(2) FinTech — Financial Innovation and the Internet 2019 Fall Kenji Saito Professor, Graduate School of Business and Finance, Waseda University [email protected] Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.1/28
Lecture 2 10/4 Overview of FinTech (2) • Lecture 3 10/11 Internet Technology and Governance (1) • Lecture 4 10/18 Internet Technology and Governance (2) • Lecture 5 10/25 The World of Apps (1) • Lecture 6 11/8 The World of Apps (2) • Lecture 7 11/15 Blockchain (1) Lecture 8 11/22 Blockchain (2) Lecture 9 11/29 Other Ledger Technology and Applications (1) Lecture 10 12/6 Other Ledger Technology and Applications (2) Lecture 11 12/13 Cyber-Physical Society and Future of Finance (1) Lecture 12 12/20 Cyber-Physical Society and Future of Finance (2) Lecture 13 1/10 FinTech Ideathon (1) Lecture 14 1/17 FinTech Ideathon (2) Lecture 15 1/24 Presentations and Conclusions Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.3/28
the Web Birth and evolution of World Wide Web Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.4/28
particular Basics of cryptography Cryptographic hash function Public key cryptography and digital signature Zero-knowledge proof Q & A session Assignment Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.5/28
CSPXTF CSPXTF CSPXTF CSPXTF CSPXTF XXXHPPHMFDPKQ XXXZBIPPDPKQ Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.7/28
Protocol (Secure) Protocol used for transferring HTML files HTML Hyper Text Markup Language Markup language for describing web pages Designed and recommended by the W3C URI Uniform Resource Identifier Identifier of an information resource on the Internet (not necessarily on WWW) URL (Uniform Resource Locator) is one way to implement URI Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.8/28
scheme Scheme https://www.google.com Host name : Port # 443 /search Path ? Search string q = refrigerator Port number, path, and search string are optional For https scheme, the port number defaults to 443 Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.9/28
Install openssl in your environment and try it out You may want to try www.google.com:443 and GET /search?q=refrigerator instead Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.10/28
request Each request is independent (state-less) It was enough to achieve its original purpose Original purpose → easy access to documents such as scientific papers But then there appeared a lot of applications for which this is inadequate. . . Want to treat a series of requests as a session Shopping, logging into membership site, etc. Art of maintaining states for that purpose Unique URL generation including a representation of the state HTTP cookies (like shared magic numbers) Access tokens Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.11/28
HFOFSBUFTUPLFO EBUBQSPUFDUFECZBDDFTTSJHIU %BUBCBTF #SPXTFS 5JNF JOEFQFOEFOUDPOOFDUJPO JOEFQFOEFOUDPOOFDUJPO IFBEFS SFTPVSDF IFBEFS IFBEFS SFTPVSDF 9Z;X 9Z;X 9Z;X EBUBQSPUFDUFE CZBDDFTTSJHIU It is important that communication paths are encrypted Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.12/28
application can make use of some features provided somewhere Web API : API by HTTP(S) requests In the case, features are provided by a web server Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.13/28
methods POST, GET (demoed), PUT, DELETE vs. CRUD (Create/Read/Update/Delete) Uniquely identify resources by URI Some demonstrations Often returns results in the form of JSON (JavaScript Object Notation) Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.14/28
and state transitions An example of state transitions (state machines) (For example, on the web, page = state, and the page presents possible operations in that state as a set of buttons) Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.15/28
digital signature Zero-knowledge proof Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.16/28
by Google and the National Research Institute for Mathematics and Computer Science (CWI), Netherlands As an alert Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.18/28
3FDFJWFS QMBJOUFYU QVCMJDLFZ QSJWBUFLFZ &ODSZQUX QVCMJDLFZ %FDSZQUX QSJWBUFLFZ 4FOEFODSZQUFEUFYU It is extremely difficult to deduce the private key from a public key Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.19/28
DPNQVUFEGSPNUIFQMBJOUFYU %FDSZQUX QSJWBUFLFZ 3FDFJWFS 4FOEFS QMBJOUFYU QMBJOUFYU TJHOBUVSF TJHOBUVSF %JTUSJCVUFQVCMJDLFZTJOBEWBODF LFZQBJS EJHFTU QVCMJDLFZ QSJWBUFLFZ EJHFTUTFFOBT FODSZQUFEEBUB Can prove that it was sent by the very person and has not been altered This illustration shows how it works with RSA (RSA : Rivest, Shamir, Adleman) ECDSA is used in Bitcoin, etc., instead (Elliptic Curve DSA : Digital Signature Algorithm) Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.20/28
Output : signature Verifying Input : <plain text, signature, public key> Output : OK or NG Whether the signature meets certain mathematical properties that can be tested using plain text and public key Private key cannot be inferred in the verification process Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.21/28
no knowledge other than what prover wants to prove Example: “I know a secret spell to open the door” ↑ Prove this without revealing the spell itself For example, repeat “coming out from the way she is told” for 20 times Completeness Verifier accepts with high probability if the proposition is true Soundness Verifier has little chance of accepting if the proposition is false Zero-knowledge Can imitate dialogue without having to be a prover (without knowledge) Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.23/28
zero-knowledge proof Example: proving “my test score is the same as yours” Only one person can enter the room at a time Room has numbered and locked voting boxes for every possible score (for example, 101 boxes) You have a key bundle, but leave only the key of your score box, and throw away the rest I enter the room and vote ⃝ for my score box and × for the rest You go into the room and unlock your score box to see if it’s voted ⃝ Digital signature (can prove that the private key is there without revealing it) is an example of non-interactive zero-knowledge proof Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.24/28
services (1) If a user is an “end (edge)”, what is the “center” involving people in the example? (2) How will the service change if the center is automated? Deadline and how to submit November 13, 2019 at 17:59 JST From Course N@vi Lecture 6 : The World of Apps (2) — FinTech — Financial Innovation and the Internet 2019 Fall — 2019-11-08 – p.27/28
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