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1d
comment Proving an encrypted message contains (but does not 100% consist of) a plain-text message?
Can you edit in the info you posted? You should be able to now. Then just flag the answer below where you provided the info and I'll delete it.
1d
revised Proving an encrypted message contains (but does not 100% consist of) a plain-text message?
edited title
1d
accepted Is multiplicative secret sharing secure?
1d
revised Formula for the number of expected collisions
changed question so last paragraph is not needed.
1d
accepted Formula for the number of expected collisions
1d
awarded  Nice Answer
2d
comment Are there any cryptosystems that use multiple keys to perform encryption instead of one or two?
When you say "to perform encryption" you mean only encryption or encryption and decryption?
2d
comment Hitting a counter example in homomorphic encryption over the integers
Maybe it is just a corner case that is so unlikely to happen with real parameters and proper use? Like in RSA if you try to encrypt a multiple of one of the prime factors, the encryption is the identity: crypto.stackexchange.com/questions/1004/…
2d
revised Hitting a counter example in homomorphic encryption over the integers
edited body
2d
comment Hitting a counter example in homomorphic encryption over the integers
Could it be order of operations? (1 xor 1) xor 1 = 0 xor 1 = 1 whereas an xor(1,1,1) = 0 for an xor operator that takes more than 2 inputs.
2d
comment Privacy and Integrity in Public Cryptography
@Loris, a lot of the issues have been described on this site: RSA in ECB mode, attacks on textbook (no padding) RSA. Encrypting large files with RSA is very inefficient and this could lead to DoS attacks too.
2d
comment CPA-security proof of “l-padded RSA” encryption scheme
That sounds like a reasonable way to do it.
2d
answered Exchanging keys via third party
2d
revised Exchanging keys via third party
edited body
2d
comment CPA-security proof of “l-padded RSA” encryption scheme
I don't know this for a fact, but notice that the problem says "prove that if ... is hard ... then ... is CPA-secure". Could it be that your professor is saying that there is no formal proof that the if statement is true? In other words, the problem is saying, assume X, now prove Y, while your profesor is saying that we don't really know if X is true? Therefore, there is no conflict.
2d
comment CPA-security proof of “l-padded RSA” encryption scheme
What is your question? There is no question mark in there. All I see are statements.
2d
comment Privacy and Integrity in Public Cryptography
@Loris, unfortunately, without that type of information it is impossible to answer. There are ways it could be done and provide confidentiality and integrity (but be very, very slow) and there are ways it could be done that completely destroys confidentiality.
2d
comment Privacy and Integrity in Public Cryptography
@Loris, but how are they encrypting large files with, I'm assuming, RSA? With RSA, if the modulus is only 2048 bits, you would have to break a large file into small chunks to encrypt. Are they using padding of any sort? All of these things will affect the security of the protocol, which is another reason to use a standard method (though it sounds like at the moment, this isn't up to you).
2d
comment Encipher the following plaintext message using the Vignere method using the key K = [4,2,3]
I'm voting to close this question as off-topic because it does not give a clear description of the problem you are facing. Please edit to include those details.
2d
revised Encipher the following plaintext message using the Vignere method using the key K = [4,2,3]
added 20 characters in body