Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
210 words
A method for anonymous, provable information exchange between a sender and an addressee in a computer network, the computer network providing a public key infrastructure, preferably with certification, and an anonymous communication channel available between network users, said method comprising the following steps: said sender C composes an offer request REQ with a subject or merchandise description MD and a digital signature SIG-c of C, REQ=(MD,SIG-c), said REQ is transmitted via said anonymous communication channel to at least one addressee M, said addressee M composes a reply REP with an offer description OD and its digital signature SIG-m, said digital signature SIG-m being computed over a selection of quantities comprising at least one of MD, OD, SIG-c, REP=(OD, SIG-m), and further including M's public key PK-m or public key certificate Cert-m, said sender C, upon receiving said reply REP, uses M's public key PK-m, known, transmitted, or extracted from said public key certificate Cert-m, to encrypt said received SIG-m, thus determining a first temporary value TMP-1, TMP-1=PK-m(SIG-m), said sender C computes a concatenation of said selection of quantities on which said signature SIG-m is based, thus determining a second temporary value TMP-2 TMP-2=H(SIG-c/MD/OD), said sender C compares said temporary values TMP-1 and TMP-2, a match indicating genuineness of said offer.
Claim 2
Independent Claim
210 words
A method for anonymous, provable information exchange between a sender and an addressee in a computer network, the computer network providing a public key infrastructure, preferably with certification, and an anonymous communication channel available between network users, said method comprising the following steps: said sender C composes an offer request REQ with a subject or merchandise description MD and a digital signature SIG-c of C, REQ=(MD,SIG-c), said REQ is transmitted via said anonymous communication channel to at least one addressee M, said addressee M composes a reply REP with an offer description OD and its digital signature SIG-m, said digital signature SIG-m being computed over a selection of quantities comprising at least one of MD, OD, SIG-c, REP=(OD, SIG-m), and further including M's public key PK-m or public key certificate Cert-m, said sender C, upon receiving said reply REP, uses M's public key PK-m, known, transmitted, or extracted from said public key certificate Cert-m, to encrypt said received SIG-m, thus determining a first temporary value TMP-1, TMP-1=PK-m(SIG-m), said sender C computes a concatenation of said selection of quantities on which said signature SIG-m is based, thus determining a second temporary value TMP-2 TMP-2=H(SIG-c/MD/OD), said sender C compares said temporary values TMP-1 and TMP-2, a match indicating genuineness of said offer.
Claim 3
Dependent Claim
29 words
The method according to claim 1, wherein the digital signature SIG-c of the sender C is a hash function of the MD and/or a randomly generated nonce R-c, SIG-c=H(MD/R-c).
Claim 4
Dependent Claim
31 words
The method according to claim 1, wherein the digital signature SIG-c of the sender C is an encryption of the MD under a randomly generated nonce R-c as key, SIG-c=R-c(MD). 4.
Claim 5
Dependent Claim
35 words
The method according to claim 1, wherein the digital signature SIG-c of the sender C is a hash function of the MD and/or a randomly generated nonce R-c, encrypted under C's secret key SK-c, SIG-c=SK-c[H(MD/R-c)].
Claim 6
Independent Claim
62 words
The method according to any of the claims 2 to 4, wherein the nonce R-c of sender C is transmitted to the addressee M, the addressee M computes a hash function of said MD and R-c, thus determining a third temporary value TMP-3, TMP-3=H(MD, R-c), said addressee M compares said temporary value TMP-3 and SIG-c, a match indicating genuineness of said SIG-c.
Claim 7
Dependent Claim
47 words
A method according to claim 5, wherein the addressee uses PK-c, either known, received, or extracted from Cert-c, to encrypt the received SIG-c, thus determining a fourth temporary value TMP-4, TMP-4=PK-c(SIG-c), said addressee compares said temporary values TMP-3 and TMP-4, a match indicating genuineness of said SIG-c.
