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1h
comment (bfxor) BruteForcer XOR v1.2 - Data Dictionary Attack on 64-bit Keys
I'm voting to close this question as off-topic because it has nothing to do with cryptography.
1h
comment Is this a valid scheme to authenticate through a 'human-readable' certificate?
I changed the third part a lot. Replays are gone, because actually you don't have an authentication scheme (my bad, sorry), but just a key exchange protocol without any computational hardness assumptions.
1h
revised Is this a valid scheme to authenticate through a 'human-readable' certificate?
changed the large part, for better understanding
1h
answered Would the Fiat Shamir identification scheme be more secure if I design it with an exponents higher than 2?
2h
answered Is this a valid scheme to authenticate through a 'human-readable' certificate?
3h
comment In modern definition, what is Enigma, and what caused its downfall?
All 8 points have been answered there. Pretty much everything in here is answered in any book about the history of cryptography. Btw. , your example for an often used phrase is not the one actually being used. It was mostly the full title of the commanding officer at the end, or the very static greeting of the weather report. Both much longer texts, which are publicly known.
4h
comment How much would it cost in U.S. dollars to brute force a 256 bit key in a year?
Fortunately, movies and tv shows have a completely and utterly wrong image of breaking encryption. In reality, there is no way to distinguish a partially correct key. All those ideas of breaking a key or password symbol by symbol is just fiction.
Mar
26
comment AES or Serpent-Twofish-AES
Here is a good guide to formatting, and I really like the "under 10 rule" for bold. To be taken serious, writing in a mature style is the least you can do.
Mar
25
comment Cycles in SHA256
That does not prevent cycles at all. All you do is to get different cycles. But as fgrieu pointed out in his answer: Most values don't belong to a cycle anyway. If the function was a permutation instead, every value would belong to a cycle.One more thing about the estimations of cycle lengths: Both random functions and random permutations can have many cycles of varying lengths. Quite sure, all those numbers are too high for either case.
Mar
25
comment How to import key BLOB generated from Microsoft CryptExportKey from Linux
Welcome to crypto-SE. However, your question is quite off-topic. Probably the people at SE or security-SE or maybe even superuser-SE can help you with your question. But please don't double-post there, let a moderator move this topic instead.
Mar
25
comment Does perfect secrecy imply uniform ciphertext distribution?
Yes and no. First, you assume a uniform distribution over the keys. That is quite often done implicitly (and it is a good thing), but that is not necessary. And then you calculate the average over all keys, but that's something else than having an actual key. But without the context from the book, I can't tell you, what they actually meant.
Mar
25
comment Bit commitment, two blobs with same bit, without revealing it?
@poncho You're right. But that is one of the general ways to construct a commitment scheme from a public key encryption scheme: You just take a public key (in this case $n$ and $t$, and to find a correct $t$ you even need to know the trapdoor), and then you commit by encrypting the message. Unveiling is done by showing your random coins (and if needed the message).
Mar
25
comment Bit commitment, two blobs with same bit, without revealing it?
The computational problem for this is the quadratic residuosity problem. Basically, this is the Goldwasser-Micali encryption scheme utilized as commitment scheme.
Mar
25
answered Does perfect secrecy imply uniform ciphertext distribution?
Mar
23
comment Should I remove these use cases of MD5/SHA1 from my program?
Honestly, I have no idea about crypto libraries in PHP. But it seems, you are using the basic commands, while (at least today) the library also supports higher level protocols, like $cipher = new Crypt_AES(CRYPT_AES_MODE_CTR);and you can use PBKDF2, etc. However, this still doesn't say anything about the quality of that library, e.g. a question on security-SE talks about this. But if you want to achieve your high security, you should invest time in researching this.
Mar
23
comment cryptographic hash function
Welcoem to crypto SE. This question looks like it is a word by word copy of a homework question. Without an actual question, own comments, your current progress, etc. I'll have to vote for closing.
Mar
23
revised Should I remove these use cases of MD5/SHA1 from my program?
added 81 characters in body
Mar
23
answered Should I remove these use cases of MD5/SHA1 from my program?
Mar
23
answered What is the best hash for HMAC?
Mar
23
comment How many attempts does it take to crack a 32-bit password hash with this scenario?
user13741 is right for this one. The reason is simple: If you hash different inputs, you can get the same hash value on several occasions. Basically, you got a $1/2^{32}$ probability for a success on every try. This is a geometric distribution, with estimated value at $2^{32}$ (if looking for one hash value). Subtracting $1$ from the exponent is applicable, when you brute force a key for a symmetric encryption, where you directly try out every possibility. For hashes, $2^{32}$ does not give you that $100\%$ chance.