Colossus Cipher Challenge Winner On Ada

An anonymous reader writes "Colossus Cipher Challenge winner Joachim Schueth talks about why he settled on Ada as his language of choice to unravel a code transmitted from the Heinz Nixdorf Museum in Germany, from a Lorenz SZ42 Cipher machine (used by the German High Command to relay secret messages during the World War II). 'Ada allowed me to concisely express the algorithms I wanted to implement.'"

Comparison with Allies cypher machine

I wonder how easy it would be to break the Allies corresponding machine, the SIGABA (http://www.quadibloc.com/crypto/ro0205.htm). It was stated that during WWII, the Lorenz machine was broken, but the SIGABA wasn't. Of course, given 60 years of computer improvements, it might be possible to break the SIGABA, now.

Re:Comparison with Allies cypher machine

Here's a recent cryptanalysis of SIGABA:

http://www.sjsu.edu/mscs/research/projects/chan_wing-on.pdf [sjsu.edu]

In normal use, it appears to have had a keyspace of about 48 bits, which is not easy to attack now with a modest distributed effort, but way out of the reach of WWII technology.

However, a variant of the machine used for communication between the US President and British PM had an effective keyspace of 95+ bits, which (if you have access to some known plaintext) can be reduced to 86 bits, which although shorter than key lengths in common use today is still out of reach.

Type Casting

For those that know the differences in Ada, its a very strongly typed language which makes it harder for a beginning programmer to pickup. It doesn't allow for type conversion and pretty much enforces strict coding rules. It would make sense that he used this since he would have complete control over what his code did exactly. This wouldn't be the case with java or other languages which allow type conversions easily, which is nice for alot of people, but can definitely lead to issues when not accounted for.

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> It doesn't allow for type conversion

It does (unchecked_conversion), but never (AFAIK) *implicitly*.

You couldn't BE more wrong

As someone whose first programming language was Ada, and who knows of several universities around the same time who chose Ada as a teaching language, I can say with certainty that you are completely wrong.

First off those strict rules help you because you spend miles less time debugging stuff you don't understand, once it compiles it will tend to run and the compiler gives helpful messages about what you are doing wrong (often including suggestions on how to fix it). With Java, and especially C and C++, let alone scripting languages the beginner spends much more time debugging non-operational code than writing the code in the first place. This tends to mean that these people focus on "getting an executable" rather than "getting it running".

Ada is a brilliant language to teach newbies in (again I've personally done this) as you can explain the abstract concepts and then have the compiler make sure they are doing it right rather than have them say "it compiles but it keeps falling over, why?".

Ada's issues are due to the mentality of lots of (IMO) unprofessional engineers who focus on the number of characters over the operational viability of a system.

And for a final point. Take a look at the complex code the guy wrote, if that was in Java, C, C++, Scala, Ruby, Perl, LISP or what ever do you think that you'd have a chance of understanding it?

I like the choice.

Use a masochistic language to break a German code...groovy.

ADA Resurgence?

Has anyone else started to notice an ADA resurgence? I feel like several years ago the general feeling was "ADA is a backwards language used only on old military projects." Now I read a positive story about ADA every few weeks! Was ADA 2005 that good of a language revision?

Re:ADA Resurgence?

Ada is not a backward language. Ada is a palindrome.

Re:ADA Resurgence?

Ada 2005 is comparatively minor (although some changes, like interfaces, are not that minor). The real improvement was Ada 95. The 95 revision managed to standardize many things that C++/java are now settling.

Ada is not trendy, but it has had built-in portable concurrency and many other killer features for more than a decade. Proper specifications are one of my favs.

Of course there are other factors, like the lack of good and free compilers. Fortunately now the gcc toolchain has put this to rest. Also there are few libraries. Really few. Binding to C is easy, but still a deterrent for the hobbyist.

