//For simplicity sake, return key and iv too.
func EncryptComment(comment string) (key, iv, ciphertext []byte) {
pre := []byte("comment1=cooking%20MCs;userdata=")
//Eat illegal characters
comment = strings.Split(comment, ";")[0]
comment = strings.Split(comment, "=")[0]
combytes := []byte(comment)
post := []byte(";comment2=%20like%20a%20pound%20of%20bacon")
plaintext := append(pre, combytes...)
plaintext = append(plaintext, post...)
plaintext = aes.Pad(plaintext, 16)
key = aes.RandBytes(16)
iv = aes.RandBytes(16)
ciphertext = aes.CBCEncrypt(key, iv, plaintext)
return
}
//Test for set 2 challenge 13
func TestECBCutAndPaste(t *testing.T) {
key := aes.RandBytes(16)
oracle := func(in string) []byte { return ProfileFor(key, in) }
//This payload will give me an padded admin block.
payload1 := "kelbyXXXXXadmin\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11\x11"
//This payload will give me a ct with "role=" at a block border.
payload2 := "kelbyXXXXXXXX"
ct1 := oracle(payload1)
ct2 := oracle(payload2)
new_ct := append(ct2[:32], ct1[16:32]...)
if !CTIsAdmin(key, new_ct) {
t.Errorf("ECBCutAndPaste: Failed to create admin profile")
}
}
//Test for challenge 25
func TestCTREdit(t *testing.T) {
plaintext := []byte("My shell, mechanical found ghost. But my ghetto is animal found toast")
key := aes.RandBytes(16)
nonce := uint64(0)
ciphertext := aes.CTREncrypt(key, nonce, plaintext)
oracle := func(ct []byte, offset int, insert []byte) []byte {
pt := aes.CTRDecrypt(key, nonce, ct)
begin := pt[0:offset]
end := pt[offset+len(insert):]
newPt := append(begin, insert...)
newPt = append(newPt, end...)
return aes.CTREncrypt(key, nonce, newPt)
}
recoveredPlaintext := CTREditAttack(ciphertext, oracle)
if string(recoveredPlaintext) != string(plaintext) {
t.Errorf("CTREdit: Attack failed.")
}
}
//Test for set 2 challenge 14
func TestECBChosenInfixAttack(t *testing.T) {
key := make([]byte, 16)
_, err := rand.Read(key)
if err != nil {
t.Errorf("ECBChosenInfixAttack: Failed reading from urandom")
}
var prefix uint32
binary.Read(rand.Reader, binary.LittleEndian, &prefix)
num := int(prefix % 32)
random_prefix := aes.RandBytes(num)
oracle := func(input []byte) []byte { return ECBChosenInfix(random_prefix, input, key) }
//Determine block size of oracle
bs := DetermineOracleBlockSize(oracle)
if bs != 16 {
t.Errorf("ECBChosenInfixAttack: Failed to determine correct block size")
}
//Determine if oracle is using ECB mode
//TODO: This is silly. You should make your cryptanalysis functions take an oracle function. Will be more reusable.
data := []byte("AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA")
if !DetectECB256Mode(oracle(data)) {
t.Errorf("ECBChosenInfixAttack: Failed to correctly guess that the oracle used ECB mode.")
}
result := ECBSecretInfixAttack(oracle)
expected_result := `Rollin' in my 5.0
With my rag-top down so my hair can blow
The girlies on standby waving just to say hi
Did you stop? No, I just drove by`
if result[:12] != expected_result[:12] {
t.Errorf("ECBChosenInfixAttack: Expected decryption did not actually match real decryption")
}
}