# Research on Blockchain Transaction Privacy Protection Methods Based on Deep Learning
## 3 Deep Learning-Based Blockchain Transaction Privacy Protection Model
### Model  
As shown in Figure 4, participants in the program primarily include the following: (1) The transaction's primary entities, the sender and the receiver, who aim to safeguard their anonymity and the confidentiality of the transaction sum through a secure transaction. In basic transaction activities, the sender transfers a certain amount of money to the receiver. (2) The miner, who verifies the legitimacy of the transaction and ensures that there is no double payment or fraud; after the transaction is verified, the miner packages it into a new block and stores it on the blockchain through a consensus mechanism to ensure the immutability of the transaction record. (3) Regulators, who are responsible for supervising and regulating the blockchain network. When necessary, they track the relevant participants and financial transactions to combat illegal financial activities. (4) Third parties, who may act as malicious actors using technical means to steal transaction-related information for undue gain.  
The scheme comprises the following seven algorithms:  
\(BG.KeyGen(p,q)\): This is the key generation process of the BG algorithm. It generates the BG algorithm's public key \(pk\) and private key \(sk\) using large primes \(p\) and \(q\). This algorithm provides probabilistic encryption, which generates different ciphertexts even if the same message is encrypted multiple times.  
\(BG.Enc(pk,m)\): This is the encryption process of the BG algorithm. It encrypts message \(m\) utilizing the public key \(pk\) of the probabilistic public-key BG algorithm to produce the ciphertext.  
\(BG.Dec(sk,ct)\): This is the decryption process of the BG algorithm. It decrypts ciphertext \(ct\) utilizing the private key \(sk\) of the probabilistic public-key BG algorithm to retrieve the plaintext. A user with the correct private key can successfully decrypt the ciphertext.  
\(IBC.KeyGen(sk,id)\): This is the key generation function of the SM9 algorithm based on IBC. Generate the user's private key by employing the SM9 algorithm's master key (\(sk\)) and the user's identifier (\(id\)).  
Figure 4: Blockchain Trading Entities.  
\(IBC.Enc(pk,m)\): This is the encryption process of the SM9 algorithm. It encrypts message \(m\) using the public key \(pk\) of the SM9 algorithm to produce ciphertext. SM9 is an identity-based encryption algorithm, which means that the encryption can be performed directly using the user's public identity information.  
\(IBC.Dec(sk,ct)\): This is the decryption process of the SM9 algorithm. It decrypts ciphertext \(ct\) using the private key \(sk\) of the SM9 algorithm to retrieve the plaintext. A user with the correct private key can decrypt successfully.  
\(IBC.Sign(sk,m)\): This is the signature process of the SM9 algorithm. It signs message \(m\) using the private key \(sk\) of the SM9 algorithm to obtain the signature value. This ensures the message remains unaltered throughout transmission, ensuring data integrity and non-repudiation.  
This scheme provides public-key encryption and decryption using the BG probabilistic public-key cryptography algorithm (with a key size of 2048 b), which provides strong security guarantees for transactions, especially in terms of its ability to counter selective plaintext attacks. We also use the SM9 algorithm based on the IBC cryptosystem (with a key size of 256 b), whose encryption strength is equivalent to the RSA encryption algorithm of 3072 b. The SM9 algorithm allows the direct use of a user's identification data as the public key, which simplifies the process of distributing and managing the key. In addition, it provides digital signature and authentication functions; this approach can secure transactions and verify user identities in certain situations. The use of these two algorithms enhances the system compatibility and flexibility, enabling the scheme to meet different transaction scenarios. By combining different encryption algorithms, a more complex security framework is constructed for the scheme, which enhances the security of the whole system.