Symmetric encryption in seahorse-nautilus

Symmetric encryption was added upstream. It needs:

• gpgme1.0>=1.4.2 (from wheezy-backports), otherwise there is a bug
• seahorse-nautilus 3.10.1 (#7429 (closed), http://bugs.debian.org/734983), or a backport of the relevant commits:
  • https://bugzilla.gnome.org/show_bug.cgi?id=325803 (commit ae25bf9): Add support for symmetric encryption in seahorse-tool
• libcryptui 3.10.0+ (#7430 (closed), http://bugs.debian.org/734984), or a backport of the relevant commits:
  • https://bugzilla.gnome.org/show_bug.cgi?id=325803
  • https://bugzilla.gnome.org/show_bug.cgi?id=699161
  • Commit cd74aa6: Add symmetric encryption as a choice in “choose recipients” dialog
  • Commit c744886: Add cryptui_need_to_get_keys_or_symmetric()
  • Commit f110e1c: Avoid repeating the self encryption key in cryptui_key_chooser_get_recipients()
  • Commit 6012bfe: Add support for symmetric encryption

Subtasks

• #8519 (closed)

Related issues

• Related to #5516 (closed)
• Has duplicate #10361 (closed)
• Blocked by #7429 (closed)
• Blocked by #7430 (closed)

Original created by @intrigeri on 6607 (Redmine)