Coded data including a digital signature with padding

1. Coded data for disposal on or in a surface, the coded data including a number of coded data portions, each coded data portion encoding:

an identity; and,

at least part of a signature, the signature being a digital signature of at least:

part of the identity; and

part of predetermined padding,

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.

2. Coded data according to claim 1 , wherein each data portion encodes a signature fragment.

3. Coded data according to claim 2 , wherein the entire signature is encoded within a plurality of data portions.

4. Coded data according to claim 1 , wherein the coded data includes a plurality of layouts, each layout defining the position of a plurality of first symbols encoding the identity, and a plurality of second symbols defining at least part of the signature.

5. Coded data according to claim 1 , wherein the coded data includes a plurality of tags, each coded data portion being formed from at least one tag.

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

7. Coded data according to claim 6 , wherein the coded data is printed on the surface using at least one of:

an invisible ink; and,

an infrared-absorptive ink.

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

9. Coded data according to claim 1 , wherein at least some of the coded data portions encode data indicative of at least one of:

a location of the respective data portion;

a position of the respective data portion on the surface;

a size of the data portions;

a size of the signature;

an identity of a signature fragment; and,

units of indicated locations.

10. Coded data 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. Coded data according to claim 1 , wherein the digital signature includes at least one of:

a random number associated with the identity;

a keyed hash of at least the identity;

a keyed hash of at least the identity produced using a private key, and verifiable using a corresponding public key;

cipher-text produced by encrypting at least the identity;

cipher-text produced by encrypting at least the identity and a random number; and,

cipher-text produced using a private key, and verifiable using a corresponding public key.

12. Coded data according to claim 1 , wherein the identity includes an identity of at least one of:

an object defining the surface;

the surface;

a region of the surface; and,

an object associated with the surface.

13. Coded data according to claim 1 , wherein at least one coded data portion further encodes at least a fragment of a data object.

14. Coded data according to claim 13 , wherein the data object includes at least one of:

the digital signature;

Multipurpose Internet Mail Extensions (MIME) data;

text data;

image data;

audio data;

video data;

application data;

contact data;

business card data;

and,

directory data.

15. Coded data according to claim 1 , wherein the surface is associated with an object, the object including at least one of:

an item of manufacture;

a pharmaceutical item;

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, such as a driver's license or passport.

16. Coded data according to claim 1 , wherein the identity includes at least one of:

an Electronic Product Code (EPC);

a National Drug Code (NDC) number;

a serial number of a pharmaceutical item;

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; and,

a card attribute including at least one of:

card type;

issuing institution;

account number;

issue date;

expiry date; and

limit.

17. Coded data according to claim 1 , wherein the coded data is adapted to be sensed by a sensing device to allow determination of the identity; and, at least part of the signature.

18. Coded data according to claim 1 , wherein the padding is associated with and unique to the identity, the padding being at least one of:

a predetermined number;

a random number.

19. Coded data for disposal on or in a surface, the coded data including a number of coded data portions, each coded data portion encoding:

an identity; and,

at least part of a signature, the signature being a digital signature of at least:

part of the identity; and

part of predetermined padding,

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.