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Curve secp256r1 is not a type of curve; it is a curve, and is standardized under that name by SECG, under the name P-256 by NIST, and under the name prime256v1 by ANSI. It also happens to be the by far the most common elliptic curve used in cryptography. The field size, curve equation, and generator point are all part of the curve spec; the point of having a ...


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Q: How long shall the RSA key be in order to be secure against practical attacks? A: Impractically large. This does not imply that RSA is unsafe against practical attacks; only that some of these attacks must be prevented by ways other than increasing the key size. That's because key size is not a parameter with a major impact on the efficiency of many ...


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Towards the security of the signature scheme, no precaution against timing attack is necessary when verifying an asymmetric signature. That's because there is no secret involved, thus no information leak to fear. However it can happen that the message, or the signature itself, is intended to be secret; a leak by timing dependency (during computation of the ...


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Yes, it is possible to deterministically generate public/private RSA key pairs from passphrases. For even passable security, the passphrase must be processed by a key-stretching function, such as Scrypt (or the better known but less recommendable PBKDF2), and salt (at least, user id) must enter the key-stretching function; the output can then be used as the ...


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You can of course add a trusted path requirement to Trent (the trusted key distribution center) on the top of the given protocol. This is however not a requirement for the scheme itself. Trent, as trusted third party serving multiple users, of course needs to know who to communicate to. So the identity cannot be encrypted with the public key of Alice or ...


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Using the Chinese Remainder Theorem I can compute $M^3$, and then take the cube root. This is why multiple recipient RSA is insecure.


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If $G$ is the distinguished point on your curve, you can perform pre-computations to speed up multiplication of $G$ by a scalar. For instance, if you need a transient key pair $\{K_{PRI},K_{PUB}\}$, you can use these pre-computed points to compute $K_{PUB} = [K_{PRI}]G$ quickly. But if you need to compute a shared secret using another public key $K'_{PUB}$, ...


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Yes, you are correct. There are various methods for scalar multiplication on elliptic curves. Some of them are optimised for fixed base-point scalar multiplication, i.e., where you a-priori know that you will mostly/exclusively perform scalar multiplications with respect to a fixed base point on the curve. Thus, one can make (extensive) pre-computations ...


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FIPS 140-2 specifies conditions applicable to the environment of RSA (and other) key generation, and refers to FIPS 186-4 for the generation itself. Several recent Java Card Smart Cards can internally generate RSA-2048 key pairs per FIPS 186-4, with security policy and FIPS 140-2 level 3 certificate to attest that. Here is the one on top of the list at time ...


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Generically speaking you can do this but you shouldn't. It may well be possible to perform specific calculations when a random number is used for both (I'll leave it to the more theoretically inclined to create a demo if this is possible for ElGamal / DSA). Another reason is that the single secret gets known then both keys/algorithms will be compromised. ...



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