QKD WIP

chapter-qkd/chapter.tex

@@ -119,6 +119,8 @@
     }
 }
 
+\hyphenation{a-me-na-ble}
+
 \begin{document}
 \dominitoc
 \faketableofcontents
@@ -244,7 +246,7 @@ interesting spin on the original Minicrypt scenario that recently has garnered s
 name Mini\textbf{Q}Crypt\cite{griloObliviousTransferMiniQCrypt2021, barootiPublicKeyEncryptionQuantum2023}. In
 MiniQCrypt, on one hand, conventional public key cryptography falls before quantum computers, but the key observation is
 that on the other hand, we can then use those quantum computers to do \emph{quantum} cryptography, re-gaining some of
-what we lost. The (im)possibility results for MiniQCrypt are nuanced, and provide something between the intact
+what we have lost. The (im)possibility results for MiniQCrypt are nuanced, and provide something between the intact
 conventional public-key cryptography in Cryptomania, and the total absence of it in classical Minicrypt.
 
 In the discourse on quantum computing and its application to cryptography, it is important to be mindful of which
@@ -254,6 +256,23 @@ symmetric cryptography. In this framework, secret key rate becomes paramount bec
 used with an information-theoretically secure encryption scheme, requiring a never-ending secret key stream. Key
 expansion functions are based on one-way-functions, which are unavailable here.
 
+While in academic sources Pessiland assumptions are common, commercial systems usually are based on Minicrypt
+assumptions. That is, commercial systems propose QKD as an alternative to classical asymmetric cryptography for
+cryptographic key exchange, but then continue to use classical symmetric cryptography for purposes such as key
+derivation and secret-key encryption. Using a computationally secure key derivation function such as Argon 2, a small,
+fixed amount of precious QKD secret key bits can be expanded into a key of almost unbounded length\footnote{Key
+derivation functions have limited output size}. Similarly, a
+computationally secure symmetric cipher such as AES can be used to encrypt almost arbitrary amounts of data using a
+single, short key\footnote{
+    We write that the amount of data that can be encrypted with a computationally secure block cipher is only
+    \emph{almost} unbounded because the cipher operates on blocks of a fixed, short size and depending on the cipher
+    mode, in most applications, collisions of two such blocks enable stochastic \emph{Birthday
+    Attacks}\cite{giraultGeneralizedBirthdayAttack1988}. Usually, for a primitive of block size $n\;\unit{\bit}$, an
+    amount of $2^\frac{n}{2}$ extracted blocks is used as an upper bound for safe usage. For a cipher using the
+    currently common block size of \qty{128}{\bit}, this bound lies at \qty{256}{\exa\byte} of
+    data\cite{bhargavanPracticalSecurity64bit2016,}.
+}.
+
 \section{The Practical Security Implications of Quantum Computing}
 \label{qc-practical-implications}