## Information Mathematics Seminar

Seminar information archive ～05/29｜Next seminar｜Future seminars 05/30～

Date, time & place | Thursday 16:50 - 18:35 128Room #128 (Graduate School of Math. Sci. Bldg.) |
---|---|

Organizer(s) | Toshiyuki Katsura |

**Seminar information archive**

### 2023/05/25

16:50-18:35 Room #128 (Graduate School of Math. Sci. Bldg.)

Security, construction, and proof of public-key encryption (2) (Japanese)

**Tatsuaki Okamoto**(NTT)Security, construction, and proof of public-key encryption (2) (Japanese)

[ Abstract ]

Explanation of security, construction and proof of public-key encryption

Explanation of security, construction and proof of public-key encryption

### 2023/05/18

16:50-18:35 Room #128 (Graduate School of Math. Sci. Bldg.)

Security, construction, and proof of public-key encryption (1) (Japanese)

**Tatsuaki Okamoto**(NTT)Security, construction, and proof of public-key encryption (1) (Japanese)

[ Abstract ]

Explanation on security, construction, and proof of public-key encryption

Explanation on security, construction, and proof of public-key encryption

### 2023/05/11

16:50-18:35 Room #128 (Graduate School of Math. Sci. Bldg.)

The security definition and proof of symmetric key encryption and public key encryption (Japanese)

**Tatsuaki Okamoto**(NTT)The security definition and proof of symmetric key encryption and public key encryption (Japanese)

[ Abstract ]

Explanation of the security definition and proof of symmetric key encryption and public key encryption

Explanation of the security definition and proof of symmetric key encryption and public key encryption

### 2023/04/27

16:50-18:35 Room #128 (Graduate School of Math. Sci. Bldg.)

The basics of cryptography II (Japanese)

**Tatsuaki Okamoto**(NTT)The basics of cryptography II (Japanese)

[ Abstract ]

Explanation of the basics of cryptography

Explanation of the basics of cryptography

### 2023/04/20

16:50-18:35 Room #128 (Graduate School of Math. Sci. Bldg.)

The basics of cryptography (Japanese)

**Tatsuaki Okamoto**(NTT)The basics of cryptography (Japanese)

[ Abstract ]

Explanation of the basics of cryptography

Explanation of the basics of cryptography

### 2023/04/13

16:50-18:35 Room #128 (Graduate School of Math. Sci. Bldg.)

Certification and signature

------Foundation of cryptography (Japanese)

**Tatsuaki Okamoto**(NTT)Certification and signature

------Foundation of cryptography (Japanese)

[ Abstract ]

Explanation on certification and signature.

Explanation on certification and signature.

### 2023/04/06

16:50-18:35 Room #128 (Graduate School of Math. Sci. Bldg.)

The role of cryptography (Japanese)

**Tatsuaki Okamoto**(NTT)The role of cryptography (Japanese)

[ Abstract ]

Explanation of the theory of cryptography

Explanation of the theory of cryptography

### 2023/01/19

16:50-18:35 Room #123 (Graduate School of Math. Sci. Bldg.)

Code-based cryptography and its decoding algorithm (Japanese)

**Shintaro Narisada**(KDDI Research, Inc.)Code-based cryptography and its decoding algorithm (Japanese)

[ Abstract ]

This talk overviews code-based cryptography and its decoding algorithm called Information Set Decoding (ISD). All lectures will be given in Japanese.

This talk overviews code-based cryptography and its decoding algorithm called Information Set Decoding (ISD). All lectures will be given in Japanese.

### 2023/01/12

16:50-18:35 Room #123 (Graduate School of Math. Sci. Bldg.)

Theory of fault-tolerant quantum computing II (Japanese)

**Yasunari Suzuki**(NTT)Theory of fault-tolerant quantum computing II (Japanese)

[ Abstract ]

To demonstrate reliable quantum computing, we need to integrate

quantum error correction techniques and achieve fault-tolerant quantum

computing. In this seminar, I will explain the basics of fault-tolerant quantum

computing and recent progress toward its experimental realization.

To demonstrate reliable quantum computing, we need to integrate

quantum error correction techniques and achieve fault-tolerant quantum

computing. In this seminar, I will explain the basics of fault-tolerant quantum

computing and recent progress toward its experimental realization.

### 2022/12/22

16:50-18:35 Room #123 (Graduate School of Math. Sci. Bldg.)

Theory of fault-tolerant quantum computing I (Japanese)

**Yasunari Suzuki**(NTT)Theory of fault-tolerant quantum computing I (Japanese)

[ Abstract ]

To demonstrate reliable quantum computing, we need to integrate quantum error correction techniques and achieve fault-tolerant quantum computing. In this seminar, I will explain the basic of fault-tolerant quantum computing and recent progress towards its experimental realization.

To demonstrate reliable quantum computing, we need to integrate quantum error correction techniques and achieve fault-tolerant quantum computing. In this seminar, I will explain the basic of fault-tolerant quantum computing and recent progress towards its experimental realization.

