Encryption large amount of data by using Asymmetric encryption.

[Bart]

Dear all,

I would like to encrypt a large amount of data by using public/private keys,
but I read on MSDN:
"Symmetric encryption is performed on streams and is therefore useful to
encrypt large amounts of data. Asymmetric encryption is performed on a small
number of bytes and is therefore only useful for small amounts of data."
There is not possibility to do it? I have tried to encrypt a 300kB file by
RSA Algorithm, but I received always "Bad length"!

Thank you,

Bart

 

[Dmitriy Lapshin [C# / .NET MVP]]

Ciao Bart,

Split the file into small blocks and encrypt each block separately.

Still, do you really need RSA encryption for all the file? You can encrypt
the file with a symmetric algorithm, write the encrypted file and then
append the symmetric key in turn encrypted with RSA.
That's similar to how SSL works - symmetric "session" keys are exchanged
encrypted with RSA (or some other asymmetric algorithm, don't remember for
sure) and then all data exchange is done with symmetric encryption to
improve speed.