feat: Add example code for ECIES encryption and decryption

This commit adds example code for ECIES encryption and decryption using the `ecies-bls12381` package. It demonstrates how to generate key pairs, encrypt a message, and decrypt the ciphertext. The code also includes error handling for encryption and decryption operations.

README.md

@@ -30,9 +30,37 @@ go get github.com/rafagomes/ecies-bls12381
 ### Import the package
 
 ```go
+package main
+
 import (
-    "github.com/rafagomes/ecies-bls12381"
+	"fmt"
+
+	eciesbls12381 "github.com/rafagomes/ecies-bls12381"
 )
+
+func main() {
+	// Generate key pair
+	publicKey, privateKey := eciesbls12381.GenerateECKeypair()
+	fmt.Println("Public Key:", publicKey)
+	fmt.Println("Private Key:", privateKey)
+
+	// Encrypt a message
+	message := []byte("Hello, BLS12381!")
+	ciphertext, err := eciesbls12381.EncryptWithEC(publicKey, message)
+	if err != nil {
+		fmt.Println("Encryption error:", err)
+		return
+	}
+	fmt.Println("Ciphertext:", ciphertext)
+
+	// Decrypt the message
+	plaintext, err := eciesbls12381.DecryptWithEC(privateKey, ciphertext)
+	if err != nil {
+		fmt.Println("Decryption error:", err)
+		return
+	}
+	fmt.Println("Plaintext:", string(plaintext))
+}
 ```
 
 ### Code Examples