### 2022/12/08

16:50-18:35 Room #123 (Graduate School of Math. Sci. Bldg.)

Near-term quantum algorithms and quantum error mitigation (Japanese)

**Suguru Endo**(NTT)Near-term quantum algorithms and quantum error mitigation (Japanese)

[ Abstract ]

The current or near-term quantum computing devices are still small and noisy. In this talk, I will near-term quantum algorithms and quantum error mitigation for improving computation accuracy.

The current or near-term quantum computing devices are still small and noisy. In this talk, I will near-term quantum algorithms and quantum error mitigation for improving computation accuracy.

### 2022/12/01

16:50-18:35 Room #123 (Graduate School of Math. Sci. Bldg.)

Quantum Computing and Cryptography (Japanese)

**Takashi Yamakawa**(NTT)Quantum Computing and Cryptography (Japanese)

[ Abstract ]

I explain several topics on quantum computing and cryptography including Shor’s algorithm for factoring and discrete logarithm, quantum money, and verification of quantum computation based on cryptography.

I explain several topics on quantum computing and cryptography including Shor’s algorithm for factoring and discrete logarithm, quantum money, and verification of quantum computation based on cryptography.

### 2022/11/24

16:50-18:35 Room #123 (Graduate School of Math. Sci. Bldg.)

Attacks for lattice problems assuring the security of lattice-based cryptography (Japanese)

**Masaya Yasuda**(Rikkyo Univ.)Attacks for lattice problems assuring the security of lattice-based cryptography (Japanese)

[ Abstract ]

Lattice-based cryptography is one of post-quantum cryptography, and it is useful for construction of high-functional encryption such as fully homomorphic encryption. In this talk, I introduce methods to attack lattice problems assuring the security of lattice based cryptography. Specifically, I present algorithms of lattice basis reduction such as LLL and BKZ that are required for solving lattice problems. I also describe how to apply reduction algorithms to attacking LWE and NTRU problems.

Lattice-based cryptography is one of post-quantum cryptography, and it is useful for construction of high-functional encryption such as fully homomorphic encryption. In this talk, I introduce methods to attack lattice problems assuring the security of lattice based cryptography. Specifically, I present algorithms of lattice basis reduction such as LLL and BKZ that are required for solving lattice problems. I also describe how to apply reduction algorithms to attacking LWE and NTRU problems.

### 2022/11/17

16:50-18:20 Room #123 (Graduate School of Math. Sci. Bldg.)

Recent progress in multivariate public key cryptography (Japanese)

**Yasuhiko Ikematsu**(Kyushu Univ.)Recent progress in multivariate public key cryptography (Japanese)

[ Abstract ]

In this talk, I explain recent progress in multivariate public key cryptography (MPKC), mainly UOV and Rainbow signature schemes.

In this talk, I explain recent progress in multivariate public key cryptography (MPKC), mainly UOV and Rainbow signature schemes.

### 2022/10/27

16:50-18:20 Room #123 (Graduate School of Math. Sci. Bldg.)

Recent Progress in Post-Quantum Cryptography (Japanese)

**Katsuyuki Takashima**(Waseda Univ.)Recent Progress in Post-Quantum Cryptography (Japanese)

[ Abstract ]

I will explain recent progress in post-quantum cryptography, particularly, in lattice cryptography.

I will explain recent progress in post-quantum cryptography, particularly, in lattice cryptography.

### 2022/10/13

16:50-18:20 Room #123 (Graduate School of Math. Sci. Bldg.)

Introduction to Attacks and Countermeasures for Cryptographic Implementation (Japanese)

**Yuichi Komano**(Toshiba Corporation)Introduction to Attacks and Countermeasures for Cryptographic Implementation (Japanese)

[ Abstract ]

Even if an encryption scheme is provably secure in some mathematical sense, against cryptographic products including a hardware/software implementation of the cryptographic scheme, it is possible to guess secret information operated in the product by analyzing observable information (side-channel information). Such guessing attack is called as side-channel attack, and lots of research have been reported on side-channel attacks using timing information or power consumption trace as observable information and on its countermeasures. In this talk, we will review the principles of side-channel attacks and countermeasures.

Even if an encryption scheme is provably secure in some mathematical sense, against cryptographic products including a hardware/software implementation of the cryptographic scheme, it is possible to guess secret information operated in the product by analyzing observable information (side-channel information). Such guessing attack is called as side-channel attack, and lots of research have been reported on side-channel attacks using timing information or power consumption trace as observable information and on its countermeasures. In this talk, we will review the principles of side-channel attacks and countermeasures.

### 2022/10/06

16:50-18:35 Room #123 (Graduate School of Math. Sci. Bldg.)

