EP0998074A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method of digital signature, and secret information management method and system
Assignee: Hitachi Ltd
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Filing: 1999-10-29
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Granted: —
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Expires: 2019-10-29
Abstract
Abstract A method of digital signature for generating a digital signature A that uses a private key d for a message M in which k pieces of numerical information u1 - uk satisfying d = f1(u1, u2, ..., uk) are distributed into and retained by k computers; with regard to each computer of the k computers, a piece of numerical information ui (1 ≤ i ≤ k) retained by itself, a piece of numerical information si generated by itself, and information obtained from pieces of numerical information generated respectively by the computers other than itself by themselves, are made to act on the message M, by that computer, to generate a partial signature ai on the message M; and partial signatures ai - ak generated respectively by the k computers are used to generate the digital signature A that uses the private key d for the message M. <IMAGE>
Inventors
- 👤 Kunihiko Miyazaki
- 👤 Kazuo Takaragi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 11:42
CPC Classifications
H; H04; H04L; H04L9/00; H04L9/08; H04L9/0891; H04L9/30; H04L9/3066; H04L9/3073; H04L9/32; H04L9/3247; H04L9/3255
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
163 words
A method of generating a digital signature, for
generating a digital signature A that uses a private
key d for a message M, wherein: k pieces of numerical information u 1 - u k satisfying d = f1(u 1 , u 2 , ..., u k ) are distributed into
and retained by k computers; with regard to each computer of said k computers,
a piece of the numerical information u i (1 ≤ i ≤ k)
retained by itself, a piece of numerical information s i generated by itself, and information obtained from
pieces of numerical information generated respectively
by the computers other than itself by themselves, are
made to act on the message M, by said each computer, to
generate a partial signature a i on the message M; and partial signatures a 1 - a k generated respectively
by said k computers are used to generate the digital
signature A that uses the private key d for the message
M.
Claim 2
Dependent Claim
183 words
The method of generating a digital signature
according to Claim 1, wherein: the k pieces of numerical information u 1 - u k satisfying d = f1(u 1 , u 2 , ..., u k ) are distributed to
and retained by each of at least two groups of k
computers, said groups being different from each other
in combination; with regard to each computer of the k computers
of each group, a piece of numerical information u i (1
≤ i ≤ k) retained by itself, a piece of numerical
information s i generated by itself, and information
obtained from pieces of numerical information generated
respectively by the computers other than itself by
themselves, which belongs to a same group as itself,
are made to act on the message M to generate the
partial signature a i on the message M, by said each
computer; and the partial signatures a 1 - a k generated by the k
computers belonging to a same group are used to
generate the digital signature A that uses the private
key d for the message M.
Claim 3
Dependent Claim
155 words
The method of generating a digital signature
according to Claim 1, wherein: j pieces of numerical information u' 1 - u' j satisfying d = f2(u' 1 , u' 2 , ..., u' j ) are distributed to
and retained by j computers different in combination
from said k computers; with regard to each computer of said j computers,
a piece of numerical information u' i (1 ≤ i ≤ j)
retained by itself, a piece of numerical information s i generated by itself, and information obtained from
pieces of numerical information generated respectively
by said j computers other than itself by themselves,
are made to act on the message M, by said each computer,
to generate a partial signature a' i ; and the partial signatures a' 1 - a' j generated by
said j computers are used to generate the digital
signature A that uses the private key d for the message
M.
Claim 4
Dependent Claim
61 words
The method of generating a digital signature
according to Claim 1, wherein: said k pieces of numerical information u 1 - u k satisfying d = f1(u 1 , u 2 , ..., u k ) are generated by a
computer that is different from said k computers that
retain said k pieces of numerical information
distributed into those k computers.
Claim 5
Dependent Claim
62 words
The method of generating a digital signature
according to Claim 1, wherein: said k pieces of numerical information u 1 - u k satisfying d = f1(u 1 , u 2 , ..., u k ) are generated by said
k computers in cooperation with each other, said k
computers retaining said k pieces of numerical
information distributed to said k computers.
