Capacity laws for steganography in a crowd
A steganographer is not only hiding a payload inside their cover, they are also hiding themselves amongst the non-steganographers. In this paper we study asymptotic rates of growth for steganographic data – analogous to the classical Square-Root Law – in the context of a ‘crowd’ of K actors, one of...
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| Format: | Conference item |
| Language: | English |
| Published: |
Association for Computing Machinery
2022
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| _version_ | 1797107208284012544 |
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| author | Ker, A |
| author_facet | Ker, A |
| author_sort | Ker, A |
| collection | OXFORD |
| description | A steganographer is not only hiding a payload inside their cover,
they are also hiding themselves amongst the non-steganographers.
In this paper we study asymptotic rates of growth for steganographic data – analogous to the classical Square-Root Law – in the context of a ‘crowd’ of K actors, one of whom is a steganographer. This converts steganalysis from a binary to a K-class classification problem, and requires some new information-theoretic tools. Intuition suggests that larger K should enable the steganographer to hide a larger payload, since their stego signal is mixed in with larger amounts of cover noise from the other actors. We show that this is indeed the case, in a simple independent-pixel model, with payload growing at O(sqrt(logK)) times the classical Square-Root capacity in the case of homogeneous actors. Further, examining the effects of heterogeneity reveals a subtle dependence on the detector’s knowledge about the payload size, and the need for them to use negative as well as positive information to identify the steganographer. |
| first_indexed | 2024-03-07T07:11:14Z |
| format | Conference item |
| id | oxford-uuid:b6c1bfa0-33d6-4885-9c08-988fa68cbecd |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T07:11:14Z |
| publishDate | 2022 |
| publisher | Association for Computing Machinery |
| record_format | dspace |
| spelling | oxford-uuid:b6c1bfa0-33d6-4885-9c08-988fa68cbecd2022-06-27T16:12:29ZCapacity laws for steganography in a crowdConference itemhttp://purl.org/coar/resource_type/c_5794uuid:b6c1bfa0-33d6-4885-9c08-988fa68cbecdEnglishSymplectic ElementsAssociation for Computing Machinery2022Ker, AA steganographer is not only hiding a payload inside their cover, they are also hiding themselves amongst the non-steganographers. In this paper we study asymptotic rates of growth for steganographic data – analogous to the classical Square-Root Law – in the context of a ‘crowd’ of K actors, one of whom is a steganographer. This converts steganalysis from a binary to a K-class classification problem, and requires some new information-theoretic tools. Intuition suggests that larger K should enable the steganographer to hide a larger payload, since their stego signal is mixed in with larger amounts of cover noise from the other actors. We show that this is indeed the case, in a simple independent-pixel model, with payload growing at O(sqrt(logK)) times the classical Square-Root capacity in the case of homogeneous actors. Further, examining the effects of heterogeneity reveals a subtle dependence on the detector’s knowledge about the payload size, and the need for them to use negative as well as positive information to identify the steganographer. |
| spellingShingle | Ker, A Capacity laws for steganography in a crowd |
| title | Capacity laws for steganography in a crowd |
| title_full | Capacity laws for steganography in a crowd |
| title_fullStr | Capacity laws for steganography in a crowd |
| title_full_unstemmed | Capacity laws for steganography in a crowd |
| title_short | Capacity laws for steganography in a crowd |
| title_sort | capacity laws for steganography in a crowd |
| work_keys_str_mv | AT kera capacitylawsforsteganographyinacrowd |