Tag Archives: Peeter Laud

Smart-ID paper: Server-Supported RSA Signatures for Mobile Devices

Abstract
We propose a new method for shared RSA signing between the user and the server so that: (a) the server alone is unable to create valid signatures; (b) having the client’s share, it is not possible to create a signature without the server; (c) the server detects cloned client’s shares and blocks the service; (d) having the password-encrypted client’s share, the dictionary attacks cannot be performed without alerting the server; (e) the composite RSA signature “looks like” an ordinary RSA signature and verifies with standard crypto-libraries. We use a modification of the four-prime RSA scheme of Damgård, Mikkelsen and Skeltved from 2015, where the client and the server have independent RSA private keys. As their scheme is vulnerable to dictionary attacks, in our scheme, the client’s RSA private exponent is additively shared between server and client. Our scheme has been deployed and has over 200,000 users.

The paper was published in proceedings of the conference ESORICS 2017, Oslo, Norway, September 11-15, 2017.

The paper contains several pages of cryptographic proofs. The RSA key generation involves “l-safe” primes, which is not a standard practice in generating RSA primes. This is worrisome, especially after it became known that the flaw in ID card was caused by other instance of nonstandard RSA prime generation.

Links:
https://link.springer.com/chapter/10.1007/978-3-319-66402-6_19

Cyber Security master’s theses defense in Tallinn University of Technology (May 2017)


Monday, May 29, 2017, Akadeemia Tee 15a, Room ICT-315.

Grades received (random order): 5, 4, 4, 3, 3, 3, 2, 2.

Time: 10:00
Student: Kristjan Oja
Title: Cyber Security Awareness For IT Students Through Practical Assignments
Supervisor: Sten Mäses
Reviewer: Tiia Sõmer

Time: 10:40
Student: Sander Arnus
Title: Providing guaranteed log delivery and proof value of logs
Supervisor: Risto Vaarandi
Reviewer: Tiit Hallas

Time: 11:20
Student: Bolaji Ayoola Ladokun
Title: An Analytical Approach to Characterization of Targeted and Untargeted Attack in Critical Infrastructure Honeypot
Supervisor: Hayretdin Bahsi
Reviewer: Risto Vaarandi

Time: 12:00-13:00 – Lunch

Time: 13:00
Student: Iryna Bondar
Title: LUDROID: Evaluation of Android Malware Detection Tools and Techniques and Development of a First Line of Defense For the User
Supervisor: Emin Caliskan
Reviewer: Toomas Lepik

Time: 13:40
Student:  Seifollah Akbari
Title: A New Method for the SYNful Knock Attack Implementation
Supervisor: Truls Ringkjob
Reviewer: Bernhards Blumbergs

Time: 14:20
Student: Safak Tarazan
Title: GPS Spoofing/Jamming Resilient Mini UAV Implementation Strategy
Supervisor: Truls Ringkjob
Reviewer: Juhan Ernits

Time: 15:20
Student: Danielle Morgan
Title: Security of Loyalty Cards Used in Estonia
Supervisor: Rain Ottis, Arnis Paršovs
Reviewer: Aleksandr Lenin

Time: 16:00
Student: Katrin Kukk
Title: Ensuring the digital continuity of e-Estonia in different crisis scenarios
Supervisor: Rain Ottis
Reviewer: Jaan Priisalu

Tuesday, May 30, 2017, Akadeemia Tee 15a, Room ICT-315.

Grades received (random order): 4, 4, 3, 3, 2, 1.

Time: 10:00
Student: Christopher David Raastad
Title: Euro 2.0 – Securing an Ethereum Crypto Fiat Currency System
Supervisor: Alex Norta
Reviewer: Raimundas Matulevicius

Time: 10:40
Student: Mobolarinwa Taofeek Balogun
Title: Comparative Analysis of Industrial IoT and HealthCare System IoT for Cyberterrorism
Supervisor: Hayretdin Bahsi
Reviewer: Ahto Buldas

Time: 11:20
Student: Chengxiang Wang
Title: Classification of Black-Box Security Reductions and Oracle Separation Techniques
Supervisor: Ahto Buldas
Reviewer: Peeter Laud

Time: 12:00-13:00 – Lunch

Time: 13:00
Student: Celik Neslisah
Title: Anomaly Detection Using Locked Shields Logs
Supervisor: Olaf Maennel
Reviewer: Mauno Pihelgas

Time: 13:30
Student: Sophio Sakhokia
Title: Developing a Cyber Security Master Programme for Georgia
Supervisor: Tiia Sõmer
Reviewer: Olaf Maennel

Time: 14:20
Student: Zaghum Awan
Title: Analytical Comprehensive Approach to Cyber Laundering and its Solutions
Supervisor: Tiia Sõmer
Reviewer: Andro Kull

Study on the lifecycle of cryptographic algorithms 2016

cybernetica_ria_crypto_algorithms_report

This study is a natural continuation of three previous studies conducted in 2011, 2013 and 2015. The fourth version of cryptographic algorithms life cycle study published on June 9, has more than 10 authors and has 163 reference source. The 2016 report is the first one in its sequence to be written in English, because the study is unique on a global scale, and the previous versions has been of great international interest.

The foreword of the report has been written by Anto Veldre:

The Dutch DigiNotar case in 2011 demonstrated the hard choices a country faces if a PKI supporting its government’s IT systems is compromised. [..] Therefore, it was decided in 2011 to assemble a scientific task force to analyse the problems and risks that reliance on cryptography is posing on the sustainable functioning of our society.

Among the usual topics in cryptography, there is quite revealing section “Cryptographic protocols over radio connection”. For example, there the authors find that Estonian public transportation cards are vulnerable to various kinds of Denial of Service and cloning attacks:

The transportation cards in Tallinn are built on MIFARE Classic, whereas in Tartu MIFARE Ultralight C cards are used. However, even though both of the cards support cryptographic authentication, this functionality is not used. In both cases, the protocol running between the card and the reader is essentially the same, consisting of transmitting the card’s unique ID and a signature. [..] While this measure prevents unauthorised parties from issuing new cards, it does not stop the card cloning attack. [..] Cloning a card that carries a monthly ticket causes direct financial loss to the transportation service provider and must hence be urgently addressed.

Even though the ID fields of transportation cards are not writeable, other fields may be. This is for example the case with Tartu bus cards that allow e.g. the signature field to be overwritten by a standard app working on a regular NFC-capable smartphone. As a result, the card will become invalid, giving us a potential Denial of Service attack.

The report analyzes different radio frequency card technologies used for physical access control.  There are many problems – transparency issues, use of weak cryptography or no cryptography at all. The authors have also interviewed Hardmeier and G4S to study deployment issues. Some of the deployment issues revealed are quite disturbing:

Interview with a company installing NFC-based access control systems revealed that it is common practice to use same keys also in several installations, making e.g. door keys of one company work at the door of another company, too.

Links:
https://www.ria.ee/public/RIA/Cryptographic_Algorithms_Lifecycle_Report_2016.pdf
https://www.ria.ee/ee/eriik-2018-valmis-2016-aasta-kruptograafiliste-algoritmide-elutsukli-uuring.html
https://blog.ria.ee/ria-aastakonverentsi-i-sessiooni-otseblogi/