How are files/text encrypted and decrypted on mobile phones?

Question

Python

There will be a server that will send encrypted data. There will be a mobile application that will access via api via http and receive encrypted text or files. So far I have no idea how to implement it. The server will be written in Python, mobile Swift. What do you need to know to complete this task, and what libraries to use?

Answer 1

Briefly.
There are synchronous ciphers, there are asynchronous ones.
The former use the same key on the server and client sides. For example AES128 The
latter use a pair of keys open / closed - we encrypt with a closed one, we decrypt it with an open one. RSA example.
Almost all algorithms are available here and there, for example, for python - pycrypto.
And to read - https://habr.com/post/265309/

Answer 2

In accordance with the Federal Law “On Licensing Certain Types of Activities”, almost all types of activities in the field of cryptography are subject to licensing.
The following are excluded from licensing:
2. activities using:
b) encryption (cryptographic) means, as well as goods containing encryption (cryptographic) means that implement either a symmetric cryptographic algorithm using a cryptographic key with a length not exceeding 56 bits, or an asymmetric cryptographic algorithm based either on the factorization method of integers, the size of which does not exceed 512 bits, either on the method of calculating discrete logarithms in the multiplicative group of a finite field of size not exceeding 512 bits, or on the method of calculating discrete logarithms in another group of size not exceeding 112 bits;
d) encryption (cryptographic) tools that are components of software operating systems, the cryptographic capabilities of which cannot be changed by users, which are designed to be installed by the user on their own without further significant support from the supplier and technical documentation (description of cryptographic transformation algorithms, interaction protocols, description of interfaces, etc. .e) for which it is available;
well, it’s also a good idea to first read what requirements are imposed by the sites through which you plan to distribute the application and the legislation of the countries from which purchases will be available