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What are some innovative encryption methods?

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Re: What are some innovative encryption methods?

#32

Post by sweis »

Your friend is not going to get PhD thesis topics by asking his friend to post on HN.

Regardless, here's what I think are interesting areas in recent crypto:

- Performance improvements in fully homomorphic encryption, starting with Gentry's work in 2009.

- Practical applications of secure multiparty computation, e.g. Dyadic Security and Google's SMC work.

- Non-NIST standards with actual adoption like Curve25519 and Chacha20-Poly1305

- Functional Encryption: http://eprint.iacr.org/2010/543

- Post-quantum crypto like New Hope (https://eprint.iacr.org/2015/1092) and Supersingular Isogenies (http://eprint.iacr.org/2011/506)

- Candidate functions for Multilinear Maps, e.g. https://eprint.iacr.org/2012/610

- Hardware-based secure enclaves like SGX

Re: What are some innovative encryption methods?

#33

Post by mseebach »

hawski wrote: post #30
mseebach wrote: post #21

Earlier quoted context omitted.

If you reuse your pad, you're vulnerable to frequency analysis, which is literally the oldest trick in the book. You might as well send in plaintext.

How easy would it be if you would go through the entire 1GB and only then from the beginning? I guess it is a question of how big messages are.

If you're only reusing it once, then I guess frequency analysis gets tricky, but the problem you have instead is that you have provided a validation function: Where, using a one-time-pad, any key that yields plausible cleartext is a possible candidate, if you have two cyphertexts encoded with the same (piece of) the one-time-pad, only keys that result in plausible decrypted cleartext for both cyphertexts are possible candidates.

This was how an early break-through in breaking the Enigma was achieved (tangentially, as the Enigma isn't a one-time-pad, but the analysis is similar): Codes were rotated daily, but the first message sent out every morning with the new codes was a weather-report. Thus, the team could immediately cull the search-space to keys that would decrypt to "Weather on [date]" for the first n characters.

Re: What are some innovative encryption methods?

#34

Post by sounds »

Someone wrote: post #29
sounds wrote: post #23

Earlier quoted context omitted.

Combined with envelope keys it can be effective for many applications. An envelope key is a securely, randomly generated key used to encrypt the large payload. Then the envelope key (much smaller than the payload) can be encrypted using a one time pad. The result is that the precious bits of encryption provided by the one time pad are used up at a predictable rate. Guessing the envelope key is more probable than gues…

If you use good encryption and a reasonable key size, that’s good in practice, but theoretically, that’s a lot less secure than a one time pad. An attacker can ‘simply’ try all possible keys and use statistics to filter out those that look like natural language. If the encrypted text is large enough, chances are you will be left with only one plausible plaintext. Also, AFAIK, we don’t know whether good encryption usi…

Your final aside, "good encryption using a key much shorter than the plaintext," is something I hadn't really thought much about and seems like a reasonable way to go directly from a one time pad to the ciphertext.

As you say, there doesn't seem to be a way to guess the key length from the ciphertext. Ignoring side channel attacks for the moment, it does seem like the one time pad could encrypt the entire message simply by using some clever way of "extending" the key.

Re: What are some innovative encryption methods?

#35

Post by mseebach »

sounds wrote: post #34
Someone wrote: post #29

Earlier quoted context omitted.

If you use good encryption and a reasonable key size, that’s good in practice, but theoretically, that’s a lot less secure than a one time pad. An attacker can ‘simply’ try all possible keys and use statistics to filter out those that look like natural language. If the encrypted text is large enough, chances are you will be left with only one plausible plaintext. Also, AFAIK, we don’t know whether good encryption usi…

Your final aside, "good encryption using a key much shorter than the plaintext," is something I hadn't really thought much about and seems like a reasonable way to go directly from a one time pad to the ciphertext. As you say, there doesn't seem to be a way to guess the key length from the ciphertext. Ignoring side channel attacks for the moment, it does seem like the one time pad could encrypt the entire message sim…

> it does seem like the one time pad could encrypt the entire message simply by using some clever way of "extending" the key

Any way of meaningfully extending the key will be vulnerable to a kind of analysis well understood 70 years ago.

This is basically what almost the entire field of cryptography is about: Figure out how you can effectively and securely encrypt things with a key that's a lot shorter than your cleartext.

Re: What are some innovative encryption methods?

#36

Post by Someone »

mseebach wrote: post #35
sounds wrote: post #34

Earlier quoted context omitted.

Your final aside, "good encryption using a key much shorter than the plaintext," is something I hadn't really thought much about and seems like a reasonable way to go directly from a one time pad to the ciphertext. As you say, there doesn't seem to be a way to guess the key length from the ciphertext. Ignoring side channel attacks for the moment, it does seem like the one time pad could encrypt the entire message sim…

> it does seem like the one time pad could encrypt the entire message simply by using some clever way of "extending" the key Any way of meaningfully extending the key will be vulnerable to a kind of analysis well understood 70 years ago. This is basically what almost the entire field of cryptography is about: Figure out how you can effectively and securely encrypt things with a key that's a lot shorter than your clea…

Indeed. The two simplest examples are the Caesar cipher (https://learncryptography.com/classical-encryption/caesar-ci..., key length of 1 character) and the Vigenère Cipher (https://learncryptography.com/classical-encryption/vigenere-..., key length as long as you want it to be)

Both extend the key by repeating it. That is not a good idea.

Re: What are some innovative encryption methods?

#39

Post by drmeena »

sweis wrote: post #32

Your friend is not going to get PhD thesis topics by asking his friend to post on HN. Regardless, here's what I think are interesting areas in recent crypto: - Performance improvements in fully homomorphic encryption, starting with Gentry's work in 2009. - Practical applications of secure multiparty computation, e.g. Dyadic Security and Google's SMC work. - Non-NIST standards with actual adoption like Curve25519 and…

Hellow sweis, actually he is posted for me, due to some technical issues I could not. how can u say that I can't get thesis topic? and thank you for your reference links.
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