The following contains spoilers for Action Comics #1050, on sale now from DC Comics.
To bring back Superman's secret identity in the DC Universe, it seems that DC has borrowed some mindwipe logic from Marvel.
In the anniversary issue Action Comics #1050, Lex Luthor activates a device that uses Manchester Black's telepathic abilities to make the entire world forget that both Clark Kent and his son, Jon, are two of Earth's Supermen. However, plenty of recorded evidence exists from the time that the heroes' secret identities were public, but this will not allow anyone who, for example, sees an old image to once again remember that Clark Kent and Superman are one and the same. To achieve this, Luthor's memory wipe includes an element from Marvel's restoration of Spider-Man's secret identity with the "One More Day" storyline.
While discussing Luthor's mindwipe with Batman, who was immune to its effects along with other heroes, Clark mentions, "There are photos that show who Jon and I are. There are articles. There's video." Batman responds, "It's not just that people have forgotten who you are. The suggestion is so strong that it extends to any images or other media people see. If it contradicts what their mind is telling them, they reject it."
How Marvel Restored Spider-Man’s Secret Identity
This is similar to how the Marvel Universe forgot that Peter Parker is Spider-Man following his secret identity reveal in Civil War. In "One More Day," Peter and his wife, Mary Jane Watson, made a deal with the devil Mephisto to save the life of Peter's Aunt May while also restoring Peter's secret identity, a deal that came at the cost of Peter and MJ's marriage. Marvel history was rewritten to make it so that Doctor Strange, Iron Man and Mister Fantastic were behind the worldwide memory wipe.
Together, the three heroes created a mystical virus that had the "ability to wipe all history, recorded, remembered or otherwise of Peter's unmasking," according to Mister Fantastic in The Amazing Spider-Man #641. As Peter explained in ASM #591, "Even if there is a stack of evidence pointing to who I really am...your mind won't let you connect the dots." This logic also applies to other Marvel characters whose secret identities have been restored, such as Matthew Murdock aka Daredevil, who breaks down his own experience in Daredevil #36, saying, "Someone could read an old front page about me as Daredevil and see something else entirely, or just...nothing."
Knowing Superman’s Secret Identity Can Now Kill You
If anyone in the DC Universe could remember that Clark or Jon is Superman by looking at an old photo or newspaper, a lot of people would likely die. Luthor added a caveat to his mindwipe that if Superman's identity is revealed to anyone who forgot, they may die from the information, such as the case with Perry White in Acton Comics #1050. Perry re-learns that Clark is Superman in the issue, which causes him to suffer a stroke and be hospitalized.
Action Comics #1050 is written by Phillip Kennedy Johnson, Tom Taylor and Joshua Williamson, illustrated by Mike Perkins, Clayton Henry and Nick Dragotta, colored by Frank Martin and lettered by Dave Sharpe. Main cover art for the issue is by Steve Beach, with variant cover artwork contributed to by various artists. The issue is now on sale from DC Comics.
Source: DC Comics