Issue #2865843: Fix encoding and decoding of IV and only do that once at each end: when adding to and reading from header

VCS Label
6.x-2.9
Core compatibility
Release type
Packaged Git sha1
3262e615e3f2d64aec53d4021f2ee28740ac4b94
Release files
74b83601c942cafc8f809f7bfe2ea7a9
Release file SHA-1 hash
683f0285fa179afedab4916389cc3735957d78c0
Release file SHA-256 hash
1eb8a09e4a40d37a4b4d71e6263cd603a96fe0699db7888b39032d214f3fd90d
c00c10f27f418a105f2a874e356a0346
Release file SHA-1 hash
1eff97293747bafa039a2394769b614cfecc0972
Release file SHA-256 hash
733a6caa468dc48e58b77bf4b0176081a2aaabd538cbad9f0e25c539bb6548a0