Reputation
13,651
Next tag badge:
99/100 score
17/20 answers
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Impact
~261k people reached

Dec
18
comment ElGamal with elliptic curves
How would your $m=x$ technique work, considering only half of the possible $x$ values are on the curve?
Dec
17
comment Lightweight Asymmetric encryption algorithm
@JoeBebel Ed25519 key generation is fast, but by far not as fast as a CSPRNG.
Dec
17
comment Efficient way to confirm identity
You'd use a handshake based on asymmetric crypto and then a MAC for all further messages. I strongly recommend using existing protocols, like TLS, DTLS or CurveCP for this.
Dec
16
comment Symmetric encryption algorithms with large IVs and authentication?
You could simply use XSalsa20Poly1305, which is authenticated encryption with a 192 bit IV.
Dec
16
comment Symmetric encryption algorithms with large IVs and authentication?
XSalsa20/XChaCha20 have a large enough IV.
Dec
16
comment Combining a block cipher with a (pseudo) OTP
"The algorithm is built on the fact that each and every ciphertext bit is required to decrypt, or even break, a block cipher encryption." Why do you believe that?
Dec
16
comment How can I study the math behind cryptography?
For your 256 bit cipher question, see How much would it cost in U.S. dollars to brute force a 256 bit key in a year?
Dec
16
comment Authenticated Encryption of UDP packets
Personally I'd probably go with a variant of CurveCP or Noise instead of DTLS.
Dec
15
comment Execution time for HMAC-MD5 on a 160 bit data using 128 bit key on a 3GHz CPU
@MaxthonChan I used the cost for hashing 64 bytes (2 blocks) from SUPERCOP on a modern Intel CPU. Since HMAC with fixed key hashes 2 blocks as well, that should be a reasonable approximation.
Dec
15
comment Lightweight Asymmetric encryption algorithm
You should also consider elliptic curves. A popular and relatively fast choice is Curve25519, but there are even faster curves.
Dec
14
comment Execution time for HMAC-MD5 on a 160 bit data using 128 bit key on a 3GHz CPU
Perhaps 800 CPU cycles if the key is fixed, twice that if it is not. That corresponds to about 0.3 µs on zour 3 GHy CPU. Details depend on the CPU in question. See eBASH
Dec
12
comment How much stronger is RC4 if it is keyed with an RSA private key?
@poncho Wouldn't a sufficiently large key eliminate the bias in the beginning of the RC4 stream caused by its weak key setup, leaving only the mostly harmless n-gram biases inherent to RC4? (of course one could just drop the beginning of the output instead)
Dec
8
comment How to test the speed of an Authenticated Encryption algorithm?
Take a look at SUPERCOP. It's a popular benchmark framework for CPU based benchmarking.
Dec
7
comment Deletion complexity in a RSA accumulator
When you say O(1) you mean with respect to the number of elements in the accumulator, right? Because the cost obviously increases with increasing modulus size.
Dec
7
comment 2 Part Encryption
Take a look at D. Boneh and M. Franklin - An efficient public key traitor tracing scheme a paper presenting a traitor tracing scheme.
Dec
7
comment 2 Part Encryption
So you want traitor tracing when a key gets leaked? In that case you might be interested in broadcast encryption. Or why is using the same key problematic?
Dec
7
comment Applying Vigenere on small strings with sorting capability
How about plaintext? Seriously, if your crypto is that weak, you might as well not use any.
Dec
6
comment Applying Vigenere on small strings with sorting capability
Related: How does order-preserving encryption work?
Dec
6
comment Why Merkle Tree doesn't suffer Birthday attack?
Birthday attack against what? Collision resistance? All hashes suffer from that one, including merkle-trees, that's why we need 256 bit hashes for 128 bits of collision resistance.
Dec
5
comment Probability approximation of no collisions
@user822719 Yes. The factor 2 in the denominator comes from $1+2+3+ ... +(t-1)=\frac{t\cdot(t-1)}{2}$.