Podcast #128: We chat with Kent C Dodds about why he loves React and discuss what life was like in the dark days before Git. Listen now.

# Tag Info

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It seems odd for one character to be lower case, but they could both be valid. I would likely guess it to be the one with all upper case characters, especially if the enemy is known to traditionally use all upper case characters for their plaintexts. Perhaps they made a typo or were trying to trick me somehow though. Either is equally probable without such ...

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Why use symmetric encryption with Public Key? The scrambling in public-key encryption systems is often limited to very specially chosen inputs. For example, RSA with modulus $n$ is good at scrambling uniform random integers between $0$ and $n$, but bad at scrambling random English text. In contrast, the stream cipher ChaCha can securely encrypt any bit ...

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An analogy that I find helpful for newer people is to think of the: Symmetric algorithm as a physical key and an associated "symmetric type of" safe Asymmetric algorithm as both an open padlock (your public key) that also has an associated "asymmetric lockbox" the physical key that unlocks the padlock (associated private key) The Password Based Key ...

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asymmetric encryption is not available; e.g. due to large data size Besides having bigger ciphertext representation, it's also proven to be slower than enciphering data with symmetric schemes. But recall that digital signatures are also available to perform verification. symmetric keys are available but you do not want them to be shared with other ...

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I think you're looking for Hybrid cryptosystems. As you correctly noted it's not only unsafe to encrypt large data with a asymmetric system it's also very slow compared to symmetric systems. That's why we usually use both of these systems together (hence hybrid) to "fill each other's gaps". We share a symmetric key using asymmetric cryptography. The ...

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is there a property that guarantees that $D_{k'}(c)$ fails to verify/decrypt? No, there is not; all the security guarantees that authenticated encryption provides is of the form "if you don't know the keys, then it is difficult to..."; it says nothing about the difficulty of anything if you do know the keys. And, it turns out that, with GCM, you can ...

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The CC2650 is a Cortex M3 with 128KB flash memory and 20KB SRAM. This is definitely not enough for RELIC or OpenSSL. TinyECC fits, but even if this is only for signatures, some symmetric cryptography will be needed in addition to it. Better options would be Cifra, libhydrogen, tweetNaCl or a minimal BearSSL build. They all fit in about 20 KB flash memory ...

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You can use any authenticated, secure cipher. AES-GCM is currently used a lot. You need a nonce per message to use AES-GCM or you can use one of the SIV variants, which calculate a nonce (Synthetic IV) assuming that the messages are all distinct. The question is more how to store the symmetric key than anything else, but that's not really a cryptography ...

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If you could guess the key, you could decrypt the challenge ciphertexts and figure out what which plaintext is which. Conversely, if the cryptosystem has ciphertext indistinguishability in this attack model, then you obviously can't figure out which plaintext is which, so you can't guess the key.

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You've described an $n$-of-$n$ threshold encryption scheme by nesting: there are $n$ shares of a secret key, and it takes all $n$ of them (in the right order, so I hope you labeled them) to recover the plaintext. Similarly, there's a simple $1$-of-$n$ threshold encryption scheme by concatenation, which is what, e.g., OpenPGP uses for multiple-recipient ...

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