Tetsu IWATA


On the Design Rationale of SIMON Block Cipher: Integral Attacks and Impossible Differential Attacks against SIMON Variants
Kota KONDO Yu SASAKI Yosuke TODO Tetsu IWATA 
Publication:   
Publication Date: 2018/01/01
Vol. E101-A  No. 1  pp. 88-98
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
lightweight block cipherintegral attackimpossible differential attackdesign rationalerotation constant
 Summary | Full Text:PDF(1.6MB)

On the Security of Non-Interactive Key Exchange against Related-Key Attacks
Hiraku MORITA Jacob C.N. SCHULDT Takahiro MATSUDA Goichiro HANAOKA Tetsu IWATA 
Publication:   
Publication Date: 2017/09/01
Vol. E100-A  No. 9  pp. 1910-1923
Type of Manuscript:  Special Section PAPER (Special Section on Discrete Mathematics and Its Applications)
Category: 
Keyword: 
related-key attacksNon-Interactive Key ExchangeDiffie-Hellman key exchange scheme
 Summary | Full Text:PDF(1.1MB)

On the Security of Schnorr Signatures, DSA, and ElGamal Signatures against Related-Key Attacks
Hiraku MORITA Jacob C.N. SCHULDT Takahiro MATSUDA Goichiro HANAOKA Tetsu IWATA 
Publication:   
Publication Date: 2017/01/01
Vol. E100-A  No. 1  pp. 73-90
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
related-key attacksSchnorr signaturesDSAElGamal signatures.
 Summary | Full Text:PDF(540KB)

Optimality of Tweak Functions in CLOC
Hayato KOBAYASHI Kazuhiko MINEMATSU Tetsu IWATA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2015/10/01
Vol. E98-A  No. 10  pp. 2152-2164
Type of Manuscript:  PAPER
Category: Cryptography and Information Security
Keyword: 
authenticated encryption schemeCLOCtweak functionsoptimalityCAESAR competition
 Summary | Full Text:PDF(1.1MB)

Type 1.x Generalized Feistel Structures
Shingo YANAGIHARA Tetsu IWATA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2014/04/01
Vol. E97-A  No. 4  pp. 952-963
Type of Manuscript:  PAPER
Category: Cryptography and Information Security
Keyword: 
blockcipherGeneralized Feistel Structure (GFS)Type 1.x GFSpermutation layer
 Summary | Full Text:PDF(756.7KB)

Cryptanalysis of 249-, 250-, ..., 256-Bit Key HyRAL via Equivalent Keys
Yuki ASANO Shingo YANAGIHARA Tetsu IWATA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2014/01/01
Vol. E97-A  No. 1  pp. 371-383
Type of Manuscript:  PAPER
Category: Cryptography and Information Security
Keyword: 
cryptanalysisblockcipherHyRALequivalent key
 Summary | Full Text:PDF(1.1MB)

Improving the Permutation Layer of Type 1, Type 3, Source-Heavy, and Target-Heavy Generalized Feistel Structures
Shingo YANAGIHARA Tetsu IWATA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2013/01/01
Vol. E96-A  No. 1  pp. 2-14
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Symmetric Key Cryptography
Keyword: 
blockciphergeneralized Feistel structure (GFS)permutation layercomputer experiment.
 Summary | Full Text:PDF(567.5KB)

Security of Hash-then-CBC Key Wrapping Revisited
Yasushi OSAKI Tetsu IWATA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2013/01/01
Vol. E96-A  No. 1  pp. 25-34
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Symmetric Key Cryptography
Keyword: 
authenticated key wrappinghash functionCBC modesecurity proofdeterministic authenticated encryption
 Summary | Full Text:PDF(307.8KB)

Further More on Key Wrapping
Yasushi OSAKI Tetsu IWATA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2012/01/01
Vol. E95-A  No. 1  pp. 8-20
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Symmetric Cryptography
Keyword: 
key wrapping schemeuniversal hash functionuniform hash functionECB modeCBC modesecurity proof
 Summary | Full Text:PDF(405.2KB)

Tweakable Pseudorandom Permutation from Generalized Feistel Structure
Atsushi MITSUDA Tetsu IWATA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2010/01/01
Vol. E93-A  No. 1  pp. 13-21
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Symmetric Cryptography
Keyword: 
Luby-Rackoff theorytweakable blockciphergeneralized feistel structuresecurity proofs
 Summary | Full Text:PDF(497.7KB)

