crypto

Cryptography/README.md

@@ -1,5 +1,8 @@
 # Cryptography
 
+* Often data is just encoded in base64 or hex. Other thimes it's just compressed (gzip).
+
+
 
 
 ## MD5
@@ -225,7 +228,34 @@ $ ./openssl s_client --no_tls1 --no_ssl3 --connect <WEBSITE>:443
 * For Identification and verification of encoding supported by the Website we can use  **EcoScan34**.
 
 
+---
 
+## Block Cipher Encryption
+
+* Electronic code book (ECB) mode.
+* Simplest and default block cipher mode.
+* Message is split into blocks and each is encrypted separately.
+* Disavantage: identical plaintext block encrypts to identical cipher text block (for example, figures).
+
+### Attacking Randomness
+
+* Good Randomness is vital for cryptographic operations.
+
+* Two common attack against a PRNG :
+	- PRGN state is reconstructed from its output.
+	- Same PRNG is used more than once.
+
+* Statistically random is not secure random!
+	- if a PRNG is seeded with a value the attacker can influence, the state of the PRNG is likely compromised.
+
+* Seed race condition attacks:
+	- System clock often used to seed PRNG
+	- Submit 10's or 100's of rquests at a time. Seed a PRNG with the same system clock and the output will be the same.
+
+
+
+
+----