When it comes to building secure blockchain networks for digital currency transactions, several technologies are being utilized to ensure the highest level of security. These technologies include:

  1. Cryptography: This is the backbone of blockchain technology and is used to secure transactions by encrypting data and ensuring that it cannot be tampered with. Cryptography also enables the creation of unique digital signatures for each transaction, making them tamper-proof and verifiable.

  2. Proof of Work (PoW): This is a consensus mechanism that is used to validate transactions on the blockchain. It requires users to perform complex mathematical calculations to validate transactions, making it difficult for malicious actors to manipulate the network.

  3. Zero-Knowledge Proofs: This technology allows for the verification of transactions without revealing any sensitive information about the transaction parties. This is useful in cases where privacy is of paramount importance.

  4. Multi-Party Computation (MPC): It is a technique that allows multiple parties to perform computations on data without revealing the data itself. This technology allows for privacy-preserving smart contracts and other secure digital transactions.

  5. Secure Hardware: Specialized hardware like Secure Element (SE) are being used to secure the private key used in digital currency transactions. This ensures that even if the device is compromised, the private key remains safe.

The use of cryptography, PoW, zero-knowledge proofs, MPC, and secure hardware are essential in building secure blockchain networks for digital currency transactions.