personal information For the security of wholesale* transactions of trusted institutions * wholesale: The sale of products, often in large quantities, to retailers or other merchants.
https://www.ecb.europa.eu/paym/intro/publications/pdf/ecb.miptopical200212.en.pdf B C Ledger subset Entity A (Sender) Entity B (Receiver) Entity C (Unauthorised third party) Transaction
C Ledger Entity A (Sender) Entity B (Receiver) Entity C (Unauthorised third party) Transaction Image reference: https://www.ecb.europa.eu/paym/intro/publications/pdf/ecb.miptopical200212.en.pdf
encryption Ledger Entity A (Sender) Entity B (Receiver) Entity C (Unauthorised third party) Transaction Image reference: https://www.ecb.europa.eu/paym/intro/publications/pdf/ecb.miptopical200212.en.pdf
S 4FDSFU Alice Blockchain Challenge 1. commit 2. Reveal 3. unlock & check Bob Alice W W $PNNJUNFOU W W $PNNJUNFOU D S $PNNJUNFOU D S Zero knowledge proof Image reference: https://blog.sigmadex.org/understanding- zero-knowledge-proof/ 4FDSFU 4FDSFU 1SPPG 1SPPG Prover Verifier Homomorphic encryption Image reference: https://www.researchgate.net/figure/In-a- fully-homomorphic-encryption-scheme-operations-on- ciphertext-space-are-mirrored-in_fig1_323598036 + = 9 : ; + = + = 1VCMJDLFZFODSZQU 1SJWBUFLFZEFDSZQU
S 4FDSFU Alice Blockchain Challenge 1. commit 2. Reveal 3. unlock & check Bob Alice W W $PNNJUNFOU W W $PNNJUNFOU D S $PNNJUNFOU D S Zero knowledge proof Image reference: https://blog.sigmadex.org/understanding- zero-knowledge-proof/ 4FDSFU 4FDSFU 1SPPG 1SPPG Prover Verifier Homomorphic encryption Image reference: https://www.researchgate.net/figure/In-a- fully-homomorphic-encryption-scheme-operations-on- ciphertext-space-are-mirrored-in_fig1_323598036 + = 9 : ; + = + = 1VCMJDLFZFODSZQU 1SJWBUFLFZEFDSZQU
S 4FDSFU Alice Blockchain Challenge 1. commit 2. Reveal 3. unlock & check Bob Alice W W $PNNJUNFOU W W $PNNJUNFOU D S $PNNJUNFOU D S Zero knowledge proof Image reference: https://blog.sigmadex.org/understanding- zero-knowledge-proof/ 4FDSFU 4FDSFU 1SPPG 1SPPG Prover Verifier Homomorphic encryption Image reference: https://www.researchgate.net/figure/In-a- fully-homomorphic-encryption-scheme-operations-on- ciphertext-space-are-mirrored-in_fig1_323598036 + = 9 : ; + = + = 1VCMJDLFZFODSZQU 1SJWBUFLFZEFDSZQU
Ledger Segregating Hidden Hidden Payment channel network Public Hidden* Unlinking One-time address Hidden Public Mixing Hidden Public Ring signature Hidden Public Hidden Hiding Pedersen commitment Public Hidden Zero knowledge proof Hidden Hidden Homomorphic encryption Public Hidden * Only the net transacted amount can be viewed and interpreted. Project Stella, Feb 2020, https://www.ecb.europa.eu/paym/intro/publications/pdf/ecb.miptopical200212.en.pdf
Proof of Account balance - Like bank account balance - Simple to understand - Efficiency Account A, 500 Account B, 1000 Account A, 400 Account B, 1100 5Y"#
lock and unlocking script • sender, receiver, amount, signature Validation • validate check UTXO is unspent and is from the sender • Check that the sender's balance is sufficient and the signature is valid Recording the state • The movement of asset is Directed acyclic graph(DAG) • key and value database of network states Advantages • Parallel processing possible • easy to implement sharding • excellent anonymity/security • Easy to develop smart contract • Easy to create transaction history for a single user Disadvantage • Smart contract design is complex • Need to prepare a plan to prevent double payment • Difficulty in parallel processing
must be possible. 3. The secure transfer must be secured by the sender, receiver, and amount. 2. All public and secure transfers must be public on a single ledger. 4. Secure transfer need to be auditable by auditor.
