Re: MD5-Hash of a SHA-1-Hash unsecure?

["Tom Ritter" <tom () ritter vg>]

> Is it less secure when I make a MD5-Hash of a SHA-1-Hash?

The IV (like the salt in a password hash) isn't meant to be a source
of security.  IV's should be able to be made public without reducing
security*.  The security of encryption lies in the key; not the IV.

Keeping the IV secret is fine, using a random one is fine, using a MD5
of a SHA is fine, using incremental is fine*.  They key to the
algorithm is much more important.

* these statements depend on the chosen algorithm and its design
providing resistance to IV-related attacks.  it applies more to block
ciphers than stream ciphers.  but using a cipher vulnerable to
IV-attacks is silly.

-tom