7 ms·

The solitaire encryption algorithm (1999)

68 points by MindTwister 14y ago

kragen 14y ago
It's been 13 years. Has there been any cryptoanalysis? I can't tell if the problem Paul Crowley found in http://www.ciphergoth.org/crypto/solitaire/ http://www.ciphergoth.org/crypto/solitaire/ is sufficient to sink it.
- gchpaco 14y ago
  A biased RNG for a stream cipher is very difficult to recover from.
  - kragen 14y ago
    What's the effect in practice? I don't know shit about cryptanalysis.
    - gchpaco 14y ago
      Unless the data is random (which is to say the additional layer of crypto is probably not buying you much) you can do e.g. frequency analysis on the output of the cipher. If you have a reasonable sized corpus (given how biased the PRNG is, probably a few thousand characters is overkill) you can probably break it effortlessly.
BMarkmann 14y ago
Cryptonomicon is a great book, btw. It was definitely the one that got me heavily into Neal Stephenson. http://en.wikipedia.org/wiki/Cryptonomicon http://en.wikipedia.org/wiki/Cryptonomicon
- crikli 14y ago
  I hadn't known that Bruce Schneier created Pontifex for the book as I didn't know who he was back in the 90's. Kinda neat to circle back to an old favorite and learn that someone with whom you've become familiar since the last read contributed a key plot point.
jsomers 14y ago
Here's a little Ruby implementation I wrote a while back: https://github.com/jsomers/solitaire https://github.com/jsomers/solitaire. I hope it's correct...
- michael_michael 14y ago
  Neat. Creating a Ruby implementation of the solitaire cipher was also problem #1 in the Ruby Quiz: http://www.rubyquiz.com/quiz1.html http://www.rubyquiz.com/quiz1.html
laumars 14y ago
This sounds a lot like OTP (One Time Pads) which is more than 100 years old and was even used, with great success, during WWII. http://en.wikipedia.org/wiki/One-time_pad http://en.wikipedia.org/wiki/One-time_pad
- opminion 14y ago
  It's a Stream Cipher, which is an approximation [1] of a One Time Pad, which allows the key to be much shorter than the plaintext. The hardest part is how to generate the pad from the key. [1] http://en.wikipedia.org/wiki/Stream_cipher#Loose_inspiration_from_the_one-time_pad http://en.wikipedia.org/wiki/Stream_cipher#Loose_inspiration...
- deleted 14y ago
  [deleted]
B-Con 14y ago
I remember writing the bulk of the Wikipedia article[1] on this cipher back in my late teens when I was getting into crypto. Checking back, it's been heavily edited, but it retains the bulk of the original structure and all of the original example that I used. Kinda neat. [1]: http://en.wikipedia.org/wiki/Solitaire_%28cipher%29 http://en.wikipedia.org/wiki/Solitaire_%28cipher%29
krakensden 14y ago
I remember reading Cryptonomicon in high school, and being fascinated and terrified by the Perl implementation of this in the book. It was a perfectly rectangular, quarter page quote, with no spaces and a terrifying proliferation of sigils.
- deleted 14y ago
  [deleted]
- sesqu 14y ago
  #!/usr/bin/perl -s $f=$d?-1:1;$D=pack('C*',33..86);$p=shift; $p=~y/a-z/A-Z/;$U='$D=~s/(.*)U$/U$1/; $D=~s/U(.)/$1U/;';($V=$U)=~s/U/V/g; $p=~s/[A-Z]/$k=ord($&)-64,&e/eg;$k=0; while(<>){y/a-z/A-Z/;y/A-Z//dc;$o.=$_}$o.='X' while length ($o)%5&&!$d; $o=~s/./chr(($f*&e+ord($&)-13)%26+65)/eg; $o=~s/X*$// if $d;$o=~s/.{5}/$& /g; print"$o\n";sub v{$v=ord(substr($D,$_[0]))-32; $v>53?53:$v} sub w{$D=~s/(.{$_[0]})(.*)(.)/$2$1$3/} sub e{eval"$U$V$V";$D=~s/(.*)([UV].*[UV])(.*)/$3$2$1/; &w(&v(53));$k?(&w($k)):($c=&v(&v(0)),$c>52?&e:$c)}
dllthomas 14y ago
I'd love to see another pass at this. I've frequently got a deck of cards on me, and a 225 bit key isn't bad for a symmetric algorithm; the question is how to extract it smoothly and easily...
dav 14y ago
Manchurian Candidate!
daniel-cussen 14y ago
I bought a set of Dungeons and Dragons dice (the set that has dice ranging from 4 to 20 faces) and coded up a Lisp program that turned a roll of 5 of these dice (approx. 16.4 bits of information) into 16 bits (sometimes you have to re-roll). With four rolls I have enough data to seed Lisp's 64-bit PRNG, which was my goal. After all, I use (random x) a whole lot. http://dcussen.posterous.com/my-first-toy-in-lisp-was-random-x http://dcussen.posterous.com/my-first-toy-in-lisp-was-random...

