Abstract: A method for distributed asymmetric decryption between a first party and a second party, each holding a different respective share of a secret key, is provided. The method comprises receiving, at the second party: a zero-knowledge proof of knowledge; and a plurality of inputs associated with a ciphertext to be decrypted, wherein the ciphertext is encrypted with a public key associated with the secret key. The method further comprises checking, by the second party, that the zero-knowledge proof of knowledge was generated based on the first party's share of the secret key; and, in response to determining that the zero-knowledge proof of knowledge was generated based on the first party's share of the secret key, sending, by the second party, information derived from the second party's share of the secret key. An example system for implementing the method is also provided.

Abstract: Disclosed herein is a method for generating a composite cryptographic signature. The method comprises receiving a message and a first part of a first party signature, wherein the first part of the first party signature is derived from the message and a first share of a first private key. The method further comprises generating a first party signature from the first part of the first party signature and a second share of the first private key and generating a second party signature from the message and a second private key. The method further comprises combining the first party signature and the second party signature to generate a composite cryptographic signature. An apparatus, a computer-readable medium for implementing this method are also disclosed.

Abstract: Disclosed herein is a method for generating a composite cryptographic signature. The method comprises receiving a message and a first part of a first party signature, wherein the first part of the first party signature is derived from the message and a first share of a first private key. The method further comprises generating a first party signature from the first part of the first party signature and a second share of the first private key and generating a second party signature from the message and a second private key. The method further comprises combining the first party signature and the second party signature to generate a composite cryptographic signature. An apparatus, a computer-readable medium for implementing this method are also disclosed.