Address whitelisting using public/private keys and ring signature

A method for verifying transfer of an asset from a side chain to a main blockchain on a side chain ledger, the side chain having a fixed set of participants, comprising:

• determining, by a processor circuitry associated with a computing device of a participant wanting to verify transfer of the asset to the main blockchain, the computing device being in communication with a sidechain server storing the side chain ledger, a set of ring signature keys, each ring signature key being based on a hash function applied to a difference between a received main blockchain address A and public offline keys associated with each participant of the fixed set, the output of the hash function being multiplied by a standard elliptic curve group generator G and added to public online keys setoff each corresponding participant, the received main blockchain address A being from a published ring signature on the side chain ledger associated with control of a public address associated with the main blockchain, the set of participants having an index where an index number is associated with each participant;
• determining, by the processor circuitry, a set of coefficients based on the determined set of ring signature keys, a received set of second uniform random scalars obtained from the published ring signature, a received first coefficient also from the published ring signature, and the hash function, each of the determined set of coefficients being further based on a previous participant coefficient according to the index;
• determining a first coefficient based on a first uniform random scalar from the received set of second uniform random scalars, a last determined coefficient according to the index and a last determined ring signature key, also according to the index;
• comparing the determined first coefficient to the received first coefficient;
• and
• comparing the received main blockchain address A to the public address associated with the main blockchain, the transfer being verified when the determined first coefficient is equal to the received first coefficient and the received main blockchain address A corresponds to the public address associated with the main blockchain, such that when the asset is transferred to the public address associated with the main blockchain, access is based on a public offline key associated with a transferring participant and control of the public address is proven without associating a participant identity with the public address.