Comment 4 for bug 509957

I've developed a solution to random crypted swap devices not having a UUID, at least for GPT (Guid Partition Tables).

The cryptswap partitions indeed don't have an ordinary UUID, but if they are GPT partitions, they do have a persistent PARTUUID (UUID assigned to partition) and are available through /dev/disk/by-partuuid/ .

Arch Linux guys have patched their cryptsetup functions to support this format: https://patchwork.archlinux.org/patch/389/

I've applied similar approach to /lib/cryptsetup/cryptdisks.functions as seen in the patch below:

--- cryptdisks.functions.orig 2013-12-20 19:42:02.048667466 +0100
+++ cryptdisks.functions.olo.partuuid.2013-12-20 2013-12-20 19:49:37.876503582 +0100
@@ -488,6 +488,9 @@
        # parse UUID= symlinks
        if [ "${src#UUID=}" != "$src" ]; then
                src="/dev/disk/by-uuid/${src#UUID=}"
+ elif [ "${src#PARTUUID=}" != "$src" ]; then
+ # inspired by https://patchwork.archlinux.org/patch/389/
+ src="/dev/disk/by-partuuid/${src#PARTUUID=}"
        elif [ "${src#LABEL=}" != "$src" ]; then
                src="/dev/disk/by-label/${src#LABEL=}"
        fi
@@ -599,6 +602,9 @@
        egrep -v "^[[:space:]]*(#|$)" "$TABFILE" | while read dst src key opts; do
                if [ "xUUID=$ID_FS_UUID" = "x$src" ]; then
                        src="/dev/disk/by-uuid/${src#UUID=}"
+ elif [ "xPARTUUID=$ID_PART_ENTRY_UUID" = "x$src" ]; then
+ # inspired by https://patchwork.archlinux.org/patch/389/
+ src="/dev/disk/by-partuuid/${src#PARTUUID=}"
                elif [ "xLABEL=$ID_FS_LABEL_ENC" = "x$src" ]; then
                        src="/dev/disk/by-label/${src#LABEL=}"
                elif [ "x$1" != "x$src" ]; then

This enables the following format for crypttab:

cryptswap1 PARTUUID=c352d0c2-3584-44a1-9de7-c2bfdb9c58f8 /dev/urandom swap,cipher=aes-cbc-essiv:sha256

Obviously, this has to also be documented in crypttab manpage (man 5 crypttab).