1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
|
package ixee.cryptopals.utils
import ixee.cryptopals.utils.crypto._
import ixee.cryptopals.utils.TupleUtils._
import ixee.cryptopals.utils.StreamUtils._
import ixee.cryptopals.utils.FunctionUtils._
import ixee.cryptopals.utils.ConversionUtils._
import javax.crypto.Cipher
import javax.crypto.spec.SecretKeySpec
object CryptoUtils {
def pkcs7pad(s: Seq[Byte], blockSize: Int): Seq[Byte] = {
val padLength = blockSize - (s.length % blockSize)
s ++ Stream.continually(padLength.toByte).take(padLength)
}
def stripPkcs7Pad(s: Seq[Byte]): Seq[Byte] =
s.dropRight(s.last)
def cbcEncrypt(builder: CbcBuilder)(data: Seq[Byte]) =
builder.encrypt.end(data)
def cbcDecrypt(builder: CbcBuilder)(data: Seq[Byte]) =
stripPkcs7Pad(builder.decrypt.end(data))
def ecbEncrypt(builder: EcbBuilder)(data: Seq[Byte]) =
builder.encrypt.end(data)
def ecbDecrypt(builder: EcbBuilder)(data: Seq[Byte]) =
stripPkcs7Pad(builder.decrypt.end(data))
def detectMode(xs: Seq[Byte]): String = {
def dupBlocks(xs: Seq[Seq[Byte]]) =
pairsOf(xs).map(tup(_ == _)).count(_ == true)
def countDupBlocks(xs: Seq[Byte]): Int =
dupBlocks(xs.grouped(16).toSeq.init.toStream)
//.... well very probably.
if (countDupBlocks(xs) > 0) "ECB"
else "CBC"
}
def isEcb(xs: Seq[Byte]): Boolean = detectMode(xs) == "ECB"
def detectEcbBlockSize(encryptor: Seq[Byte] => Seq[Byte]): Int = {
val pad = (2 to 512 by 2).map("@" * _).zipWithIndex.map {
_.mapAll(_1 = _.asBytes, _2 = _ + 1)
}
val minPadSize = pad
.map( { encryptor(_) } <-: _ )
.find( { x => isEcb(x._1) })
.map(_._2)
minPadSize.get // if this was a None we have serious possibility of this not being ECB
}
def extractUnknownViaEcbOracle(encrypt: Seq[Byte] => Seq[Byte]) = {
val blockSize = detectEcbBlockSize(encrypt)
def rainbow(prefix: Seq[Byte]): Map[Seq[Byte], Byte] = {
(0 to 255)
.map(_.toByte)
.map(prefix :+ _)
.map(encrypt)
.map(_.take(16).toSeq)
.zipWithIndex
.map(_ :-> { _.toByte } )
.toMap
}
def probeFirstBlockAndPaddings: (Seq[Byte], Map[Int, Seq[Byte]]) = {
def prefix(known: Seq[Byte]) = (" " * (blockSize - 1 - known.length)).asBytes
def genRainbow(known: Seq[Byte]) = rainbow(prefix(known) ++ known)
def firstCryptedBlock(known: Seq[Byte]) = encrypt(prefix(known)).take(blockSize).toSeq
def nextByte(known: Seq[Byte]) = genRainbow(known)(firstCryptedBlock(known))
(0 until 16).foldLeft((Seq[Byte](), Map[Int, Seq[Byte]]())) { (ac, idx) =>
(ac._1 :+ nextByte(ac._1), ac._2 + (idx -> encrypt(prefix(ac._1))))
}
}
def probeLastBlockSize: Int = {
val baseBlockCount = encrypt(Seq[Byte]()).length
val firstLargerCiphertext = (0 until blockSize)
.map(" " * _).map(_.asBytes).map(encrypt)
.zipWithIndex
.find(_._1.length != baseBlockCount)
// this will always be Some(_) because
// somewhere between 0..blockSize WILL grow the text.
firstLargerCiphertext.get._2
}
println("Last block is " + probeLastBlockSize + " bytes")
val (firstBlock, ciphertexts) = probeFirstBlockAndPaddings
/*
* zip together cipher blocks so that they look like
* rot0b0, rot1b0, rot2b0, rot3b0, rot4b0, rot5b0, rot6b0, rot7b0
* rot0b1, rot1b1, rot2b1, ...
*
*/
val transposed = ciphertexts.toSeq.sortBy(_._1).map(_ :-> { x =>
val y = x.grouped(16).toSeq
println(y.length)
y
})
// println("Also...")
// println(rainbow(firstBlock.tail)(transposed(1)(0)))
val prefix = firstBlock.tail
val currRainbow = rainbow(prefix)
println(ciphertexts(0).drop(16).take(16))
val next = currRainbow(ciphertexts(0).drop(16).take(16).toSeq)
println("Next: " + new String(Array(next.toByte)))
val nowPrefix = (prefix.tail :+ next)
val r2 = rainbow(nowPrefix)
val next2 = r2(ciphertexts(1).drop(16).take(16).toSeq)
println("Next: " + new String(Array(next2.toByte)))
val pref3 = (nowPrefix.tail :+ next2)
val r3 = rainbow(pref3)
val next3 = r3(ciphertexts(2).drop(16).take(16).toSeq)
println("Next: " + new String(Array(next3.toByte)))
firstBlock
}
}
|
