\documentclass[10pt,a4paper]{article}

% Packages
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\usepackage{seqsplit}           % Splits long words.
%\usepackage{opensans}          % Can't make this work so far. Shame. Would be lovely.
\usepackage[normalem]{ulem}     % For underlining links
% Most of the following are not required for the majority
% of cheat sheets but are needed for some symbol support.
\usepackage{amsmath}            % Symbols
\usepackage{MnSymbol}           % Symbols
\usepackage{wasysym}            % Symbols
%\usepackage[english,german,french,spanish,italian]{babel}              % Languages

% Document Info
\author{Rithick}
\pdfinfo{
  /Title (ab.pdf)
  /Creator (Cheatography)
  /Author (Rithick)
  /Subject (ab Cheat Sheet)
}

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% Header and Footer
\pagestyle{fancy}
\fancyhead{} % Set header to blank
\fancyfoot{} % Set footer to blank
\fancyhead[L]{
\noindent
\begin{multicols}{3}
\begin{tabulary}{5.8cm}{C}
    \SetRowColor{DarkBackground}
    \vspace{-7pt}
    {\parbox{\dimexpr\textwidth-2\fboxsep\relax}{\noindent
        \hspace*{-6pt}\includegraphics[width=5.8cm]{/web/www.cheatography.com/public/images/cheatography_logo.pdf}}
    }
\end{tabulary}
\columnbreak
\begin{tabulary}{11cm}{L}
    \vspace{-2pt}\large{\bf{\textcolor{DarkBackground}{\textrm{ab Cheat Sheet}}}} \\
    \normalsize{by \textcolor{DarkBackground}{Rithick} via \textcolor{DarkBackground}{\uline{cheatography.com/123084/cs/23086/}}}
\end{tabulary}
\end{multicols}}

\fancyfoot[L]{ \footnotesize
\noindent
\begin{multicols}{3}
\begin{tabulary}{5.8cm}{LL}
  \SetRowColor{FootBackground}
  \mymulticolumn{2}{p{5.377cm}}{\bf\textcolor{white}{Cheatographer}}  \\
  \vspace{-2pt}Rithick \\
  \uline{cheatography.com/rithick} \\
  \end{tabulary}
\vfill
\columnbreak
\begin{tabulary}{5.8cm}{L}
  \SetRowColor{FootBackground}
  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Cheat Sheet}}  \\
   \vspace{-2pt}Not Yet Published.\\
   Updated 5th June, 2020.\\
   Page {\thepage} of \pageref{LastPage}.
\end{tabulary}
\vfill
\columnbreak
\begin{tabulary}{5.8cm}{L}
  \SetRowColor{FootBackground}
  \mymulticolumn{1}{p{5.377cm}}{\bf\textcolor{white}{Sponsor}}  \\
  \SetRowColor{white}
  \vspace{-5pt}
  %\includegraphics[width=48px,height=48px]{dave.jpeg}
  Measure your website readability!\\
  www.readability-score.com
\end{tabulary}
\end{multicols}}




\begin{document}
\raggedright
\raggedcolumns

% Set font size to small. Switch to any value
% from this page to resize cheat sheet text:
% www.emerson.emory.edu/services/latex/latex_169.html
\footnotesize % Small font.

