Generating secure keys for encryption

Very often, we need to create secure keys that can be used in digital signatures or for signing a JWT.
It is very important to create a secure key so that the encryption is strong. A good post about this is here - https://docs.oracle.com/cd/E19424-01/820-4811/aakfw/index.html

Jotting down some snippets from the article:

The strength of encryption is related to the difficulty of discovering the key, which in turn depends on both the cipher used and the length of the key. 

Encryption strength is often described in terms of the size of the keys used to perform the encryption: in general, longer keys provide stronger encryption. Key length is measured in bits.

Different ciphers may require different key lengths to achieve the same level of encryption strength

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A key is nothing but a byte array that is passed to the encryption algorithm.  Hence if you are storing the key in a properties file, please makes sure that you have stored it in Base64 format.

Spring provides very simple methods for generating secure keys as shown below.