Course :- Cryptology

[tauruskhan]

Asalam -0-Alikum
aj sey main ik cource shorow ker raha hoon jis ka name hay

Crytology
umeed hay key app ko pasand ayeh ga

Cryptanalysis:-
yeh bagair key kay uninteligble message ko intelligible message main transform kerna hota hay

Crytography:-
cryptography is the practice of enciphering or encoding a message so that it can be read by someone for whom it is intended, but not by anyone for whom it is not intended. yeh with key hota hay

Crytology:-
yeh mathematic ki branch hay jo key crytography and crytanalysis per mushtamil hay

course shorow kernay sey pehlay kuch definitions dehk lain

key space:-
tumam possible values jo kay key ho sakti haan
key space kehlati haan

plaintext space:-
usi tarah un tumam values ka set jo key plaint text key tor per aa saktay haan

ciphertext space:-
set of all possible values of ciphertext

[tauruskhan]

Re: Cource :- Cryptology

Role of Cryptographer:-
1. is baat ka kheal rakna key information sirf authurized person dehk sakey
2. information apni mukarar jaga durust tarekay sey pohanchay

Main services Provided by Cryptography:-
1. Confidentiality
yani key information autherized person hi sirf dehkay
2. Authentication
reciever jan sakey kay message kis ki taraf sey aya hay, koi introder to kisi aur key name sey message naeen bej raha kaheen
3. Integrity
reciever verify ker sakey key message rastey main tabdeel kaheen naeen hoa yani introder kisi legitmate message ko change ker kay false message na bej raha ho
4 Non reudiation
sender ko baad main mokarnay ki ijzat na ho key us ney message naeen beja tha

[tauruskhan]

Crytographic Algorithms

Crytographic Algorithms
in ko cipher bi bola jata hay
yeh mathematical functions hotey haan jin ko encryption and decryption key liya istamal kia jata hay

Symmmetric Algorithms
in ko conventional algorithms bi bola jata hay
symmetric algos main normally encryption and decryption key liya ik ( one ) key hi use hoti hay
is key liya zarori hay key sender and reciver communication key liya pehlay ik key per agree hoon pir communication start ho gi


Symmetric Algorithms ki tumam security us key main hoti hay
ager key ka pata lag jaey to koi bi in algos key through messages ko
encrypt and decrypt ker sakta hay

jab tak communication ko secret raknay ki zarorat ho , key bi secret raki jati hay


Types of Symmetric Algorithms:-
1. Block Algos
yeh wo ciphers hotey haan jo key groups of bit per operate kertay haan
2. Stream Algos
yeh wo ciphers hotey haan jo key individual characters per operate hotey haan , usually plaintext key binary digits per lakin aik wakat main aik

Asymmetric Algorithms:-
in ko public key algorithms bi kaha jata hay
in main encryption and decrytion key leya alag alag keys istamal hoti haan
in ko public key algorithm is leya kaha jata hay key aksar encryption key ko public ker dia jata hay , yani
key koi bi stranger encrypt ker sakta hay
lakin decrypt sirf authorized person hi keray ga

[sheem]

Re: Cource :- Cryptology

ahaan

kuch kuch samaj mai aya hai

anyways thanx for tutorial

aur b likhti rahein

[Bheegi-Palkain]

Re: Cource :- Cryptology

Asslam_O_Alikum WR WB

Me kay kuch nahi aya samjh main ...

zara easy karya na .. me ka demgh zara kum hay ...

I ll wait more

FeaamnAlalh

[*Hala*]

Re: Cource :- Cryptology

nice sharing.... well u plz give a little explaniation ..... :eye:

[Muhammad Khalil]

Re: Course :- Cryptology

intersting cary one plz

[Shaim]

Re: Course :- Cryptology

me ko IT nahi ataa
me ko seekhna to hai perrrrrrrrrr ye kaa tha sirr k ooper se guzar gaya:tauba :pagal:
INNNNNNNNA MUSHKIIIL
main fail ho jaon giiiiiiiiiiii

[Shaim]

Re: Course :- Cryptology

tumhaaraa SAR chhoTaa hai yaa QAD? :kr: :kr: :kr: :kr: :kr:

:alhamd: dono hi thiik hain:lpop:
per lagta hai apka qad n sir xtra bara hai:khi: ...........aisa karin ap samjhaa dain:mm:

[tauruskhan]

Re: Course :- Cryptology

me ko IT nahi ataa
me ko seekhna to hai perrrrrrrrrr ye kaa tha sirr k ooper se guzar gaya:tauba :pagal:
INNNNNNNNA MUSHKIIIL
main fail ho jaon giiiiiiiiiiii

walikum as salam
itna bi muskil naeen hay , zara ghor sey paro

[Muhammad Khalil]

Re: Course :- Cryptology

nxt post ka waite hay..............

[tauruskhan]

Re: Course :- Cryptology

common ciphers:-

1. ceaser cipher:-
yeh nihayat simple cipher tha.
is ki mathematical equation hay

y=(x+3) mod 26

lets take an example
in cryptography we assign the values with the alphabets

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
0 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

her character key nechay us ki value likhi hay

ab misal key tur per
plain text hay hamara

PT : ME HERE

y1=(M +3) mod 26 =(12+3) mod 26 = 15 mod 26 =15=P
y2=(E+3) mod 26 =(4+3) mod 26 =7mod 26 =7=H
y3= (H +3) mod 26=(7+3)mod 26=10mod 26 =10=K
y4=(E+3) mod 26=(4+3) mod 26 =7mod 26 =7=H
y5=(R+3) mod 26=(17+3) mod 26= 20 mod 26 = 20=U
y6=(E+3) mod 26=(4+3) mod 26 =7mod 26 =7=H

is tarah
encrypt ho ker ceaser cipher key sath
me here = PH KHUH

---------------------------
yeh thee encryption ab decryption key liya
mathematical equation hoti hay
x=(y+23)mod 26

is leya key ager hmm normally kertay to hoti
x=y-3 mod 26
hmm jantey haan key mod ki property haan key ager hmm 26 add ker dain to result main koi farak naeen perta. and yeh hmm normally is leya kertay han key hmm -ve value ko naeen letay

so -3 +26=23
so equation bani
x=(y+23) mod 26

ab app is equation key through khod ph khuh ko decrypt kareen
ok
------------------------------------------------

[Muhammad Khalil]

Re: Course :- Cryptology

amazing reallllly its ..nice to have this course

[tauruskhan]

Re: Course :- Cryptology

2. Shift cipher:

yeh ceaser cipher ki advance shakal thee
is ki mathematical equation thee

y =(x+k ) mod 26
yahan 3 ki jaga ik aur variable lay lia gia tha k

ager k=3 ho ga to yeh ceaser cipher

assignment
PT : khalil
cipher text khud baneen

--------------------

[Muhammad Khalil]

Re: Course :- Cryptology

let me try