It's emphasis in making maintenance easy over quick programming really pays in the end, not even in the middle/long term but shortly after getting familiar with the language. I find myself much more productive. When something compiles, I'm sure that the only bugs remaining are logical, not some funny pointer or unexpected type conversion or overflow. Nowadays I rarely fire the debugger more than once a month. My C/C++ has improved because Ada forbids the things that are considered bad practices in C/C++, but you still end doing because "you know better".

I think that Ada is getting now more exposure because, albeit a niche language, Adacore is pushing hard behind it. Also, its SPARK derivative by Praxis has made some headlines with large and difficult projects getting flying marks. SPARK has made static analysis a reality for large projects.

I'd say that anyone capable of discipline will enjoy the benefits of Ada. It's not the thing for quick hacking, but it is perfect for anything not trivial. Software engineers should love it. I have heard somewhere that it is a safe C++, and I concur: feature-wise is more or less on par, it catches bugs sooner and prevents many typical ones.

Have I already said that concurrency is built-in and portable :P? And that inter-thread communication is really well done?

Re:What are the good ones?

Can't give you advice on the PC, but on the Mac, the default compiler is the GNU compiler suite. That's where the C, C++, and Objective-C compilers come from.

The GNU compiler suite also has an ADA compiler (GNAT, GNU Ada Translator). Should be possible to get it and plug it in without much trouble, and then it'd integrate with everything else. Heck, should be possible to include ADA modules into an Objective-C Cocoa application, even.

There is also a GNU FORTRAN, worth checking out. Even today, you can't do mathematics as efficiently in C as you can in FORTRAN. (This is because of the language; in Fortran, taking the address of an existing variable isn't normal, so variables don't end up with the possibility of "aliases" that they don't know about, which means a lot more stuff can safely be done all in registers and stuff like that.)

There is also a GNU Pascal, but unlike ADA and FORTRAN, I'm not personally aware of any reason to actually use it.

Compiler price..

I think that the main reason why Ada has 'lost' to C++ is that some time ago, C++ compiler were either cheap or free whereas Ada compiler were expensive.

Too bad since Ada is 'by default' a language which is more secure than C++..

hmm.

I often wondered at the time if this was a fair test?

I mean the german fellow was near teh transmitting station and got a very good signal and started right away.

Bletchley Park on the other hand, because of the atmospheric conditions did not get a signal until late in the day and started late. On the other hand the german SW took only 46 seconds.

I'm not saying that the german fellow should not of won, he did fair and square - but there seemed to be no mention in much of the news at the time of the receiver issues.

On the plus side, it was excellent publicity for the park and colossus. If only Churchill had not ordered then scrapped then Britain could of led the technological era.

Concise??!!

I can't imagine using the words concise and Ada in the same sentence.

Constricted - maybe. Painful - most certainly.

Re:Concise??!!

I can't imagine using the words concise and Ada in the same sentence.

Perhaps you should read what you just wrote.

other factors often dominate language choice

Like the author of the article, I have a tendency to dabble with a variety of programming languages. I haven't used Ada seriously, but I am intrigued by it, especially in contrast to the looser languages that are currently popular. A lot of bytes have been spilled on the topic of static and dynamic typing, bondage & discipline vs. unit testing, etc. While these discussions often devolve to religious wars, I do think that language matters. Never mind Sapir-Whorf or Turing, some languages are simply more or less pleasurable or powerful for certain tasks.

That said, often the language itself is not the dominant factor in choosing the language. As nice as (Ada | Erlang | Haskell | Lisp | Ruby) is, it's not going to be my first choice if another language has a readily available library that will make it easier to write the program. I can write web applications in Lisp, but I probably won't. There is probably a parser generator for Ada, but I'd rather use Flex and Bison, or maybe ANTLR. And when it comes to my first choice, independent of problem domain, I'll usually pick Python, in part because of its extensive library.

Re:other factors often dominate language choice

Well libraries. That's a huge part of language choices these days; you really choose frameworks or libraries and live with the language as a consequence. A lot of what we do these days is glue stuff together.

