Wang Xiaoyun (simplified Chinese: 王小云; traditional Chinese: 王小雲; pinyin: Wáng Xiǎoyún; born 1966) is a Chinese cryptographer and computer scientist. She is a professor in the Department of Mathematics and System Science of Shandong University and an academician of the Chinese Academy of Sciences.
At the rump session of CRYPTO 2004, she and co-authors demonstrated collision attacks against MD5, SHA-0 and other related hash functions. (A collision occurs when two distinct messages result in the same hash function output). They received a standing ovation for their work.
In February 2005 it was reported that Wang and co-authors had found a method to find collisions in the SHA-1 hash function, which is used in many of today's mainstream security products. Their attack is estimated to require less than 269 operations, far fewer than the 280 operations previously thought needed to find a collision in SHA-1. Their work was published at the CRYPTO '05 conference. In August 2005, an improved attack on SHA-1, discovered by Wang, Andrew Yao and Frances Yao, was announced at the CRYPTO conference rump session. The time complexity of the new attack is claimed to be 263.
Wang was born in Zhucheng, Shandong Province. She gained bachelor (1987), master (1990) and doctorate (1993) degrees at Shandong University, and subsequently lectured in the mathematics department from 1993. Her doctoral advisor was Pan Chengdong. Wang was appointed assistant professor in 1995, and full professor in 2001. She became the Chen Ning Yang Professor of the Center for Advanced Study, Tsinghua University in 2005.
- Key Lab of Cryptologic Technology and Information Security, Shandong University, retrieved 2015-07-21.
- Randall, James (March 11, 2005), Hash Function Update Due to Potential Weaknesses Found in SHA-1, RSA Laboratories, retrieved 2015-07-21.
- "Chinese Professor Cracks Fifth Data Security Algorithm", The Epoch Times, January 11, 2007, archived from the original on January 15, 2015.
- Leyden, John (August 19, 2005), "SHA-1 compromised further: Crypto researchers point the way to feasible attack", The Register.
- Tan Kah Kee Award in Information Technological Sciences, Tan Kah Kee Science Award Foundation, 2006, retrieved 2015-07-21.
- Wang Xiaoyun at the Mathematics Genealogy Project