At the beginning of this work, cryptography is described and how it differs from cryptology, and a cryptosystem is defined. Then it is described what cryptographic primitives are and their division according to several criteria is given. The main requirement for stream ciphers is that they behave like pseudorandom generators. There are several ways to implement stream ciphers, linear-feedback shift registers and nonlinear-feedback shift register. The most famous stream ciphers are Trivimu and RC4 which was used as part of the encryption system in TLS and SSL. Block ciphers encrypt each block of input separately, they are considered well designed if the best known attack has a time complexity roughly equal to the time complexity of finding the key using the brute-force search, the required level of security is achieved by the confusion-diffusion paradigm and the block size must not be less than 64 bits. The substitution-permutation network is the basis for constructing much more well-known algorithms such as AES and DES. AES is just the name given to the Rijndeal algorithm by winning a competition announced in 1977. to find a replacement for the DES algorithm, its block size is 128 bits and there are several versions depending on the length of the master key. In addition to being used in practice as part of the Lucifer cipher, the Feistel network was also used in DES. Finally, we described the DES algorithm, which is the most famous block cipher and has been the standard for security for many years. It was developed in 1970 by IBM in cooperation with the NSA, and since it was no longer considered secure over time, it was succeeded by 3DES, which is still used in practice today.