Introduction

Differences between Clear Text, Cryptography Protocols & VPNs

Clear-text:

• Easy to intercept, eavesdrop & mangle.

• Use clear-text only on trusted networks.

Cryptographic Protocols:

• Protocol encrypts information transmitted to protect the communication.

• Prevents eavesdropping.

• Need to transmit clear-text anyways? Wrap your communication into a tunnel.

• Protocol for Tunneling = VPN.

VPN:

• A VPN uses cryptography to extend a private network over a public one.

• Protected connection a to a a private network.

• A VPN connection is needed for using the course Labs.

HTTP(s) Traffic Sniffing with Wireshark

There are 2 websites using HTTP and HTTPS respectively, differences in the communication can be checked through a sniffer as Wireshark and using the command 'Follow TCP Stream':

Basic Binary and Hexadecimal Arithmetic

Binary

1 + 1 = 10

111 + 1 = 1000

1101b = 13d

Converting Decimal and to Binary

Divide by 2 and keep a not of the remainder iterating the same operation until the dividend is zero.

13d is 1011b:

Step	Operation	Remainder
1	13 / 2 = 6	1
2	6 / 2 = 3	0
3	2 / 2 = 1	1
4	1 / 2 = 0	1

Binary Operators

Name	Description	Example
NOT	Negation	NOT 1101 = 0010
AND	if (both bits in the comparing position are ones) -> 1; else 0	1001 AND 1100 = 1000
OR	if (at least one of the bits is one) -> 1; else 0	1001 OR 1100 = 1101
XOR	if (just one of the bits is one) -> 1; else 0	1001 XOR 1100 = 0101

Hexadecimal

Hex	0	1	2	3	4	5	6	7	8	9	A	B	C	D	E	F
Dec	0	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15

0x3a1 = 3a1h = 929d

Conversion	Operation	Total
3 = 3	3 * 16^2	768
a = 10	10 * 16^1	160
1 = 1	1 * 16^0	1

Converting decimal to hexadecimal

Similar to converting decimal to binary: 1019d = 0x3FB

Number/16	Result	Reminder * 16
1019 / 16	63.6875	0.6875 * 16 = 11 (B)
63 / 16	3.9375	0.9375 * 16 = 15 (F)
3 / 16	0.1875	0.1875 * 16 = 3
0 / 16	--