Content deleted Content added
m Robot - move category per CFD 2008 April 1 |
Count Count (talk | contribs) →External links: rm spam links |
||
| (57 intermediate revisions by 30 users not shown) | |||
Line 1:
'''Transient-key cryptography''' is a form of [[
==Public-key vs. transient-key
Both [[public key]] and transient-key systems can be used to generate [[digital signature]]s that assert that a given piece of data has not changed since it was signed. But the similarities end there. In a traditional public key system, the public/private keypair is typically assigned to an individual, server, or [[organization]]. Data signed by a private key asserts that the signature came from the indicated source. Keypairs persist for years at a time, so the private component must be carefully guarded against disclosure; in a public-key system, anyone with access to a private key can counterfeit that
In transient-key systems, however, the keypair is assigned to a brief interval of time, not to a particular person or entity. Data signed by a specific private key becomes associated with a specific time and date. A keypair is active only for a few minutes, after which the private key is permanently destroyed. Therefore, unlike public-key systems, transient-key systems do not depend upon the long-term security of the private keys.
==Establishing data integrity with transient-key timestamps==▼
In a transient-key system, the source of time must be a consistent standard understood by all senders and receivers. Since a local [[system clock]] may be changed by a user, it is never used as a source of time. Instead, data is digitally signed with a time value derived from [[Universal Coordinated Time|Universal Coordinated Time (UTC)]] accurate to within a millisecond, in accordance with the [[ANSI ASC X9.95 Standard|ANSI ASC X9.95 standard for Trusted Timestamping]].{{citation needed|date=March 2024}} Whenever a time interval in a transient-key system expires, a new public/private keypair is generated, and the private key from the previous interval is used to digitally certify the new public key. The old private key is then destroyed. This "key-chaining" system is the immediate ancestor of the [[Blockchain]] technology in vogue today.
For the new interval, time values are obtained from a trusted third-party source, and specific moments in time can be [[
The start times of the chain and of each interval can be coupled together to form an unbroken sequence of public keys, which can be used for the following:
* To irrefutably identify the time at which a set of data was signed.
* To identify the exact state of the data at the time it was signed.
As an extra security measure, all requests for signatures made during an interval are stored in a [[Data log|log]] that is [[
==Cross-verification==
[[Image:Cross-Certification.png|
Through independently operating servers, '''cross-certification''' can provide third-party proof of the validity of a time interval chain and irrefutable evidence of consensus on the current time. A web of interconnected cross-certifying servers in a distributed environment creates a widely witnessed chain of trust that is as strong as its strongest link. By contrast, entire [[Hierarchy|hierarchies]] of traditional public key systems can be compromised if a single private key is exposed. ▼
An individual transient key interval chain can be cross-certified with other transient key chains and server instances. Through cross-certification, Server A signs Server B's interval chain, the signed data of which is the interval definition. In effect, the private keys from Server B are used to sign the public keys of Server A. In the diagram, a server instance is cross-certified with two other server instances (blue and orange).▼
▲Through independently operating servers, '''cross-certification''' can provide third-party proof of the validity of a time interval chain and irrefutable evidence of consensus on the current time. Transient-key cryptographic systems display high [[Byzantine fault tolerance]]. A web of interconnected cross-certifying servers in a distributed environment creates a widely witnessed chain of trust that is as strong as its strongest link. By contrast, entire [[Hierarchy|hierarchies]] of traditional public key systems can be compromised if a single private key is exposed.
▲[[Image:Cross-Certification.png|thumbnail|320px|A private key is cross-certified using two other transient-key servers.]]
▲An individual transient key interval chain can be cross-certified with other transient key chains and server instances. Through cross-certification, Server A signs Server B's interval chain, the signed data of which is the interval definition. In effect, the private keys from Server B are used to sign the public keys of Server A. In the diagram, a server instance is cross-certified with two other server instances (blue and orange). Cross-certification requires that the timestamp for the interval agree with the timestamp of the cross-certifying server within acceptable tolerances, which are user-defined and typically a few hundred milliseconds in duration.
==Network archives==
Along with intervals, cross-certifications are stored in a network archive. Within a transient-key network, the [[
==Verification==
During an interval, the transient private key is used to sign data concatenated with trusted timestamps and authenticity certificates. To [[File verification|verify]] the data at a later time, a receiver accesses the [[Persistence (computer science)|persistent]] public key for the appropriate time interval. The public key applied to the digital signature can be passed through published cryptographic routines to unpack the [[Cryptographic hash function|hash]] of the original data, which is then compared against a fresh hash of the stored data to verify data integrity. If the signature successfully decrypts using a particular
Transient-key cryptography was invented in 1997 by Michael D. Doyle of Eolas Technologies Inc., while working on the [[Visible Embryo Project]]<ref>{{cite patent |country=US |number=6381696 |title=Method and system for transient key digital time stamps |gdate=2002-04-30 |inventor=MD Doyle}}</ref><ref>{{cite patent |country=US |number=7047415 |title=System and method for widely witnessed proof of time |gdate=2006-05-16 |invent1=MD Doyle |invent2=PF Doyle |invent3=GW Bernsohn |invent4=JD Roberts }}</ref><ref>{{cite patent |country=US |number= 7210035 |title=System and method for graphical indicia for the certification of records |gdate=2007-04-24 |invent1=MD Doyle |invent2=RG Hamilton |invent3=MC Perrone |invent4=PF Doyle}}</ref> and later acquired by and productized by ProofSpace, Inc. It has been adopted as a national standard in the ANSI ASC X9.95 standard for Trusted Timestamping. Transient-key cryptography is the predecessor to [[Forward secrecy]] and formed the foundation of the forward-signature-chaining technology in the [[Bitcoin]] [[blockchain (database)|blockchain]] system.
==See also==
[[Category:Cryptography]]▼
* [[Certificateless cryptography]]
[[Category:Asymmetric-key cryptosystems]]▼
* [[Certificate-based encryption]]
[[Category:Banking technology]]▼
[[Category:Data security]]▼
==References==
{{Crypto navbox | public-key}}▼
{{reflist}}
▲[[Category:Banking technology]]
▲[[Category:Data security]]
| |||