\begin{multicols*}{3}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Asymmetric Encryption}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Uses publicprivate key pair} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Each user generates a pair of public and private keys} \tn 
% Row Count 3 (+ 2)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Public Key is known to everyone and is used to encrypt data} \tn 
% Row Count 5 (+ 2)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Private Key is only known to the key owner and used for decryption} \tn 
% Row Count 7 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Used in 3 categories}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{–Encryption/Decryption (provide secrecy)} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{–Digital signatures (provide authentication)} \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{–Key exchange (of session keys)} \tn 
% Row Count 3 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Diffie-Hellman key exchange}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{First public-key type scheme} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Proposed by Diffie \& Hellman in 1976} \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{A practical method for public exchange of a secret key} \tn 
% Row Count 4 (+ 2)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Cannot be used to exchange an arbitrary message} \tn 
% Row Count 5 (+ 1)
% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Security relies on the difficulty of computing discrete logarithms} \tn 
% Row Count 7 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{1.74195 cm} x{3.23505 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Diffie-Hellman algorithm}}  \tn
% Row 0
\SetRowColor{LightBackground}
q & prime number \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
α & α\textless{}q ,α primitive root of q \tn 
% Row Count 3 (+ 2)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{{\bf{User A}}} \tn 
% Row Count 4 (+ 1)
% Row 3
\SetRowColor{white}
Select    PR=Xa & Xa\textless{}q \tn 
% Row Count 6 (+ 2)
% Row 4
\SetRowColor{LightBackground}
Calculate PU=Ya & Ya=α\textasciicircum{}Xa mod q \tn 
% Row Count 8 (+ 2)
% Row 5
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{{\bf{User B}}} \tn 
% Row Count 9 (+ 1)
% Row 6
\SetRowColor{LightBackground}
Select    PR=Xb & Xb\textless{}q \tn 
% Row Count 11 (+ 2)
% Row 7
\SetRowColor{white}
Calculate PU=Yb & Yb=α\textasciicircum{}Xb mod q \tn 
% Row Count 13 (+ 2)
% Row 8
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{{\bf{Secret key calculation}}} \tn 
% Row Count 14 (+ 1)
% Row 9
\SetRowColor{white}
User A & K=(Yb)\textasciicircum{}Xa mod q \tn 
% Row Count 15 (+ 1)
% Row 10
\SetRowColor{LightBackground}
User B & K=(Ya)\textasciicircum{}Xb mod q \tn 
% Row Count 16 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{{\bf{Disadvantages}}}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Cannot be used for asymmetric key exchanges} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Man-in-the-Attack} \tn 
% Row Count 2 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{ElGammal-Cryptosystem}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Presented in 1984 by Tather Elgammal} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Used for encrypting messages} \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Based on discrete lagarithmic problem} \tn 
% Row Count 3 (+ 1)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Disadvantages}}} \tn 
% Row Count 4 (+ 1)
% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Decryption is slow} \tn 
% Row Count 5 (+ 1)
% Row 5
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Duplicates message length by factor of two during encryption} \tn 
% Row Count 7 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{1.94103 cm} x{3.03597 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{ElGammal algorithm}}  \tn
% Row 0
\SetRowColor{LightBackground}
Select large prime & q \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
Select & p , p is primitive root of q \tn 
% Row Count 4 (+ 2)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{{\bf{User A}}} \tn 
% Row Count 5 (+ 1)
% Row 3
\SetRowColor{white}
Choose private key & Xa , 1 \textless{} Xa \textless{} q-1 \tn 
% Row Count 7 (+ 2)
% Row 4
\SetRowColor{LightBackground}
Compute public key & Ya=p\textasciicircum{}Xa mod q \tn 
% Row Count 9 (+ 2)
% Row 5
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{{\bf{Similarly User B calculates Xb and Yb}}} \tn 
% Row Count 10 (+ 1)
% Row 6
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{{\bf{Encryption from A}}} \tn 
% Row Count 11 (+ 1)
% Row 7
\SetRowColor{white}
Message M & 0\textless{}=M\textless{}=q-1 \tn 
% Row Count 12 (+ 1)
% Row 8
\SetRowColor{LightBackground}
Choose k & 1\textless{}=k\textless{}=q-1 \tn 
% Row Count 13 (+ 1)
% Row 9
\SetRowColor{white}
Compute & K=Ya\textasciicircum{}k mod q \tn 
% Row Count 14 (+ 1)
% Row 10
\SetRowColor{LightBackground}
Compute & C1=p\textasciicircum{}k mod q \tn 
% Row Count 15 (+ 1)
% Row 11
\SetRowColor{white}
Compute & C2=KM mod q \tn 
% Row Count 16 (+ 1)
% Row 12
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{-{}-{}-Ciphertext(C1,C2)} \tn 
% Row Count 17 (+ 1)
% Row 13
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{{\bf{Decryption from B}}} \tn 
