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NMCSP2008 Batch-I
Module XVII
Cryptography
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Module Objectives
What is PKI
RSA
MD-5 SHA
SSL
PGP SSH
Encryption Cracking Techniques
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Module Flow
Public KeyCryptography
Working ofEncryption
RSA
MD5Secure HashAlgorithm (SHA)
DigitalSignatures
Secure SocketLayer (SSL)
RC5 Secure Shell(SSH)
Code BreakingMethodologies
DiskEncryption
HackingTools
Pretty GoodPrivacy (PGP)
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Public-key Cryptography
Public-key cryptography was invented in 1976 by
Whitfield Diffie and Martin Hellman.
In this system, each person gets a pair of keys, called
the public key and the private key.
Each person's public key is published while the private
key is kept secret.
Anyone can send a confidential message by just usingthe public key, but the message can only be decrypted
using a private key that is in the sole possession of the
intended recipient.
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Working of Encryption
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Digital Signature
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RSA (Rivest, Shamir, Adleman)
RSA is a public-key cryptosystem developed by MIT
professors Ronald L Rivest, Adi Shamir, and Leonard M
Adleman in 1977 in an effort to help ensure internet
security.
RSA uses modular arithmetic and elementary number
theory to do computations using two very large prime
numbers.
RSA encryption is widely used and is the 'de-facto'
encryption standard.
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Example of RSA algorithm
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RSA Attacks
Brute forcing RSA factoring
Esoteric attack
Chosen ciphertext attack
Low encryption exponent attack
Error analysis
Other attacks
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MD5
The MD5 algorithm uses a message of arbitrary
length as its input and produces a 128-bit
"fingerprint" or "message digest" of the input as
its output.
The MD5 algorithm is intended for digital
signature applications, where a large file must
be "compressed" in a secure manner, before
being encrypted with a private (secret) key,
under a public-key cryptosystem such as RSA.
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SHA (Secure Hash Algorithm)
The SHA algorithm takes as its input a message
of arbitrary length and produces as its output a
160-bit "fingerprint" or "message digest" of theinput.
The algorithm is slightly slower than MD5, but
the larger message digest makes it more secureagainst brute-force collision and inversion
attacks.
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SSL (Secure Socket Layer)
SSL stands for Secure Sockets Layer and is a
protocol developed by Netscape for
transmitting private documents via the
Internet.
SSL works by using a private key to encrypt
data that is then transferred over the SSL
connection.
The SSL Protocol is application protocol
independent.
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RC5 is a fast block cipher designed by RSA Security in
1994.
It is a parameterized algorithm with a variable block
size, a variable key size, and a variable number of
rounds. The upper limit on the block size is 128 bit.
RC6 is a block cipher based on RC5. Like RC5, RC6 is a
parameterized algorithm where the block size, the key
size and the number of rounds are variable again. The
upper limit on the key size is 2040 bits.
RC5
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What is SSH?
The program, SSH (Secure Shell), is a securereplacement for telnet and the Berkeley r-utilities(rlogin, rsh, rcp and rdist).
It provides an encrypted channel for logging intoanother computer over a network, executing commandson a remote computer, and moving files from onecomputer to another.
SSH provides a strong host-to-host and userauthentication as well as secure encryptedcommunications over an insecure internet.
SSH2 is a more secure, efficient and portable version ofSSH that includes SFTP, an SSH2 tunneled FTP.
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Government Access to Keys (GAK)
Government Access to Keys (also known as key escrow)
means that software companies will give copies of all
keys (or at least enough of the key that the remainder
could be cracked very easily) to the government.
The government promises that they would hold the keys
in a secure way and only use them to crack keys when a
court issues a warrant to do so.
To the government, this issue is similar to the ability to
wiretap phones.
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RSA Challenge
The RSA Factoring challenge is an effort, sponsored by
RSA Laboratories, to learn about the actual difficulty infactoring large numbers of the type used in RSA keys.
A set of eight challenge numbers, ranging in size from
576 bits to 2048 bits are given.
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distributed.net
www.distributed.net
An attempt to crack RC5 encryption using a network of
computers world wide
The client utility, when downloaded from
distributed.net, runs the crack algorithm as a
screensaver and send results to the distributed.net
connected servers.
The challenge is still running...
