Cryptographically concealing amounts and asset types for independently verifiable transactions

A method for verifying an encrypted transaction having a plurality of different assets being transacted on a blockchain ledger, the method comprising, for each received asset type:

• receiving, by a processor of a computer system in communication via a network connection with a server storing the blockchain ledger, an encrypted received amount, an encrypted output value, a first ring signature, and a second ring signature in a block appended to the blockchain, the block further comprising a digital signature signed using a private key associated with a prior owner, the digital signature comprising a hash of a previous transaction value stored on the blockchain ledger in a prior block;
• verifying, by the processor, that the digital signature is valid using a public key associated with the prior owner, the public key being part of key pair with the private key associated with the prior owner, wherein verification is denied if the digital signature cannot be validated using the public key associated with the prior owner;
• verifying, by the processor, the first ring signature and second ring signature, wherein verification is denied if either ring signature fails verification;
• extracting the encrypted received amount and the encrypted output value from the received block, the encrypted received amount comprising an amount received of an asset, a blinded asset tag associated with the asset type and a second blinding value, the blinded asset tag comprising a first blinding value, and the encrypted output value comprising an associated blinding amount;
• verifying the transaction if the sum of the encrypted received amount and the encrypted output value for the asset is zero;
• and
• denying verification to the transaction if the sum of the encrypted received amount and the encrypted output value for the asset is a nonzero value.

A method for decrypting amounts and assets transacted on a blockchain ledger, the method comprising:

• using a separately-received address to retrieve a block from a blockchain, the block comprising a plurality of asset types, the block further comprising, for each asset type, an encrypted received amount, an encrypted output value, a first ring signature, and a second ring signature, the block being retrieved via a network connection from a server storing the blockchain, the block further comprising a digital signature signed using a private key associated with a prior owner, the digital signature comprising a hash of a previous transaction value retrieved from a server over a network from a blockchain stored on the server, the previous transaction value being stored on the server in a prior block;
• for each asset type of the block:
• using a private key to access the first ring signature, the first ring signature being associated with a correctly-valued public key for each digit of the encrypted received amount, the correctly-valued public key being selected from a group of four public keys for each digit of the encrypted received amount of the asset, the private key corresponding to a second blinding value;
• applying an XOR operation to the smallest digit of the encrypted received amount of the asset;
• repeating the applying the XOR operation to each digit of the encrypted received amount of the asset;
• identifying a repeated pattern within an output of the XOR operation;
• using the positions of the repeated pattern within the output of the XOR operation to determine the received amount from the encrypted received amount of the asset;
• using a difference between a first blinding value and an output coefficient to access the second ring signature, the second ring signature being associated with a key value for each digit of a blinded asset tag.

A method for encrypting an amount transacted on a blockchain ledger, the method comprising:

• adding, by a processor, a blinding amount to an input value being transacted, thereby created an encrypted input value;
• generating, by the processor, an output value corresponding to the input value;
• encrypting, by the processor, the generated output value to create an encrypted output value, the encrypted output value including a corresponding blinding amount such that the input value blinding amount and the generated output value blinding amount cancel each other out when added together, wherein both the input value and the output value being transacted are values falling with a value range, the value range being defined so that a sum of any two values within the range does not exceed an overflow threshold, a sum of the encrypted input value and the encrypted output value equaling zero;
• generating, by the processor for the encrypted output value, a plurality of rangeproofs, the rangeproofs showing that the input value falls within the value range, each rangeproof being associated with a different public key, the generating comprising:
• converting, by the processor, each rangeproof into a plurality of scalar values, each scalar value having a predetermined number of decimal places;
• setting for each plurality of scalar values, by the processor, a selected scalar to zero;
• normalizing, by the processor, the remainder of each plurality of scalar values based on an original value of the selected scalar, thereby reducing a number of each plurality of scalar values by one;
• completing, by the processor, the plurality of rangeproofs using the normalized scalar values;
• signing each public key, by the processor, with a ring signature based on a public key of a recipient, thereby encrypting the remainder of the plurality of rangeproofs, wherein a single memory amount is shared among each public key;
• storing, by the processor, the encrypted input value, the encrypted output value, and the encrypted rangeproofs in a block, the block further comprising a digital signature signed using a private key associated with a prior owner, the digital signature comprising a hash of a previous transaction value retrieved from a server over a network from a blockchain stored on the server, the previous transaction value being stored on the server in a prior block;
• and
• transmitting, by the processor, the block over a network connection to a server storing a blockchain, the block being subsequently published on the blockchain.