transfer must be possible. 3. The secure transfer must be secured by the sender, receiver, and amount. Category PETs Transaction Information Sender Receiver Amount Segregating Ledger Segregating Hidden Hidden Payment channel network Public Hidden* Unlinking One-time address Hidden Public Mixing Hidden Public Ring signature Hidden Public Hidden Hiding Pedersen commitment Public Hidden Zero knowledge proof Hidden Hidden Homomorphic encryption Public Hidden Requirements 4. Secure transfer need to be auditable by auditor. 2. All public and secure transfers must be public on a single ledger.
transfer must be possible. 3. The secure transfer must be secured by the sender, receiver, and amount. Category PETs Transaction Information Sender Receiver Amount Segregating Ledger Segregating Hidden Hidden Payment channel network Public Hidden* Unlinking One-time address Hidden Public Mixing Hidden Public Ring signature Hidden Public Hidden Hiding Pedersen commitment Public Hidden Zero knowledge proof Hidden Hidden Homomorphic encryption Public Hidden Requirements 4. Secure transfer need to be auditable by auditor. 2. All public and secure transfers must be public on a single ledger.
transfer must be possible. 3. The secure transfer must be secured by the sender, receiver, and amount. Category PETs Transaction Information Sender Receiver Amount Segregating Ledger Segregating Hidden Hidden Payment channel network Public Hidden* Unlinking One-time address Hidden Public Mixing Hidden Public Ring signature Hidden Public Hidden Hiding Pedersen commitment Public Hidden Zero knowledge proof Hidden Hidden Homomorphic encryption Public Hidden Requirements 4. Secure transfer need to be auditable by auditor. 2. All public and secure transfers must be public on a single ledger.
and All secure transfer are handled with ZKP. Transactions between secret and public balances. Secure transfer is UTXO model, public transfer is Account model. Encrypt UTXO of secure transfer with one-time encryption key.
- Sender signature required - Receiver and encrypted UTXO attestation with ZKP - The public balance is burned - Mint new UTXO and used as input for secret UTXO HidingTransaction FODSZQUFECPEZ PXOFS WBMVF secret UTXO Account value Secure transfer public balance → secret balance Transaction • Sender • Amount • Receiver • Input UTXO • Output UTXO • ZKP Proof • signature
- Sender signature required - Receiver and encrypted UTXO attestation with ZKP - The public balance is burned - Mint new UTXO and used as input for secret UTXO HidingTransaction PXOFS TFOEFS WBMVF CMPDLIFJHIU mint UTXO FODSZQUFECPEZ PXOFS WBMVF secret UTXO Account value Burn Account value Secure transfer public balance → secret balance
- Sender and encrypted UTXO attestation with ZKP - The secret balance is burned - New account value is created and added to the receiver’s balance RevealingTransaction Secure transfer secret balance → public balance Account value + A value secret UTXO FODSZQUFECPEZ PXOFS "WBMVF Transaction • Sender • Amount • Receiver • Input UTXO • Output UTXO • ZKP Proof
- Sender and encrypted UTXO attestation with ZKP - The secret balance is burned - New account value is created and added to the receiver’s balance RevealingTransaction Secure transfer secret balance → public balance PXOFS SFDFJWFS "WBMVF CMPDLIFJHIU burn UTXO Account value + A value secret UTXO FODSZQUFECPEZ PXOFS "WBMVF Mint Account value
- Sender and encrypted UTXO attestation with ZKP - The secret balance is burned - New account value is created and added to the receiver’s balance RevealingTransaction Secure transfer secret balance → public balance PXOFS SFDFJWFS #WBMVF CMPDLIFJHIU burn UTXO Account value + B value secret UTXO FODSZQUFECPEZ PXOFS "WBMVF secret UTXO FODSZQUFECPEZ PXOFS "# WBMVF Mint Account value