68 points by MindTwister 14y ago

It's been 13 years. Has there been any cryptoanalysis? I can't tell if the problem Paul Crowley found in http://www.ciphergoth.org/crypto/solitaire/ http://www.ciphergoth.org/crypto/solitaire/ is sufficient to sink it.

gchpaco 14y ago
A biased RNG for a stream cipher is very difficult to recover from.
- kragen 14y ago
  What's the effect in practice? I don't know shit about cryptanalysis.
  - gchpaco 14y ago
    Unless the data is random (which is to say the additional layer of crypto is probably not buying you much) you can do e.g. frequency analysis on the output of the cipher. If you have a reasonable sized corpus (given how biased the PRNG is, probably a few thousand characters is overkill) you can probably break it effortlessly.

BMarkmann 14y ago

Cryptonomicon is a great book, btw. It was definitely the one that got me heavily into Neal Stephenson. http://en.wikipedia.org/wiki/Cryptonomicon http://en.wikipedia.org/wiki/Cryptonomicon

crikli 14y ago
I hadn't known that Bruce Schneier created Pontifex for the book as I didn't know who he was back in the 90's. Kinda neat to circle back to an old favorite and learn that someone with whom you've become familiar since the last read contributed a key plot point.

jsomers 14y ago

Here's a little Ruby implementation I wrote a while back: https://github.com/jsomers/solitaire https://github.com/jsomers/solitaire. I hope it's correct...

michael_michael 14y ago
Neat. Creating a Ruby implementation of the solitaire cipher was also problem #1 in the Ruby Quiz: http://www.rubyquiz.com/quiz1.html http://www.rubyquiz.com/quiz1.html

laumars 14y ago

This sounds a lot like OTP (One Time Pads) which is more than 100 years old and was even used, with great success, during WWII. http://en.wikipedia.org/wiki/One-time_pad http://en.wikipedia.org/wiki/One-time_pad

opminion 14y ago
It's a Stream Cipher, which is an approximation [1] of a One Time Pad, which allows the key to be much shorter than the plaintext. The hardest part is how to generate the pad from the key. [1] http://en.wikipedia.org/wiki/Stream_cipher#Loose_inspiration_from_the_one-time_pad http://en.wikipedia.org/wiki/Stream_cipher#Loose_inspiration...
deleted 14y ago
[deleted]

B-Con 14y ago

I remember writing the bulk of the Wikipedia article[1] on this cipher back in my late teens when I was getting into crypto. Checking back, it's been heavily edited, but it retains the bulk of the original structure and all of the original example that I used. Kinda neat. [1]: http://en.wikipedia.org/wiki/Solitaire_%28cipher%29 http://en.wikipedia.org/wiki/Solitaire_%28cipher%29

krakensden 14y ago

I remember reading Cryptonomicon in high school, and being fascinated and terrified by the Perl implementation of this in the book. It was a perfectly rectangular, quarter page quote, with no spaces and a terrifying proliferation of sigils.

deleted 14y ago
[deleted]
sesqu 14y ago
#!/usr/bin/perl -s $f=$d?-1:1;$D=pack('C*',33..86);$p=shift; $p=~y/a-z/A-Z/;$U='$D=~s/(.*)U$/U$1/; $D=~s/U(.)/$1U/;';($V=$U)=~s/U/V/g; $p=~s/[A-Z]/$k=ord($&)-64,&e/eg;$k=0; while(<>){y/a-z/A-Z/;y/A-Z//dc;$o.=$_}$o.='X' while length ($o)%5&&!$d; $o=~s/./chr(($f*&e+ord($&)-13)%26+65)/eg; $o=~s/X*$// if $d;$o=~s/.{5}/$& /g; print"$o\n";sub v{$v=ord(substr($D,$_[0]))-32; $v>53?53:$v} sub w{$D=~s/(.{$_[0]})(.*)(.)/$2$1$3/} sub e{eval"$U$V$V";$D=~s/(.*)([UV].*[UV])(.*)/$3$2$1/; &w(&v(53));$k?(&w($k)):($c=&v(&v(0)),$c>52?&e:$c)}

dllthomas 14y ago

I'd love to see another pass at this. I've frequently got a deck of cards on me, and a 225 bit key isn't bad for a symmetric algorithm; the question is how to extract it smoothly and easily...

dav 14y ago

Manchurian Candidate!

daniel-cussen 14y ago

I bought a set of Dungeons and Dragons dice (the set that has dice ranging from 4 to 20 faces) and coded up a Lisp program that turned a roll of 5 of these dice (approx. 16.4 bits of information) into 16 bits (sometimes you have to re-roll). With four rolls I have enough data to seed Lisp's 64-bit PRNG, which was my goal. After all, I use (random x) a whole lot. http://dcussen.posterous.com/my-first-toy-in-lisp-was-random-x http://dcussen.posterous.com/my-first-toy-in-lisp-was-random...