@node enMeshing
@section Key meshing

There is no key meshing western algorithm analogue. That algorithm
changes cipherkey each kilobyte of data processed. It is used together
with @ref{en2814789, GOST 28147-89} and is defined in
@url{https://tools.ietf.org/html/rfc4357.html, RFC 4357}. CryptoPro
developers tell that it is intended to resist side-channel attacks.

Implementation is rather simple and uses two crypt/decrypt operations
over the key and initialization vector.

@verbatim
# for each KiB of data
def mesh(old_key, old_iv):
    new_key = ecb_decrypt(old_key, MESH_CONST)
    new_iv = ecb_encrypt(old_key, old_iv)
    return new_key, new_iv
@end verbatim

It has already showed usefulness: there is @url{https://sweet32.info/,
Sweet32} attack on all 64-bit blockciphers, that is not applicable to
when key meshing used.