What is used in the 12.10 full disk encryption?

I previously had been using TrueCrypt, but recently re-installed Ubuntu and used 12.10's full disk encryption option (re-installed for other reasons). I never got any choice in how it did that. I don't know what cipher is used or the key size, or anything besides the passphrase really. Where can I find details about this sda5_crypt?

Edit: Seeing this mistake is humorous, but for those curious, sda5 refers to the hard drive and partition, not the encryption system.

Full disk encryption is using the dm-crypt kernel module, managed by Luks/cryptsetup. If you choose to encrypt your home directory, eCryptfs is used instead. These are two different technologies. I assume you chose full disk encryption here in my answer.

Use the command

# cryptsetup luksDump /dev/sda5

to view the current detailed configuration for sda5. And another example:

# cryptsetup status sda5_crypt
/dev/mapper/sda5_crypt is active and is in use.
  type:    LUKS1
  cipher:  aes-cbc-essiv:sha256
[...]

Read more on dm-crypt on Wikipedia: dm-crypt and more on eCryptfs on Wikipedia: eCryptfs.