CEHv8 module 19 cryptography

Học viện Công Nghệ Thông Tin Bach Khoa A | WModule Objectives What Is SSH Secure Shell?. Học viện Công Nghệ Thông Tin Bach Khoa Cryptography Cryptography is the fd into a scrambied

security News

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The 2012 epidemic of ransom malware appears to have turned even nastier

as 30 Australian businesses hawe now asked police for help coping with attacks in a matter of days

According to local news, police im the state of Queensland have received reports from a dozen businesses while many other are believed to have chosen to keep incidents to themselves

Businesses affected included those in the medical, entertainment, reta# and insurance sectors, the news source said, with several dozen affected im total

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£2,000) ransom via Western Union to get back access to important financial records, including credit

card data and debtor invoices The attackers dermnanded the money within seven days or the sum would

increase by AUD $1,000 per week

Worryingly, this attack used 256-bit encryption, to all intents and purposes Impossible to crack Wf the

key has not been exposed during the attack

“Alot of businesses can't afford the interruptions to their trade and will pay straight away,” detective superintendant Brien Hay of Queensland's fraud and corporate crime group told press

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Học viện Công Nghệ Thông Tin Bach Khoa

A | WModule Objectives

What Is SSH (Secure Shell) ? Cryptography Attacks

Public Key Infrastructure (PKI) Cryptanalysis Tools Certification Authorities Online MDS Decryption Tools

Học viện Công Nghệ Thông Tin Bach Khoa

Cryptography

Cryptography is the fd into a scrambied

as lộ code that is Gecrypted and sent across a private or

oublic network

Cryptography is used to protect confidential data such as

, Chat sessions, web transactions, personal hii — data, e-commerce applications, etc

Ptatrrtext Cephertext Ciphertext Plaintext

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Học viện Công Nghệ Thông Tin Bach Khoa

Symmetric Encryption (secret-kevy,

Cx^ «ewe Tce One keer tote

shared-key, and private-key} Th my 0 ete > VỐ a —— >> meer

s A wwe eee oe ee

“ở “sự - «4 > *ˆ ` oe) for encryption as it does for seeenenent o~ar | sesesesane

Cipher text Pla:e test

decryption

Pain text

Asymmetric Encryption Asymmetric Encryption

Asymmetric encryption (public-key)

for

DOecryphon

Encryptior

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¬w oerespanes encryption and Gecryption reese key:

are known as public and private keys

tr t*swˆs: tt

Piain teat Plaw te xt Cipher text

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BACH KHOA

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under control of a S6-bit key

that takes a fixed-tength string of plaintext bits and

transforms it into a ciphertext bitstring of the same tengthn

Due to the of DES with today’s technologies, some organizations repeat the

process three times (3DES) tor added strength, until they can afford to update their equipment to AES capabilt:es

Học viện Công Nghệ Thông Tin Bach Khoa

Advanced Encryption Standard (AES)

securing sensitive but unclassified material

by US government agencies

Cipher (byte án(4*°Nb], byte out(4*kb]

for round = i step 1 to Wr~l1 SubBytes istate)

7a SubBy tes (state)

itis a parameterized algorithm with a variable —_ }—

block size, a variable key size, and a variable number of rounds The key sive is 128-bits

RCS RC6 ts a symmetric key Diock cipher derived from RC5

with two additional features

Ì *% Jses four 4-b(t working repsters (2C5S wees two 2-bit regrters) f : —_

Học viện Công Nghệ Thông Tin Bach Khoa

aetna

The DSA and Related Signature

schemes

FIPS 186-2 specifies the Digital Seenature - The digital signature ts computed using 3

^lgor:thm (O54) that may Se used im the == set of rules (Le., the OSA) and a set of ecnerabon and verification of cegita! = xararreters such that the identity of the

corresponding 5 To compute a, select an element g in 7", and compute gy” " mod p j

private key & Nae 1, pectorm step five again with a đđfererd ở

7 S#elect a random Øø such that 1 ¢ a < q-l

& Compute y = a’ mod p

Ốc li 6A nan SG a6 na nan sa (006.6 ee TT)

(Rivest Shamir Adleman)

¬ oo

RSA is an Internet encryption and suthenticaien

— & 3 : system that uses an algorithm developed by Ron

`N a Rivest, Adi Shamur, and Leonard Adieman

RSA encryption is widely used and is one of the de

oO facto encryption standard

it uses modular arithmetic and elementary

\) number theories to perform computations

using two large prime numbers

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Học viện Công Nghệ Thông Tin Bach Khoa

farst prime number

second prime number modulus igive this pubiic exponent igive this

«= (C^D mod Po (c*2753) mod 3233

this

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= The RSA Signature Scheme

À'q©rithr Key generaton tor he I

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IViessage Digest (One-way Hash) clEH

