Bug report: shifted CheckStr with full improvements

[ncanceill]

EDIT: This is a duplicate of #8.

Testing with full improvements, using RANDOM_SEED=0, results in CheckStr being shifted by 1 when extracting.

Investigating...

See log:

test_algoi_full_embed (__main__.SpecialAlgoImprovedTestCase) ...
DEBUG:  
===== CONFIG =====
DEBUG:  == input: "../sample/test_long.pdf.qdf"
DEBUG:  == redundancy: 0.8444218515250481
DEBUG:  == bit depth: 6
DEBUG:  == using improvements: YES
INFO:   Key: "S3cr3|-"
INFO:   Embedding data, please wait...
DEBUG:  FlagStr1 (CheckStr) (20)    [8, 45, 49, 15, 4, 54, 28, 60, 10, 23, 10, 34, 35, 5, 34, 39, 26, 0, 9, 24]
DEBUG:  FlagStr2 (20)   [7, 41, 36, 27, 33, 46, 27, 55, 41, 14, 28, 53, 41, 35, 62, 0, 21, 30, 31, 21]
DEBUG:  Data (35)   [12, 19, 8, 51, 13, 3, 20, 54, 21, 6, 33, 41, 28, 52, 37, 51, 16, 16, 40, 61, 31, 5, 61, 31, 21, 4, 21, 19, 21, 5, 61, 31, 31, 3, 13]
DEBUG:  Jitter  0
INFO:   Done embedding.
INFO:   Output file: "../sample/test_long.pdf.out.fix.pdf"
DEBUG:  Embedded data (28)  "123456ThisIsA
=|__TEST__|="
DEBUG:  Total nb of TJ ops  7537
DEBUG:  Total nb of TJ ops used 75
DEBUG:  Total nb of TJ ops used for data    35
ok

test_algoi_full_extract (__main__.SpecialAlgoImprovedTestCase) ...
DEBUG:  
===== CONFIG =====
DEBUG:  == input: "../sample/test_long.pdf.out.fix.pdf.qdf"
DEBUG:  == redundancy: 0.8444218515250481
DEBUG:  == bit depth: 6
DEBUG:  == using improvements: YES
INFO:   Key: "S3cr3|-"
INFO:   Input file: "../sample/test_long.pdf.out.fix.pdf"
INFO:   Extracting data, please wait...
DEBUG:  FlagStr (20)    [7, 41, 36, 27, 33, 46, 27, 55, 41, 14, 28, 53, 41, 35, 62, 0, 21, 30, 31, 21]
DEBUG:  End position found  71
DEBUG:  Data Checksum (20)  [22, 57, 5, 40, 55, 44, 36, 8, 55, 38, 1, 55, 43, 39, 49, 2, 43, 51, 55, 54]
DEBUG:  CheckStr (20)   [45, 49, 15, 4, 54, 28, 60, 10, 23, 10, 34, 35, 5, 34, 39, 26, 0, 9, 24, 12]
DEBUG:  Data (32)   [19, 8, 51, 13, 3, 20, 54, 21, 6, 33, 41, 28, 52, 37, 51, 16, 16, 40, 61, 31, 61, 31, 21, 4, 21, 19, 21, 61, 31, 31, 3, 13]
ERROR:  CheckStr does not match embedded data
M�\Ò\ÐB�_õõDU5}}ðÍcorrupted) (24)   L�Í
FAIL