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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)
val baseCiphertext = encrypt(Seq())
def blocksIn(xs: Seq[Byte]) = xs.length / blockSize
val baseBlockCount = blocksIn(baseCiphertext)
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 suffixRainbow(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 firstLargerCiphertext = (0 until blockSize)
.map(" " * _).map(_.asBytes).map(encrypt)
.zipWithIndex
.find(x => blocksIn(x._1) != baseBlockCount)
// this will always be Some(_) because
// somewhere between 0..blockSize WILL grow the text.
blockSize - firstLargerCiphertext.get._2
}
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 cipherBlocks = ciphertexts.toSeq.sortBy(_._1).map(_ :-> { x =>
x.grouped(16).toSeq
})
val (middleBlocks, lastBlocks) =
cipherBlocks.foldLeft((Seq[Seq[Seq[Byte]]](), Seq[Option[Seq[Byte]]]()))( (ac, curr) => {
val maybeLastBlock =
if (curr._2.length > baseBlockCount) Some(curr._2.last)
else None
val middleBlocks = curr._2.take(baseBlockCount).tail
(ac._1 :+ middleBlocks, maybeLastBlock +: ac._2)
}) :-> { _.flatten :+ baseCiphertext.takeRight(16)}
def breakLastBlock(blocks: Seq[Seq[Byte]]) = {
/*
* plaintext looks something like...
* X 15 15 15 15 15 ... 15
* Y X 14 14 14 14 ... 14
* ... pkcs7
*/
// drop the first block because it will be 16 16 16 16 16 16 ... 16
blocks.tail.foldLeft(Seq[Byte]()) { (bytes, block) => {
val postfix = pkcs7pad("?".asBytes ++ bytes, blockSize).tail
suffixRainbow(postfix)(block) +: bytes
}}
}
def breakBlock(plaintext: Seq[Byte], padded: Seq[Seq[Byte]]): Seq[Byte] =
padded.foldLeft(Seq[Byte]()) { (blockText: Seq[Byte], block: Seq[Byte]) => {
val prefix = (plaintext ++ blockText).takeRight(blockSize - 1)
val b = rainbow(prefix)(block)
blockText :+ b
}}
val middleBytes =
middleBlocks.transpose.init.foldLeft(firstBlock) { (plaintext, padded: Seq[Seq[Byte]]) =>
plaintext ++ breakBlock(plaintext, padded)
}
middleBytes ++ breakLastBlock(lastBlocks)
}
}
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