The two biggest selling points of blockchain and crypto technology are decentralization and security. Adding transactions as blocks in a distributed ledger will solve the need for a centralized authority to oversee the process, hence the decentralization.
On the security front, crypto products use advanced cryptographic methods to encrypt personal data and limit access.
This article will tell you everything you need to know about a public key scheme, crypto algorithms, and their importance.
I will also give you a brief overview of the most popular crypto algorithms out there and how they stack up against each other.
What is a Public Key Scheme?
To secure access to the operations of a node, blockchain platforms use something known as a public key scheme. It is a cryptographic system that uses a pair of keys- a public key and a private key.
A public key, like your PayPal username, can be widely shared. The private key is like your PayPal password.
The private key is kept confidential to maintain the privacy of your account, whether it is your wallet, dApps, or smart contracts.
What is a Crypto algorithm?
A crypto algorithm is an algorithm that can generate a public-private key pair with the help of mathematical equations. Also known as a cryptographic algorithm, it is a series of steps that can encrypt and decrypt a string of characters.
When a message is encrypted, it is converted into an unreadable format, referred to as a ciphertext. Decryption is the reverse process, turning it back to the original, called plaintext.
Best Public-Key Scheme Crypto Algorithms
Now that we have covered the basics, let’s move on to the best Crypto Algorithms out there. Remember that each of these algorithms has its strengths and weaknesses, and the decision of which one to choose depends entirely upon the context.
Rivest-Shamir-Adleman (RSA)
RSA is the most popular and widely adopted crypto algorithm out there. With RSA, users can create and publish a public key based on two large prime numbers, along with an auxiliary value.
The prime numbers will be kept as secret. It allows anyone to encrypt messages with the public key but can only be decoded by someone who knows the private key.
RSA keys are typically 1024 or 2048 bits long, but experts believe that 1024-bit keys could become breakable shortly.
The security of RSA relies on the practical difficulty of having the processing power to factor the product of two large prime numbers.
However, RSA is relatively slow, and hence not commonly used to directly encrypt user data. Instead, it is used to transmit shared keys for symmetric-key cryptography, which are then used for bulk encryption and decryption.
Diffie–Hellman key exchange protocol
This protocol allows two parties, each having a public-private key pair, to establish a shared secret over an insecure channel.
It requires the two parties to agree upon two numbers: a large prime number p, and a generator g of p, which is the primitive root of p. These two numbers are shared with the public. Each party generates a private key, which is a random number, which is then used to generate a public key. The public key is calculated as g raised to the power of the private key.
Security of the Diffie–Hellman key exchange depends upon the difficulty of the discrete logarithm. Even if someone knows the public keys and the parameters p and g, it is not practical for them to find out the private key.
Digital Signature Algorithm (DSA)
DSA is commonly used for digital signatures and involves a private key that is used to sign a message and a public key that is used to verify the signature. It is based on the mathematical concepts of modular exponentiation and the discrete logarithm problem.
There are two steps in the key generation process of DSA- parameter generation and per-user keys. The signature generation process passes the original message (M) through the hash function (H#) to get the hash digest (h). The system provides message authentication and integrity and will prevent repudiation of signatures.
Elliptic Curve Digital Signature Algorithm (ECDSA)
ECDSA is a variant of DSA that uses elliptic curve cryptography. It offers more security with shorter keys. With ECDSA, the user creates and publishes a public key based on two large secret prime numbers and an auxiliary value, just like in DSA.
The user then passes the original message through a hash function to get a hash digest and then selects a cryptographically secure random integer from a specific range. The user calculates the curve point and the signature. The receiver of the message can verify the signature using the sender’s public key.
The security of ECDSA relies on the difficulty of the elliptic-curve discrete logarithm problem. Even if someone knows the public keys and the parameters, it is computationally non-practical for them to calculate the private keys.
ElGamal
ElGamal is a public key cryptosystem based on the Diffie–Hellman key exchange. The first party generates a public-private key pair.
A public key will consist of the values (G, q, g, h) that are published, and a private key ‘x’ is kept a secret. A second party encrypts a message under this public key as ciphertext (c1, c2). This will be decrypted with the private key ‘x’.
The security of ElGamal encryption relies on the difficulty of computing discrete logarithms. The algorithm can be described as first performing a Diffie–Hellman key exchange to establish a shared secret, and then using this as a one-time pad for encrypting the message.
Conclusion
A public key scheme allows crypto accounts to connect with the rest of the world without compromising on security.
A cryptographic algorithm allows a user to generate a near-fool-proof way to generate a secure private key. Currently, there are plenty of crypto algorithms to choose from offering varying value propositions. However, be mindful that no encryption method is completely impervious to cyber attacks.
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