What? Why? Where? How?

By Volodymyr Korobeynyk

Cryptography

Kryptos

What is this? Where this is located?

Kryptos is a sculpture by the American artist Jim Sanborn that is located on the

grounds of the Central Intelligence Agency (CIA) in Langley, Virginia.

BETWEEN SUBTLE SHADING AND THE ABSENCE OF LIGHT LIES THE

NUANCE OF IQLUSION

IT WAS TOTALLY INVISIBLE HOWS THAT POSSIBLE ? THEY USED THE

EARTHS MAGNETIC FIELD X THE INFORMATION WAS GATHERED AND

TRANSMITTED UNDERGRUUND TO AN UNKNOWN LOCATION X DOES

LANGLEY KNOW ABOUT THIS ? THEY SHOULD ITS BURIED OUT THERE

SOMEWHERE X WHO KNOWS THE EXACT LOCATION ? ONLY WW THIS

WAS HIS LAST MESSAGE X THIRTY EIGHT DEGREES FIFTY SEVEN

MINUTES SIX POINT FIVE SECONDS NORTH SEVENTY SEVEN DEGREES

EIGHT MINUTES FORTY FOUR SECONDS WEST X LAYER TWO

SLOWLY DESPARATLY SLOWLY THE REMAINS OF PASSAGE DEBRIS THAT

ENCUMBERED THE LOWER PART OF THE DOORWAY WAS REMOVED

WITH TREMBLING HANDS I MADE A TINY BREACH IN THE UPPER LEFT

HAND CORNER AND THEN WIDENING THE HOLE A LITTLE I INSERTED THE

CANDLE AND PEERED IN THE HOT AIR ESCAPING FROM THE CHAMBER

CAUSED THE FLAME TO FLICKER BUT PRESENTLY DETAILS OF THE

ROOM WITHIN EMERGED FROM THE MIST X CAN YOU SEE ANYTHING Q ?

Part 4 has so far not been publicly solved.

Cryptography basic terms

Encrypt: Scrambling data to make it unrecognizable

Decrypt: Unscrambling data to its original format

Cipher: Another word for algorithm

Key: A complex sequence of alpha-numeric characters, that allows you to

scramble and unscramble data

Plaintext: Decrypted or unencrypted data (it doesn’t have to be text only)

Ciphertext: Data that has been encrypted

Concealment ciphers

Used to hide a message in plain sight.

Worthie Sir John: Hope, that is the best comfort of the afflicated, cannot

much, I fear me, help you now. That I would saye to you, is this only: if

ever I may be able to requite that I do owe you, stand not upon asking

me: Tis not much I can do: but what I can do, bee you verie sure I wille.

I knowe that, if deathe comes, if ordinary men fear it, it frights not you,

accounting is for a high hounour, to have such a rewarde of your loyalty.

Pray yet that you may be spare this soe bitter, cup, I fear not that you

will grudge any suffereings; onlie if bie submission you can turn them

away, tis the part of a wise man. Tell me, as If you can, I do for you

anythinge that you can wolde have done. The general goes back on

Wednesday.

Restinge your servant to command. R.J.

The third letter after every punctuation

mark:panel at east end of chapel slides

Substitution ciphers

The transformation can be represented by aligning two alphabets; the

cipher alphabet is the plain alphabet rotated left or right by some

number of positions. For instance, here is a Caesar cipher using a left

rotation of three places, equivalent to a right shift of 23 (the shift

parameter is used as the key).

Caesar cipher

Transposition ciphers

Spartan scytale

Book cipher

Terms like code and cipher are often used to refer to any form of

encryption. However, there is an important distinction between codes and

ciphers in technical work; it is, essentially, the scope of the transformation

involved. Codes operate at the level of meaning; that is, words or phrases

are converted into something else. Ciphers work at the level of individual

letters, or small groups of letters, or even, in modern ciphers, with

individual bits.

Traditionally book ciphers work by replacing words in the plaintext of a

message with the location of words from the book being used. In this

mode, book ciphers are more properly called codes.

