if (-e "/dev/random"){ .... } else { .... }
To generate a nice seed where you don't have /dev/random, you can do a checksum on your environment. Here are some sources of bits that are not random, but hard to reproduce:
- concatenate keys and values of %ENV{}
- process id, ppid
- current time
- process table
- disk statistics
- network interface report, especially if it can list counters
- inode number of $0, and arguments if any
- names of arguments, if any
- strings coming out of the memory allocator (allocate some references, stringify them)
Once you have a big string you can pipe it through a compression or cipher algorithm, just to distribute bits across 8bit space evenly, and use unpack to count the sum (see examples in perldoc).
/dev/random collects entropy from drivers, timers, and so forth, so essentially you're doing a cheap emulation of that.
If you get something nice, make a module out of it: Entropy::Gather::Win32 or something.
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