mirror of
https://github.com/maride/afl-transmit.git
synced 2024-10-18 02:56:33 +00:00
87 lines
2.2 KiB
Go
87 lines
2.2 KiB
Go
package net
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import (
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"crypto/aes"
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"crypto/cipher"
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"crypto/rand"
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"encoding/base64"
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"flag"
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"fmt"
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"io"
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)
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var (
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key string
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sharedGCM cipher.AEAD
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nonceSize int
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)
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// RegisterCryptFlags Registers the flags required for cryptography
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func RegisterCryptFlags() {
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flag.StringVar(&key, "key", "", "32 random bytes, base64-wrapped, to AES-encrypt traffic between nodes")
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}
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// InitCrypt creates a cipher object out of the key handed over via --key
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func InitCrypt() error {
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// Check if a key was handed over
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if key == "" {
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// no key, no service
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return nil
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}
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// Unwrap base64'ed crypto bytes
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rawKey, base64Err := base64.StdEncoding.DecodeString(key)
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if base64Err != nil {
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return fmt.Errorf("failed to unpack base64'ed key: %s", base64Err)
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}
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// Create cipher object using that key
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block, cipherErr := aes.NewCipher(rawKey)
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if cipherErr != nil {
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return fmt.Errorf("failed to use your key as AES256 key: %s", cipherErr)
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}
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// Create GCM with cipher object
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gcm, gcmErr := cipher.NewGCM(block)
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if gcmErr != nil {
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return fmt.Errorf("failed to create GCM for your key: %s", gcmErr)
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}
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// Set shared GCM instance
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sharedGCM = gcm
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nonceSize = gcm.NonceSize()
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// No error to report
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return nil
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}
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// CryptApplicable checks if we are able to encrypt or decrypt things, means if this instance was given a proper key
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func CryptApplicable() bool {
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// if the shared GCM object is set, we were able to get the key off user's hands, else we don't crypt
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return sharedGCM != nil
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}
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// Encrypt encrypts the given bytes using the symmetric key
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func Encrypt(plain []byte) ([]byte, error) {
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// create nonce and fill it with random bytes
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nonce := make([]byte, nonceSize)
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_, readErr := io.ReadFull(rand.Reader, nonce)
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if readErr != nil {
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return nil, fmt.Errorf("failed to get random bytes: %s", readErr)
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}
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// Encrypt plaintext
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return sharedGCM.Seal(nonce, nonce, plain, nil), nil
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}
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// Decrypt decrypts the given bytes using the symmetric key
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func Decrypt(enc []byte) ([]byte, error) {
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// Sanity check on input
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if len(enc) < sharedGCM.NonceSize() {
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return nil, fmt.Errorf("failed to decrypt packet: too short")
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}
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// Decrypt encrypted bytes
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return sharedGCM.Open(nil, enc[:nonceSize], enc[nonceSize:], nil)
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}
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