Claim 8
Dependent Claim
53 words
The method according to claim 1, wherein the digital signature SIG-m of the addressee M is a hash function of the chosen selection of quantities of MD, OD, SIG-c, SIG-m=H(SIG-c/MD/OD), and the concatenation to derive TMP-2 is a hash function of said same selection of quantities used to compute said SIG-m, TMP-2=H(SIG-c/MD/OD). 8.
Claim 9
Independent Claim
41 words
The method according to any of the claims 2 to 4, wherein the digital signature SIG-m of the addressee M is a hash function of the chosen selection of quantities of MD, OD, SIG-c, encrypted under M's secret key SK-m, SIG-m=SK-m(H(SIG-c/MD/OD)).
Claim 10
Dependent Claim
40 words
The method according to claim 1, wherein, the sender has an a priori knowledge of the addressee's public key PK-m, and the addressee M encrypts the offer description OD with its secret key SK-m and transmits a reply REP=(SK-m(OD), SIG-m).
Claim 11
Dependent Claim
23 words
The method according to claim 1, wherein the sender C further transmits its user identification ID-c to the addressee M as identity proof.
Claim 12
Independent Claim
36 words
The method according to any of the claims 2 to 4, wherein the sender C further transmits the nonce R-c to the addressee M, enabling identification of said sender C by verification of its signature SIG-c.
Claim 13
Dependent Claim
31 words
The method according to claim 1, wherein the sender C and/or the addressee M are keeping state in that at least one of them stores incoming requests REQ and/or replies REP.
Claim 14
Independent Claim
228 words
A system for anonymous, provable information exchange between a sender and an addressee in a computer network, the computer network providing a public key infrastructure, preferably with certification, and an anonymous communication means between network users, said system comprising: means in said sender C for composing an offer request REQ=(MD, SIG-c) with a subject or merchandise description MD and a digital signature SIG-c of C, means for making said offer request REQ anonymous, means for transmitting said anonymous offer request to at least one addressee M, means in said addressee M for composing a reply REP=(OD, SIG-m) with an offer description OD and a digital signature SIG-m of M, said digital signature SIG-m being computed over a selection of quantities comprising at least one of MD, OD, SIG-c, and further including M's public key PK-m or public key certificate Cert-m, means in said sender C, upon receiving said reply REP, for encrypting said received SIG-m and determining a first temporary value TMP-1=PK-m(SIG-m), using M's public key PK-m, known, transmitted, or extracted from said public key certificate Cert-m, means for computing a concatenation of said selection of quantities on which said signature SIG-m is based and determining a second temporary value TMP-2=H(SIG-c/MD/OD), means in said sender for comparing said first and said second temporary values TMP-1 and TMP-2, a matching of TMP-1 and TMP-2 indicating genuineness of said offer.
Claim 15
Independent Claim
228 words
A system for anonymous, provable information exchange between a sender and an addressee in a computer network, the computer network providing a public key infrastructure, preferably with certification, and an anonymous communication means between network users, said system comprising: means in said sender C for composing an offer request REQ=(MD, SIG-c) with a subject or merchandise description MD and a digital signature SIG-c of C, means for making said offer request REQ anonymous, means for transmitting said anonymous offer request to at least one addressee M, means in said addressee M for composing a reply REP=(OD, SIG-m) with an offer description OD and a digital signature SIG-m of M, said digital signature SIG-m being computed over a selection of quantities comprising at least one of MD, OD, SIG-c, and further including M's public key PK-m or public key certificate Cert-m, means in said sender C, upon receiving said reply REP, for encrypting said received SIG-m and determining a first temporary value TMP-1=PK-m(SIG-m), using M's public key PK-m, known, transmitted, or extracted from said public key certificate Cert-m, means for computing a concatenation of said selection of quantities on which said signature SIG-m is based and determining a second temporary value TMP-2=H(SIG-c/MD/OD), means in said sender for comparing said first and said second temporary values TMP-1 and TMP-2, a matching of TMP-1 and TMP-2 indicating genuineness of said offer.