func isPadValid(ct, iv []byte) bool {
block, _ := aes.NewCipher(key)
res := make([]byte, len(ct))
copy(res, ct)
util.CBCDecrypt(block, iv, res, res)
_, err := util.CheckPadding(res)
// fmt.Println(res, err == nil)
return err == nil
}
func aesDecrypt(s *big.Int, ct, iv []byte) (t []byte) {
sum := sha1.Sum([]byte(s.String()))
blockA, _ := aes.NewCipher(sum[0:16])
tPadded := make([]byte, len(ct))
util.CBCDecrypt(blockA, iv, tPadded, ct)
t, err := util.CheckPadding(tPadded)
if err != nil {
log.Fatal(err, tPadded)
}
return
}
func main() {
ct, iv0 := getMsg()
fmt.Println("len:", len(ct), "blocks:", len(ct)/16)
pt := attackPadding(ct[:16], iv0)
for i := len(ct) - 16; i < len(ct); i += 16 {
p := attackPadding(ct[i:i+16], ct[i-16:i])
pt = append(pt, p...)
}
pt, err := util.CheckPadding(pt)
fmt.Println("Plaintext:", string(pt), "\nPadding is valid:", err == nil)
}
func main() {
fmt.Println(util.CheckPadding([]byte("ICE ICE BABY\x04\x04\x04\x04")))
fmt.Println(util.CheckPadding([]byte("ICE ICE BABY\x05\x05\x05\x05")))
fmt.Println(util.CheckPadding([]byte("ICE ICE BABY\x01\x02\x03\x04")))
}