% Row Count 18 (+ 1)
% Row 14
\SetRowColor{LightBackground}
Recover key & K=C1\textasciicircum{}Xa mod q \tn 
% Row Count 19 (+ 1)
% Row 15
\SetRowColor{white}
Compute message & M=C2*K-1 mod q \tn 
% Row Count 20 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{RSA}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Uses large integers (eg.1024 bits)} \tn 
% Row Count 1 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{2.38896 cm} x{2.58804 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{RSA key generation}}  \tn
% Row 0
\SetRowColor{LightBackground}
Select two large primes p and q & p not equal to q \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
Calculate & n\textless{}-{}-p*q \tn 
% Row Count 3 (+ 1)
% Row 2
\SetRowColor{LightBackground}
Calculate & O(n)\textless{}-{}-(p-1)*(q-1) \tn 
% Row Count 4 (+ 1)
% Row 3
\SetRowColor{white}
Select e & 1\textless{}e\textless{}O(n) and e is coprime to O(n) \tn 
% Row Count 6 (+ 2)
% Row 4
\SetRowColor{LightBackground}
Calculate & d\textless{}-{}-e\textasciicircum{}-1mod O(n) \tn 
% Row Count 7 (+ 1)
% Row 5
\SetRowColor{white}
Public key & PU=\{e,n\} \tn 
% Row Count 8 (+ 1)
% Row 6
\SetRowColor{LightBackground}
Private key & PR=\{d,n\} \tn 
% Row Count 9 (+ 1)
% Row 7
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{{\bf{Encryption}}} \tn 
% Row Count 10 (+ 1)
% Row 8
\SetRowColor{LightBackground}
Plaintext & M\textless{}n \tn 
% Row Count 11 (+ 1)
% Row 9
\SetRowColor{white}
Ciphertext & C=M\textasciicircum{}e(mod n) \tn 
% Row Count 12 (+ 1)
% Row 10
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{{\bf{Decryption}}} \tn 
% Row Count 13 (+ 1)
% Row 11
\SetRowColor{white}
Plaintext & C \tn 
% Row Count 14 (+ 1)
% Row 12
\SetRowColor{LightBackground}
Ciphertext & M=C\textasciicircum{}d(mod n) \tn 
% Row Count 15 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Key Distribution Techniques}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Means of delivering key to two parties who wish to communicate} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{For symmetric encryption to work,two parties must exchange the same key} \tn 
% Row Count 4 (+ 2)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Public-key cryptosystems are mostly used to encrypt secret keys} \tn 
% Row Count 6 (+ 2)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Frequent key exchanges are desirable to limit the amount of data compromised} \tn 
% Row Count 8 (+ 2)
% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{The strength of any cryptographic system relys on key distribution technique} \tn 
% Row Count 10 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Advantages and Disadvantages}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Hard to crack since it involves factorization of prime numbers} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Can be very slow in cases where large data needs to be encrypted} \tn 
% Row Count 4 (+ 2)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Man-in-the-Middle attack} \tn 
% Row Count 5 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{p{0.9954 cm} x{3.9816 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Key Distribution Models}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{{\bf{Model 1}}} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
A-\textgreater{}B & PUa||IDa \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
B-\textgreater{}A & E(PUa,ks) \tn 
% Row Count 3 (+ 1)
% Row 3
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{-Ensures confidentiality but not authentication} \tn 
% Row Count 4 (+ 1)
% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{-Vulnerable to man-in-the-middle attack} \tn 
% Row Count 5 (+ 1)
% Row 5
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{{\bf{Model 2}}} \tn 
% Row Count 6 (+ 1)
% Row 6
\SetRowColor{LightBackground}
A-\textgreater{}B & E(PUb,{[}N1||IDa{]}) \tn 
% Row Count 7 (+ 1)
% Row 7
\SetRowColor{white}
B-\textgreater{}A & E(PUa,{[}N1||N2{]}) \tn 
% Row Count 8 (+ 1)
% Row 8
\SetRowColor{LightBackground}
A-\textgreater{}B & E(PUa,N2) \tn 
% Row Count 9 (+ 1)
% Row 9
\SetRowColor{white}
A-\textgreater{}B & E(PUb,E(PRa,Ks)) \tn 
% Row Count 10 (+ 1)
% Row 10
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{-ensures both confidentiality and authentication} \tn 
% Row Count 11 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{x{1.04517 cm} x{3.93183 cm} }
\SetRowColor{DarkBackground}
\mymulticolumn{2}{x{5.377cm}}{\bf\textcolor{white}{Distribution of public keys:}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{{\bf{Public announcement}}} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{{\bf{Feeding in a Publicly available directory}}} \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{-Both vulnerable to forgery(anyone can claim to be someone)} \tn 
% Row Count 4 (+ 2)
% Row 3
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{{\bf{Public Key Authority}}} \tn 
% Row Count 5 (+ 1)
% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{-A trusted third party(KDC)} \tn 
% Row Count 6 (+ 1)
% Row 5
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{-Provides session keys to users who wish to communicate} \tn 
% Row Count 8 (+ 2)
% Row 6
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{-Requires users to be registered} \tn 
% Row Count 9 (+ 1)
% Row 7
