Security document scanner

1. A sensing device for use with a security document, the security document having disposed thereon or therein coded data including a plurality of coded data portions, each coded data portion being indicative of an identity of the security document and a signature part, the signature part being a part of a digital signature of at least the identity, the sensing device including:

a sensor for sensing a plurality of coded data portions; and,

a processor for:

determining, using sensed coded data portions, a sensed identity, a plurality of signature parts, and an identifier for each signature part;

generating a sensed signature from the plurality of signature parts by arranging signature parts according to respective identifiers;

determining a generated identity from the sensed signature; and

authenticating the security document by comparing the sensed identity and the generated identity.

2. A sensing device according to claim 1 , wherein the sensing device further includes an indicator for indicating the sensed identity of the security document.

3. A sensing device according to claim 1 , wherein the processor further:

generates, using the sensed identity and a key, and uses the key to determine the generated identity from the sensed signature.

4. A sensing device according to claim 1 , wherein the digital signature is a digital signature of the identity and at least part of predetermined padding, the padding being at least one of:

a predetermined number; and,

a random number.

5. A sensing device according to claim 1 , wherein the processor further:

accesses, using the sensed identity, tracking data indicative of, for each of a number of existing security documents:

the identity of the security document; and,

tracking information indicative of the location of the security document; and,

at least one of:

determines, using the tracking information, if the security document is a duplicate of one of the existing security documents; and,

updates the tracking information.

6. A sensing device according to claim 1 , wherein the coded data is substantially invisible to an unaided human.

7. A sensing device according to claim 1 , wherein the coded data is printed on the surface using at least one of:

an invisible ink; and,

an infrared-absorptive ink.

8. A sensing device according to claim 1 , wherein the coded data is provided substantially coincident with visible human-readable information.

9. A sensing device according to claim 1 , wherein at least some of the coded data portions encode at least one of:

a location of the respective coded data portion;

a position of the respective coded data portion on the surface;

a size of the coded data portions; and,

units of indicated locations.

10. A sensing device according to claim 1 , wherein the coded data includes at least one of:

redundant data;

data allowing error correction;

Reed-Solomon data; and,

Cyclic Redundancy Check (CRC) data.

11. A sensing device according to claim 1 , wherein the security document is at least one of:

a currency note;

a check;

a credit or debit card;

a redeemable ticket, voucher, or coupon;

a lottery ticket or instant win ticket; and,

an identity card or document.

12. A sensing device according to claim 1 , wherein the identity is indicative of at least one of:

a currency note attribute including at least one of:

currency;

issue country;

denomination;

note side;

printing works; and

serial number;

a check attribute including at least one of:

currency;

issuing institution;

account number;

serial number;

expiry date;

check value; and

limit;

a card attribute including at least one of:

card type;

issuing institution;

account number;

issue date;

expiry date; and

limit.

13. A sensing device according to claim 1 , wherein the coded data is arranged in accordance with at least one layout having n-fold rotational symmetry, where n is at least two, the layout including n identical sub-layouts rotated 1/n revolutions apart about a centre of rotation, at least one sub-layout including rotation-indicating data that distinguishes that sub-layout from each other sub-layout.

14. A sensing device according to claim 1 , wherein the coded data is arranged in accordance with at least one layout having n-fold rotational symmetry, where n is at least two, the layout encoding orientation-indicating data comprising a sequence of an integer multiple m of n symbols, where m is one or more, each encoded symbol being distributed at n locations about a centre of rotational symmetry of the layout such that decoding the symbols at each of the n orientations of the layout produces n representations of the orientation-indicating data, each representation comprising a different cyclic shift of the orientation-indicating data and being indicative of the degree of rotation of the layout.