 RF pulse transmitter having incidental phase modulation (IPM) correction |
| The present invention relates to an RF pulse transmitter, preferably for use in precision distance ... |
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| Method and apparatus for reducing off-channel interference produced by a linear transmitter |
| What is claimed is: 1. In a linear transmitter that includes an information signal source and a ... |
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| Radio transmitter with power amplifier linearizer |
| According to the a first aspect of the present invention, a radio transmitter is provided ... |
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| Radio receiver |
| Therefore, this invention was created in view of the above-mentioned facts, and an object thereof ... |
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| Noninvasive diagnostic system for coronary artery disease |
| Accordingly, the present invention has been developed to overcome the foregoing shortcomings by ... |
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| Method and apparatus for checking continuity of optic transmission |
| The present invention is directed at an apparatus for and a method of detecting whether or not a ... |
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| Transmission power control circuit |
| An object of the invention is in that the gate bias voltage of the RF power module is varied in ... |
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| Protected amplifier apparatus |
| In FIG. 1, an input lead 10 provides RF signals to an ALC (automatic level control) block gain ... |
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| Transmitter testing method |
| OF INVENTION While the present invention will be described more fully hereinafter with reference ... |
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Administration and utilization of secret fresh random numbers in a networked environment
| Details |
Inventors: Cuccia, David; Epstein, Michael A.; Pasieka, Michael S.;
Assignee: Philips Electronics North America Corporation (New York, NY)
Primary Examiner: Swann; Tod R.
Assistant Examiner: Callahan; Paul
Attorney, Agent or Firm: Piotrowski; Daniel J.
In a public key cryptosystem employing the El-Gamal algorithm, secret fresh random numbers are generated at a server and private keys of users, as encrypted with a symmetric algorithm by using individual user identifying keys determined by hashing the users' respective passphrases or biometric information (fingerprint, voiceprint, retina scan, or face scan) are maintained in a store accessible to the server, and the fresh random numbers and encrypted private keys are transmitted to the user equipment when needed via a network which is not secure. In order to prevent an attacker from discovering the random numbers or employing formerly used random numbers in a block replay attack, an interchange in the nature of a challenge response protocol is employed which passes at least one secret fresh random number from the server to the user equipment while also authenticating the user to the server. In this interchange, a first random number to be distributed to the user for use in signing a document and a second random number which is to be used by the user in forming a signature of a hashing together of the first and second random numbers as part of the challenge response protocol, are supplied to the user equipment in encrypted form together with a freshness value, and a signature by the server of a hashing together of the first and second random numbers and the freshness value. |
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS It should be understood that while the present invention is discussed hereinafter in terms of an exemplary system and method for obtaining digitally signed documents of a plurality of users in a networked environment which have been signed employing the El-Gamal algorithm, the principles of the present invention are equally applicable to distribution of secret fresh random numbers, and/or to distribution of a combination of a secret fresh random number and an encrypted private key, for other purpose.
Further, when used for digital signatures, it should be appreciated that such signatures may be applied to a variety of data, files, programs or other "documents", whether originated, modified or reviewed by users.
In any event, the digital signature may be thought of as manifesting an approval by the user of a document.
One aspect of the present invention is that it employs user identifying keys Kpass for each user, for securing private keys KprUser.
The user identifying keys Kpass can only be derived from user identifying information obtained by interaction with the user physically present at the user equipment.
The user identifying information may be either a fanciful series of words, termed a passphrase, entered by a user or biometric information, such as a fingerprint, voiceprint, retina scan or face scan, obtained by measurement or scanning of the user.
It is very difficult to guess passphrases as opposed to passwords as there are many possible phrases.
For example, a particularly good passphrase may concatenate two phrases which are in different languages.
Guessing such a passphrase would be extremely difficult using normally available computer power.
Also, biometric information is particularly unique and immune to a guessing attack.
Referring first to FIG.
1 of the drawing, there is shown a networked system 10 comprised of a plurality of computer stations, terminals or other user computing and/or communication equipment 12 and a server 16 interconnected or capable of communicating via a wired or wireless network 14
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Audio Signal Processing 
