Encryption Decryption

Encryption and Decryption

  • Encryption: The fundamental process of data encryption involves processing plaintext files or data according to a specific algorithm to transform them into an unreadable segment of code, commonly referred to as "ciphertext". This method aims to protect data from unauthorized theft or reading by non-authorized entities.
  • Decryption: Decryption is the inverse process of encryption, converting the encoded information back into its original data.

Encryption algorithms are categorized into symmetric and asymmetric encryption. In symmetric encryption, the encryption and decryption keys are identical. In contrast, asymmetric encryption uses different keys for encryption and decryption. Additionally, there is a class of hash algorithms that do not require keys.
Common symmetric encryption algorithms include DES, 3DES, and AES. Common asymmetric algorithms include RSA and DSA. Hash algorithms primarily include SHA-1 and MD5.
Symmetric encryption algorithms are among the earliest applied encryption methods, also known as shared-key encryption algorithms. In symmetric encryption, only a single key is used; both the sender and receiver utilize this same key to encrypt and decrypt data respectively. This necessitates that both parties know the encryption key in advance.

  1. Data Encryption Process: In symmetric encryption, the data sender processes the plaintext (original data) together with the encryption key through special encryption procedures to generate complex ciphertext for transmission.
  2. Data Decryption Process: Upon receiving the ciphertext, the data receiver must use the same encryption key and the inverse algorithm of the encryption method to decrypt the ciphertext in order to restore it to readable plaintext.

Asymmetric Encryption

Asymmetric encryption algorithms, also known as public-key encryption algorithms, require two keys: one called the public key (publickey), and the other the private key (privatekey).
Since encryption and decryption utilize two distinct keys, this method is termed asymmetric encryption.

  1. If data is encrypted using the public key, it can only be decrypted with the corresponding private key.
  2. If data is encrypted using the private key, it can only be decrypted with the corresponding public key.

Example: Party A generates a pair of keys and makes one of them (the public key) public to others. Party B, who possesses this public key, uses the key to encrypt sensitive information before sending it to Party A. Party A then decrypts the encrypted information using its other dedicated key (the private key).