DEK_MASK about dukpt.net HOT 5 CLOSED

sorry forgot

  private static readonly BigInteger DEK_MASK = BigInt.FromHex("0000000000FF00000000000000FF0000");

from dukpt.net.

Based on the excerpt, your logic is correct. However, I specifically stayed away from using string concatenation to perform these calculations because of the way C#'s BigInteger handles signedness in hex, which can throw off your results very slightly. Besides, it's much more natural to represent recombining the left and right sides using bitwise operators.

Expanded:

var key = DeriveKey(ipek, ksn);
key = key ^ DekMask;
var left = (key & Ms16Mask) >> 64;
var right = (key & Ls16Mask);
left = Transform("TripleDES", true, key, left);
right = Transform("TripleDES", true, key, right);
var dek = left << 64 | right;
return dek;

Minified:

var key = DeriveKey(ipek, ksn) ^ DekMask;
return Transform("TripleDES", true, key, (key & Ms16Mask) >> 64) << 64 
     | Transform("TripleDES", true, key, (key & Ls16Mask));

Let me know if that works for you, otherwise I'll take a closer look at it.

from dukpt.net.

Hi, Yeah, i had the same result with the hex string.
i already got the solution and it works. same as your code.
Thanks,

On Thu, Jul 10, 2014 at 10:37 AM, sgbj [email protected] wrote:

Based on the excerpt, your logic is correct. However, I specifically
stayed away from using string concatenation to perform these calculations
because of the way C#'s BigInteger handles signedness in hex, which can
throw off your results very slightly. Besides, it's much more natural to
represent recombining the left and right sides using bitwise operators.

Expanded:

var key = DeriveKey(ipek, ksn);key = key ^ DekMask;var left = (key & Ms16Mask) >> 64;var right = (key & Ls16Mask);left = Transform("TripleDES", true, key, left);right = Transform("TripleDES", true, key, right);var dek = left << 64 | right;return dek;

Minified:

var key = DeriveKey(ipek, ksn) ^ DekMask;return Transform("TripleDES", true, key, (key & Ms16Mask) >> 64) << 64
| Transform("TripleDES", true, key, (key & Ls16Mask));

Let me know if that works for you, otherwise I'll take a closer look at it.

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Reply to this email directly or view it on GitHub
#7 (comment).

Rafael Gonzalez
Developer
www.emobilepos.com

from dukpt.net.

Hi,
Where i should put this code,

var key = DeriveKey(ipek, ksn);
key = key ^ DekMask;
var left = (key & Ms16Mask) >> 64;
var right = (key & Ls16Mask);
left = Transform("TripleDES", true, key, left);
right = Transform("TripleDES", true, key, right);
var dek = left << 64 | right;
return dek;

pls reply

from dukpt.net.

Hi all,

finally it got worked.. Thanks to all .............bye

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