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diff --git a/index.html b/index.html deleted file mode 100644 index 1fd52b1..0000000 --- a/index.html +++ /dev/null @@ -1,148 +0,0 @@ -<!DOCTYPE html> -<html> - <head> - <title>Forbidden Salamanders</title> - <meta charset="utf-8"> - <meta name="viewport" content="width=device-width, initial-scale=1.0"> - <link rel="stylesheet" type="text/css" href="/static/styles.css"> - <link rel="stylesheet" type="text/css" href="/forbidden-salamanders/static/styles.css"> - <link rel="shortcut icon" type="image/x-icon" href="/forbidden-salamanders/static/favicon.ico"> - </head> - <body> - <div class="container"> - <div> - <div class="home"> - <a href="/forbidden-salamanders" class="home-title">Forbidden Salamanders</a> - <span> at </span><a href="/">cyfraeviolae.org</a> - </div> - <div class="crumbs"> - <a href="/git/forbidden-salamanders">source code</a> - <span class="sep"> · </span> - <a href="/forbidden-salamanders/nonce-reuse">nonce reuse</a> - <span class="sep"> · </span> - <a href="/forbidden-salamanders/nonce-truncation">nonce truncation</a> - <span class="sep"> · </span> - <a href="/forbidden-salamanders/key-commitment">key commitment</a> - </div> - </div> - <p> - The FIPS-compliant sorcerer Roseacrucis uses the <a href="https://en.wikipedia.org/wiki/Galois/Counter_Mode">Advanced Encryption Standard in Galois/Counter Mode</a> - to correspond with his retinue. The Library’s cryptanalysts - have intercepted the communication channel, but we need your - help to exploit their broken protocols. - </p> - <p> - Choose one of the following missions. - </p> - <p> - <strong><a href="/forbidden-salamanders/nonce-reuse">Nonce - reuse</a>.</strong> Due to rising entropy prices, Roseacrucis has - started to reuse nonces. You must perform the Forbidden Attack in order to - recover the authentication key and forge arbitrary ciphertext. - </p> - <p> - <strong><a href="#">Nonce truncation</a>.</strong> The sorcerer - aims to conserve bandwidth by truncating nonces from twelve bytes - to four. Use the enemy as a decryption oracle to once again, - recover the authentication key and forge arbitrary ciphertext. - </p> - <p> - <strong><a href="#">Key commitment</a>.</strong> One of - our agents has infiltrated Roseacrucis’ inner circle, but all - secret keys are required to be surrendered to the - counterintelligence authority. Help her send ciphertexts to the - Library that decrypt to confidential information under one key, but - innocuous banter under another. - </p> - <br> - <details> - <summary> - Though it is not required to complete your missions, we now - review the construction of AES-GCM. - </summary> - <p> - AES-GCM is a block cipher that accepts a key of 16 bytes, - a nonce of 12 bytes, plaintext, and additional authenticated data. - It returns ciphertext and a message authentication code (MAC). - </p> - <p> - The ciphertext is computed as in <a href="https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Counter_(CTR)">counter mode</a>, whereas the MAC is computed using the algorithm GMAC. - </p> - <p> - Let - \[ - m = \alpha^{128}+\alpha^7 + \alpha^2 + \alpha + 1 - \] - \[ - \mathbb{K} = \mathbb{F}(2^{128})/m. - \] - </p> - <p> - The finite field \(\mathbb{K}\) can be - interpreted as the set of polynomials with coefficients in \(\mathbb{F}_2\) - of degree less than \(128\). Multiplication - is performed modulo \(m\). This field is of characteristic 2; - e.g., \((\alpha^5 + 1)+(\alpha^5 + 1) = 0\). - </p> - <p> - We interpret 16-byte blocks as elements in \(\mathbb{K}\) - in little-endian bit order: - \[ - b_0b_1b_2\ldots{}b_{127} \mapsto - b_0 + b_1\alpha + b_2\alpha^2 + \ldots + b_{127}\alpha^{127}, - \] - where \(b_0\) is the least significant bit of the first byte of - the block. - </p> - <p> - 12-byte nonces are interpreted as 96-bit integers in big-endian - byte order. Let \(\operatorname{Byte} = [0, 2^8-1]\) and - \(x_i\) refer to the \(i\)th 16-byte chunk of the bytestring - \(x\). - </p> - <p> - \(\operatorname{encode_{big}}(x, n)\) encodes an integer \(x\) into \(n\) bytes in big-endian - byte order. \(\operatorname{pad_n}(x, p)\) pads the length of - the bytestring \(x\) to the nearest multiple of \(n\) with the - byte \(p\). \(\operatorname{AES}(k, x)\) refers to - the <a href="https://en.wikipedia.org/wiki/Advanced_Encryption_Standard">128-bit AES block cipher</a>. - </p> - <br> - <div class="algorithm"> - <p>\(\operatorname{GMAC}(h\in \mathbb{K}, s\in \mathbb{K}, aad\in \operatorname{Byte}^{y}, c\in \operatorname{Byte}^{z})\)</p> - <ol class="algorithm-code"> - <li>\( len = \operatorname{encode_{big}}(8y, 8) \mathbin\Vert \operatorname{encode_{big}}(8z, 8) \)</li> - <li>\( blocks = \operatorname{pad}_{16}(aad, 0) \mathbin\Vert \operatorname{pad}_{16}(c, 0) \mathbin\Vert len \mathbin\Vert s \)</li> - <li>\( N = \frac{\vert blocks \vert}{16} \)</li> - <li>\( \operatorname{return} \sum\limits_{i=1}^{N} blocks_{N-i} h^{i-1}\)</li> - </ol> - </div> - <br> - <br> - <div class="algorithm"> - <p>\(\operatorname{AES-GCM}(k\in \operatorname{Byte}^{16}, n\in \operatorname{Byte}^{12}, aad\in \operatorname{Byte}^{y}, m\in \operatorname{Byte}^{z})\)</p> - <ol class="algorithm-code"> - <li> \( r = \mathop{\Vert}\limits_{n'=2^{32}n+2}^{2^{32}n+2^{32}-1} \operatorname{AES}(k, n') \)</li> - <li> \( c = r \oplus m \) </li> - <li> \( h = \operatorname{AES}(k, 0) \) </li> - <li> \( s = \operatorname{AES}(k, 2^{32}n + 1) \) </li> - <li> \( \operatorname{return} c, \operatorname{GMAC}(h, s, aad, c) \)</li> - </ol> - </div> - </details> - <!-- <script id="MathJax-script" async src="/forbidden-salamanders/static/mathjax.js"></script> --> - <!-- <script type="text/x-mathjax-config"> --> - <!-- MathJax.Hub.Config({ TeX: { extensions: ["AMSmath.js", "AMSsymbols.js"] }}); --> - <!-- </script> --> -<script> -MathJax = { - tex: { - extensions: ["AMSmath.js", "AMSsymbols.js"] - } -}; -</script> -<script id="MathJax-script" async - src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml.js"> -</script> - </body> -</html> |