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Sep
17
reviewed No Action Needed Is it secure to concatenate two 16-bit random numbers into a 32-bit one?
Sep
17
reviewed Close What are the practical limitations of Asymmetric encryption vs Symmetric encryption?
Sep
15
comment How to generate unique (random) numbers that can be traced back to a unique source number?
10 digits would be easier, since then you could simply use a 32 bit block cipher like Skip32 instead of needing complicated format preserving encryption like FFX mode.
Sep
15
comment Is this a proper PBKDF2 key derivation function algorithm?
You should use better variable names and you should split the implementations into independent parts. The hash, HMAC, PBKDF2 and printing hex strings are all separate concerns and should be decoupled in the code.
Sep
15
comment How to generate unique (random) numbers that can be traced back to a unique source number?
How big should the numbers be?
Sep
14
reviewed No Action Needed Comparing two definitions of one-way function
Sep
14
reviewed No Action Needed Are there any test vectors for the CMS content type AuthEnvelopedData (for AES-GCM)?
Sep
14
reviewed Close Why does plain RSA not work with big messages ($m>n$)?
Sep
14
comment In the RSA encryption system, are there not multiple messages m that give the same cipher text c?
Since $113 = 2 \cdot 55 + 3 \equiv 3 \pmod {55}$ these are considered the same value in modular arithmetic. You need restrict it to $0 \leq m < n$ if you want to treat $m$ as an integer.
Sep
11
comment How to propagate error in variable-sized message?
FFX mode works for short messages, unfortunately it's pretty complicated. For longer messages you could use EME mode (encipher-mask-encipher). That's quite a lot of complexity (and still weaker security), just to save a few bytes for IV and MAC.
Sep
10
comment Why is ECIES complex?
Your suggestion sounds more complex than ECIES to me.
Sep
10
comment Is there an encryption format that preserves length and only outputs alphanumerics?
Why use crypto at all? Can't you simply store the codes in your database?
Sep
10
comment Implement AES with 16 bit block size?
You could use AES in FFX mode.
Sep
8
comment Variable length variable output encryption with out any padding?
Look for format preserving encryption. But if you can afford it, you should use an IV and a MAC, even if they cost a couple of bytes.
Sep
7
comment How To prove Any Change to $v=a\cdot y+b$ maks $y=(a)^{−1}\cdot (v−b)$ Uni. random value
Please do not ask nearly identical questions on multiple sites of the stackexchange network. How To prove Any Change to v=a⋅y+b maks y=(a)−1(v−b) Uni. random value on math.se should suffice.
Sep
6
reviewed Approve OpenPGP Public-Key algorithm
Sep
6
comment Calculation of time needed to crack DES with my CPU
A playstation 3 seems to be able to test about a 850 million DES keys per second.
Sep
6
revised Calculation of time needed to crack DES with my CPU
edited tags
Sep
6
comment Calculation of time needed to crack DES with my CPU
5000 CPU cycles per block sounds quite slow to me.
Aug
22
awarded  Enlightened