Vigenère cipher

The Vigenère cipher is a method of encrypting alphabetic text by using a

series of different Caesar ciphers based on the letters of a keyword. It is a

simple form of polyalphabetic substitution

Plaintext: ATTACKATDAWN

Key: LEMONLEMONLE

Ciphertext:

LXFOPVEFRNHR

The idea behind the Vigenère

cipher, like all polyalphabetic

ciphers, is to disguise plaintext

letter frequencies

Enigma machine

The Enigma machine looked

roughly like a typewriter except that

it had a number of different rotors,

sort of like the odometer on your

car. These rotors were placed next

to one another on a shaft and then

spun to set the shift in letters for

substitution.

XOR operation

Majority of modern algorithms use the XOR operation during the

encryption process.

Exclusive disjunction essentially means 'either one, but not both'. In

other words, one is true if and only if the other is not true.

Plaintext = baby = 01100010 01100001 01100010 01111001

XOR key = data = 01100100 01100001 01110100 01100001

Ciphertext = ???? = 00000110 00000000 00010110 00011000

Cryptographic hash function

A cryptographic hash function is a mathematical algorithm that maps

data of arbitrary size to a bit string of a fixed size (a hash function)

which is designed to also be one-way function, that is, a function which

is infeasible to invert. The input data is often called the message, and

the output (the hash value or hash) is often called the message digest

or simply the digest. Example: SHA-1 (Secure Hash Algorithm 1)

Base64Base64 is a group of similar binary-to-text encoding schemes that represent

binary data in an ASCII string format by translating it into a radix-64

representation. The term Base64 originates from a specific MIME content

transfer encoding.TWFuIGlzIGRpc3Rpbmd1aXNoZWQsIG5vdCBvbmx5IGJ5IGhpcyByZWFzb24sIGJ1dC

BieSB0aGlz

IHNpbmd1bGFyIHBhc3Npb24gZnJvbSBvdGhlciBhbmltYWxzLCB3aGljaCBpcyBhIGx1c

3Qgb2Yg

dGhlIG1pbmQsIHRoYXQgYnkgYSBwZXJzZXZlcmFuY2Ugb2YgZGVsaWdodCBpbiB0a

GUgY29udGlu

dWVkIGFuZCBpbmRlZmF0aWdhYmxlIGdlbmVyYXRpb24gb2Yga25vd2xlZGdlLCBleG

NlZWRzIHRo

ZSBzaG9ydCB2ZWhlbWVuY2Ugb2YgYW55IGNhcm5hbCBwbGVhc3VyZS4=

Algorithms

Symmetric key algorithms all use one key to encrypt data and the same

key to decrypt it. That’s why they are called symmetric.

Example: 3DES (Triple Data Encryption Algorithm ), AES (Advanced

Encryption Standard, Rijndael)

Asymmetric keys making two separate keys that are mathematically

connected. You use a “private” key that you never reveal to anyone to

decrypt the data you’ve received and the recipient uses their

corresponding “public” key that everyone can have to encrypt the data.

Example: RSA (Ron Rivest, Adi Shamir, and Leonard Adleman)

Advanced Encryption Standard

AES is based on a design principle known as a substitution-

permutation network, combination of both substitution and

permutation.

AES is a variant of Rijndael which has a fixed block size of 128

bits, and a key size of 128, 192, or 256 bits.

The key size used for an AES cipher specifies the number of

repetitions of transformation rounds that convert the input, called the

plaintext, into the final output, called the ciphertext. The number of

cycles of repetition are as follows:

10 cycles of repetition for 128-bit keys.

12 cycles of repetition for 192-bit keys.

14 cycles of repetition for 256-bit keys.

Advanced Encryption Standard1.KeyExpansions—round keys are derived from the cipher key using Rijndael's key

schedule. AES requires a separate 128-bit round key block for each round plus one

more.

2.InitialRound

2.1.AddRoundKey—each byte of the state is combined with a block of the round key

using bitwise XOR.

3.Rounds

3.1.SubBytes—a non-linear substitution step where each byte is replaced with another

according to a lookup table.

3.2.ShiftRows—a transposition step where the last three rows of the state are shifted

cyclically a certain number of steps.

