A Blockchain-based Mapping System

Transcription

1 A Blockchain-based Mapping System IETF 98 Chicago March 2017 Jordi Paillissé, Albert Cabellos, Vina Ermagan, Fabio Maino 1

2 A short Blockchain tutorial 2

3 Blockchain - Introduction Blockchain = decentralized, secure and trustless database Add blocks of data one after another Protected by two mechanisms: Chain of signatures Consensus algorithm First appeared: Bitcoin, to exchange money Many more applications are possible 3

4 Blockchain - Transactions Transaction Sender s Public Key Sender s signature Tx Data 4

5 Blockchain - Transactions Transaction Sender s Public Key 1 Transactions are broadcasted to all the nodes Sender s signature P2P network Tx Data 5

6 Blockchain - Transactions Transaction Sender s Public Key 1 Transactions are broadcasted to all the nodes Sender s signature P2P network Tx Data 2 A node collects transactions into a block Block Prev. Hash Nonce Transactions 1 N 6

7 Blockchain - Transactions Transaction Sender s Public Key 1 Transactions are broadcasted to all the nodes Sender s signature P2P network Tx Data 2 A node collects transactions into a block 3 Compute consensus algorithm Block New Block Prev. Hash Nonce Prev. Hash Nonce Transactions 1 N Transactions 1 N 7

8 Blockchain - Transactions Transaction Sender s Public Key 1 Transactions are broadcasted to all the nodes Sender s signature P2P network Tx Data 2 A node collects transactions into a block 3 Compute consensus algorithm 4 Broadcast new block to the network Block New Block Prev. Hash Nonce Prev. Hash Nonce Transactions 1 N Transactions 1 N 8

9 Blockchain - Transactions Transaction Sender s Public Key 1 Transactions are broadcasted to all the nodes Sender s signature P2P network Tx Data 2 A node collects transactions into a block 3 Compute consensus algorithm 4 Broadcast new block to the network Block Prev. Hash Nonce New Block Prev. Hash Nonce 5 The other nodes verify the consensus algorithm and accept the block Transactions 1 N Transactions 1 N 9

10 Blockchain - Properties Decentralized: all nodes have the entire blockchain No prior trust required Append-only and immutable: added transactions cannot be modified Verifiable Blockchain Technology, Sutardja Center (UC Berkeley) 10

11 A Blockchain-based Mapping System Overview 11

12 Basic Idea Objective: Store mappings in the blockchain EID prefixes are distributed to all participants Each owner writes their mappings (EID-to-RLOC) in the blockchain Map Resolvers read the blockchain to find the mappings Idea: A mapping is equivalent to a bitcoin transaction Wallet: One (or more) mappings Transaction: Defining a mapping Blockchain: A public ledger of the mappings, from the current owner to the root 12

13 1-Writes Genesis block, claims all EID space WRITE ROOT blockchain n n+1 n+2 13

14 1-Writes Genesis block, claims all EID space 2-Writes Prefix owner mapping WRITE ROOT Delegation EID-prefix owner blockchain n n+1 n+2 14

15 1-Writes Genesis block, claims all EID space 2-Writes Prefix owner mapping 3-Writes Prefix RLOC mapping WRITE ROOT Delegation EID-prefix owner Delegation EID-prefix owner blockchain n n+1 n+2 15

16 1-Writes Genesis block, claims all EID space 2-Writes Prefix owner mapping 3-Writes Prefix RLOC mapping WRITE ROOT Delegation EID-prefix owner Delegation EID-prefix owner blockchain n n+1 n+2 2-Fetch mappings READ 1-Map-Request EIDpref RLOC1 RLOC2 RLOC3 xtr 3-Map-Reply MR/MS with blockchain 16

17 Pros and Cons Pros Infrastructure less and decentralized Fast lookup 17

18 Pros and Cons Pros Infrastructure less and decentralized Fast lookup Secure: Non-repudiation Resilience Integrity Authentication 18

19 Pros and Cons Pros Infrastructure less and decentralized Fast lookup Secure: Non-repudiation Resilience Integrity Authentication No prior trust required Simple rekeying 19

20 Pros and Cons Pros Infrastructure less and decentralized Fast lookup Secure: Non-repudiation Resilience Integrity Authentication No prior trust required Simple rekeying Cons Slow updates 20

21 Pros and Cons Pros Infrastructure less and decentralized Fast lookup Secure: Non-repudiation Resilience Integrity Authentication No prior trust required Simple rekeying Cons Slow updates Costly bootstrapping Large storage required 21

22 Pros and Cons Pros Infrastructure less and decentralized Fast lookup Secure: Non-repudiation Resilience Integrity Authentication No prior trust required Simple rekeying Cons Slow updates Costly bootstrapping Large storage required Can be mitigated using a dedicated chain 22

23 Pros and Cons Pros Infrastructure less and decentralized Fast lookup Secure: Non-repudiation Resilience Integrity Authentication No prior trust required Simple rekeying Cons Slow updates Costly bootstrapping Large storage required Can be mitigated using a dedicated chain Throughput depends on: Propagation speed in the P2P network Consensus algorithm 23

