Having the chance to validate the intermediate step of part 1 let you find out, that you are on the right track.

For part 1 you have to read the music notes and perform the backward transposition. For part 2 you then have to perform the backward substitution.[/list:u]

Re: Challenge "Music Code"  

  By: be on May 28, 2011, 3:37 p.m.

Wenn ja, dann hätte man, selbst wenn man die Musiknoten richtig abgelesen und die Transposition gelöst hätte, noch immer eine monoalphabetische Substitution zu lösen.
Das ist bei einer so kurzen Textlänge (105) Zeichen und einem Alphabet von 36 Zeichen doch relativ schwierig, oder?

Ja, der zweite Teil der Aufgabe ist die Lösung eines relativ kurzen Textes, der mit einer monoalphanetischen Substitution verschlüsselt wurde. Aber es ist ein "typischer" deutscher Text, und m.H. der Hinweise am Ende der Aufgabe kann man die Aufgabe lösen – auch ohne Brute-force-mäßig vorzugehen.

Re: Challenge "Music Code"  

  By: smai on May 30, 2011, 11:16 p.m.

Wenn ja, dann hätte man, selbst wenn man die Musiknoten richtig abgelesen und die Transposition gelöst hätte, noch immer eine monoalphabetische Substitution zu lösen.
Das ist bei einer so kurzen Textlänge (105) Zeichen und einem Alphabet von 36 Zeichen doch relativ schwierig, oder?

Ja, der zweite Teil der Aufgabe ist die Lösung eines relativ kurzen Textes, der mit einer monoalphanetischen Substitution verschlüsselt wurde. Aber es ist ein "typischer" deutscher Text, und m.H. der Hinweise am Ende der Aufgabe kann man die Aufgabe lösen – auch ohne Brute-force-mäßig vorzugehen.

Anmerkung: Sven-from-de hat diesen Kommentar vor der Aufspaltung des Rätses in zwei Teile geschrieben.

Re: Challenge "Music Code - Part 1"  

  By: fretty on June 23, 2011, 11:53 p.m.

Ok so I have had one attempt so far. I have a question though.

The accepted solution is all 105 values in order, after reversing the transposition. Surely if this is the case then the way of including the key in the music, as mentioned in the slides, does not hold here since those notes would also be part of the 105 values yet nothing to do with the plaintext?

Does this mean that the transposition key is nothing to do with the notes at all in this instance and is JUST to do with the title of the piece?

I tried the obvious thing with the key (using the numerical values as a column transposition key, backwards from the description in the slides) but didnt get the OK (although in practice I have no idea how you would know that this particular output is "wrong"). Is it possible to have a hint on what to do with the numbers in the title?

Re: Challenge "Music Code - Part 1"  

  By: be on June 24, 2011, 7:05 p.m.

The accepted solution is all 105 values in order, after reversing the transposition.
Does this mean that the transposition key has nothing to do with the notes at all in this instance and is JUST to do with the title of the piece?

Hello,

English:

  • Yes, part 1 requires only to reverse the transposition of the notes.
  • Yes, the transposition key is within the words in the title.
    I guess this is a hint good enough as some of you already had the correct idea developed by themselves.

German:

  • Ja, in Teil 1 ist nur die Transposition der Notenbezeichner rückgängig zu machen.
  • Ja, der Transpositionsschlüssel steckt in den Worten des Titels. Ich denke, das reicht als Hinweis, denn einige andere Teilnehmer sind damit auch selbst auf die richtige Idee gekommen.

Have fun and best regards, BE (by proxy of the author)

Re: Challenge "Music Code - Part 1"  

  By: fretty on June 25, 2011, 12:11 a.m.

Ok, I was a little confused since in the slides it says that the transposition key is always hidden in the music itself. Now that I know that this is not the case in this instance, I can get cracking with the title (i've tried two obvious ways of using it already with no luck).

Re: Challenge "Music Code - Part 1"  

  By: fretty on July 15, 2011, 10:40 a.m.

Can someone check my previous attempts at this? I think I am doing the right thing but fear I have made a slight error in my entry.

There is no way to know whether a given answer is correct for this challenge before you enter it (unless you break stage 2 first before stage 1).

Re: Challenge "Music Code - Part 1"  

  By: DarkFibre on July 15, 2011, 6:59 p.m.

Can someone check my previous attempts at this? I think I am doing the right thing but fear I have made a slight error in my entry.

There is no way to know whether a given answer is correct for this challenge before you enter it (unless you break stage 2 first before stage 1).

I'm at the same point. I've been attacking stage 2 in the hopes it will help me find my typo in stage 1, but I'm stuck there, too, so now my plan is to get a musician friend to double check my work on stage 1. First the naturals screwed me up, but now I think my durations are off. Or I am just transposing wrong…

Re: Challenge "Music Code - Part 1"  

  By: fretty on July 16, 2011, 12:16 a.m.

Well I know how to read music and I am sure that I have got the durations and accidentals correct etc, I just have no clue how to use the title of the piece of music to perform the transposition (other than in the obvious way, which I am sure you have tried too).

Maybe we can collaborate on this via PM?

Re: Challenge "Music Code - Part 1"  

  By: alanduring on July 17, 2011, 6:30 p.m.

Maybe we can collaborate on this via PM?

OK (author)

Re: Challenge "Music Code - Part 1"  

  By: fretty on July 17, 2011, 6:39 p.m.

All is solved now!

I just made a few silly errors and used the title in the wrong way (it really is not the obvious use).

Re: Challenge "Music Code - Part 1"  

  By: Veselovský on Aug. 10, 2011, 2:50 a.m.

I think that this challenge is not for testing your skills in decryption but for testing your skills in correcting errors made by an author of a cypher himself.
(in real life very common especially for some older cypher-texts when people didn't have computers)

I suspect that reversing a transposition should be done in the other way than it is actually described in "pdf" file.

Notes from music sheet should be firstly put in columns with an ordered sequence of notes (or numbers from the title) and then change the order of columns according to the original sequence of numbers in the title and not the other away. That is how it is described in "pdf".

I have done it both ways and still it is wrong.
I've got a very good tip for next challenge… the title would be "Crack this RSA encryption" but in description file there would be a cypher-text encrypted by Caesar Cipher :-DDD … I'm not sure if there is such a level of difficulty on this web ;-)

Re: Challenge "Music Code - Part 1"  

  By: Veselovský on Aug. 10, 2011, 7:48 a.m.

I managed to do it by myself. I am proud :-)
It wasn't a mistake of an author, but mine. My apologies.

…I just haven't checked all possibilities of the title that it can be understood…


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