This is a really good short video intro to Cryptography:
https://www.youtube.com/watch?v=-yFZGF8FHSg
It is a well-produced video that hits on a lot of the basic points really effectively.
Thanks d!
This will be very helpful to many–myself included. 
“…they may be dealing with one or more ersatz Zodiacs–other psychotics eager to get into the act, or perhaps even other murderers eager to lay their crimes at the real Zodiac’s doorstep.“ L.A. Times, 1969
I have a couple of questions if you or someone else knowledgeable of cryptography wont mind answering.
The first: What catagory would the cipher in this link http://www.wsj.com/articles/SB124648494429082661 fall under? Frankly, and this comes from someone who knows nothing about ciphers, I feel this is about in line with Jarvles question of FBI tactics regarding the 340 when speaking of columns and shifting lines.
Second: The 340 cipher has a couple sets of symbols a distance apart from one another. An example would be fby. What would the distance say, if anything, about the keyword length?
Third: what cipher types work with keywords and diagonal tactics?
Oh and thank you for providing the link to the YouTube video concerning cryptography.
Soze
I have a couple of questions if you or someone else knowledgeable of cryptography wont mind answering.
The first: What catagory would the cipher in this link http://www.wsj.com/articles/SB124648494429082661 fall under? Frankly, and this comes from someone who knows nothing about ciphers, I feel this is about in line with Jarvles question of FBI tactics regarding the 340 when speaking of columns and shifting lines.
Looks like a type of simple transposition combined with some "flavors". The "key" is a numerical sequence, repeated 3 times. The numbers represent the order in which the lines of cipher are rearranged. When you rearrange the lines, you then read the plaintext from top to bottom. But also, each line starts with some number of random letters, so you really can’t read the plaintext from top to bottom unless you first remove the filler.
Here are some clippings of the American Scientist article which goes into more details on the cipher to Jefferson:
https://www.evernote.com/shard/s1/sh/cd … cd9b8f0910
Thank you for the reply and for the link to the write up on Jeffersons cipher. I will certainly look at it.
Soze
I’m sorry. I don’t mean to take over your "intro to cryptography" and literally make it an "intro to cryptography" but I am finding myself with more questions.
First, is it necessary for a cipher type like I linked to above, require random characters at the start? Could they be in the middle, end or spread out?
Secondly, I looked up transposition cipher (partially. Not finished reading), noticed permutation and the example given, and wondered if the punctuation after the word "thing" in card could be an indication to the order of columns (2, 3, 1)? Meaning true cipher length being at most 6 across with 10 symbols being random?
Is this wrong thinking and if so why?
Soze
Correction: 11. Cipher is 17 by 20 is it not.
First, is it necessary for a cipher type like I linked to above, require random characters at the start? Could they be in the middle, end or spread out?
It depends. I think that the more complicated the enciphering process, the harder the result is to decrypt (generally speaking). Especially if there is more randomness in the key. Patterson’s cipher to Jefferson was kind of unique – I’m not sure if anyone else adopted that particular technique, so it may not be well-studied. At any rate, it is vulnerable to modern attacks because the guy who broke it ran a computer program that could do the thousands of computations needed to recover the key. I’d guess that changing the location of random characters would increase the difficulty of those computations.
Secondly, I looked up transposition cipher (partially. Not finished reading), noticed permutation and the example given, and wondered if the punctuation after the word "thing" in card could be an indication to the order of columns (2, 3, 1)? Meaning true cipher length being at most 6 across with 10 symbols being random?
I suppose it’s possible. Others have tried numerous permutations of columnar transposition but I don’t think anyone has tried the system used in the cipher to Jefferson. My hunch is that it’s unlikely Zodiac used such a system since it was unique to Patterson. I’m not sure if that system ever appeared in any cryptology literature that Zodiac may have had access to, meaning he would have had to re-invent that system on his own.