24 Comparison with LISP-DDT* LISP-DDT Blockchain Root Node 1 Node 2 Node N DDT1 DDT2 Chain Chain Chain MS1.1 MS1.2 MS2.1 + Fast update Dynamic mappings - Manual configuration - First query slow + No infrastructure + Easy management + First query fast - Update Delay Static mappings *Delegated Database Tree: hierarchical delegation of prefixes, similar to DNS 24

25 Issues with RPKI RPKI Blockchain Anonymity [1] Prefixes linked to owner name Prefixes linked to a public key Revocation Performed by CAs Performed automatically (validity time) or impossible Certificate management [2] Complex No certificates [1] Wählisch, Matthias, et al. "RiPKI: The tragic story of RPKI deployment in the Web ecosystem." Proceedings of the 14th ACM Workshop on Hot Topics in Networks. ACM, [2] George, Wes. "Adventures in RPKI (non) Deployment." NANOG,

26 Scalability Approx. 600 GB in 2034 One mapping for each block of /24 IPv4 address space Growth similar to BGP churn* Prefix delegation + mappings Each transaction approx. 400 bytes Only prefixes: approx. 40 GB in 20 years (worst case + BGP table growth*) *Source: 26

27 A Blockchain-based Mapping System Prototyping 27

28 Design considerations Bitcoin is too restrictive: Only for money transfer Huge blockchain file size (approx. 100 GB) High bootstrap time (several days*) Low throughput (7 transactions/sec.) New blockchain technologies: More scalable Smart contracts *depends on connection speed 28

29 Dedicated chain Public (anyone can use it) but dedicated (only for mappings) It only stores: Prefix delegations Mappings Map Server addresses fast updates Automate functions with smart contracts: Add new mapping Revoke Rekey Verify mapping 29

30 Prototype New mappings Java SDK Validate New mappings Hyperledger P2P network 30

31 Prototype LISP Flow Mappings Mappings New mappings Java SDK Validate New mappings Map-Request Map-Reply xtr Hyperledger P2P network 31

32 Deployment LISP Beta Network Uses LISP-DDT* Replace DDT nodes with this prototype Root Node 1 Node 2 Node N DDT1 DDT2 Chain Chain Chain MS1.1 MS1.2 MS2.1 * 32

33 Deployment LISP Beta Network Uses LISP-DDT* Replace DDT nodes with this prototype Root Node 1 Node 2 Node N DDT1 DDT2 Chain Chain Chain MS1.1 MS1.2 MS2.1 Map-Request * Map-Reply xtr 33

34 Deployment LISP Beta Network Full mapping system Less Map Servers Root Node 1 Node 2 Node N DDT1 DDT2 Chain Chain Chain MS1.1 MS1.2 MS2.1 Map-Request Map-Reply xtr 34

35 A Blockchain-based Mapping System IETF 98 Chicago March 2017 Jordi Paillissé, Albert Cabellos, Vina Ermagan, Fabio Maino 35

36 A Blockchain-based Mapping System Appendix: transaction examples 36

37 First transaction Map-Resolver trust the Public Key of the Root, that initially claims all EID space by writing the genesis block Root can delegate all EID space to itself and use a different keypair New Transaction Hash(P+ root)= Root@1 I own all the address space Root@2 37

38 Prefix delegation Root delegates EID-prefixes to other entities (identified by Hash(Public Key)) by adding transactions New Transaction delegate (rest of space) 0.0/ /8 Owners can further delegate address blocks to other entities or write MS addresses (and MS s Public Key) Deleg1@ New Transaction delegate Deleg1@2 (rest of space) 0.0.1/24 Deleg3@ 0.0.2/24 MS@ and P+ 38

39 Writing mappings Just like delegating a prefix, but instead of the Map Server address, we write the mapping New Transaction Deleg3@ maping 0.0.1/24 is at RLOC1 39

40 Rekeying Delegating the owned EID-prefixes to itself using a new key set. Simpler than traditional rekeying schemes Can be performed independently, i.e. each owner can do it without affecting other owners Same procedure for mappings 40

41 Map-Reply Authentication MS public key can also be included in the delegations Since blockchain provides authentication and integrity for this key, MRs can use it to verify Map-Replies 2-Retrieve MS RLOC and MS s Public Key 1-Map-Request 3-Map-Request xtr 6-Map-Reply MR 4-Signed Map-Reply MS 5-Verify With MS s Private Key signature 41

42 More about the Consensus Algorithm Rules used by nodes to agree on which data to accept Eg. Bitcoin uses Proof of Work Miners compute Proof of Work Finding a nonce that when added to the data makes its hash start with N zeros. Hard Other algorithms are being explored: Proof of Stake: nodes with more assets are more likely to add blocks Practical Byzantine Fault Tolerant: reach a minimum number of endorsements from nodes in order to add data Deposit-based: assets are lost if a node performs an illegal operation (security deposit) 42