Rainbow tables and cryptographic
<p>I came across this problem in Bruce Schneider book. </p>

<p>We know that Rain bow tables can be used on stored hashes. Suppose a file (English text)is encrypted using a password, using the following scheme.</p>

<p>The password is hashed and the hash is used to encrypt the file via AES. The cipher is stored, and the password and hashes are thrown away.
Explain:
1. How Dictionary attacks can be used to recover the password.
2. Why rainbow tables are not usable?
3. How rainbow table can be used, if the file has a known standard header.</p>

<p>I could understand question 1 and 2. But I couldn't get around with 3.
Please help. </p>