ANALOG Computing Code Cracking Contest of 1984

[itaych]

Hi all,

 

In ANALOG Computing issues 24-26 (Nov.84-Jan.85) the following announced appeared:

 

Here's a little contest that should keep all the code-crackers out there occupied.
The numbers below, when decoded, are a message in standard Atari ASCII. The numbers are in the proper sequence, and have been encrypted using a simple algorithm.

145 211 145 185 255 186 112 88
183 174 224 34 145 126 226 178
51 207 191 129 188 234 4 191
199 175 178 243 197 16 118 43
210 198 166 241 237 194 211 94
213 171 252 246 233 178 12 218
210 203 172 129 133 219 23 186
206 170 203 141 126 246 117 203
190 250 212 206 22 160 197 161
182 183 246 20 53 141

 

The prize offered to the first five correct entries was a free one-year cassette or disk subscription.

 

The deadline for submitting a solution was January 1 and yet the correct answer was not published in the forthcoming issues. Only when a reader inquired about the matter did the magazine respond, half a year later in issue 32 (July 85):

 

The answer to the code cracker contest is

 

"Behind every good programmer there stands an Atari computer. Congratulations!"

 

Don't feel too bad; no one figured it out.

 

Interestingly the magazine never explained what the encryption scheme was. Can anybody figure it out?

[devwebcl]

in which page of Nov.84 is it ?

[+thegoldenband]

Interesting. Am I reckoning correctly that there are 77 characters in the message, but 78 numbers?

 

Statistically there's a strong skew towards numbers higher than %10000000, which suggests a Boolean NOT or something similar, but having $FF early in the message is a curveball. The double letter isn't evident in the encrypted text. Maybe (probably?) the compression algorithm is somehow encoding the delta between adjacent values/letters, but something else is happening to keep it from being patterned.

[Shawn Jefferson]

There might actually be two spaces after the period, making the cipher text the same length as the clear text.

[itaych]

in which page of Nov.84 is it ?

Page 76. May I suggest obtaining the PDF version and using the search capabilities of your favorite reader

[devwebcl]

Page 76. May I suggest obtaining the PDF version and using the search capabilities of your favorite reader

 

hahahaha, actually I thought these PDFs were jpegs into that format, and weren't text searchable lol.

[Roydea6]

 

My look at Analag.

[itaych]

I found the following to be true, unfortunately neither is enough to establish a pattern.

 

cleartext[0] = cypher[0] XOR cypher[1]

 

and also

 

cleartext[0] = abs(cypher[0] - cypher[1])

 

Also, if cleartext is a result of some computation involving cypher and cypher[i+1] then that would explain why the cypher is one character longer than the cleartext.

[ClausB]

The cypher is probably full of typos, if they did to it what they did to my article.

[devwebcl]

The cypher is probably full of typos, if they did to it what they did to my article.

what is your article ?

[ClausB]

http://atariage.com/forums/topic/130940-article-transporting-atari-computer-programs-to-the-5200/?do=findComment&comment=1580189

[kenjennings]

"...I sent them a clean printout and a floppy disk with the proofread article in some Atari format. They said they could not convert the disk to their typesetter so they manually retyped it and filled it full of typos. ..."

 

An Atari magazine couldn't handle the contents of a disk of Atari material. If they had a format preference they could have asked if you could rework it yourself. It's all so scary.

 

Could be worse, I guess. At least their binary program hex dumps usually typed in and worked as advertised.