Women, though, have also taken advantage of another aspect of the breakdown in authority — by speaking out through the newly aggressive news media, defying social taboos to demand attention for a problem the old government often denied. At the same time, some Islamist elected officials have used their new positions to vent some of the most patriarchal impulses in Egypt’s traditional culture and a deep hostility to women’s participation in politics.

The female victims, these officials declared, had invited the attacks by participating in public protests. “How do they ask the Ministry of Interior to protect a woman when she stands among men?” Reda Saleh Al al-Hefnawi, a lawmaker from the Muslim Brotherhood’s political party, asked at a parliamentary meeting on the issue.

The revolution initially promised to reopen public space to women. Men and women demonstrated together in Tahrir Square peacefully during the heady 18 days and nights that led to the ouster of Mr. Mubarak. But within minutes of his departure the threat re-emerged in a group attack on the CBS News correspondent Lara Logan. There are no official statistics on women attacked — partly because few women report offenses — but all acknowledge that the attacks have grown bolder and more violent.

By the second anniversary of the revolution, on Jan. 25, the symbolic core of the revolution — Tahrir Square — had become a no-go zone for women, especially after dark.

During a demonstration that day against the new Islamist-led government, an extraordinary wave of sexual assaults — at least 18 confirmed by human rights groups, and more, according to Egypt’s semiofficial National Council of Women — shocked the country, drawing public attention from President Mohamed Morsi and Western diplomats.