Trying to emulate an algorithm in Go that is basically AES ECB Mode encryption.
Here's what I have so far
func Decrypt(data []byte) []byte {
cipher, err := aes.NewCipher([]byte(KEY))
if err == nil {
cipher.Decrypt(data, PKCS5Pad(data))
return data
}
return nil
}
I also have a PKCS5Padding algorithm, which is tested and working, which pads the data first. I cant find any information on how to switch the encryption mode in the Go AES package (it's definitely not in the docs).
I have this code in another language, which is how I know this algorithm isn't working quite correctly.
EDIT: Here is the method as I have interpreted from on the issue page
func AESECB(ciphertext []byte) []byte {
cipher, _ := aes.NewCipher([]byte(KEY))
fmt.Println("AESing the data")
bs := 16
if len(ciphertext)%bs != 0 {
panic("Need a multiple of the blocksize")
}
plaintext := make([]byte, len(ciphertext))
for len(plaintext) > 0 {
cipher.Decrypt(plaintext, ciphertext)
plaintext = plaintext[bs:]
ciphertext = ciphertext[bs:]
}
return plaintext
}
This is actually not returning any data, maybe I screwed something up when changing it from encripting to decripting
Answer
Electronic codebook ("ECB") is a very straightforward mode of operation. The data to be encrypted is divided into byte blocks, all having the same size. For each block, a cipher is applied, in this case AES, generating the encrypted block.
The code snippet below decrypts AES-128 data in ECB (note that the block size is 16 bytes):
package main
import (
"crypto/aes"
)
func DecryptAes128Ecb(data, key []byte) []byte {
cipher, _ := aes.NewCipher([]byte(key))
decrypted := make([]byte, len(data))
size := 16
for bs, be := 0, size; bs < len(data); bs, be = bs+size, be+size {
cipher.Decrypt(decrypted[bs:be], data[bs:be])
}
return decrypted
}
As mentioned by @OneOfOne, ECB is insecure and very easy to detect, as repeated blocks will always encrypt to the same encrypted blocks. This Crypto SE answer gives a very good explanation why.