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 secure communications system is provided. The secure communications system in one in which there are authorities with previously-certified public verification keys. The method begins by having a user U present an authority a verification key PK.sub.U. The authority then identifies the presenting user as U. Thereafter, the authority verifies that the presenting user knows the secret signing key associated with PK.sub.U. If so, the authority computes a digital signature S relative to the authority's own public key PK.sub.A of its verification that PK.sub.U is the public key of user U. The authority then issues a certificate that PK.sub.U is the public key of user U, the certificate including both S and a certificate for PK.sub.A.
Claims23
A method for certifying pieces of data in a secure communications system with at least two levels of authorities, comprising the steps of:
- presenting a piece of data requiring certification to a first-level authority for inspection of a given property;
- if the piece of data passes the inspection of the first-level authority, having the first-level authority send to a higher authority a digital signature evidencing that the piece of data has passed the inspection of the first-level authority;
- and
- if the digital signature of the first-level authority is correct, having the higher authority issue a certificate, which does not include a signature of the first level authority, that the piece of data possesses the given property.
A method for certifying public keys of a digital signature scheme where there is at least one authority A with a certified public verification key PK.sub.A, comprising the steps of:
- having a user U present an authority B, having a verification key PK.sub.B, a verification key PK.sub.U together with a message correctly signed with respect to verification key PK.sub.U ;
- having authority B identify the presenting user as U;
- having authority B verify that the presented digital signature of U is a correct digital signature of the message with respect to the presented verification key PK.sub.U ;
- having authority B compute a digital signature S relative to PK.sub.B of the fact that PK.sub.U is a legitimate public key of user U;
- and
- having authority A issue a certificate that PK.sub.U is the public key of user U, which can be verified without a separate certificate for PK.sub.B, the certificate including a certificate for PK.sub.A whenever PK.sub.A is not certified by virtue of being universally known to users of the signature scheme.
A method for certifying public keys of a digital signature scheme in a secure communications system where there is at least one authority with a certified public verification key PK.sub.A, comprising the steps of:
- having a user U present an authority a verification key PK.sub.U ;
- having the authority identify the presenting user as U;
- having the authority verify that the presenting user knows the secret signing key associated with PK.sub.U ;
- having the authority compute a digital signature S relative to PK.sub.A of the fact that PK.sub.U is the public key of user U;
- and
- having the authority issue a certificate that PK.sub.U is the public key of user U, the certificate including both S and a certificate for PK.sub.A.
A method for certifying public keys of a digital signature scheme where there are a plurality of authorities A.sub.1, . . . , A.sub.n, where each authority A.sub.i has a secret signing key SK.sub.i and a matching verification key PK.sub.i known to A.sub.i+1, and a verification key of A.sub.n, PK.sub.n, is already certified or universally known to users of a signature scheme, comprising the steps of:
- having user U present A.sub.1 a verification key PK.sub.U ;
- having authority A.sub.1 verify, by means of a predetermined procedure, that PK.sub.U possesses some properties out of a set of predetermined properties;
- for i<n, having authority A.sub.i send authority A.sub.i+1 at least a properly chosen digital signature, with respect to verification key PK.sub.i, indicating that PK.sub.U has been verified to possess some predetermined properties;
- having A.sub.n issue a certificate for PK.sub.U which can be verified to be correct given a certificate for PK.sub.n, which certificate for PK.sub.U does not include at least one certificate for PK.sub.i for some i<n, but which may include a certificate for PK.sub.n if PK.sub.n is not universally known to the users of the signature scheme.
A method for certifying public keys of a digital signature scheme where there are a plurality of authorities A.sub.1, . . . , A.sub.n, where each i<n authority A.sub.i can send authority A.sub.i+1 authenticated messages so that at least A.sub.i+1 can be sure that these messages genuinely come from A.sub.i, and authority A.sub.n has a signing key SK.sub.n and an associated public key PK.sub.n, which is either certified or universally known to users of a signature scheme, comprising the steps of:
- having a verification key PK.sub.U presented to authority A.sub.1 ;
- having authority A.sub.1 verify, by means of a predetermined procedure, that PK.sub.U possesses some properties out of a set of predetermined properties;
- for all i<n, having authority A.sub.i send authority A.sub.i+1 an authenticated message indicating that PK.sub.U has been verified to possess some predetermined properties;
- having A.sub.n issue a certificate for PK.sub.U which can be verified valid if PK.sub.n is known to be the public key of authority A.sub.n, and which may include a certificate for PK.sub.n if PK.sub.n is not universally known to the users of the signature scheme, wherein the certificate for PK.sub.U does not include any certificate relative to authority A.sub.i for some i<n.
A method for certifying public keys of a digital signature scheme where there is at least one authority with a certified public verification key PK.sub.A, comprising the steps of:
- having a user U present an authority a verification key PK.sub.U together with a message correctly signed with respect to verification key PK.sub.U and indicating that U is the owner of verification key PK.sub.U ;
- having the authority identify the presenting user as U;
- having the authority verify that the presented digital signature of U is a correct digital signature of the message with respect to the presented verification key PK.sub.U ;
- having the authority compute a digital signature S relative to PK.sub.U of the fact that PK.sub.U is a legitimate public key of user U;
- and
- having the authority issue a certificate that PK.sub.U is the public key of user U, the certificate including both S and a certificate for PK.sub.U.
Dependencies are inferred from the claim text.