Update README.md

Signed-off-by: Jan Tytgat <jan.tytgat@corelayer.eu>

README.md

@@ -21,3 +21,62 @@ Next, you can manually add the import statement to your ```.go```-file, or have
 ```text
 import github.com/jantytgat/go-transcrypt
 ```
+
+### Encryption key
+
+The encryption key is a string provide to encrypt the data with.
+A function ```CreateHexKey(bitSize int)``` is available to create a random key based on an RSA Private Key, and returns
+it as a hex-encoded string.
+
+```go
+var err error
+var key string
+if key, err = transcrypt.CreateHexKey(2048); err != nil {
+panic(err)
+}
+```
+
+### Salt
+
+A salt is also required for proper encryption.
+It is possible to either generate a new salt for every call, by leaving the salt to ```nil``` when calling the ``
+Encrypt``` function.
+If you want to use a specific salt, you can either provide it manually (at least 12 bytes) or generate one.
+
+```go
+var salt []byte
+if salt, err = transcrypt.CreateSalt(); err != nil {
+panic(err)
+}
+```
+
+## Operations
+
+Currently, the following data types are supported for encryption:
+
+- string
+- int
+
+### Encrypt
+
+```go
+var inputString = "hello world"
+var encryptedString string
+if encryptedString, err = transcrypt.Encrypt(key, salt, transcrypt.AES_256_GCM, inputString); err != nil {
+panic(err)
+}
+```
+
+### Decrypt
+
+```go
+var decryptedString any
+if decryptedString, err = transcrypt.Decrypt(key, encryptedString); err != nil {
+panic(err)
+}
+```
+
+## Example
+
+An example is available in the [examples](https://github.com/jantytgat/go-transcrypt/tree/main/examples/simple)
+directory.