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{-Just like a directory composed of users public key} \tn 
% Row Count 11 (+ 2)
% Row 8
\SetRowColor{LightBackground}
\mymulticolumn{2}{x{5.377cm}}{-User interacts with the directory to obtain any desired public key securely} \tn 
% Row Count 13 (+ 2)
% Row 9
\SetRowColor{white}
\mymulticolumn{2}{x{5.377cm}}{{\bf{Interaction Model:}}} \tn 
% Row Count 14 (+ 1)
% Row 10
\SetRowColor{LightBackground}
A-\textgreater{}auth & Request|T1 \tn 
% Row Count 15 (+ 1)
% Row 11
\SetRowColor{white}
auth-\textgreater{}A & Epr\_auth{[}KPU\_b|Request|T1{]} \tn 
% Row Count 16 (+ 1)
% Row 12
\SetRowColor{LightBackground}
A-\textgreater{}B & Epu\_b{[}IDA|N1{]} \tn 
% Row Count 17 (+ 1)
% Row 13
\SetRowColor{white}
B-\textgreater{}auth & Request|T2 \tn 
% Row Count 18 (+ 1)
% Row 14
\SetRowColor{LightBackground}
auth-\textgreater{}B & Epr\_auth{[}KPU\_a|Request|T2{]} \tn 
% Row Count 19 (+ 1)
% Row 15
\SetRowColor{white}
B-\textgreater{}A & Epu\_a{[}N1|N2{]} \tn 
% Row Count 20 (+ 1)
% Row 16
\SetRowColor{LightBackground}
A-\textgreater{}B & Epu\_b{[}N2{]} \tn 
% Row Count 21 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}--}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Public-Key Certificates:}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Certificates allow key exchange without realtime access to Public-Key Authority} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{A certificate binds user identity to public key} \tn 
% Row Count 3 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Certificate contains all necessary details appended by its hash} \tn 
% Row Count 5 (+ 2)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Helps user claim accountability for a Key} \tn 
% Row Count 6 (+ 1)
% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{{\bf{X\_509 Certificates:}}} \tn 
% Row Count 7 (+ 1)
% Row 5
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Issued by a Certification Authority (CA)} \tn 
% Row Count 8 (+ 1)
% Row 6
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Part of CCITT X.500 directory service standards} \tn 
% Row Count 9 (+ 1)
% Row 7
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Defines the framework for authentication} \tn 
% Row Count 10 (+ 1)
% Row 8
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Uses public-key crypto \& digital signatures} \tn 
% Row Count 11 (+ 1)
% Row 9
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{X.509 certificates are widely used and has 3 versions} \tn 
% Row Count 13 (+ 2)
% Row 10
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Each version with information extended} \tn 
% Row Count 14 (+ 1)
% Row 11
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Certificate contains information such as Public Key, Digital Signature , Issuer, Version, Serial Number, Time Stamp.} \tn 
% Row Count 17 (+ 3)
% Row 12
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{{\bf{X.509 Version 3:}}} \tn 
% Row Count 18 (+ 1)
% Row 13
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Has been recognised that additional information is needed in a certificate} \tn 
% Row Count 20 (+ 2)
% Row 14
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{-email/URL, policy details, constraints} \tn 
% Row Count 21 (+ 1)
% Row 15
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Rather than explicitly naming new fields defined a general extension model} \tn 
% Row Count 23 (+ 2)
% Row 16
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{-Identifier, Criticality Indicator, Value} \tn 
% Row Count 24 (+ 1)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Hash Functions}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Accepts variable length input M and produces fixed-size hash h} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{{\bf{h = H(M)}}} \tn 
% Row Count 3 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Principal object is data integrity} \tn 
% Row Count 4 (+ 1)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{It is infeasible to find object} \tn 
% Row Count 5 (+ 1)
% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{- With pre-specified hash{\bf{(One-Way Property)}}} \tn 
% Row Count 6 (+ 1)
% Row 5
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{-Two objects mapping to same hash{\bf{(Collision -Free Property)}}} \tn 
% Row Count 8 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Message Authentication Code(MAC):}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Also known as a keyed hash function} \tn 
% Row Count 1 (+ 1)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Concerned with integrity and authentication} \tn 
% Row Count 2 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Calculates hash from the message and encrypts with the secret key-\textgreater{}Cryptographic Checksum or MAC or Tag} \tn 
% Row Count 5 (+ 3)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{-Then is appended to the message} \tn 
% Row Count 6 (+ 1)
% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{-The reciever calcutates the hash of message and compares} \tn 
% Row Count 8 (+ 2)
% Row 5
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{-Same hash value confirms that the message came from the stated sender (its authenticity) and has not been changed.} \tn 
% Row Count 11 (+ 3)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}

