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US5537475A Expired / Lapsed US ⏱️ 0.0 years remaining

Efficient digital signature algorithm and use thereof technical field

Assignee: Individual
•
Filing: 1994-02-01
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Granted: 1996-07-16
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Expires: 2014-02-01
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Abstract

Abstract A digital signature scheme wherein the signature of a message M relative to a public key is computed by means of a secret key. The scheme begins by having the user select a number x independent of M. This step may occur off-line and before there is any knowledge of the particular message M to be signed. To sign the message, the routine computes a description of a function G which is dependent of the message M, and then applies the function G to x to produce a string z. The routine outputs z and a description of a second function F as the desired signature of the message M. Thus according to the invention a signature of the message is obtained by applying to an independent argument x a function dependent on M. This operation provides enhanced efficiency and security over the prior art and facilitates use of the scheme to allow multiple users of a secure communications system to share the same public key; alternatively, the scheme is useful for generating short certificates of public keys used in such systems.

Inventors

  • 👤 Silvio Micali

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-30 00:01
CPC Classifications
H; H04; H04L; H04L9/00; H04L9/30; H04L9/3006; H04L9/302; H04L9/32; H04L9/3247; H04L9/3255

Claims Analysis

Total Claims: 11
Claim 1
Independent Claim 116 words
A digital signature scheme wherein the signature of a message M relative to a public key is computed by means of a secret key by: (a) selecting a number x independent of M; (b) computing a string σ dependent on M, wherein the string σ together with the secret key specify a permutation G.sub.σ composed from a given set of permutations, the secret key is a number that squared mod n at least once, yields a number computable from public information identifying the signer; (c) applying the permutation G.sub.σ to the number x to produce a string z; and (d) releasing the string z and the string σ as the digital signature of the message M.
Claim 2
Dependent Claim 116 words
A digital signature scheme wherein the signature of a message M relative to a public key is computed by means of a secret key by: (a) selecting a number x independent of M; (b) computing a string σ dependent on M, wherein the string σ together with the secret key specify a permutation G.sub.σ composed from a given set of permutations, the secret key is a number that squared mod n at least once, yields a number computable from public information identifying the signer; (c) applying the permutation G.sub.σ to the number x to produce a string z; and (d) releasing the string z and the string σ as the digital signature of the message M.
Claim 3
Dependent Claim 29 words
The digital signature scheme as described in claim 1 wherein the string σ is obtained from the number x and the message M by a computation that includes hashing.
Claim 4
Dependent Claim 15 words
The digital signature scheme as described in claim 1 wherein the yielded number is 4.
Claim 5
Dependent Claim 31 words
The digital signature scheme as described in claim 1 wherein a group of signers share the same public key, and wherein at least two of the signers have distinct secret keys.
Claim 6
Dependent Claim 22 words
The digital signature scheme as described in claim 4 wherein a given agent computes the secret key of at least one signer.
Claim 7
Dependent Claim 34 words
The digital signature scheme as described in claim 1 wherein the set of given permutations include one permutation mapping a square mode n to S·x 2 mod n, where S is a given number.
Claim 8
Dependent Claim 42 words
The digital signature scheme as described in claim 1 wherein the public key includes a composite number n and one permutation in the set of permutations maps a square mod n to Sx 2 mod n, where S is a fixed number.
Claim 9
Dependent Claim 30 words
The digital signature scheme as described in claim 7, wherein a group of signers share the same public key and at least two of the signers have distinct secret keys.
Claim 10
Dependent Claim 23 words
The digital signature scheme as described in claim 8 wherein at least one agent computes the secret key of at least one signer.
Claim 11
Dependent Claim 43 words
The digital signature scheme as described in claim 8 wherein a set of agents choose the secret key of at least one signer, and wherein information in possession of a single agent does not enable the single agent to compute the secret keys.

References Cited (Backward Citations)

US4625076A Cited
US5276737A Cited
US5276737B1 Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1999-07-16 2000-01-15 2000-07-16 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 2003-07-16 2004-01-15 2004-07-16 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2007-07-16 2008-01-15 2008-07-16 $7700.00 Window Closed / Lapsed

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