from cryptography.fernet import Fernet def encrypt_message(public_key, message): # Get the public key in bytes public_key_bytes = bytes.fromhex(public_key) # Generate a symmetric key symmetric_key = Fernet.generate_key() # Encrypt the message using the symmetric key f = Fernet(symmetric_key) encrypted_message = f.encrypt(message.encode()) # Encrypt the symmetric key using the public key rsa_key = RSA.import_key(public_key_bytes) cipher_rsa = PKCS1_OAEP.new(rsa_key) encrypted_key = cipher_rsa.encrypt(symmetric_key) return encrypted_key, encrypted_message

import ecdsa # Generate a private key private_key = ecdsa.SigningKey.generate(curve=ecdsa.SECP256k1) # Get the public key public_key = private_key.get_verifying_key() # Encode the keys to hexadecimal format private_key_hex = private_key.to_string().hex() public_key_hex = public_key.to_string().hex() print(f'Private key: {private_key_hex}') print(f'Public key: {public_key_hex}') from cryptography.fernet import Fernet def encrypt_message(public_key, message): # Get the public key in bytes public_key_bytes = bytes.fromhex(public_key) # Generate a symmetric key symmetric_key = Fernet.generate_key() # Encrypt the message using the symmetric key f = Fernet(symmetric_key) encrypted_message = f.encrypt(message.encode()) # Encrypt the symmetric key using the public key rsa_key = RSA.import_key(public_key_bytes) cipher_rsa = PKCS1_OAEP.new(rsa_key) encrypted_key = cipher_rsa.encrypt(symmetric_key) return encrypted_key, encrypted_message from cryptography.fernet import Fernet def encrypt_message(public_key, message): # Get the public key in bytes public_key_bytes = bytes.fromhex(public_key) # Generate a symmetric key symmetric_key = Fernet.generate_key() # Encrypt the message using the symmetric key f = Fernet(symmetric_key) encrypted_message = f.encrypt(message.encode()) # Encrypt the symmetric key using the public key rsa_key = RSA.import_key(public_key_bytes) cipher_rsa = PKCS1_OAEP.new(rsa_key) encrypted_key = cipher_rsa.encrypt(symmetric_key) return encrypted_key, encrypted_message
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What is a 51 Percent attack on a Blockchain

by publicnotice.crypto@gmail.comDecember 28, 2022January 4, 2023
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A 51% attack is a type of cyber attack that occurs when a group of miners or malicious actors control more than 50% of the computing power on a blockchain network. This gives them the ability to manipulate the network in a number of ways, including:

  1. Double spending: The attackers can spend the same cryptocurrency multiple times, essentially creating new money out of thin air.
  2. Reversing transactions: The attackers can reverse transactions that have already been verified and recorded on the blockchain.
  3. Blocking transactions: The attackers can block new transactions from being added to the blockchain, effectively shutting down the network.
  4. Changing the blockchain’s history: The attackers can change the history of the blockchain, including altering the transaction record and altering the balance of users’ accounts.

A 51% attack is a major concern for blockchain networks, as it can lead to a loss of trust in the network and undermine the integrity of the blockchain. To prevent a 51% attack, blockchain networks rely on decentralization and a large number of miners spread across a wide geographic area. This makes it difficult for any one group to gain control of a significant portion of the network’s computing power.

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