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1

Yes, there are ways to do this. RSA-KEM The sender RSA-KEM select a uniform random integer x between 2 and n-1, where n is the RSA modulus with at least n>=2^2048. Use HKDK to derive a 128, 192, or 256 it key k k = KDF(x) Encrypt the data with (c,tag) =AES-GCM_ENC(k, message) Encrypt the $x$ with the receivers public key K = RSA_enc(pk,x) Send (K,c,tag) ...


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Do these two keys have the same strength, or by leaving the hyphens in the key am I reducing the security by a partly-known-key attack? A: aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa B: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa These are not different keys. These are only different representations of the same key. It does not matter if one represents a key as binary, ...


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There is still no problem as long as the key strength is good enough. The format of the key is strange here. You can remove the dashes and they are the same. Known values don't add to the strength of the key. Both have the same strength (or entropy!). We already assume the attackers know this kind of knowledge. The usual way to process such information is ...


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I think you misunderstood something there: If a liquor store asks a customer if they're of drinking age, what's preventing the customer from just lying as many times as needed to buy their alcohol? Nothing, but this is not an example of a zero-knowledge proof. The example here would require the prover to show something to the liquor store staff that proves,...


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This depends on the block cipher mode that's used and/or any message authentication that the system may do. But plain old encryption-only modes likes AES-CBC and AES-CTR are vulnerable to malleability attacks, where an attacker who can get some ciphertext (or even better, ciphertext/plaintext pairs) is able to modify it to produce a message some aspects of ...


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The k parameter in elliptic-curve cryptography is supposed to be a secret value that is never reused, and it's usually obtained from a random number generator. Two high-profile hacks that were possible due to not using secure random numbers for it: It led to the PlayStation 3's private key being leaked Many Bitcoin apps on Android lost the contents of their ...


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Don't forget that entropy alone is not sufficient. Most random number generators are pseudo random number generators. A source may produce high entropy number sequences but if the sequence is predictable enough it fails as a good random source. A classic example of this would be the digits of π (pi). The sequence has high entropy but is readily determined.


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Debain 2008 DSA-1571-1 openssl -- predictable random number generator Luciano Bello discovered that the random number generator in Debian's openssl package is predictable. This is caused by an incorrect Debian-specific change to the openssl package (CVE-2008-0166). As a result, cryptographic key material may be guessable. And from Lessons from the Debian/...


2

There was an opensource ransomware named HiddenTear that created a random encryption key, but the key used Environment.TickCount as the seed, making it trivial to bruteforce the key. It also created a version.txt file containing the encrypted computer name. So to break it you would use a ballpark estimate of how long the computer was running when the malware ...


3

One notorious PRNG attack was the attack on the PRNG that was used for SSL in early versions of Netscape, as published in this paper written in 1996 by two PhD students at Berkeley. As explained in the paper, the PRNG relied on three sources of 'entropy': the time of day, the process ID, and the parent process ID.


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I’m going to assume that RSA has the security properties that we hope it does. In particular, I’ll assume that, if someone knows a message p, a public key pubKey, and the value of enc(p,pubKey), then it will be hard for them to calculate the corresponding private key, priKey. And, even if they have lots and lots of plain text / cipher text pairs, your ...


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There are lots of mixing terminology here. In short RSA Signing is Not RSA Decryption by Cornell CS. RSA is a trapdoor permutation, unfortunately, that can be both used for encryption and signature. This makes a common confusion. First of all, although, RSA can be used for encryption, we don't. We prefer hybrid-encryption where a public key cryptosystem is ...


13

There is a common misconception that signing a message is the same as encrypting the message with the private key. This notion is fundamentally incorrect, as pointed out by Thomas Pornin at If the public key can't be used for decrypting something encrypted by the private key, then how do digital signatures work?. As Pornin explains, encryption/...


2

Wedge attack was applicable on DDA cards (Dynamic Data Authentication) which were being superseded by CDA cards (Combined Data Authentication) at the time when vulnerability was disclosed. The researchers behind the vulnerability proposed a solution to fix DDA cards in his write-up: Defending against wedge attacks in Chip & PIN but there's no track ...


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It is not certain that there is a 100% secure solution to any static-secret problem (that's what you're describing btw). Also, there is always a trust relationship between your users and your service. You certainly don't want to be storing your user's secrets -- use it and discard it immediately is a good model. All risks must be properly assessed, according ...


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Since the question is about the NI (New Instruction) set for AES, NI accelerates the the AES algorithm. A right answer could be (also according to Intel docs): cpuid | grep -i aes | sort | uniq If you want to be sure, you can also try the following command: sort -u /proc/crypto | grep module This really gives the kernel modules that are loaded, which should ...


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There is no single source of randomness on a device and there is no single way to create randomness, i.e. it is specific to the OS and maybe the OS version and maybe the OS configuration and maybe even the specific application. See for example TPM to feed random number generator for how to add (not replace) the TPM random generator as a source for randomness ...


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