Innovation and Cryptoventures. Technology 101. Lee Jacobs and Campbell R. Harvey. February 22, 2017

Transcription

1 Innovation and Cryptoventures Technology 101 Lee Jacobs and Campbell R. Harvey February 22, 2017

2 What is a computer? Electronic device that has the ability to store, retrieve, and process data Hardware Memory volatile (RAM) and non-volatile (ROM, NVRAM, flash, solid-state) Processor Peripheral devices keyboard, monitor, etc. Software instructions that can be stored and run by hardware Virtual Machine emulation of a computer run on virtualized hardware

3 Computer vs Network The value of computing has nearly been tapped out. Value in the information economy is driven by the networked connection of computers. Computers enabled us to more efficiently store, retrieve, and process data. Networked connections enable the efficient sharing of information between billions of devices. VS.

4 How does data travel between sources? Open Systems Interconnect () Model Internet Protocol Suite () Conceptual models for communication systems Standard protocols that enable communication between diverse computing functions Partitions systems into abstraction layers Each layer serves the needs of the layers directly above and below it Data from each layer needs not be aware of those layers not directly above or below

5 How does data travel between sources? User computer has data to be sent. Data is processed through protocol stack layers. Binary data is converted to electrical signals on a wire.

6 Network Interface Physical Layer Physical media connection between devices (e.g. ethernet, wifi) Data is transformed into binary values (1 s and 0 s) that correspond to electrical signals

7 Digital Signaling Electrical signal that represents a sequence of discrete values Binary 0 and 1 digits (aka bits ) represented by alternation of discrete waveforms Alternations occur in amplitude, frequency, or phase of waves Binary Data Amplitude-Shift Keying Frequency-Shift Keying Phase-Shift Keying

8 Binary Addressing Binary numbers are represented by 0 s and 1 s Decimal numbers represented by digits 0 through 9 IPv4 Addresses are 32 bits and are represented in four blocks of 8 bits in decimal notation, e.g., (note maximum 8 bit number is 255)* Hexadecimal numbers represented by 16 digits (0-9, a-e) MAC Addresses use 8 bit hexadecimal octet notation (e.g. a0:99:9b:1b:87:33) Addresses are used to determine traffic destinations across networks *Maximum number of addresses = 2 32 = 4,294,967,296

9 Decimal Notation Each bit represents a different decimal value 8 bits in each dotted decimal byte Each byte sums to a decimal value 0 through

10 Hexadecimal Notation 8 bits in each hexadecimal octet byte Each byte represents two hexadecimal digits a0:99:9b:1b:87:

11 Network Interface Data Link Layer Media Access Control (MAC) Unique identification address of a computer s network interface 48 bit address divided into 6 groups of 2 hexadecimal digits e.g. a0:99:9b:1b:87:33 = Determines destination of traffic on local network Each host on a segment has a unique MAC address and knows its neighbors addresses Traffic destined for local neighbors addressed directly to that neighbor Traffic destined outside local segment is sent to default gateway router 6 - Presentation 4 - Application

12 Network Interface Data Link Layer

13 Network Internet Layer Host Addressing and Identification IPv4 32 bit addresses (e.g., ) 4.3 billion usable addresses 32 possible binary values = 2 32 Less reserved addresses private, link-local, loopback, multicast, and testing Public IP addressing exhausted in 2011 Private IP addressing IPv6 128 bit addresses (e.g. 2001:db8:85a3:8d3:1319:8a2e:370:7348) Solution to exhaustion of IPv4 public address space 42 undecillion* usable addresses (4.2 x ) 128 possible binary values = Less reserved addresses private, link-local, loopback, multicast, and testing *Trillion, Quadrillion, Quintillion, Sextillion, Septillion, Octillion, Nonillion, Decillion, Undecillion

14 Network Internet Layer Packet Routing Various routing protocols used to route packets across best possible path from source to destination

15 Routing Protocols Specify how routers communicate with each other to determine best path for traffic between any two nodes on a network Each router has only knowledge of its directly connected neighbors Routing protocol shares network topology first among immediate neighbors then throughout the entire network Interior Gateway Protocols Share routing information within a local network Examples Enhanced Interior Gateway Routing Protocol (EIGRP), Open Shortest Path First (OSPF), Routing Information Protocol (RIP) Exterior Gateway Protocols 6 - Presentation Share routing information between local networks, i.e. across internet Border Gateway Protocol (BGP) 4 - Application

