I am developing a client-side app in Go that relies on AES CFB. The server-side is written in C. My problem is that Go's AES CFB implementation appears to differ from many others (including OpenSSL). I wrote this to test my theory:-
package main
import (
"fmt"
"encoding/hex"
"crypto/cipher"
"crypto/aes"
)
func encrypt_aes_cfb(plain, key, iv []byte) (encrypted []byte) {
block, err := aes.NewCipher(key)
if err != nil {
panic(err)
}
encrypted = make([]byte, len(plain))
stream := cipher.NewCFBEncrypter(block, iv)
stream.XORKeyStream(encrypted, plain)
return
}
func decrypt_aes_cfb(encrypted, key, iv []byte) (plain []byte) {
block, err := aes.NewCipher(key)
if err != nil {
panic(err)
}
plain = make([]byte, len(encrypted))
stream := cipher.NewCFBDecrypter(block, iv)
stream.XORKeyStream(plain, encrypted)
return
}
func main() {
plain := []byte("Hello world.....")
key := []byte("01234567890123456789012345678901")
iv := []byte("0123456789012345")
enc := encrypt_aes_cfb(plain, key, iv)
dec := decrypt_aes_cfb(enc, key, iv)
fmt.Println("Key: ", hex.EncodeToString(key))
fmt.Println("IV: ", hex.EncodeToString(iv))
fmt.Println("Enc: ", hex.EncodeToString(enc))
fmt.Println("In: ", hex.EncodeToString(plain))
fmt.Println("Out: ", hex.EncodeToString(dec))
}
When this is run, it appears to work perfectly, however, if the encrypted bytes are pasted into another AES implementation and decrypted using the same key and IV, the plaintext is corrupted (except for the first Byte). http://aes.online-domain-tools.com/ provides a simple means to test this. Any suggestions why this might be happening and how I can resolve it?
Thanks Steve