I uninstalled cryptsetup and now I cannot boot the system.

[metman]

Whole disk was encrypted.
If you need any more info let me know.

[Bulkley]

What about your backup? Most of us have bombed our system and lost data. When it's bad enough we learn to back up.

This may be time to use a rescue CD to boot the system and reinstall cryptsetup.

[p.H]

Of course you cannot open an encrypted device without cryptsetup.
So I guess the boot is stuck into the initramfs shell ?

What did you uninstall exactly ? There are several cryptsetup* packages :
cryptsetup : dummy transitional package which depends on cryptsetup-initramfs and cryptsetup-run
cryptsetup-run : startup scripts for encrypted (non-root/hibernation) devices
cryptsetup-initramfs : cryptsetup integration into the initramfs for root/hibernation devices
cryptsetup-bin : the actual cryptsetup tool

If you removed cryptsetup-initramfs, then the initramfs for the current kernel is rebuilt without cryptsetup. But if there is an older kernel, maybe its initramfs was not rebuilt and still has cryptsetup. Otherwise, you have to boot another system which has cryptsetup (live system, Debian installer in rescue mode...), open the encrypted device, chroot into the installed system, and reinstall the missing packages.