Abstract: Identifier-based signcryption methods and apparatus are disclosed both for signing and encrypting data, and for decrypting and verifying data. The signcryption methods use computable bilinear mappings and can be based, for example, on Weil or Tate pairings. A message sender associated with a first trusted authority carries out integrated signing/encryption processes to send a signed, encrypted message to an intended recipient associated with a second trusted authority. The recipient then carries out integrated decryption/verification processes to recover the original message and verify its origin.

Abstract: Identifier-based signcryption methods and apparatus are disclosed both for signing and encrypting data, and for decrypting and verifying data. The signcryption methods use computable bilinear mappings and can be based, for example, on Weil or Tate pairings. A message sender associated with a first trusted authority carries out integrated signing/encryption processes to send a signed, encrypted message to an intended recipient associated with a second trusted authority. The recipient then carries out integrated decryption/verification processes to recover the original message and verify its origin.

Abstract: Identifier-based signcryption methods and apparatus are disclosed both for signing and encrypting data, and for decrypting and verifying data. The signcryption methods use computable bilinear mappings and may be based, for example, on Weil or Tate pairings. Known, efficient, signing/verifying processes are judiciously combined with particular encryption/decryption processes to achieve efficient, yet secure, signcryption methods.

Abstract: A trusted authority is provided for identifier-based cryptography. The trusted authority has a secret and derives first and second elements at least the second of which it publishes. The first element is derived from an identifier associated with the trusted authority; the second element is a combination of the first element and the secret. The trusted authority provides a private-key generation service involving the generation of a private key for a third party in dependence on the secret and an identifier string associated with that third party.

Abstract: Signcryption methods and apparatus are provided that combine the functions of signing and encrypting data to obtain private and authenticated communications. The signcryption methods are based on RSA and permit compact ciphertexts to be produced and non-repudiation to be provided in a straightforward manner.