func encryptOracle(src []byte) []byte {
key := util.RandAes128()
block, _ := aes.NewCipher(key)
out := make([]byte, len(src))
copy(out, src)
// random prepend and append
prefixSize := util.RandByte()%10 + 5
postfixSize := util.RandByte()%10 + 5
postfix := util.RandBytes(int(postfixSize))
out = append(util.RandBytes(int(prefixSize)), out...)
out = append(out, postfix...)
// padding
out = util.PadTo(out, 16)
// fmt.Println("before enc", out)
// random encryption mode
mode := util.RandByte()
if mode%2 == 0 {
// ecb
fmt.Println("ecb")
util.ECBEncrypt(block, out, out)
} else {
// cbc
fmt.Println("cbc")
iv := util.RandAes128()
util.CBCEncrypt(block, iv, out, out)
}
return out
}
func aesCrypt(s *big.Int, t []byte) (ct, iv []byte) {
sum := sha1.Sum([]byte(s.String()))
blockA, _ := aes.NewCipher(sum[0:16])
tPadded := util.PadTo(t, 16)
ct = make([]byte, len(tPadded))
iv = util.RandBytes(16)
util.CBCEncrypt(blockA, iv, ct, tPadded)
return
}
func crypt(userdata []byte) []byte {
res := bytes.Replace(userdata, []byte("="), []byte("%3D"), -1)
res = bytes.Replace(res, []byte(";"), []byte("%3B"), -1)
res = append(prefix, res...)
res = append(res, postfix...)
block, _ := aes.NewCipher(key)
res = util.PadTo(res, 16)
util.CBCEncrypt(block, iv, res, res)
return res
}
func getMsg() (ct, iv []byte) {
ct, err := base64.StdEncoding.DecodeString(msgs[util.RandByte()%10])
if err != nil {
log.Fatal("Cannot decode", err)
}
iv = util.RandAes128()
block, _ := aes.NewCipher(key)
ct = util.PadTo(ct, block.BlockSize())
util.CBCEncrypt(block, iv, ct, ct)
return ct, iv
}
func main() {
encoded := util.ReadFile("10.txt")
src, _ := base64.StdEncoding.DecodeString(string(encoded))
key := []byte("YELLOW SUBMARINE")
iv := make([]byte, 16)
block, _ := aes.NewCipher(key)
util.CBCDecrypt(block, iv, src, src)
util.CBCEncrypt(block, iv, src, src)
util.CBCDecrypt(block, iv, src, src)
fmt.Println(string(src))
}