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For protecting the copyright of a text and recovering its original content harmlessly, this paper proposes a novel reversible natural language watermarking method that combines arithmetic coding and synonym substitution operations. By analyzing relative frequencies of synonymous words, synonyms employed for carrying payload are quantized into an unbalanced and redundant binary sequence. The quantized binary sequence is compressed by adaptive binary arithmetic coding losslessly to provide a spare for accommodating additional data. Then, the compressed data appended with the watermark are embedded into the cover text via synonym substitutions in an invertible manner. On the receiver side, the watermark and compressed data can be extracted by decoding the values of synonyms in the watermarked text, as a result of which the original context can be perfectly recovered by decompressing the extracted compressed data and substituting the replaced synonyms with their original synonyms. Experimental results demonstrate that the proposed method can extract the watermark successfully and achieve a lossless recovery of the original text. Additionally, it achieves a high embedding capacity. Published version

Excessive power dissipation is one of the major issues in the testing of VLSI systems. Many techniques are proposed for scan test, but there are not so many for logic BIST because of its unmanageable randomness. This paper presents a novel low switching activity BIST scheme that reduces toggle frequency in the majority of scan chain inputs while allowing a small portion of scan chains to receive pseudorandom test data. Reducing toggle frequency in the scan chain inputs can reduce test power but may result in fault coverage loss. Allowing a small portion of scan chains to receive pseudorandom test data can make better uniform distribution of 0 and 1 and improve test effectiveness significantly. When compared with existing methods, experimental results on larger benchmark circuits of ISCAS’89 show that the proposed strategy can not only reduce significantly switching activity in circuits under test but also achieve high fault coverage.

In text steganography based on synonym substitution, the synonym number in synonym set is not always some powers of 2. In traditional methods, the redundant synonyms are always abandoned. Two different coding schedules, which made full use of the abandoned synonym to improve the security of the steganographic system, are proposed in this paper. The synonyms in a synonym set are dynamically divided into coded words and backup words. One method divides the cover text into blocks to hide the secret information for the first time and then uses a highly efficient coding schedule to embed the secret information for the second and third time. The other method employs the backup words to prevent the increase the number of synonym pairs, keeping the statistical characteristics of synonym pairs unchanged.