MPP Characteristics of Variants of Merkle-Damgård Iterated Hash Functions
Shungo NAKAMURA Tetsu IWATA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2010/01/01
Vol. E93-A  No. 1  pp. 93-101
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Hash Function
Keyword: 
Merkle-Damgård iterated hash functionmulti-property-preserving characteristicssecurity proof
 Summary | Full Text:PDF(198KB)

Security of the Five-Round KASUMI Type Permutation
Tetsu IWATA Tohru YAGI Kaoru KUROSAWA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2008/01/01
Vol. E91-A  No. 1  pp. 30-38
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Symmetric Cryptography
Keyword: 
blockcipherKASUMIadaptive chosen plaintext and chosen ciphertext attacksprovable security
 Summary | Full Text:PDF(262.5KB)

How to Construct Super-Pseudorandom Permutations with Short Keys
Tetsu IWATA Kaoru KUROSAWA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2007/01/01
Vol. E90-A  No. 1  pp. 2-13
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Symmetric Cryptography
Keyword: 
Luby-Rackoff theorysuper-pseudorandomnessFeistel permutationMISTY-type permutation
 Summary | Full Text:PDF(265.6KB)

How to Improve Interpolation Attack
Kaoru KUROSAWA Tetsu IWATA Quang Viet DUONG 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2005/01/01
Vol. E88-A  No. 1  pp. 9-15
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Symmetric Key Cryptography
Keyword: 
block cipherinterpolation attackroot finding algorithmresultant
 Summary | Full Text:PDF(178.6KB)

On the Security of a MAC by Mitchell
Tetsu IWATA Kaoru KUROSAWA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2005/01/01
Vol. E88-A  No. 1  pp. 25-32
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Symmetric Key Cryptography
Keyword: 
message authentication codeOMACsecurity proofssecurity gappseudorandom permutation
 Summary | Full Text:PDF(679.9KB)

On the Correctness of Security Proofs for the 3GPP Confidentiality and Integrity Algorithms
Tetsu IWATA Kaoru KUROSAWA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2004/05/01
Vol. E87-A  No. 5  pp. 1110-1118
Type of Manuscript:  Special Section LETTER (Special Section on Discrete Mathematics and Its Applications)
Category: 
Keyword: 
cryptographyf 8f 9modes of operationprovable securityblock cipherpseudorandom permutation
 Summary | Full Text:PDF(211.8KB)

On the Pseudorandomness of KASUMI Type Permutations
Tetsu IWATA Tohru YAGI Kaoru KUROSAWA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2004/05/01
Vol. E87-A  No. 5  pp. 1098-1109
Type of Manuscript:  Special Section LETTER (Special Section on Discrete Mathematics and Its Applications)
Category: 
Keyword: 
cryptographyblock cipherKASUMIpseudorandomnessprovable security
 Summary | Full Text:PDF(296.6KB)

On the Universal Hash Functions in Luby-Rackoff Cipher
Tetsu IWATA Kaoru KUROSAWA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2004/01/01
Vol. E87-A  No. 1  pp. 60-66
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Symmetric Cipher
Keyword: 
cryptographyblock cipherFeistel permutationsuper-pseudorandomness
 Summary | Full Text:PDF(254.2KB)

TMAC: Two-Key CBC MAC
Kaoru KUROSAWA Tetsu IWATA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2004/01/01
Vol. E87-A  No. 1  pp. 46-53
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Symmetric Cipher
Keyword: 
cryptographyCBC MACblock cipherprovable security
 Summary | Full Text:PDF(277.9KB)

Inclusion Relations of Boolean Functions Satisfying PC(l) of Order k
Tetsu IWATA Kaoru KUROSAWA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2003/01/01
Vol. E86-A  No. 1  pp. 47-53
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: Symmetric Ciphers and Hash Functions
Keyword: 
cryptographyBoolean functionpropagation characteristicinclusion relations
 Summary | Full Text:PDF(411.7KB)

Round Security and Super-Pseudorandomness of MISTY Type Structure
Tetsu IWATA Tomonobu YOSHINO Tomohiro YUASA Kaoru KUROSAWA 
Publication:   IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Publication Date: 2002/01/01
Vol. E85-A  No. 1  pp. 2-10
Type of Manuscript:  Special Section PAPER (Special Section on Cryptography and Information Security)
Category: 
Keyword: 
cryptographyblock cipherround securitysuper-pseudorandomnessMISTY type structure
 Summary | Full Text:PDF(304.5KB)