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<b>Cryptopgraphy</b>"The science of altering communication so that it cannot be understood without the key.
pg 5"
<b>Cryptography Origins</b>"Derived from Kryptos which means ""Hidden"" and Grafo which means ""Write"". The study of message secrecy."
<b>Truncated</b>Shortened in Duration or Extent.
<b>Integer</b>Whole Number.<br>
<b>Cipher</b>Algorithm Used for Encrypting and Decrypting.
<b>S - Box</b>SUbsituition Box
<b>Permutation</b>A way in which a set or number of things can be arranged.
<b>Ciphertext</b>The Encrypted Text.<br>pg 10
<b>Atbash Cipher</b>Hebrew code which substitutes the first letter of the alphabet for the last and the second letter for the second to last.<br>pg 12
<b>Until the latter part of the 20th century, cryptography was almost exclusively used by...</b>Military and Governments.<br>pg 7
<b>Mono-Alaphebet Substitution</b>The most primitive of cryptographic algorithms.<br>pg 9
<b>Mono-Alaphebet Substitution Examples</b><ul><li>Caesar Cipher</li><li>Atbash Cipher</li><li>Affine Cipher</li><li>Rot 13 Cipher</li></ul><div>pg9</div>
<b>Caesar Cipher</b>"<ul><li>First Used by Julius Caesar</li><li>Every letter is shifted to the left or right</li><li>The Shifting is the Key</li><li>The shift is called the ""alphabet""</li><li>One of the oldest encryption methods</li></ul><div>pg 9</div>"
<b>Letter and Word Frequency</b>"<ul><li>Every languaguage has a certain letter and word frequency. Meaning some letters are used more frequently than others</li><li>Most common English letter""A""</li><li>Most Common English word ""The""</li></ul>"
<b>The Caesar Cipher is referred to as a...</b>Moni Alphabet Substitution or Single Alphabet Substitution.<br>pg 10
<b>Frequent single letter word repeated in a text, is most likely...</b>"The letter ""A""<br>pg 10"
<b>The same 3 letter string repeated points to a common word, which would probably be...</b>"""The""<br>pg 10"
<b>The substitution scheme that is chosen is referred to as...</b>Substitution Alphabet<br>pg 10
<b>In the English language, the two most common two letter combinations are...</b>"""EE"" and ""OO""<br>pg 10"
"<b>By discovering the frequent use of the word ""The"" and letter""A"", you have now found the...</b>"Substitution Scheme<br>pg 10
<b>Mono-Alphabet substitution and Single Alphabet substitution means that all...</b>Letters in the Plaintext will be shifted by the same amount.<br>pg 10
<b>AES</b>Advanced Encryption Standard<br>pg 10
<b>Affine Cipher</b>Each letter in the alphabet is mapped to some numeric value.<br>pg 13
Affine Cipher Formula = ax + b (mod M)a = Some Multiple<br>x = Plaintext letters numeric equivalent<br>b = The Shift<br>M = The size of the Alphabet<br>pg 13<br>
<b>ROT13</b><ul><li>All characters are rotated 13 characters through the alphabet.</li><li>Essentially a <u>Caesar Cipher</u>&nbsp;that always shifts 13 characters.</li></ul><div>pg 14</div>
<b>Scytale</b>"<ul><li>A physical cylinder that was used to encrypt messages.</li><li>Writer of the message wraps parchment around the rod.</li><li>Recipient uses rod of the same diameter as the one used to create the message.</li><li>Attributed to the Spartans</li></ul><img src=""paste-552cf79c4740aab743d5753437ee2fba08d46da6.jpg""><br>pg 15"
<b>Mono-Alphabet substitution is also known as...</b>Single Substitution (Single Cipher)
<b>Single Substitution (Single Cipher) also known as...</b>Mono - Alphabet Substitution<br>
<b>Single Substitution Weaknesses</b>"<ul><li>Literacy rates have increased</li><li>All languages have letter and word frequency</li><li>Most common letter words: ""The"" ""And""</li><li>Most common single letter words: ""I"" ""A""</li><li>Easy to Brute Force attack</li></ul><div>pg 16</div>"
<b>Multi-Alphabet Subsititution is also known as...</b>Poly - Alphabetic Substitution<br>pg 17
Multi - Alphabet Substitution and Poly -&nbsp; Alphabetic Substitutions use...Multiple Alphabets (Keys)<br><br><b>Examples: </b>First letter shifted +1<br>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;Second letter shifted +2<br>&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;Third letter shifted -1<br>pg 17
<b>Examples of Poly - Alphabetic Substitutions</b><ul><li>Cipher Disck</li><li>Vignere Cipher</li><li>Enigma Machine</li></ul><div>pg 17</div>
<b>Cipher - Disk (1466, Alberti)</b>"<ul><li>A physical device used to encrypt</li><li>Poly - Alphabetic</li><li>A physical disk that was turned and produced a new cipher each turn</li></ul><div><img src=""paste-f46aa4965193b71d38956ad8003c2ec97c965ad2.jpg""><br></div>"
<b>Vignere Cipher</b><ul><li>Most well known Poly - Alphabet Cipher</li><li>Used a series of Mono - Alphabet Ciphers</li><li>Invented in 1553 by Bellaso</li></ul>
<b>Gronsfiled Cipher</b><ul><li>Variant of the Vignere Cipher</li><li>Uses 10 Different Alphabets</li></ul><div>pg 22</div>
<b>Polybius Cipher</b>Each letter is represented by two numbers.<br><br>pg 24
<b>ADFGX Cipher</b><ul><li>Used by Germans in the first World War</li><li>Key for the algorithm is a six - by - six sequence of letters.</li></ul><div>pg 25</div>
<b>Homophonic Substitution</b><ul><li>One of the earliest attempts to make substitution ciphers more robust by <i><u><b>MASKING</b></u></i> letter frequencies.</li></ul><div>pg 26</div>
<b>Null Ciphers</b><ul><li>The message is hidden in unrelated text.</li><li>Sender and recepient have prearranged to use some pattern, taking a certain letters from the message.</li></ul><div>pg 28</div>
<b>Rail Fence Ciphers</b>"<ul><li>Most Widely Known Transposition Cipher</li><li>Take the message that you want to encrypt and alter each letter on a different row.</li><li>""Attackatdawn"" is written as:&nbsp;<img src=""paste-0ccc0eafb93764f87fb6f400e6a3e4141133fa37.jpg"" width=""82""><br></li></ul>&nbsp; &nbsp; &nbsp;pg 29"
<b>One - Time Pad</b>The Plaintext is somehow altered by a random string of data so that the resulting cipher text is truly random.<br><br>pg 29
<b>Vernam Cipher</b>Uses the Binary XOR function<br><br>pg 29
<b>Enigma Machine</b><ul><li>Used by the Germans in World War 2</li><li>Was a Multi - Alphabet system</li><li>Last of the historical ciphers</li></ul><div>pg 30</div>
<b>Allied Cipher Machines During&nbsp; WWII</b><ul><li>American SIGABA</li><li>British TyperX</li></ul><div>pg 30</div>
<b>Cryptool Software</b>Allows you to enter text and choose a Historical algorithm, then encrypt that text.<br><br>pg 32
<b>Playfair Cipher (Named after Lord Playfair</b><ul><li>Invented in 1851 by Wheatston</li><li>More complex than most Historical Ciphers. Encrypts two letters&nbsp; rather than one.</li><li>Uses a 5 by 5 table</li><li>No more secure than other classic ciphers such as vignere</li><li>Complexity does not equal security</li></ul><div>pg 34</div>