Specification Writing as Construction of Hierarchically Structured Clusters of Operators. - Kokichi Futatsugi; Koji Okada (IFIP Congress, 1980)

A Hierarchical Structuring Method for Functional Software Systems. - Kokichi Futatsugi; Koji Okada (ICSE, 1982)

Parameterized Programming in OBJ2. - Kokichi Futatsugi; Joseph A. Goguen; José Meseguer 001; Koji Okada (ICSE, 1987)

Nonperfect Secret Sharing Schemes and Matroids. - Kaoru Kurosawa; Koji Okada; Keiichi Sakano; Wakaha Ogata; Shigeo Tsujii (EUROCRYPT, 1993)

Combinatorial Interpretation of Secret Sharing Schemes. - Kaoru Kurosawa; Koji Okada (ASIACRYPT, 1994)

Security of the Center in Key Distribution Schemes. - Kaoru Kurosawa; Koji Okada; Keiichi Sakano (ASIACRYPT, 1994)

Lower Bound on the Size of Shares of Nonperfect Secret Sharing Schemes. - Koji Okada; Kaoru Kurosawa (ASIACRYPT, 1994)

Low Exponent Attack Against Elliptic Curve RSA. - Kaoru Kurosawa; Koji Okada; Shigeo Tsujii (Inf. Process. Lett., 1995)

Combinatorial Lower Bounds for Secret Sharing Schemes. - Kaoru Kurosawa; Koji Okada (Inf. Process. Lett., 1996)

New Combinatorial Bounds for Authentication Codes and Key Predistribution Schemes. - Kaoru Kurosawa; Koji Okada; Hajime Saido; Douglas R. Stinson (Des. Codes Cryptogr., 1998)

MDS secret-sharing scheme secure against cheaters. - Koji Okada; Kaoru Kurosawa (IEEE Trans. Inf. Theory, 2000)

On the bound for anonymous secret sharing schemes. - Wataru Kishimoto; Koji Okada; Kaoru Kurosawa; Wakaha Ogata (Discret. Appl. Math., 2002)

Simple and Efficient Group Signature Scheme Assuming Tamperproof Devices. - Takuya Yoshida; Koji Okada (IWSEC, 2008)

Unforgeability of Re-Encryption Keys against Collusion Attack in Proxy Re-Encryption. - Ryotaro Hayashi 001; Tatsuyuki Matsushita; Takuya Yoshida; Yoshihiro Fujii; Koji Okada (IWSEC, 2011)

Estimation of Risk Countermeasure Effects Based Upon Project-Behavior Simulation System. - Ayaka Oshima; Koji Okada (IIAI-AAI, 2017)

Proposal of a Method to Understand and Model Dynamic Mechanisms Existing in Business Context. - Koji Okada; Hayato Nishizono; Kosuke Tsubouchi; Tatsuya Hirukawa (IIAI-AAI, 2018)

Proposal of a Method Extracting Strategic Phrases from Japanese Enterprise Disclosure Documents. - Shu Kawanami; Ken Hidema; Koji Okada (IIAI-AAI, 2020)

Applying Business Ecosystem Analysis Methods into Edge Computing Device Business for E-Solutions. - Koji Sekiguchi; Koji Okada (IIAI-AAI-Winter, 2021)