Claim 6
Dependent Claim
77 words
The method according to Claim 1, wherein: said piece of numerical information s i is
information that can not obtain said private key d by
using the message M, a public key Q pairing with the
private key d, and the digital signature A, even if
said piece of numerical information s i is made open to
others except for the computers of the group to which
the computer that generated said numerical information
s i belongs.
Claim 7
Independent Claim
184 words
A system of generating a digital signature, in
which k computers 1 - k are used to generate a digital
signature A that uses a private key d on a message M,
wherein: a computer i (1 ≤ i ≤ k) retains one piece of
numerical information u i out of k pieces of numerical
information u 1 - u k satisfying d = f1(u 1 , u 2 , ..., u k ),
and has a means for generating a partial signature a i on
the message M, with the piece of numerical information
u i owned by itself, a piece of numerical information s i generated by itself, and information obtained from
pieces of numerical information generated respectively
by the computers other than itself by themselves, being
made to act on the message M, by said computer i; and said k computers 1 - k cooperate with each other
in using partial signatures a i - a k generated
respectively in the computers 1 - k, to generate the
digital signature A that uses the private key d on the
message M.
Claim 8
Independent Claim
92 words
A method of generating a digital signature, for
generating a digital signature A that uses a private
key d on a message M, wherein: a common key is generated by using information
used for generating the digital signature A, and by
using a public key Q' pairing with a private key d'
owned by a destination of the message M, and the generated common key is used to encrypt the
message M, so that a cryptogram of the message M is
generated together with the digital signature A on said
message M.
Claim 9
Dependent Claim
89 words
A method for verifying a digital signature A
generated by the method of Claim 8, the verification
being performed using a public key Q pairing with said
private key d, wherein: said common key is generated by using information
used for verifying the digital signature A and by using
said private key d'; and the generated common key is
used to decrypt the cryptogram of the message M,
thereby obtaining the message M at the same time with
the verification of the digital signature A on the
message M.
Claim 10
Independent Claim
89 words
A device for generating a digital signature, for
generating a digital signature A that uses a private
key d on a message, wherein: a common key is generated by using information
used for verifying the digital signature A and by using
a public key Q' pairing with a private key d' owned by
a destination of the message M; and the generated
common key is used to encrypt the message M, thereby
generating a cryptogram of the message M together with
the digital signature A on the message M.
Claim 11
Dependent Claim
87 words
A device for verifying the digital signature A,
which is generated by the device of Claim 10 and uses a
public key Q pairing with said private key d, wherein: said common key is generated by using information
used for verifying the digital signature A and by using
said private key d', and the generated common key is
used to decrypt a cryptogram of the message M, thereby
obtaining the message M at the same time with
verification of the digital signature A on the message
M.
Claim 12
Independent Claim
76 words
A method of decentralizedly managing a secret
information d, wherein: k pieces of numerical information u 1 - u k satisfying d = f1(u 1 , u 2 , ..., u k ) are distributed into
and retained by k computers out of n computers, and at
the same time, distributed into and retained by m (m <
k) computers out of the n computers, said m computers
being different in combination from said k computers.
Claim 13
Independent Claim
112 words
A method of decentralizedly managing a secret
information d, wherein: k pieces of numerical information u 1 - u k satisfying d = f1(u 1 , u 2 , ..., u k ) are distributed into
and retained by k computers, and at the same time, at
least one u i (1 ≤ i ≤ k) out of said k pieces of
numerical information u 1 - u k is divided into j pieces
of numerical information u' 1 - u' j satisfying u i = f2(u' 1 ,
u' 2 , ..., u' j ), so that said j pieces of numerical
information are distributed into and retained by j
computers.
Claim 14
Independent Claim
89 words
A method of decentralizedly managing a secret
information d, in which each of n computers
decentralizedly manages the secret information d so
that the secret information can be generated by using k
pieces of numerical information owned by k computers
out of the n computers, wherein: a number c of computers that retain respectively
damaged pieces of numerical information is counted, and
when c becomes more than or equal to a prescribed value
t (k < t < n), an instruction to update the secret
information d is given.
References Cited (Backward Citations)
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