But if I create the keys and use them directly (no writing to and reading from file) it all works fine.
Maybe this is interesting: If I print the key before writing I get the following:

key=Password valu=A day so foul & fair
key=Version valu=1.91
key=Checked valu=0
key=Identity valu=Lord Macbeth <macbeth@glamis.com>
 ..... key=_phi=> 7210735926686440535829990956186709974464809186521836
+355832311976096790529618024634910931659740003773771843595827999358462
+719066220022694321619622387401960
 ..... key=_n=> 721073592668644053582999095618670997446480918652183635
+583231197609679052961819700359005877557710889766589552041195848079762
+1578108309291796942263931673339
 ..... key=_q=> 100915410784627151408499821928866674137454562910056455
+419204814119795206900509
 ..... key=_u=> 714532683424886856966240721230579098216677719924554328
+67392661202846337370871
 ..... key=_dp=> 55244914096508209456284400117059592742268460981246650
+212332286378244672760967
 ..... key=_dq=> 36302843828674577225696808359880055897158426599215535
+471345551979357835961943
 ..... key=_d=> 880471060418539224794851735339212418508575599615030917
+0194136550910004929385
 ..... key=_e=> 641184135470923308460913000233054168594704091053521728
+905021305093331347031478407043455534130351495979870847598261273194948
+5272487877726082773168046267553
 ..... key=_p=> 65537
key=Cipher valu=Blowfish
[download]

If I print the code after writing it to file (so I haven't red it yet!):

key=Version valu=1.91
key=Checked valu=0
key=Identity valu=Lord Macbeth <macbeth@glamis.com>
key=private_encrypted valu=Tie::EncryptedHash=HASH(0x8451cb0)
key=Cipher valu=Blowfish
[download]

Luca