Symmetric key encryption is a cryptographic algorithm in which same keys are used for both, encryption and decryption of the information. Sometimes it is also referred to as the secret key cryptosystem and is the fastest mode of encryption. But, the usage of the same key for conversion and extraction of the data from the ciphertext is a major drawback of this algorithm, as this makes it vulnerable to a number of possible attacks, like the known-plaintext attacks and brute-force analysis. To enhance the security of this method, we are proposing a stream cipher, that changes the key for every message or bit of information that is shared between the two parties involved in the communication. This ensures that a different ciphertext is produced even for the same message, every time it is encrypted, thus making the procedure immune to these possibilities. To achieve this, in our work, we have proposed a method of producing pseudo-random numbers generated from a seed value known beforehand to both the users. Using this pseudo-random generator, we can change the key every-time a message is shared between the sender and the receiver. The generator also depends upon the index of the message being communicated, making it even more difficult to break the cipher, if the knowledge about the sequence of the communication is unknown.