An encryption and decryption method and device employing zipper-type dynamic hashing and NLFSR techniques. An encryption process comprises the following steps: using a nonlinear feedback function and a bit-manipulation Boolean function to pre-process a seed key, so as to form a keystream sequence; changing, according to the bit-manipulation Boolean function employing the keystream sequence, a bit value of a plaintext sequence, so as to form a pseudo-plaintext sequence; dividing, according to the keystream sequence, the pseudo-plaintext sequence into multiple pseudo-plaintext subsequences; and calculating, according to a hash mapping rule depending on the keystream sequence, a dynamic hash address corresponding to a binary bit of each respective pseudo-plaintext sequence, and mapping, by means of a hash function, the multiple pseudo-plaintext subsequences to a ciphertext space, so as to form a ciphertext stream sequence. The present application has the following beneficial effects: keystream generators, beside using nonlinear feedback shift registers, also use a bit-manipulation Boolean function so as to obtain keystreams having a longer period and improved randomness; moreover, bit-manipulation rules for plaintexts and mapping rules employing zipper-type dynamic hashing are used to increase the difficulty of decoding ciphertext stream sequences.