This problem, however is a completely different kind of programming. It's old school stuff: building everything you need yourself to run on really slow hardware. And hardware is always slow relative to crypto problems. Ever try to implement RSA encryption from scratch? I have. There's a reason the public key stuff is only used for key exchange.

I think the usefulness of Ada on this kind of problem is related to the issue of testing being costly. When I started in this business, compiling and linking a two hundred line program took about fifteen minutes. Something like unit testing would have been utterly impractical. So a strictly typed language was for nearly everyone a good idea.

Over the last couple of years, I've been trying my hand at a number of difficult algorithmic problems. This is not the stuff that 99% of the programmers in the world do professionally, including me.

Working on these problems was like programming was in the old days. Not only was it just you and the problem with no frameworks to come between, every output becomes a milestone when it takes a program days to generate. It also means that the style of programming is different. You don't worry so much about language restrictions introducing frictional losses into the code/test/recode cycle. You do worry more about mistakes that make it past the compiler.

Ada's philosophy is that coding should be, if not exactly slower certainly more deliberate. If you are running something for which your hardware is monumentally slow, then this is a good style to work in.

Horses for courses

Its not really surprising that he found ADA nicer to use than C for this sort of project because its not the sort of thing C was created for. People seem to think that C was designed as an all purpose programming language - it wasn't. It was specifically designed as a systems programming language that could substitute for assembler 99% of the time. Its abilities lie in low level manupulation of memory and I/O , not in high level mathematics algorithms (though obviously it can do this too).

Then of course C++ came along which wanted to have its cake and eat it and the end result was a nasty mishmash of low and high level constructs which is difficult to learn , unintuitive and generally messy to use.

Re:Let the raging tardfight commence

He should have used a real programming language like Java or VB.Net.

Pffft. Real men write programs like this:

$ cat >/bin/myprogram

Wimp using ASCII

01010111 01101001 01101101 01110000 00100000 01110101 01110011 01101001 01101110 01100111 00100000 01000001 01010011 01000011 01001001 01001001

Re:

Real men use magnetic needle and steady hand.
And don't get me start on real programmers and their in-air-light-refraction-affecting butterflies.

Re:Let the raging tardfight commence

For the most part the language doesn't matter that much. ADA, C, C++, PASCAL, BASIC, LISP... Almost every languge can get the job done. It is just a matter on how well it handles different details. I like Python for its List Processing and Top Down Design. Some people like Visual Basic for its ease in creating good interfaces. Some people like C and C++ because they can control the system at a lower level.
ADA being a government/military based languge I am not to suprised that it won the competition decifering a goverment/military code. (it is more complex then that)

Re:Programmer not langauge.

Well it is more complex then that. Different language syntax can help or hinder someones performance for a particular job. For example old C didn't have much to say in terms of string handling if you wanted to use a string you needed to do a Char *VarName then when working with that languge you need to insure memory managment and that you don't create buffer overflows..... A big pain if you didn't make youself some good String functions you spend a lot of your programming just making sure your program doesn't blow up. vs. Newer Languges And the String class in C++ where you can concatinate get sub strings parse.... it makes doing such job much easier and a lot less anoying. Most well programed languges will not prevent you from getting anything done. However there is the Human element of the equasion if the syntax is to difficult for a particular job then the person will tire out and make more mistakes. The winner of this competition felt that ADA syntax offered him the ability to solve the problem better, thus helped him to win.

I have written Web Apps in FORTRAN 77 just to prove that you can. However I wouldn't say it would be OK to consult a client to do the same, as it really isn't the right tool for the job.

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He should have used Brainfuck [wikipedia.org]!

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Actually most colleges don't want to be typecasted a "C++ school" or an "ADA school". It's more important to learn data structures and theory. If you went to a good school, the language something is written is trivial, learning the syntax should not be tha

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Brian

As a cat once told me, "Anonymous Coward, ur doin it wrong."