3.3.MixColumns—a mixing operation which operates on the columns of the state,

combining the four bytes in each column.

3.4.AddRoundKey

4.Final Round (no MixColumns)

4.1.SubBytes

4.2.ShiftRows

4.3.AddRoundKey.

.NET cryptographic primitives

The System.Security.Cryptography namespace provides cryptographic

services, including secure encoding and decoding of data, as well as

many other operations, such as hashing, random number generation, and

message authentication.

private const int _saltSize = 32;

In cryptography, a salt is random data that is used as an additional input to

a one-way function that "hashes" a password or passphrase. The primary

function of salts is to defend against dictionary attacks versus a list of

password hashes and against pre-computed rainbow table attacks.

A new salt is randomly generated for each password. In a typical setting,

the salt and the password are concatenated and processed with a

cryptographic hash function, and the resulting output (but not the original

password) is stored with the salt. Hashing allows for later authentication

while protecting the plaintext password in the event that the authentication

data store is compromised.

Initialization vector

An IV or initialization vector is, in its broadest sense, just the initial value

used to start some iterated process.

public static string EncryptPllainTextToCiphertextAES(string plainText, string securityKey){

using (var keyDerivationFunction = new Rfc2898DeriveBytes(securityKey, _saltSize)){

byte[] saltBytes = keyDerivationFunction.Salt;byte[] keyBytes = keyDerivationFunction.GetBytes(32);byte[] ivBytes = keyDerivationFunction.GetBytes(16);

using (var aesManaged = new AesManaged()){aesManaged.KeySize = 256;

using (var encryptor = aesManaged.CreateEncryptor(keyBytes, ivBytes)){

MemoryStream memoryStream = null;CryptoStream cryptoStream = null;

return WriteMemoryStream(plainText, ref saltBytes, encryptor, ref memoryStream, ref cryptoStream);

}}

}}

private static string WriteMemoryStream(string plainText, ref byte[] saltBytes, ICryptoTransform encryptor, refMemoryStream memoryStream, ref CryptoStream cryptoStream)

{try{

memoryStream = new MemoryStream();try{

cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write);using (var streamWriter = new StreamWriter(cryptoStream)){

streamWriter.Write(plainText);}

}finally{

if (cryptoStream != null){

cryptoStream.Dispose();}

}var cipherTextBytes = memoryStream.ToArray();Array.Resize(ref saltBytes, saltBytes.Length + cipherTextBytes.Length);Array.Copy(cipherTextBytes, 0, saltBytes, _saltSize, cipherTextBytes.Length);return Convert.ToBase64String(saltBytes);

}finally{

if (memoryStream != null){

memoryStream.Dispose();}

}}

public static string DecryptCipherTextToPlainTextAES(string ciphertext, string securityKey){

var allTheBytes = Convert.FromBase64String(ciphertext);var saltBytes = allTheBytes.Take(_saltSize).ToArray();var ciphertextBytes = allTheBytes.Skip(_saltSize).Take(allTheBytes.Length

_saltSize).ToArray();

using (var keyDerivationFunction = new Rfc2898DeriveBytes(securityKey, saltBytes)){

var keyBytes = keyDerivationFunction.GetBytes(32);var ivBytes = keyDerivationFunction.GetBytes(16);

return DecryptWithAES(ciphertextBytes, keyBytes, ivBytes);}

}

private static string DecryptWithAES(byte[] ciphertextBytes, byte[] keyBytes, byte[] ivBytes){

using (var aesManaged = new AesManaged()){

using (var decryptor = aesManaged.CreateDecryptor(keyBytes, ivBytes)){

MemoryStream memoryStream = null;CryptoStream cryptoStream = null;StreamReader streamReader = null;

try{

memoryStream = new MemoryStream(ciphertextBytes);cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read);streamReader = new StreamReader(cryptoStream);

return streamReader.ReadToEnd();}finally{

if (memoryStream != null){

memoryStream.Dispose();memoryStream = null;

}}

}}

}

Solving Kryptos

Thank you!

Q&A