Cryptography is one of the most critical concepts in Information Technology. Wherever there is data, there is a need for cryptography to secure it. Cryptography is encrypting data into ciphertext using a particular encryption algorithm. Ciphertext cannot be read until decoded and deciphered to plaintext using a decryption algorithm. Keys and special arithmetic functions achieve the process of encryption and decryption. Cryptography is divided into symmetric ciphers, asymmetric ciphers, and protocols. All the algorithms are discussed thoroughly and implemented using Java programing language. In comparison, Advance Encryption Standard (AES) is the most secure algorithm for data transmission, but if we need digital signatures, public-key cryptography provides digital signatures. Hence each algorithm is specified for different sectors. A password manager is developed using Java, and encryption is done with AES Rijndael. The cryptosystem uses the 256-bit key size. For top-secret level information, it is recommended by NIST to use AES for encryption and decryption as its large key lengths are impossible to crack using current computational power.