All Questions

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Monoalphabetic cipher key

I'm new to cryptography and have just completed homework on Monoalphabetic cipher. I managed to decrypt the cipher text successfully but I cannot identify the key from my plaintext to ciphertext ...
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Recently I'm reading the paper 2-Pass Key Exchange Protocols from CPA-Secure KEM in CT-RSA 2014. I sense that there are some problems with the proof in the section4.2--Original Twisted PRF Trick. In ...
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Cipher Alphabet

Present the first 50 characters of the plaintext of the ciphertext below. NPKLMBAMMAKLNFKCSDABAUADMRMADBAMMAKVFKGSDGVRPEREFBBAEMPUABX PDEBQGASBBMVFLPWBAMMAKLFNMRASBIRSTAMMRAEFBQCDLPDIFKMSLGPSOK ...
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Good references for learning proofs in security and crypto

I see in many crypto papers, they prove the security of a scheme by defining an adversary that can break the scheme, and then reaching some sort of contradiction that a baseline protocol is also ...
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Infer encoding mechanism from n-grams distance

I have a series of obfuscated strings which across the set of strings have regions of high variance and regions of low variance (implying some encoding mechanism as opposed to an encryption procedure ...
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A one way Function provably reversible at N applications with the same seed?

I'm looking for a Function that is generally one way from some secret F(s, A) -> Y, where A is known, Y is produced (also known), and s is kept secret. But whose repeated application results in the ...
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Is it safe to salt MAC's key?

Assuming salt is public and is MAC'd with message. Attacker can modify salt. $k = KDF(password, salt)$ $tag = MAC_k(salt || message)$ Is it safe to salt MAC's key, which is derived with KDF?
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Use case of RSA CRT

I discovered the CRT version of RSA cryptosystem which is used in many crypto libraries (openSSL, Java...). The use of the Chinese Remainder Theorem improves the speed of decryption so why it's not ...
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Efficiently show/prove knowledge of third party secret without leaking information

Say Alice publishes (i.e. all parties in the universe) a key or certificate $x$ and sends a secret $s$ to Bob. Bob then publishes some data $d$ (his identity or a message or smt.) and an ...
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How secure is a lagged fibonacci sequence for encrypting brief messages?

Say I start with a 26-letter keyword and convert the letters into 26 integers (A=0, B=1...Z=25) nr[0] to nr[25]. Then I create a stream, nr[26] onwards, with a lagged fibonacci sequence where nr[n]= ...
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New to Cryptography [on hold]

A friend of mind asked me if I could take a crack at this here: PRSAO EGERA UIADM WEHDN ISNRA SAWUA AESSR EFGDO SOGVO RBEEE AARTE SCTDF MENUI BRTTL MEYTU MTMEU AIKWH UTKWE RWAHM NPWRA EESON ONESE ...
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What do you call one time pad where pseudo-random numbers are used?

What is the encryption method called when pseudo-random numbers are used instead of true random numbers?
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Crypto (mainly binary [on hold]

So I have this binary data, and I am not really sure where to even start with decrypting it... I ran it through python's binascii library (b2a_uu, b2a_hex, b2a_qp) and I haven't gotten even a place to ...
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Is there any probabilistic version of RSA?

I have now studying the RSA, but I think that is it possible to have some probabilistic version like a random bit string "r" XORed with the key? Is there any probabilistic version of RSA? Thak you ...
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Large file validation on an embedded system through hash and encryption

As a preface, I have to say that I am a noob in this area. Having said that, I will ask the question. I have a situation where I need to validate and protect against tampering a handful of large ...
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DES-X , computation load and storage

The passage said that the computational load to attack DES-X can be reduced to approximately $2^{(56+64)}=2^{120}$ steps,and the storage of data sets should be $2^{64}$. But I can't figure why ...
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What can be learned from the ciphertext of LibSodium's crypto_box_detached()?

LibSodium, (https://github.com/jedisct1/libsodium), has a function crypto_box_detached() which does authenticated encryption using the public key of the recipient ...
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Does the size of a SSH ECDSA key determine the hash algorithm?

I am a bit lost in understanding what I read on authentication, signature, etc. Is the size of the ECDSA keys produced by ssh-keygen -t ecdsa -b 256 linked to the ...
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Is AES's parity key-dependent?

Is the parity of the permutation of the set $\{0,1\}^{128}$, defined by AES encryption for a certain fixed key, dependent on this key? DES, and any pure Feistel cipher, has even parity for any key. ...
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A simulation for the BB84 quantum key distribution protocol [duplicate]

I am looking for a Python/Java/C/C++ (any programming language, actually) simulation for the BB84 qkd protocol. I am very new to this field and I just want to better understand how it works and maybe ...
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Verify signed file using GPG by passing in signature hosted online rather than stored locally (i.e. in keyring)? [migrated]

Is it possible to pass the URL of a GnuPG signature when executing a verify query against a signed file? For example, instead of: gpg --verify file.txt Is there ...
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Protection of Elliptic Curve Implementations against side-channel attacks [on hold]

Recent fast elliptic curve implementations, for example a presentation at Eurocrypt 2014 (earlier presentation slides, the paper) talks about protection against only timing attacks. Why only timing ...
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Does a stream cipher require a KDF when it's key is variable length?

RC4 has a variable length key. Is it still necessary to use a key derivation function, such as PBKDF2, to initialize it? Would using a single character password weaken it's output when compared to a ...
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Security of chameleon hash functions

With the knowledge of the trapdoor, we are able to compute the same digest for differents messages. I've read that given two messages $m$, $m'$ and two numbers $r$, $r'$ such that ...
In the definition of functional encryption ($FE$): $FE.Setup(1^k)$ takes as input the security parameter $1^k$ and outputs a master public key $fmpk$ and a master secret key $fmsk$. \$FE.KeyGen(fmsk, ...