Identification in the presence of side information with application to watermarking
Identification in the presence of side information with application to watermarking
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DOI：
10.1109/18.923724
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发表时间：
2001-05-01
影响因子：
2.5
通讯作者：
Merhav, N
中科院分区：
文献类型：
--
作者：
Steinberg, Y;Merhav, N
从信息论的角度分析了水印码作为具有边信息的识别码，边信息仅在发送端或在两端都可用。虽然信息隐藏者在一定的失真水平内将秘密消息（水印）嵌入covertext消息（通常是文本，图像，声音或视频流）中，但攻击者（在此建模为无记忆信道）处理所得到的水印消息（在有限的附加失真内），试图使水印无效。在水印编码的大多数应用中，解码器不需要像在普通编码通信系统中那样执行完全解码，而仅需要测试水印是否存在，如果存在，则测试它是否与特定的假设模式匹配。这一事实促使我们将水印问题视为一个识别问题，其中原始封面文本源作为边信息。在大多数应用中，该边信息仅对编码器可用，但有时它也可以对解码器可用。对于边信息在编码器和解码器都可用的情况下，我们推导出一个公式的识别能力，也提供了一个表征可实现的错误指数。对于边信息仅在编码器处可用的情况，我们推导出识别能力的上界和下界。所有的表征得到的单字母表达式。
Watermarking codes are analyzed from an information-theoretic viewpoint as identification codes with side information that is available at the transmitter only or at both ends. While the information hider embeds a secret message (watermark) in a covertext message (typically, text, image, sound, or video stream) within a certain distortion level, the attacker, modeled here as a memoryless channel, processes the resulting watermarked message (within limited additional distortion) in attempt to invalidate the watermark. In most applications of watermarking codes, the decoder need not carry out full decoding, as in ordinary coded communication systems, but only to test whether a watermark at all exists and if so, whether it matches a particular hypothesized pattern. This fact motivates us to view the watermarking problem as an identification problem, where the original covertext source serves as side information. In most applications, this side information is available to the encoder only, but sometimes it can be available to the decoder as well. For the case where the side information is available at both encoder and decoder, we derive a formula for the identification capacity and also provide a characterization of achievable error exponents. For the case where side information is available at the encoder only, we derive upper and lower bounds on the identification capacity. All characterizations are obtained as single-letter expressions.