\begin{tabularx}{5.377cm}{X}
\SetRowColor{DarkBackground}
\mymulticolumn{1}{x{5.377cm}}{\bf\textcolor{white}{Digital Signatures :}}  \tn
% Row 0
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Concerned with integrity , authentication, Non-repudiation} \tn 
% Row Count 2 (+ 2)
% Row 1
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Operation is similar to that of the MAC} \tn 
% Row Count 3 (+ 1)
% Row 2
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Model-1:}}} \tn 
% Row Count 4 (+ 1)
% Row 3
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Instead the hash value of a message is encrypted with a user's private key} \tn 
% Row Count 6 (+ 2)
% Row 4
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Anyone who knows the user's public key can verify the integrity of the message} \tn 
% Row Count 8 (+ 2)
% Row 5
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{An attacker who wishes to alter the message would need to know the user's private key} \tn 
% Row Count 10 (+ 2)
% Row 6
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{-This provides authentication.} \tn 
% Row Count 11 (+ 1)
% Row 7
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{{\bf{Model 2 :}}} \tn 
% Row Count 12 (+ 1)
% Row 8
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Once the encrypted hash of the message is calulated and appended to original message} \tn 
% Row Count 14 (+ 2)
% Row 9
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Once again it is encrypted with the symmetric secret key} \tn 
% Row Count 16 (+ 2)
% Row 10
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{Reciever decrypts it with the symmetric key then public key} \tn 
% Row Count 18 (+ 2)
% Row 11
\SetRowColor{white}
\mymulticolumn{1}{x{5.377cm}}{Then calculates hash of message and compares} \tn 
% Row Count 19 (+ 1)
% Row 12
\SetRowColor{LightBackground}
\mymulticolumn{1}{x{5.377cm}}{This ensures confidentiality as well as authentication} \tn 
% Row Count 21 (+ 2)
\hhline{>{\arrayrulecolor{DarkBackground}}-}
\end{tabularx}
\par\addvspace{1.3em}


% That's all folks
\end{multicols*}

\end{document}