International Business Machines Corporation

Other

Victor Shoup

Sandeep Kishan Singhal

Stefan Georg Hild

Michael Steiner

Luke James O'Connor

Carl Binding

Yen-Min Huang

Klaus Kursawe

Christian Cachin

Ronald Cramer

Jan Leonard Camenisch

Joy Algesheimer

Frank Petzold

The present scheme improves the security of encrypted data or information by using of a practical public-key cryptosystem that is able to resist adaptive attacks. The disclosed scheme does not leak any information about the secret of the used key. Therefor the scheme generates an extended private key and public key. A message m, also referred to as plaintext, is encryptable to a ciphertext t by using the public key. Only a recipient with the right private key is able to decrypt the ciphertext t. But before a decryption starts, a verification of the ciphertext t takes place. Such a verification allows to prove the legitimation of the ciphertext t. That means, the ciphertext t is investigated and either decrypted back to the plaintext or rejected if a chosen ciphertext is fed, ie. the ciphertext is illegitimate or invalid.

Practical non-malleable public-key cryptosystem

A method is provided for reducing a known value modulo a shared secret value among network devices exchanging messages in a network. The reduction results in a share of reduced value for each network device of a reduced value. Each network device has its share of known value and its share of shared secret value. It performs an inversion step for deriving from the share of shared secret value a share of the inverse of the shared secret value by using an approximation process, resulting in a share of inverse value; a multiplication step for deriving from the share of inverse value by use of the share of known value a share of multiplied inverse value; a rounding step for rounding the share of multiplied inverse value; and a calculation step for deriving the share of reduced value from the share of known value, the rounded share of multiplied inverse value, and the share of shared secret value. The method reduces values with a public modulus but also enables several network devices to reduce their known values with a modulus shared among them, but not becoming public. After the reduction, a faster computation with the reduced values or the shares thereof can be achieved. The proposed method can be implemented in threshold protocols in which computation occurs in a group where a modulus is not known but distributed. Furthermore, a network device is provided comprising a processor for executing the method incorporated in a computer program product.

Method for reducing a value modulo a shared secret

A method, system, and computer program product for establishing security parameters that are used to exchange data on a secure connection. A piggy-backed key exchange protocol is defined, with which these security parameters are advantageously exchanged. By piggy-backing the key exchange onto other already-required messages (such as a client's HTTP GET request, or the server's response thereto), the overhead associated with setting up a secure browser-to-server connection is minimized. This technique is defined for a number of different scenarios, where the client and server may or may not share an encoding scheme, and is designed to maintain the integrity of application layer communication protocols. In one scenario, a client requests a server to propose a message encoding scheme. If the client has security-sensitive data to transmit with its request, it waits for the proposed scheme before sending this sensitive data to the server. Otherwise, the server may inform the client of the message encoding scheme in the same transmission used to send a response to a client's request.

Piggy-backed key exchange protocol for providing secure, low-overhead browser connections when a client requests a server to propose a message encoding scheme

Byzantine Agreement requires a set of parties in a distributed system to agree on a value even if some parties are corrupted. The invention comprises a method for achieving agreement among participating network devices in an asynchronous network is disclosed that makes use of cryptography, specifically of threshold digital signatures and a distributed coin-tossing protocol.

Method of achieving multiple processor agreement in asynchronous networks

Methods and apparatus for achieving agreement among participating network devices in an asynchronous network for deciding on a common value is disclosed, whereby the common value is validated by a justification and both together satisfy a predetermined predicate. Moreover, a method for reliably broadcasting messages in an order within the asynchronous network is described. Up to one third or more of the participating network devices might be faulty in arbitrary ways.

Agreement and atomic broadcast in asynchronous networks

A method, system, and computer program product for establishing security parameters that are used to exchange data on a secure connection. A piggy-backed key exchange protocol is defined, with which these security parameters are advantageously exchanged. By piggy-backing the key exchange onto other already-required messages (such as a client's HTTP GET request, or the server's response thereto), the overhead associated with setting up a secure browser-to-server connection is minimized. This technique is defined for a number of different scenarios, where the client and server may or may not share an encoding scheme, and is designed to maintain the integrity of application layer communication protocols. In one scenario, a client and a server exchange secure messages using a trusted third party.

Piggy-backed key exchange protocol for providing secure low-overhead browser connections from a client to a server using a trusted third party

A method for achieving agreement among n participating network devices to an agree-value in a network is disclosed. The method proposes an optimistic approach to the consensus problem, whereby the number t of faulty devices is less than n/3. It is distinguished between an optimistic and pessimistic case. In the pessimistic case, a fallback agreement protocol is performed that reaches the same agree-value as the method in the optimistic case outputs.

Method of achieving optimistic multiple processor agreement in potentially asynchronous networks

A method, system, and computer program product for establishing security parameters that are used to exchange data on a secure connection. A piggy-backed key exchange protocol is defined, with which these security parameters are advantageously exchanged. By piggy-backing the key exchange onto other already-required messages (such as a client's HTTP GET request, or the server's response thereto), the overhead associated with setting up a secure browser-to-server connection is minimized. This technique is defined for a number of different scenarios, where the client and server may or may not share an encoding scheme, and is designed to maintain the integrity of application layer communication protocols. In one scenario, a client and server share a common message encoding scheme.

Piggy-backed key exchange protocol for providing secure, low-overhead browser connections to a server with which a client shares a message encoding scheme

The present scheme improves the security of encrypted data or information by using of a practical public-key cryptosystem that is able to resist adaptive attacks. The disclosed scheme does not leak any information about the secret of the used key. Therefor the scheme generates an extended private key and public key. A message m, also referred to as plaintext, is encryptable to a ciphertext t by using the public key. Only a recipient with the right private key is able to decrypt the ciphertext r. But before a decryption starts, a verification of the ciphertext t takes place. Such a verification allows to prove the legitimation of the ciphertext t. That means, the ciphertext t is investigated and either decrypted back to the plaintext or rejected if a chosen ciphertext is fed, ie. the ciphertext is illegitimate or invalid.

A method, system, and computer program product for establishing security parameters that are used to exchange data on a secure connection. A piggy-backed key exchange protocol is defined, with which these security parameters are advantageously exchanged. By piggy-backing the key exchange onto other already-required messages (such as a client's HTTP GET request, or the server's response thereto), the overhead associated with setting up a secure browser-to-server connection is minimized. This technique is defined for a number of different scenarios, where the client and server may or may not share an encoding scheme, and is designed to maintain the integrity of application layer communication protocols. In one scenario, a client proposes a message encoding scheme, but the server will not use this proposed scheme. The server proposes a different scheme, after which the client re-issues its request for secure content.

Piggy-backed key exchange protocol for providing secure, low-overhead browser connections when a server will not use a message encoding scheme proposed by a client

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Zurich, Switzerland

Victor Shoup