Skip to main content

Insecure encryption algorithm

Need​

Implementation of secure encryption algorithms

Context​

  • Usage of Go 1.16 for building high-performance and scalable applications
  • Usage of crypto/aes for AES encryption and decryption
  • Usage of crypto/cipher for encryption and decryption operations
  • Usage of crypto/rand for generating random numbers and cryptographic operations
  • Usage of fmt for formatting text and strings
  • Usage of socket.io for real-time communication and event-based messaging
  • Usage of log for logging and debugging purposes
  • Usage of net/http for handling HTTP requests and responses in a Node.js server
  • Usage of Gin framework for building web applications in Go

Description​

Non compliant code​

package main

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"fmt"
	"io"
	"log"
	"net/http"

	"github.com/gin-gonic/gin"
)

func main() {
	r := gin.Default()

	r.GET("/encrypt", func(c *gin.Context) {
		plaintext := []byte("Hello, World!")
		key := []byte("myveryweakkey12") // 16 bytes key

		block, err := aes.NewCipher(key)
		if err != nil {
			log.Fatal(err)
		}

		ciphertext := make([]byte, aes.BlockSize+len(plaintext))
		iv := ciphertext[:aes.BlockSize]
		if _, err := io.ReadFull(rand.Reader, iv); err != nil {
			log.Fatal(err)
		}

		mode := cipher.NewCBCEncrypter(block, iv)
		mode.CryptBlocks(ciphertext[aes.BlockSize:], plaintext)

		c.String(http.StatusOK, fmt.Sprintf("%x", ciphertext))
	})

	r.Run() // listen and serve on 0.0.0.0:8080
}

The code above is a simple Go application using the Gin framework. It has an endpoint /encrypt that takes a plain text ("Hello, World!") and a weak encryption key ("myveryweakkey12") to encrypt the plain text using the AES encryption algorithm in CBC mode.

The vulnerability lies in the use of a weak encryption key and an insecure encryption algorithm. AES (Advanced Encryption Standard) itself is not insecure, but the way it is being used here makes it insecure.

The encryption key "myveryweakkey12" is hard-coded into the application, which is a bad practice as it exposes the key to anyone who has access to the source code. Furthermore, the key is not strong enough, it's a short 12 characters string which can be easily brute-forced.

Additionally, the application uses the CBC (Cipher Block Chaining) mode for AES which is known to have several vulnerabilities, including susceptibility to padding oracle attacks.

In a real-world application, encryption keys should never be hard-coded into the application and should be stored securely. Also, a more secure mode for AES should be used, such as GCM (Galois/Counter Mode) which provides both encryption and authentication.

Steps​

  • Replace the insecure encryption algorithm with a secure one, such as AES-GCM or ChaCha20-Poly1305.
  • Generate a strong and random encryption key.
  • Ensure that the encryption key is securely stored and not hardcoded in the code.
  • Use a secure random number generator to generate the initialization vector (IV).
  • Implement proper error handling for encryption operations.
  • Consider using authenticated encryption to ensure both confidentiality and integrity of the data.
  • Regularly update the encryption algorithm and key management practices to stay up-to-date with the latest security standards.

Compliant code​

package main

import (
	"crypto/aes"
	"crypto/cipher"
	"crypto/rand"
	"encoding/hex"
	"fmt"
	"io"
	"log"
	"net/http"

	"github.com/gin-gonic/gin"
	"golang.org/x/crypto/chacha20poly1305"
)

func main() {
	r := gin.Default()

	r.GET("/encrypt", func(c *gin.Context) {
		plaintext := []byte("Hello, World!")

		// Generate a new random key
		key := make([]byte, chacha20poly1305.KeySize)
		if _, err := io.ReadFull(rand.Reader, key); err != nil {
			log.Fatal(err)
		}

		// Create a new ChaCha20-Poly1305 cipher
		aead, err := chacha20poly1305.NewX(key)
		if err != nil {
			log.Fatal(err)
		}

		// Generate a new random nonce
		nonce := make([]byte, chacha20poly1305.NonceSizeX)
		if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
			log.Fatal(err)
		}

		// Encrypt the plaintext
		ciphertext := aead.Seal(nil, nonce, plaintext, nil)

		// Return the encrypted data
		c.String(http.StatusOK, fmt.Sprintf("%x", ciphertext))
	})

	r.Run() // listen and serve on 0.0.0.0:8080
}

The original code was using an insecure encryption algorithm (AES-CBC) with a hardcoded encryption key. This is a security vulnerability as it makes the encryption predictable and susceptible to attacks.

The updated code uses the ChaCha20-Poly1305 encryption algorithm, which is currently considered secure. The encryption key is randomly generated for each encryption operation, which makes the encryption more secure and unpredictable. The key is generated using a secure random number generator, which is also used to generate a random nonce for the encryption.

The encryption operation is performed using an AEAD (Authenticated Encryption with Associated Data) cipher. This ensures both the confidentiality and integrity of the data, as it provides encryption and authentication in a single step.

The code also includes proper error handling for the encryption operations, which is important to prevent potential crashes or undefined behavior in case of an error.

Please note that the encryption key should be securely stored and managed, and not hardcoded in the code. This is not demonstrated in the code snippet, but it's an important aspect of secure encryption practices.

References​

Last updated on