Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
13 Cards in this Set
- Front
- Back
|
Breaking DES
|
-Brute Force=2 ^56
-Linear Crypt Analysis=2^43 -Differential Crypt Analysis = 2^47 |
|
|
3DES with 3 keys
|
- 2^168 possible keys
- c= E(K3, D(K2,E( K1,P1))) |
|
|
PGP Encryption
|
-use Symmetric or shared key to Encrypt pay load
-Use Asymmetric key to encrypt the Symmetric Key -Both the above are trasmitted |
|
|
PGP
|
Pretty Good Privacy
|
|
|
issues with 3DES
|
Since 2DES is an encryption with K1 followed by a decryption with K2 can be cracked using "Meet in the middle" attack.
|
|
|
Birthday attack math
|
if we try [1.2 * Sqrt( number of possible occurrences)] times we will get a collision
|
|
|
Dictionary Attack
|
Using a list of most common words as password.
|
|
|
Base64
|
- binary to text encoding scheme
- not a complicated encryption - used in email - Convert non printable characters to printable chars |
|
|
How is Base 64 done ?
|
- Use 24 bit buffer or 3 bytes. use ASCII to convert text to base 10 and then to binary)
- divide 24 bits into 4 6 bit groups - each 6 bit is converted into base 10 equivalent - map the base 10 to base 64 character set - base 64 char set - [A-Za-z0-9+/] - after 76 chars , add a new line - when filling buffer, at the end of the message if there is not enough bytes to make it 24 bits(3 bytes or chars), pad the text with "="( or 00 binary) |
|
|
Key's used in ATM
|
K base D - daily Key
K base M - machine Key K base T - transaction key - per transaction MAC(Message authentication Code) - For the first time, bank would use the daily key to encrypt the message. Verifies the integrity of the message. Transaction key for the response will be calculated by (original K base T) XOR (message MAC) |
|
|
Blow Fish
|
initializing the Key take 521 execution. very very inefficient.
|
|
|
KDF
|
DK=KDF(Key, Salt, Iterations) DK= Derived Key KDF = Key Derivation Functions |
|
|
Properties of KDFs
|
- Intentionally slow
- Not slow such that it impacts daily use - Good at hiding password - hard to crack |