16 Transport Layer Basic channel for data exchange Type of traffic protocol is defined and marked with a port number by upper layers. A virtual channel is created between two hosts based off of this protocol marking. Traffic marked with a protocol is considered interesting to each session channel. Uninteresting traffic can be ignored by that channel. Most familiar protocols have a TCP or UDP port # SMTP (25), POP3 (110), IMAP (143) Domain Name Service (53) HTTP (80), HTTPS (443) 6 - Presentation 4 - Application

17 Application Layer Application layer protocols are sets of standards for diverse communication systems to exchange data and provide user services Applications are unaware of and indifferent to lower or layers other than the transport layer connection (i.e. network, data link, and physical layers). All that is necessary for applications to communicate is a session established by transport layer. Examples of Protocols Domain Name Service (DNS) Hypertext Transfer Protocol (HTTP) Virtual Private Network (VPN) 6 - Presentation 4 - Application

18 Composition and Transfer of Information A single message is broken down into many digestible size pieces of application data and encapsulated at each protocol stack layer to be passed along to the next layer then forwarded to its destination. Application Layer Data Segment Transport Layer Data Header Packet Network Layer Segment Header Data Link Layer Physical Layer Frame Packet Header Presentation 4 - Application

19 Public Key Infrastructure (PKI) Set of roles, policies and procedures to manage the use of public-key encryption and digital certificates Almost all secure internet services use PKI (e.g., , HTTPS, TLS, VPN) Authentication public key used to verify identity of message sender Confidentiality only holder of the private key can decrypt message encrypted with public key, once encrypted message can not be tampered with Non-repudiation recipient is not able to deny the receipt 6 - Presentation of message 4 - Application

20 Public Key Infrastructure (PKI) Public-Key Encryption Unique public-private key pair created by each user Private key encrypts and public key decrypts Private key is held only by its creator Public key is held by a trusted certificate authority to be used by those communicating with the owner of the key pair Digital Certificate Certificate authority verifies the identity of the owner of the certificate Certificate is signed by private key, so only its legitimate owner can use it 6 - Presentation 4 - Application

21 Public Key Infrastructure (PKI) Source:

22 Public Key Infrastructure (PKI) Source:

23 Domain Name Service (DNS) Phonebook for the internet, translates human-friendly domain names into computer-friendly IP addresses Plays a role in just about every internet service we use

24 Domain Name Service (DNS) DNS Servers exist in a hierarchy with root servers controlling each type of top-level domain (e.g.,.com,.edu,.gov) Subordinate publicly and privately controlled resolvers accept requests from hosts for internet addresses

25 Simple Mail Transfer Protocol (SMTP) used to send from host to local mail server and between mail servers Post Office Protocol (POP3) or Internet Message Access Protocol (IMAP) used to deliver from mail server to destination host POP3 delivers message and deletes from server IMAP stores message on server, as used in webmail Public Key Infrastructure (PKI) provides authentication via digital signatures and confidentiality via encryption

26 1. Bob generates SMTP format message to Alice and sends to his local mail server.

27 2. Local mail server resolves destination domain name (unc.edu) and sends to remote mail server using SMTP.

28 3. Remote server stores message in Alice s mailbox.

29 4. Alice picks up message from mail server when she logs on using POP3 or IMAP.

30 Hypertext Transfer Protocol (HTTP) Request-response protocol in client-server computing model Client identifies website host using DNS then requests resources from host IP address Foundation protocol for data transmission over the worldwide web

31 Virtual Private Network (VPN) Provides confidentiality, integrity, and authentication of information exchanged over network Point-to-point VPN Secure connection ( tunnel ) established between two network appliances, often using IPSec Tunnel serves similar to transport layer connection Client-Based VPN (SSL/TLS/HTTPS) Terms often used synonymously Secure Sockets Layer Predecessor to current protocols, less secure due to support for only older key exchange algorithms (e.g., RSA) Transport Layer Security Tunnel serves as connection similar to transport layer channel Accessed via client-based application such as AnyConnect Supports modern key exchange algorithms (e.g., elliptic curve cryptography) HTTPS HTTP over SSL/TLS Traditional HTTP communication takes place over a secure channel created by TLS Clientless application accessed via web browser 6 - Presentation 4 - Application

32 Virtual Private Network (VPN) TLS Handshake