Related to : Basic decryption for simple encryption algorithm

AES C# Encryption Decryption FIPS 
Your plaintext, key and IV seem to be specified in hexadecimals, so
you need to decode the hexadecimals to get to the underlying bytes
instead of performing UTF8 encoding.
You can get a byte array from hex here. Note that the name of the
method should have something with hex in in, don't call it
StringToByteArray or atoi or something stupid like that.

ECC Encryption and Decryption in Java 
In general you are required to perform hybrid encryption with ECC.
ECIES for instance is basically a key agreement followed by symmetric
encryption. So you cannot directly encrypt anything with ECIES, which
is the most common ECC method for encryption. Basically you should
couple it to a symmetric cipher. This is actually the best scheme for
RSA encryption as well, most of the time.
As you can

Review: Protocol for encryption/decryption of big files with authentication 
Some points:
A) Hashing of the encrypted data, with the hash not encrypted itself.
One of the possible things a malicious human M could do without any
hash: Overwrite the encrypted file with something else. M doesnÂ´t
know key, the plaintext before and/or the plaintext after this action,
but he can change the plaintext to something different (usually, it
becomes garbage data). Destruction is

encryption algorithm rijnadael C# on Delphi 
I think the Init and DecryptString methods use arrays as parameters
but you are using strings, which are also basically also arrays in
Delphi, but special ones. You have to point at the correct first item
which is 1 unlike 0 in C.
You can of course first also transform your AnsiStrings in array of
bytes and feed that to the methods.
.Init(aKey[1], ....)
and
.Decrypt(din[1])
hth

Complexity of a basic algorithm? 
When determining complexities, we don't include constants or
coefficients. Instead of O(2N + 2), it should be O(n). We only care
about numbers if they're exponential, i.e. 2^n or n^2, log2(n), etc.
Putting that aside, are you sure this is O(n)? O(n) would mean that it
runs n times, but it looks like j is going to catch up to n before n
times. See what I'm saying?
EDIT: Ok, here's what's going o
