A break of SHA1 (ie SHA1 preimage oracle) breaks u&#x2F;random. This is less secure than something that is broken if SHA1 <i>and</i> SHA2 are broken. But since there are no known full breaks of either, this is &quot;merely&quot; hypothetical.<p>We can define our measure of entropy such that the output of AES (&#x2F;SHA1) qualifies, or such that it does not. The way it is used in the random&#x2F;urandom distinction, it&#x27;s clearly not meant to include PRNG output.