Method for certifying public keys in a digital signature scheme
OwnerSilvio Micaliinventor
Life of this patent
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Abstract
A method for certifying public keys of a digital signature scheme in a communications system is provided. The secure communications system is one in which there are at least two levels of authorities. A user presents a piece of data to an intermediate level authority who, upon verifying the data, causes an issuing authority to issue a certificate that the piece of data posses a given property. Although the certificate is compacted by not having it contain a pubic key of the intermediate authority, nonetheless, information is stored in order to keep the intermediate authority accountable.
Claims46
A method for certifying pieces of data in a system having authorities that certify data, comprising the steps of:
- (a) presenting a piece of data requiring certification to a first authority for inspection of a given property;
- (b) if the piece of data passes the inspection of the first authority, causing a second authority to receive an indication that the piece of data has passed the inspection of at least the first authority;
- (c) having the second authority issue a certificate that the piece of data possesses the given property, the second authority including in the certificate a signature of the second authority and the second authority omitting from the certificate a public key of the first authority;
- and
- (d) storing accountability information that renders at least the first authority accountable for pieces of data that the first authority contributes to certify.
A method for certifying public keys where there are a plurality of authorities A.sub.1, . . . , A.sub.n that certify data, where each i<n authority A.sub.i is configured to send authority A.sub.i+1 authenticated messages that are verifiable by A.sub.i+1 as having genuinely come from A.sub.i, and authority A.sub.n has a signing key SK.sub.n and an associated certified public key, PK.sub.n, the method comprising the steps of:
- (a) having a verification key PK.sub.U presented to authority A.sub.1 ;
- (b) having authority A.sub.1 verify, by means of a predetermined procedure, that PK.sub.U possesses some properties out of a set of given properties;
- (c) for all i<n, having authority A.sub.i send authority A.sub.i+1 a message indicating that PK.sub.U has been verified to possess the given properties;
- (d) having A.sub.n issue a certificate for PK.sub.U, A.sub.n including in the certificate a signature provided using SK.sub.n and A.sub.n omitting from the certificate a public key of at least one authority A.sub.j for some j<n;
- and
- (e) storing accountability information that renders A.sub.j accountable for keys that A.sub.j contributes to certify.
Dependencies are inferred from the claim text.