QR visual cryptography by cabi5boh

View this thread on: hive.blog | peakd.com | ecency.com

programming · @cabi5boh · Jul 18 '16

$0.05

QR visual cryptography

<html>
<p>Some time ago, I wrote a script that implements visual cryptography for QR codes. From an input text, it generates a QR code, and then, it splits it into random image shares. When the shares are superposed, they reveal the QR code.</p>
<p>This way, I thought it would be cool to print them on transparent film (slides) so that they will reveal the QR code only when superposed in the right orientation.</p>
<p>This is an example:</p>
<p><img src="https://s32.postimg.org/lyhc20o91/NPF8qs_T.jpg" width="1066" height="800"/></p>
<p>and this is the result when the slides are superposed:</p>
<p><img src="https://s32.postimg.org/bptg9xpl1/Ku6_IZ4r.jpg" width="1066" height="800"/></p>
<p>Alignment has to be done in the right orientation (out of 8 possible) and needs sub-millimeter adjustment to form an image.</p>
<p>Some QR code readers will read it directly; others might need some contrast forcing:</p>
<p><img src="https://s32.postimg.org/s23hzo3wl/ck_Kkwws.jpg" width="1066" height="800"/></p>
<h1>The crypto</h1>
<p>Individually, each share leaks no information about the resulting image. There is hence no risk in using QR's error correction, even at its 30% maximum. The formalism can be adapted to N-of-M schemes, but I implemented only the 2-of-2 (shown above) and 2-of-3 cases. There is also the possibility of a steganographic mode where the individual slides can show decoy images.</p>
<p><a href="https://gist.github.com/oriolpont/ce961d4dd6276ef55bee">This is the script.</a></p>
<p>I did not know it at first, but I was made aware that the implementation I followed was a case of <a href="http://link.springer.com/chapter/10.1007/BFb0053419">Naor and Shamir's Visual Cryptography</a>.</p>
<p>There is also <a href="https://www.facebook.com/video.php?v=712573078796691">a video showing the criticality of alignment</a> and <a href="https://imgur.com/a/RyzIs">a simulation of a 2-of-3 example</a>.</p>
<p>When I posted it some time ago (in another forum), it started rather interesting discussions.</p>
<p>Anyway, enjoy it!</p>
<p>(and feel free to ask me anything about this)</p>
</html>

👍 solidgold, q00p, cabi5boh, ema90, shaemish1888, bullionstackers

`author`	cabi5boh
`permlink`	46ncqq-qr-visual-cryptography
`category`	programming
`json_metadata`	{"tags":["programming","cryptography","qr"],"image":["https://s32.postimg.org/lyhc20o91/NPF8qs_T.jpg","https://s32.postimg.org/bptg9xpl1/Ku6_IZ4r.jpg","https://s32.postimg.org/s23hzo3wl/ck_Kkwws.jpg"],"links":["https://gist.github.com/oriolpont/ce961d4dd6276ef55bee","http://link.springer.com/chapter/10.1007/BFb0053419","https://www.facebook.com/video.php?v=712573078796691","https://imgur.com/a/RyzIs"]}
`created`	2016-07-18 18:04:15
`last_update`	2016-07-18 18:04:15
`depth`	0
`children`	4
`last_payout`	2016-08-24 09:52:18
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.046 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	2,111
`author_reputation`	634,191,438,766
`root_title`	"QR visual cryptography"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	170,202
`net_rshares`	27,089,436,534
`author_curate_reward`	""

properties (23)vote details (6)

voter	rshares	pct
cabi5boh	242,188,522	100%
q00p	4,306,231,193	100%
ema90	194,400,807	100%
shaemish1888	94,647,307	100%
solidgold	22,167,895,716	100%
bullionstackers	84,072,989	100%

@bullionstackers · Jul 21 '16

$0.02

cani5boh
Thanks for the post

bullionstackers

👍 solidgold, cabi5boh, bullionstackers

`author`	bullionstackers
`permlink`	re-cabi5boh-46ncqq-qr-visual-cryptography-20160721t025650984z
`category`	programming
`json_metadata`	{"tags":["programming"]}
`created`	2016-07-21 02:56:51
`last_update`	2016-07-21 02:56:51
`depth`	1
`children`	0
`last_payout`	2016-08-24 09:52:18
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.024 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	45
`author_reputation`	163,180,943,634,376
`root_title`	"QR visual cryptography"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	236,700
`net_rshares`	21,621,945,696
`author_curate_reward`	""

properties (23)vote details (3)

voter	rshares	pct
cabi5boh	247,189,364	100%
solidgold	21,292,955,586	100%
bullionstackers	81,800,746	100%

@solidgold · Jul 18 '16

$0.04

Excellent posts!  I've suddenly seen a new perspective; thanks.

👍 solidgold, cabi5boh, grahnite, bullionstackers

`author`	solidgold
`permlink`	re-cabi5boh-46ncqq-qr-visual-cryptography-20160718t180745003z
`category`	programming
`json_metadata`	{"tags":["programming"]}
`created`	2016-07-18 18:07:45
`last_update`	2016-07-18 18:07:45
`depth`	1
`children`	2
`last_payout`	2016-08-24 09:52:18
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.039 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	63
`author_reputation`	2,524,341,564,215
`root_title`	"QR visual cryptography"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	170,280
`net_rshares`	22,159,561,827
`author_curate_reward`	""

properties (23)vote details (4)

voter	rshares	pct
cabi5boh	247,032,293	100%
solidgold	21,724,731,640	100%
bullionstackers	81,800,746	100%
grahnite	105,997,148	100%

@bullionstackers · Jul 22 '16

Me too

👍 bullionstackers

`author`	bullionstackers
`permlink`	re-solidgold-re-cabi5boh-46ncqq-qr-visual-cryptography-20160722t135958724z
`category`	programming
`json_metadata`	{"tags":["programming"]}
`created`	2016-07-22 14:00:00
`last_update`	2016-07-22 14:00:00
`depth`	2
`children`	0
`last_payout`	2016-08-24 09:52:18
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.000 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	6
`author_reputation`	163,180,943,634,376
`root_title`	"QR visual cryptography"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	274,052
`net_rshares`	52,102,431
`author_curate_reward`	""

properties (23)vote details (1)

voter	weight	wgt%	rshares	pct	time
bullionstackers	0 B		52,102,431	100%

@cabi5boh · Jul 18 '16

Glad you enjoyed it

👍 solidgold, cabi5boh, bullionstackers

`author`	cabi5boh
`permlink`	re-solidgold-re-cabi5boh-46ncqq-qr-visual-cryptography-20160718t214457646z
`category`	programming
`json_metadata`	{"tags":["programming"]}
`created`	2016-07-18 21:44:57
`last_update`	2016-07-18 21:44:57
`depth`	2
`children`	0
`last_payout`	2016-08-24 09:52:18
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.000 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	19
`author_reputation`	634,191,438,766
`root_title`	"QR visual cryptography"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	174,094
`net_rshares`	22,068,915,742
`author_curate_reward`	""

properties (23)vote details (3)

voter	rshares	pct
cabi5boh	242,188,522	100%
solidgold	21,744,926,474	100%
bullionstackers	81,800,746	100%