How to decrypt data using symmetric key cryptography in Go?

To decrypt data using symmetric key cryptography in Go, you can use the crypto/aes package. Here's an example code that demonstrates the decryption process:

package main

import (
	"crypto/aes"
	"crypto/cipher"
	"fmt"
)

func main() {
	key := []byte("0123456789abcdef") // 16-byte symmetric key

	// Example ciphertext
	ciphertext := []byte{129, 254, 8, 35, 35, 232, 122, 62, 31, 46, 212, 201, 225, 195, 172, 112}

	// Create the AES cipher block
	block, err := aes.NewCipher(key)
	if err != nil {
		panic(err.Error())
	}

	// Create a new CBC mode decrypter
	iv := []byte("initializationvec") // 16-byte initialization vector
	decrypter := cipher.NewCBCDecrypter(block, iv)

	// Create a buffer for storing the decrypted data
	plaintext := make([]byte, len(ciphertext))

	// Decrypt the data
	decrypter.CryptBlocks(plaintext, ciphertext)

	// Remove padding (if any) from the plaintext
	unpaddedPlaintext := unpadPKCS7(plaintext)

	fmt.Printf("Decrypted data: %s\n", string(unpaddedPlaintext))
}

// PKCS7 unpadding function
func unpadPKCS7(data []byte) []byte {
	padding := data[len(data)-1]
	return data[:len(data)-int(padding)]
}

Make sure to replace the key, ciphertext, and iv variables with your own values. The example code above assumes you are using CBC mode and a PKCS7 padding scheme. You may need to change the padding scheme and block mode based on your requirements.

Note: It's important to handle errors and use proper error handling measures in production code.