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2 04977595 19901211 380/24 Method and apparatus for implementing
++electronic++ ++cash++
Inventor: Ohta; Kazuo
Assignee: Nippon Telegraph and Telephone Corporation
Abstract:
In an ++electronic++ ++cash++ implementing method, a user makes a
++bank++ apply a ++blind++ signature to user information Vi produced, by a
one-way function, from secret information Si containing identification
information, thereby obtaining signed user information. Further, the user
makes the ++bank++ apply a ++blind++ signature to information containing
authentication information Xi produced, by a one-way function, from random
information Ri, thereby obtaining signed authentication information. The
user uses an information group containing the signed user information, the
signed authentication information, the user information and the
authentication information, as ++electronic++ ++cash++ for payment to a
++shop++. The ++shop++ verifies the validity of the signed user
information and the signed authentication information, and produces and
sends to the user an inquiry. In response to the inquiry the user produces
a response Yi by using secret information and random information and sends
it to the ++shop++. Having verified the validity of the response the
++shop++ accepts the ++electronic++ ++cash++.
3 05224162 19930629 380/24 ++Electronic++ ++cash++ system
Inventor: Okamoto; Tatsuaki
Assignee: Nippon Telegraph and Telephone Corporation
Abstract:
In an ++electronic++ ++cash++ system, K sets of ++blind++ signature
information are derived from secret information containing identification
information of a user, K/2 sets of them are opened and a ++bank++ attaches
a ++blind++ signature to the remaining K/2 sets of information. The user
obtains a signed license from the ++blind++ signature. The user generates
++blind++ signature information from the license and a desired amount of
money and gets a ++blind++ signature of the ++bank++ to the ++blind++
signature information and obtains ++electronic++ ++cash++ signed by the
++bank++ from the ++blind++ signature. The user presents to a ++shop++ a
residue power root of a node in a money hierarchial structure and the
++electronic++ ++cash++, corresponding to the amount of money to be used,
and the ++shop++ verifies their validity and, if they are valid, offers
inquiry information to the user. The user offers, as response information,
a residue power root of the node corresponding to the amount of money to
be used to the ++shop++. The ++shop++ verifies the validity of the
response information and, if it is valid, acknowledges the payment with
++electronic++ ++cash++ of the amount of money to be used.
4 04759063 19880719 380/30 ++Blind++ signature systems
Inventor: Chaum; David L.
Abstract:
A cryptographic system allows, in one exemplary use, a supplier to
cryptographically transform a plurality of messages responsive to secret
keys; the transformed messages to be digitally signed by a signer; and the
signed transformed messages returned to the supplier to be transformed by
the supplier, responsive to the same secret keys, in such a way that a
++digital++ signature related to each original message is developed by the
supplier. One important property of these systems is that the signer
cannot determine which transformed message received for signing
corresponds with which ++digital++ signature-even though the signer knows
that such a correspondence must exist.
6 04914698 19900403 380/30 One-show ++blind++ signature systems
Inventor: Chaum; David
Abstract:
Numbers standing for ++cash++ money can be ++spent++ only one time
each, otherwise the --account-- from which they were ++withdrawn++ would
be revealed. More generally, a technique for issuing and showing ++blind++
++digital++ signatures ensures that if they are shown responsive to
different challanges, then certain information their signer ensures they
contain will be revealed and can be recovered efficiently. Some
embodiments allow the signatures to be unconditionally untraceable if
shown no more than once. Extensions allow values to be encoded in the
signatures when they are shown, and for change on unshown value to be
obtained in a form that is aggregated and untraceable.
11 04949380 19900814 380/30 Returned-value ++blind++ signature
systems
Inventor: Chaum; David
Abstract:
A payer party obtains from a signer party by a ++blind++ signature
system a first public key ++digital++ signature having a first value in a
withdrawal transaction; the payer reduces the value of the first signature
obtained from the first value to a second value and provides this
reduced-value form of the signature to the signer in a payment
transaction; the signer returns a second ++digital++ signature to the
payer by a ++blind++ signature system in online consummation of the
payment transaction; the --paper-- derives from the first and the second
signature a third signature having a value increased corresponding to the
magnitude of the difference between the first and the second values.
Furthermore, the following additional features are provided: payments are
unlinkable to withdrawals; a ++shop++ between the payer and signer can be
kept from obtaining more value than desired by the payer; the first value
need not be revealed to the signer or intermediary in the payment
transaction; the returned difference can be accumulated across multiple
payment transactions; and the returned difference can be divided between a
plurality of payment transactions.
19 04759064 19880719 380/30 ++Blind++ unanticipated signature
systems
Inventor: Chaum; David L.
Abstract:
An improved ++blind++ signature system not requiring computation
during ++blinding++ for anticipating which of a plurality of possible
signatures will be made during signing, while still allowing the
++blinding++ party to unblind and recover the unanticipated kind of
signature on what was ++blinded++. An exemplary embodiment ++blinds++ by
forming a product including a plurality of generators raised to powers
normally secret from the signing party, and unblinds by forming a product
with the multiplicative inverse of a signed form of the generators raised
to the original powers. Re-blinding allows a signature on a value to be
transformed into a signature on a particular ++blinded++ form of the
value.
23 04206315 19800603 380/23 ++Digital++ signature system and
apparatus
Inventor: Matyas; Stephen M.
Assignee: International Business Machines Corporation
Abstract:
A ++digital++ signature machine provides a simplified method of
forming and verifying a signature that is appended to a ++digital++
message. A sender transmits a signature with the usual signature keys and
with validation table entries that correspond to the unsent keys and with
the compressed encoding of the next validation table. The receiver uses
the compressed encoding of the next validation table to form validation
table entries from the signature keys so that the receiver has a full
validation table. This validation table is compressed and compared with
the compressed encoding which was received from the sender in a preceding
message.
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