Cryptographic cipher strength highly depends on the statistical performance of its generated keystream. The generated keystream is constructed stochastically for the statistical behavior of the secure key. This enormous behavior proves that the level of security proffered by the cipher. When the key behaves in a random nature, it increases the encryption performance of a high-quality keystream. Many key generation techniques use a pseudorandom binary sequence as a key due to its randomness in nature. Keeping with this view, in this paper pseudorandom binary sequence, generated key is applied in encryption & decryption of text & images, which is tested by frequency (mono bit) test.