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author | Camil Staps | 2016-02-12 15:01:00 +0100 |
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committer | Camil Staps | 2016-02-12 15:01:00 +0100 |
commit | efd533331d6a7f0c51ef857af448a6c84c3084ed (patch) | |
tree | 7f28f4e20a215784f27643ad49029332204528b2 /Assignment 6 | |
parent | Makefile (diff) |
Removed spaces in path
Diffstat (limited to 'Assignment 6')
-rw-r--r-- | Assignment 6/CamilStaps-assignment6.tex | 143 |
1 files changed, 0 insertions, 143 deletions
diff --git a/Assignment 6/CamilStaps-assignment6.tex b/Assignment 6/CamilStaps-assignment6.tex deleted file mode 100644 index 0cf6b88..0000000 --- a/Assignment 6/CamilStaps-assignment6.tex +++ /dev/null @@ -1,143 +0,0 @@ -\documentclass[a4paper]{article} - -\usepackage{amsmath,amssymb,amsthm,url,graphicx,comment,enumerate,color,array,inconsolata,minted,subcaption,adjustbox} -\usepackage[margin=2cm]{geometry} -\usepackage[hidelinks]{hyperref} -\usepackage{fancyvrb} -\usepackage{scrextend} - -\usepackage{fancyhdr} % Custom headers and footers -\pagestyle{fancyplain} % Makes all pages in the document conform to the custom headers and footers -\fancyhead{} % No page header - if you want one, create it in the same way as the footers below -\fancyfoot[L]{} % Empty left footer -\fancyfoot[C]{Copyright {\footnotesize\copyright} 2015 Camil Staps} % Empty center footer -\fancyfoot[R]{\thepage} % Page numbering for right footer -\renewcommand{\headrulewidth}{0pt} % Remove header underlines -\renewcommand{\footrulewidth}{0pt} % Remove footer underlines -\setlength{\headheight}{13.6pt} % Customize the height of the header - -\title{Homework $6$} -\author{Camil Staps (s4498062)} - -\DeclareMathOperator{\ord}{ord} -\DeclareMathOperator{\lcm}{lcm} -\DeclareMathOperator{\lsb}{lsb} -\DeclareMathOperator{\Prob}{Pr} -\DeclareMathOperator{\Adv}{Adv} - -\DeclareMathAlphabet{\pazocal}{OMS}{zplm}{m}{n} - -\usepackage{algpseudocode} - -\begin{document} -\maketitle - -\section*{Solution} - -\begin{enumerate} - \item We double the point using formulae described at \url{https://crypto.stanford.edu/pbc/notes/elliptic/explicit.html}. We compute $R=2P=[x_R,y_R]$ with $x_R=\lambda^2-11-2\cdot2,y_R=\lambda\cdot(2-x_R)-7$ where - - $$\lambda = \frac{3\cdot2^2+2\cdot11\cdot2+17}{2\cdot7} = 73\cdot14^1 \equiv 11\cdot20 \equiv 3 \pmod{31}.$$ - - As explained there, this gives the tangent line on $\mathcal{E}$ at $P$: $y=\lambda\cdot x-6+7=3x+1$. - - Furthermore we have $x_R = 3^2-15=-6\equiv25\pmod{31}, y_R=3\cdot(2-25)-7=-76\equiv17\pmod{31}$ and thus $2P=R=[25,17]$. - - \item - \begin{enumerate} - %\item We have $15^3+23\cdot15^2+7\cdot15+1 \equiv 5 \pmod{41}$ and $8^2 \not\equiv 5 \pmod{41}$, so $P$ is not on $\mathcal{E}$. We have $2^3+23\cdot2^2+7\cdot2+1 \equiv 33 \equiv 19^2 \pmod{41}$, so $Q$ is on $\mathcal{E}$. - \item We have $16^3+35\cdot16+17 = 4673 \equiv 40 \equiv 1024 = 32^2 \pmod{41}$, so $P$ is on $\mathcal{E}$. We have $9^3+35\cdot9+17 = 1061 \equiv 36 \equiv 1225 = 35^2 \pmod{41}$, so also $Q$ is on $\mathcal{E}$. - \item For doubling $P$, we