Domain 3 - Security Engineering Flashcards
Twofish
A symmetrical cryptography algorithm adapted from Blowfish and uses up to 256 bit keys on 128 bit blocks. It was a finalist for AES.
Blowfish
A symmetrical cryptography algorithm developed by Bruce Schneier that is very fast and memory efficient. It is a Festal-type cipher that divides the input blocks into halves and then uses them in XORs against each other. Key sizes up to 448 bits on 64 bit blocks.
CAST
A symmetrical cryptography algorithm developed by Carlisle Adams and Stafford Tavares. CAST-128 is a Feistal-type block cipher with 64 bit blocks. CAST-256 was an unsuccessful candidate for AES.
Secure and Fast Encryption Routine (SAFER)
A symmetrical cryptography algorithm with all internally used algorithms being patent-free. Block cipher with 64 or 128 bit blocks.
International Data Encryption Algorithm (IDEA)
A symmetrical cryptography algorithm developed as a replacement for DES and uses 128 bit keys on 64 bit blocks.
RC5
A symmetrical cryptography algorithm developed by Ron Rivest of RSA. Keys can vary from 0 to 2040 bits, rounds can adjust from 0 to 255 and input blocks can be 16, 32 or 64 bits.
It has 4 modes of operation:
RC5 - block cipher mode similar to DES ECB
RC5-CBC - cipher block chaining mode
RC5-CBC-Pad - Similar to CBC but can handle any length of plaintext input
RC5-CTS - cipher text stealing will generate cipher text equal in length to plain text for any length
RC4
A symmetrical cryptography algorithm developed by Ron Rivest and is stream-based. Key lengths of 8 to 2048 bits. No current, practical ways to attack. WEP cracks using RC4 are related to implementation issues rather than algorithm.
Null Cipher
An option used to tell the encryption system to not use any cipher.
Substitution Cipher
Simple substitutes one letter for another. Caesar cipher and ROT-13 are examples.
Playfair Cipher
A substitution cipher where an agreed on keyword is written into a 5 by 5 square with the remaining alphabet filling the latter slots. Message is broken into 2 character groups and rules are followed to use the square to map to 2 character cipher text groups. Allies used heavily in the Second World War.
The Rail Fence
A transposition cipher that writes plain text into diagonal lines across two or more rows. The cipher text is simply the new rows appended in order.
Rectangular Substitution Tables
A transposition cipher that writes plain text into an agreed upon grid size with the cipher text created in an agreed upon method i.e. columns first to last, top to bottom.
Monoalphabetic Cipher
A simple substitution cipher that uses one mapping between plain text and cipher text characters. Caesar cipher is an example that offset the alphabet by 3 letters.
Polyalphabetic Cipher
A substitution cipher that uses more than one mapping between plain text and cipher text characters. For example, four alphabets could be used switching between them in order for each character of plain text. Designed to make frequency analysis more difficult.
Blais de Vigenere Cipher
A polyalphabetic cipher that uses 26 alphabets with each one offset by one place. An agreed upon keyword is used to determine which alphabet is used for each position in the text.
Bell-LaPadula Model
Originally developed for the U.S. Department of Defense. It is focused on maintaining the confidentiality of objects.
Bell-LaPadula - Simple Security Property
“No read up”: a subject at a specific classification level cannot read an object at a higher classification level. Subjects with a Secret clearance cannot access Top Secret objects, for example.
Bell-LaPadula - Security Property
“No write down”: a subject at a higher classification level cannot write to a lower classification level. For example, subjects who are logged into a Top Secret system cannot send emails to a Secret system.