Functions xi [=eễ=%=

representation called a message

digest of any arbitrary block of information

‘ Message digests are aiso calied one-way bash functions because they cannot be reversed

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it is an algorithm for generating cryptographically secure one-way hash, _—

U.S Federal information Processing Standard =

2 & produces a 160-bit

digest from a message with a maximum length of (2 ~ 1) bits, and resembles the MDS algorithm

is then invertibly permuted

Học viện Công Nghệ Thông Tin Bach Khoa

SSH is a secure

replacement for te!net and the Berkeley remote-utilities (riogin, rsh, rcp, and rdist)

Authentication

it provides an encrypted Provides strong +ost-to

channe! for remote ee ae be eh as

logging, command authentication, and execution and file secure communication transfcrx cover an irsecure tnternet

SSHM2 is a more secure, efficient, and portable version of SSH that includes SFTP, an SSH2 tunneted FIP

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Cryptography Tool: Advanced Encryption Package

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public key algorithms for

it uses public key

CommuniCrypt File Encryption Tools

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GNU Privacy Guard

Arte //www upg org

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Cryptanalysis Tools

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Public Key Infrastructure (PKI) is a

required to create, manage, distribute, use, store, and revoke

Lertifiicate Management

System

Generates, destributes, stores,

and verifies certificates

Public Key Infrastructure (PKI)

(Cont'd)

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Học viện Công Nghệ Thông Tin Bach Khoa

Digital Signature

Digital signature used asymmetrex cryptography to simulate the security properties ofa

A Oievtal signature may be turther protected, Dy encrypting the signed email for confmMentiaimy

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Học viện Công Nghệ Thông Tin Bach Khoa

@ it uses! to encrypt data transferred over SSL connections

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7 : Teter WIIh the cremisster secret

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to {cxvet key Ea rae ‘

each other, select Chere Corwhuane nesta str encryption method

Ciert bey exchange | « — ` 5

Học viện Công Nghệ Thông Tin Bach Khoa

nh encryption 0eotects Onsk ercryption works wm a similar wish the use of an encryption

stored program for your disk, you can

wey as

om Gisk Dy converting Ft into an and protects data even when the to burn

umreadable code wiing disk

OS not active encryption softwere or hardware falling onto the wrong hands

Oeste the dick, and kéo A from

Prewacy Passphrase Hidden Volumes Voturme Encryption Blue Ray OVD Backug

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CIEH

TrveCrypt is disk encryption software that creates a virtual encrypted disk within a

file and mounts it as a real disk

nt encrypts an entire partition or storage Gevice such as USB flash drive or hard drive

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Disk Encryption Tool: GiliSoft

Full Disk Encryption

SafeBit Disk Encryption

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DiskCryptor

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Symantec Drive Encryption

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DriveCrypt Plus Pack

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previous encryptions

#z

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feeds it into the cipher, and analyzes the ; using thts information the

resultene ciphertext xey used to generate ciphertext ts deduced

sO as to decipher other messages

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Học viện Công Nghệ Thông Tin Bach Khoa

of ciphertexts of his own choosing

Extraction of cryptographic secrets

{e.g the password to an encrypted Rubber Hose

file) from a person by ‹ Attack

Học viện Công Nghệ Thông Tin Bach Khoa

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Code Breaking Methodologies

it orvolves the use of social Cryptography keys are discovered by

engmeennge techreques to extract trying every possible combination

keys, which are chose tndomy ^^ stretch of written language, certain

7+ letters and combinations of letters occur

with varying frequencies

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DAI HOC

Defeating a cryptograpivc

scheme by trying 2 large

number of possible keys

until the correct encryption

Brute-force attack is a high

resource and tmme intensive

process, however, more

certam to actweve results

xey, time constramt, and

systerr security mechanisms

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IVieet-in-the-Middle Attack on Digital Signature Schemes

The attack works Dy end ana

it can be used for " even on digital signatures that

use rmrnultiple-encryption scheme

tot ed wit® intermediate Decrypted with a =

; “john” ; š* kewl te Ciphertext 1 AvBr

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l m = ' {rsisvygrirvd {<9 intermediate Decrypred with “AvÐzr'

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CryptoBench

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iCrypTool

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EverCrack

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AlphaPeeler

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Draft Crypto Analyzer

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Linear Hull Cryptanalysis of

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; CÌ Cryptography is the conversion of data into a scrambled code that is

sent across a private or public network and Gecrypted by its recipients

J Using Public Key Infrastructure (PKI), anyone can send a confidential message using public information, which can only be decrypted with a private-key in the sole

possession of the intended recipient w— AESis a symmetric-key algorithm for securing sensitive but unclassified material by U.S government agencies

as oe ryptography attacks are based on the assumption that the cryptanalyst has access to the encrypted information

wt Public Key Infrastructure (PKI) is a set of hardware, software, people, policies, and procedures required to create, manage, distribute, use, store, and revoke digital certifecates

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