On a New Quantitative Definition of the Complexity of Organized Matters (Japanese)

**Tatsuaki Okamoto**(NTT)On a New Quantitative Definition of the Complexity of Organized Matters (Japanese)

[ Abstract ]

Scientific problems are classified into three classes: problems of simplicity, problems of disorganized complexity, and problems of organized complexity. For example, classical dynamics can be used to analyze and predict the motion of a few ivory balls as they move about on a billiard table. This is a typical problem of simplicity. Imagine a large billiard table with millions of balls rolling over its surface, colliding with one another and with the side rails. This is a typical problem of disorganized complexity. Problems of organized complexity, however, deal with features of an organization such as living things, ecosystems, and human societies. The quantitative definition of complexity is the most fundamental and important notion in problems of (organized and disorganized) complexity. The quantitative definition of disorganized complexity has been established to be entropy. In contrast, there is no agreed-upon quantitative definition for organized complexity, although many definitions have been proposed for this aim. In this talk, first, I will show the shortcomings of the existing definitions for organized complexity. I will then introduce a new definition and present that the new definition has solved all problems with the existing definitions. Finally, I will show some applications. This talk is based on the following paper.

Tatsuaki Okamoto, ‘‘A New Quantitative Definition of the Complexity of Organized Matters,’’ Complexity, Volume 2022, Article ID 1889348 (2022)

https://www.hindawi.com/journals/complexity/2022/1889348/

Scientific problems are classified into three classes: problems of simplicity, problems of disorganized complexity, and problems of organized complexity. For example, classical dynamics can be used to analyze and predict the motion of a few ivory balls as they move about on a billiard table. This is a typical problem of simplicity. Imagine a large billiard table with millions of balls rolling over its surface, colliding with one another and with the side rails. This is a typical problem of disorganized complexity. Problems of organized complexity, however, deal with features of an organization such as living things, ecosystems, and human societies. The quantitative definition of complexity is the most fundamental and important notion in problems of (organized and disorganized) complexity. The quantitative definition of disorganized complexity has been established to be entropy. In contrast, there is no agreed-upon quantitative definition for organized complexity, although many definitions have been proposed for this aim. In this talk, first, I will show the shortcomings of the existing definitions for organized complexity. I will then introduce a new definition and present that the new definition has solved all problems with the existing definitions. Finally, I will show some applications. This talk is based on the following paper.

Tatsuaki Okamoto, ‘‘A New Quantitative Definition of the Complexity of Organized Matters,’’ Complexity, Volume 2022, Article ID 1889348 (2022)

https://www.hindawi.com/journals/complexity/2022/1889348/

### 2022/07/07

16:50-18:35 Room #123 (Graduate School of Math. Sci. Bldg.)

Design and control of quantum computers XIII (Japanese)

**Yasunari Suzuki**(NTT)Design and control of quantum computers XIII (Japanese)

[ Abstract ]

How to use quantum computer II

How to use quantum computer II

### 2022/06/30

16:50-18:35 Room #123 (Graduate School of Math. Sci. Bldg.)

Design and control of quantum computersXII (Japanese)

**Yasunari Suzuki**(NTT)Design and control of quantum computersXII (Japanese)

[ Abstract ]

How to use quantum computer I

How to use quantum computer I

### 2022/06/23

16:50-18:35 Room #123 (Graduate School of Math. Sci. Bldg.)

Design and control of quantum computersXI (Japanese)

**Yasunari Suzuki**(NTT)Design and control of quantum computersXI (Japanese)

[ Abstract ]

On the error-correcting code of quantum computer.

On the error-correcting code of quantum computer.

### 2022/06/16

16:50-18:35 Room #123 (Graduate School of Math. Sci. Bldg.)

Design and control of quantum computers X (Japanese)

**Yasunari Suzuki**(NTT)Design and control of quantum computers X (Japanese)

[ Abstract ]

Error-correcting of quantum computer

Error-correcting of quantum computer

### 2022/06/09

16:50-18:35 Room #123 (Graduate School of Math. Sci. Bldg.)

Design and control of quantum computers IX (Japanese)

**Yasunari Suzuki**(NTT)Design and control of quantum computers IX (Japanese)

[ Abstract ]

On stabilizer codes and toric codes

On stabilizer codes and toric codes

### 2022/06/02

16:50-18:35 Room #123 (Graduate School of Math. Sci. Bldg.)

Design and control of quantum computers VIII (Japanese)

**Yasunari Suzuki**(NTT)Design and control of quantum computers VIII (Japanese)

[ Abstract ]

Explanation of error correcting code of quantum computer

------stabilizer method

Explanation of error correcting code of quantum computer

------stabilizer method

### 2022/05/26

16:50-18:35 Room #123 (Graduate School of Math. Sci. Bldg.)

Design and control of quantum computers VII (Japanese)

**Yasunari Suzuki**(NTT)Design and control of quantum computers VII (Japanese)

### 2022/05/19

16:50-18:35 Room #123 (Graduate School of Math. Sci. Bldg.)

Design and control of quantum computersVI (Japanese)

**Yasunari Suzuki**(NTT)Design and control of quantum computersVI (Japanese)