compute $\lambda = \frac{3\cdot x_P^2 + 35}{2\cdot y_P} = 803\cdot64^{-1} \equiv 24\cdot23^{-1} \equiv 24\cdot25 \equiv 26\pmod{41}$. This gives - \begin{align*} - x_{2P} &= \lambda^2-2x_P = 26^2-2\cdot16 = 644 \equiv 29 \pmod{41}\\ - y_{2P} &= \lambda(x_P-x_{2P}-y_P = 26(16-29) - 32 = -370 \equiv 40 \pmod{41} - \end{align*} - yielding $2P = [29,40]$. - - For adding, we compute $\lambda=\frac{y_P-y_Q}{x_P-x_Q}=-3\cdot7^{-1}\equiv38\cdot6\equiv23\pmod{41}$. This gives - \begin{align*} - x_{P+Q} &= \lambda^2-x_P-x_Q = 23^2-25=551\equiv12\pmod{41}\\ - y_{P+Q} &= \lambda(x_P-x_{P+Q})-y_P = 23\cdot4-32 = 60 \equiv 19 \pmod{41} - \end{align*} - yielding $P+Q = [12,19]$. - \end{enumerate} - - \newpage - \item - \begin{enumerate} - \item Using sage: - - \begin{minted}[fontsize=\footnotesize,breaklines,tabsize=0]{python} - sage: n = 99177088366023448437328155378814540807926939493785872596706396776111511 - sage: e = 49 - sage: s_1 = 52182506035573798513195935894740627677637125435048460721682242234091429 - sage: s_2 = 47616461307709097579789645077805168973449178313679751343338944408311333 - sage: mod(s_1 ^ e, n) - 12345678901234567 - sage: mod(s_2 ^ e, n) - 28500797465696216321448721267454933034082336986084351692960292520620026 - \end{minted} - - It's definitely not certain, but \texttt{12345678901234567} looks more like a message than the other result, so I would guess that \texttt{s\_1} is the correct signature. - - \item Using the method from the slides, we compute $q = \gcd(n,s_1-s_2)$ and then $p=\frac{n}{q}$ with: - - \begin{minted}[fontsize=\footnotesize,breaklines,tabsize=0]{python} - sage: q = gcd(n, s_1 - s_2); q - 1264980678894295608947972498859964913 - sage: p = n / q; p - 78402057850174397975612616068106247 - \end{minted} - - \item This is textbook RSA. - - \begin{minted}[fontsize=\footnotesize,breaklines,tabsize=0]{python} - sage: m = 12345678901234567 - sage: m = mod(m, n) - sage: d = inverse_mod(e, (p-1)*(q-1)) - \end{minted} - - And verifying: - - \begin{minted}[fontsize=\footnotesize,breaklines,tabsize=0]{python} - sage: m ^ d == s_1 - True - \end{minted} - - \item - Simply implementing the algorithm from the slides gives: - - \begin{addmargin}[2em]{0pt} - \begin{minted}[fontsize=\footnotesize,breaklines,tabsize=0,linenos]{python} - """Sign a message using Garner's method - - Arguments (all ints): - p -- the first prime used to generate the RSA key - q -- the second prime used to generate the RSA key - d -- the private key - m -- the message to sign - """ - def sign(p, q, d, m): - n = p * q - d_p = mod(d, p - 1) - d_q = mod(d, q - 1) - i_q = inverse_mod(q, p) - m = mod(m, n) - s_p = int(mod(m ** d_p, p)) - s_q = int(mod(m ** d_q, q)) - s = s_q + q * int(mod(i_q * (s_p - s_q), p)) - return s - \end{minted} - \end{addmargin} - - A usage example (also providing verification): - - \begin{minted}[fontsize=\footnotesize,breaklines,tabsize=0]{python} - sage: load("garner.py") - sage: sign(p, q, d, m) - 52182506035573798513195935894740627677637125435048460721682242234091429 - \end{minted} - \end{enumerate} -\end{enumerate} - -\end{document} |