**Symmetric Key**

- A symmetric key algorithm require the
**same key**for both encryption of a plaintext and decryption of a cipher text. - This same key is also called a shared secret.
- Symmetric key algorithm are generally much faster (hundreds to thousands times) to encrypt and decrypt a message than asymmetric key algorithm.
- Big disadvantage of using a symmetric key algorithm is that both sender (Alice) and receiver (Bob) needs to know the shared secret.
- Few symmetric key algorithms: AES (Advanced Encryption Standard). Triple DES (Data Encryption Standard)

**Example :-**

**Asymmetric Key**

- An asymmetric key algorithm requires two keys called a public key and private key. One of the key is used for encryption of a plaintext and the other key is used for decryption of the cipher text.
- If Alice generates a private key and a corresponding public key, than anyone allowed to know her public key, but Alice must keep her private secret.
- A big disadvantage is that asymmetric key algorithms are generally much slower (hundred to thousands times) to encrypt and decrypt a message than symmetric key algorithms.
- The advantage of using an asymmetric key algorithm is that any sender can encrypt a message using the receiver public key, but only the receiver can decrypt the cipher text using its private key.
- A public key and private key are mathematically interconnected. Meaning each public key has only one corresponding private key.
- Few asymmetric key algorithms: RSA (Rivest Shamir Adleman), ECDSA (Elliptic Curve Digital Signature Algorithm)
- In blockchain the Elliptic Curve Digital Signature Algorithm is often used.

**Examples :-**

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