关键词: 盲水印, 离散余弦变换, 国际数据加密算法, 人眼视觉频率响应

Abstract: This thesis introduces the concept of digital watermark，and proposes one kind of DCT-based blind encryption watermark algorithm.Using International Data Encryption Algorithm（IDEA） encrypt the watermark image pixel or image file，according to human visual frequency response theory determine watermark embedded position to achieve the blind watermark，then using discrete cosine transform relize data embedded and extracted.The experimental results show this algorithm can realize the encryption data blind watermark and this algorithm can effectively protect data.

Key words: blind watermark, discrete cosine transform, International Data Encryption Algorithm, human visual frequency response