User talk:Holly Eskew
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Data Encryption Standard (DES) v. Vernam Cipher
The Cipher of Ché Guevara: When in 1967 the Bolivian army captured and executed the revolutionary Ché Guevara, they found on his body a worksheet showing how he prepared a message for transmission to Cuban president Fidel Castro. Guevara used the unbreakable cipher invented by Gilbert Vernam in 1918. The letters of Guevara's message (in Spanish) were first translated into one- and two-digit decimal numbers by a fixed rule, namely: A6 E8 I39 M70 Q71 U52 Y1 B38 F30 J31 N76 R58 V50 Z59 C32 G36 K78 O9 S2 W56 D4 H34 L72 P79 T0 X54. By itself this procedure would have provided virtually no protection. The message digits were then strung together in convenient five-digit blocks. They became the top line of each three-line group on the worksheet. The middle line of each group is the key, a sequence of random digits known only to Guevara and Castro.
Next the message and key were added (without carries) to produce a cryptogram, forming the bottom line of each three-line group. Because of the addition of the random key digits, this cryptogram is itself a random decimal sequence, carrying no information about the original message, except to someone who know the key. The cryptogram was then transmitted to Cuba by an insecure channel such as shortwave radio. At the receiving end, Castros cipher office would have subtracted the same random key digits, reconstructing the number sequence in the top row, and then would have translated the numbers back into the letters of the message.
Many spies and diplomats have used the Vernam cipher throughout the 20th century. The key, rather than consisting of decimal digits, can be a long random sequence of the binary digits 0 and 1, and the additions and subtractions would be carried out in base 2 by machine, rather than in base 10 by hand. Nevertheless, the key must still be hand-carried from the place where it is generated to the places where it will be used, and it must be assiduously guarded during all phases of delivery and storage to prevent it from falling into the hands of an adversary.
Further Reading: THE CODEBREAKERS: THE STORY OF SECRET WRITING. David Kahn. Macmillian, 1967 MODERN CRYPTOLOGY: A TUTORIAL. Gilles Brassard in Lecture Notes in Computer Science, Vol. 325. Springer-Verlag, 1988. QUANTUM CRYPTOGRAPHY BASED ON BELLS THEOREM. Arthur K. Ekert in Physical Review Letters, Vol. 67, No. 6, pages 661-663; August 5, 1991. EXPERIMENTAL QUANTUM CRYPTOGRAPHY. Charles H. Bennett, Francois Bessette, Gilles Brassard, Louis Salvail and John Smolin in Journal of Cryptology, Vol. 5, No. 1, pages 3-28; 1992. QUANTUM CRYPTOGRAPHY WITHOUT BELLS THEOREM. Charles H. Bennett, Gilles Brassard and N. David Mermin in Physical Review Leters, Vol. 68, No. 5, pages 557-559; February 3, 1992.
[edit] an attempt to build a comprehensive and detailed guide to cryptography in the Wikipedia
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[edit] Quartz Cryptography
Quartz (cryptography), the name of a public-key cryptography signature scheme:
[edit] Points to remember
Variables refer to data and may need to be declared before being defined. Data comes in many types and the operations you can successfully perform will depend on the type of data you are using. Simple data types include character strings, numbers, Boolean or 'truth' values. Complex data types include collections, files, dates and user defined data types. There are many operators in every programming language and part of learning a new language is becoming familiar with both its data types and the operators available for those types. The same operator (e.g. addition) may be available for different types, but the results may not be identical, or even apparently related!
Dictionary or Hash In the same way that a literal dictionary associates a meaning with a word a dictionary type contains a value associated with a key, which may or may not be a string. The value can be retrieved by ?indexing? the dictionary with the key. Unlike a literal dictionary, the key doesn?t need to be a character string (although it often is) but can be any immutable type including numbers and tuples. Similarly the values associated with the keys can have any kind of data type. Dictionaries are usually implemented internally using an advanced programming technique known as a hash table. For that reason a dictionary may sometimes be referred to as a hash. This has nothing to do with drugs! :-)
Because access to the dictionary values is via the key, you can only put in elements with unique keys. Dictionaries are immensely useful structures and are provided as a built-in type in Python although in many other languages you need to use a module or even build your own. We can use dictionaries in lots of ways and we'll see plenty examples later, but for now, here's how to create a dictionary in Python, fill it with some entries and read them back:
>>> dct = {} >>> dct['boolean'] = "A value which is either true or false" >>> dct['integer'] = "A whole number" >>> print dct['boolean'] A value which is either true or false Notice that we initialize the dictionary with braces, then use square brackets to assign and read the values.
Just as we did with lists we can initialize a dictionary as we create it using the following format:
>>> addressBook = { ... 'Fred' : ['Fred', '9 Some St',' Anytown', '0123456789'], ... 'Rose' : ['Rose', '11 Nother St', 'SomePlace', '0987654321'] ... } >>> The key and value are separated by a colon and the pairs are separated by commas. This time we have made our address book out of a dictionary which is keyed by name and stores our lists as the values. Rather than work out the numerical index of the entry we want we can just use the name to retrieve all the information, like this:
>>> print addressBook['Rose'] ['Rose', '11 Nother St', 'SomePlace', '0987654321'] >>> print addressBook['Fred'][3] 0123456789 In the second case we indexed the returned list to get only the telephone number. By creating some variables and assigning the appropriate index values we can make this much easier to use:
>>> name = 0 >>> street = 1 >>> town = 2 >>> tel = 3 And now we can use those variables to find out Rose's town:
>>> print addressBook['Rose'][town] SomePlace Notice that whereas 'Rose' was in quotes because the key is a string, the town is not because it is a variable name and Python will convert it to the index value we assigned, namely 2. At this point our Address Book is beginning to resemble a usable database application, thanks largely to the power of dictionaries. It won't take a lot of extra work to save and restore the data and add a query prompt to allow us to specify the data we want. We will do that as we progress through the other tutorial topics.
Due to their internal structure dictionaries do not support very many of the collection operators that we?ve seen so far. None of the concatenation, repetition or appending operations work. To assist us in accessing the dictionary keys there is an operation that we can use, keys(), which returns a list of all the keys in a dictionary. For example to get a list of all the names in our address book we could do:
>>> print addressBook.keys() ['Fred','Rose'] Note however that dictionaries do not store their keys in the order in which they are inserted so you may find the keys appear in a strange order, indeed the order may even change over time. Don't worry about that, you can still use the keys to access your data and the right value will still come out OK.
[[1]] --Hols 15:53, 30 September 2005 (UTC)
[edit] olmedia
Rare n. Same as ʻōʻū-holo-wai-o-Laʻa. (For. 5:565.) ʻō,ʻū-holo-wai PPN hoʻoku. ʻō.kū
n.v. Live bird used as decoy; to decoy. Rare
[edit] ♦
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[edit] speech
holly Kāwaʻu, ʻaiea.
[edit] symbols that represent whole words or vowl sounds that have meaning
h holly Kāwaʻu, ʻaiea.
[edit] Template:H:h
in Deaf community, there is a distinction between the "D" and little d. Big "D" is for cultural style and little "d" is physical.
Big "H" is indincation for breathing!
<<adduser vds1>>
[edit] cyrpto-standards are changing, code talk is too; symbols tare taking over
DATA ENCRYPTION STANDARD (DES) v. VERNAM CIPHER