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PGP Pretty Good Privacy
Pretty Good Privacy (PGP) is a software packageoriginally developed by Philip R. Zimmermann thatprovides cryptographic routines for e-mail and filestorage applications.
Zimmermann took existing cryptosystems, andcryptographic protocols, and developed a program thatruns on multiple platforms. It provides messageencryption, digital signatures, data compression ande-mail compatibility.
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Code Breaking: Methodologies
The various methodologies used for codebreaking are as follows:
Brute Force Frequency Analysis
Trickery and Deceit
One-Time Pad
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Cryptography Attacks
Cryptography attacks are based on theassumption that the cryptanalyst has knowledgeof the information encrypted.
Cryptography attacks are of seven types: Ciphertext only attack
Known-plaintext attack
Chosen-plaintext
Adaptive chosen-plaintext attack
Chosen-ciphertext attack
Chosen-key attack
Rubber hose attack
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Disk Encryption
Disk encryption works similarly to text messageencryption.
With the use of an encryption program for your
disk, you can safeguard any, and all,information burned onto the disk and keep itfrom falling into the wrong hands.
Encryption for disks is incredibly useful if and
when you need to send sensitive informationthrough the mail.
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Hacking Tool: PGP Crack
http://munitions.iglu.cjb.net/dolphin.cgi?action=render&category=0406
PGP crack is a program designed to brute-force
a conventionally encrypted file with PGP or a
PGP secret key.
The file "pgpfile" must not be ascii-armored.
The file "phraselist should be a file containing
all of the passphrases that will be used to
attempt to crack the encrypted file.
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Magic Lantern
It is new surveillance software that would allowagents to decode the hard-to-break encrypteddata of criminal suspects.
Magic Lantern works by infecting a suspect'scomputer with a virus that installs "keylogging"software -- a program that can capture thekeystrokes typed into a computer.
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WEPCrack
WEPCrack is an open source tool for breaking802.11 WEP secret keys.
This tool is Perl based, and are composed of the
following scripts: WeakIVGen.pl
prism-getIV.pl
WEPCrack.pl
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Cracking S/MIME encryption using idleCPU time
It tries to brute-force an S/MIME encryptede-mail message, by translating an S/MIMEencrypted message to RC2 format, and thentrying all the possible keys to decrypt themessage.
This brute-force utility comes in two forms:
Command line
Screen Saver
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CypherCalc
It is a full-featured,programmable calculatordesigned for multi precisioninteger arithmetic.
It is intended for use in thedesign, testing, and analysisof cryptographic algorithmsinvolving key exchanges,modular exponentiation,modular inverses, and
Montgomery Math.It has built-in GCD, andSHA-1 tools, and a CRC toolthat can generate CRC tablesfor your applications.
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Command Line Scriptor
Automate file encryption/decryption digitalsigning and verification.
Send files/e-mail securely without any userintervention.
Ensure all of the important data is securedwithout relying on user input.
Bulk delete files at a pre-defined date and time.
Integrates cryptographic techniques intoexisting applications.
Processes incoming secure files from anyOpenPGP compliant application.
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Screenshot Of Command Line Scriptor
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CryptoHeaven
CryptoHeaven allows groups to send encrypted e-mail,securely backup and share files, pictures, charts,
business documents, and any other form of electronicmedia in a secure environment.
No third parties, including server administrators,government agencies, big brothers and others watching,have access to plaintext versions of transmittedinformation.
Some of the features of the service include securedocument storage, secure document sharing anddistribution, secure message boards, secure e-mail, andsecure instant messaging.
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Summary
Using Public Key Infrastructure (PKI), anyone can send a confidentialmessage using public information, which can only be decrypted with aprivate key in the sole possession of the intended recipient.
RSA encryption is widely used and is a 'de-facto' encryption standard.
The MD5 algorithm is intended for digital signature applications,where a large file must be compressed securely before being encrypted
SHA algorithm takes as its input a message of arbitrary length andproduces as its output a 160-bit message digest of the input.
Secure Sockets Layer, SSL, is a protocol for transmitting privatedocuments via the Internet.
RC5 is a fast block cipher designed by RSA Security.
SSH (Secure Shell) is a secure replacement for telnet, and the Berkeleyr-utilities, providing an encrypted channel for logging into anothercomputer over a network, executing commands on a remote computer,and moving files from one computer to another.