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Dec
30
answered Which bitwise operations are used in SHA-256?
Dec
30
comment Would it be better to use HKDF or SCrypt for deriving a child key?
Note that Bitcoin uses a special construct to derive public keys. Public keys are part of key pairs. I'm not sure if either construct allows you to use the key as planned.
Dec
30
answered Would it be better to use HKDF or SCrypt for deriving a child key?
Dec
29
comment When/why is RSA (hybrid) encryption used rather than alternatives?
Like this the question is fine, I hope it provides enough info to Myath to successfully answer the org. question.
Dec
29
comment How secure is 'Plain Old RSA'
I could pretty easily identify $40 \times 3$ digits set to zero, so it's not secure by that observation alone. Repeating the plaintext would also be an issue.
Dec
29
comment Would it be better to use HKDF or SCrypt for deriving a child key?
This seems to be used in bitcoin like transactions, a description of the key derivation can be found here
Dec
29
comment When/why is RSA (hybrid) encryption used rather than alternatives?
"Where else are public-key encryptions really used?" is too broad. We can answer some of your questions and/or remove some of doubts in the first to last paragraph. In that case the (title of the) question should however be reworded and the last paragraph should be removed. I'm however currently voting to close.
Dec
29
comment Modular exponentiation on calculator for textbook RSA
@otus It's still about cryptography though, and I think the question will pop up again if we close it anyways. There are currently three upvotes and three downvotes. I suggest we keep it as it is obviously disputed, and I think we should leave disputed questions be disputed but open.
Dec
29
revised Modular exponentiation on calculator for textbook RSA
changed title, reformatted, removed fluff
Dec
28
comment Two different keys decrypting same content
Small note: usually direct binary concatenation is not used. PGP for instance specifies a container format which can list the public keys that were used to (indirectly) encrypt the message.
Dec
28
comment Two different keys decrypting same content
You cannot use tags within pre-formatted text. Either you provide (pseudo) code or you use MathML on this site.
Dec
28
comment Two different keys decrypting same content
... include the keys with the ciphertext, not add in the mathematical sense of course.
Dec
28
comment Two different keys decrypting same content
Usually this is enabled by encrypting a random data key with two user specific keys, and then encrypting the message with the data key. You then add the encrypted (wrapped) keys to the ciphertext
Dec
28
comment Schnorr Ring Signatures - wrong hash results
Are you sure you haven't got $p$ as well? It's part of the curve definition, e.g. in Bouncy you can do params.getCurve().getField().getCharacteristic();
Dec
27
revised Shamir's Secret Scheme : Knowing the threshold
deleted 185 characters in body
Dec
27
comment Password in first line of file for AES-256 encryption
Yeah ok, for really secure passwords it is secure.
Dec
26
revised How should I generate secure random numbers deterministically?
deleted 7 characters in body
Dec
26
comment Password in first line of file for AES-256 encryption
Funny enough the OpenSSL API documentation tells us the single iteration / non-PBKDF2, proprietary BytesToKey function is not secure if I'm not mistaken. But I don't think there is any way to force it to use PBKDF2 and a number of iterations on the command line. Can you confirm this?
Dec
24
comment What is the most secure ECC Curve?
Hmmm. Ok, seems i have been misinformed. I'll chech it after star wars :)
Dec
24
comment What is the most secure ECC Curve?
The goldilocks curve could be interesting for you.