memfrob function converts an array of data to something
unrecognizable and back again. It is not encryption in its usual sense
since it is easy for someone to convert the encrypted data back to clear
text. The transformation is analogous to Usenet’s “Rot13” encryption
method for obscuring offensive jokes from sensitive eyes and such.
memfrob works on arbitrary binary data, not just
For true encryption, See Cryptographic Functions.
This function is declared in string.h.
Preliminary: | MT-Safe | AS-Safe | AC-Safe | See POSIX Safety Concepts.
memfrob transforms (frobnicates) each byte of the data structure
at mem, which is length bytes long, by bitwise exclusive
oring it with binary 00101010. It does the transformation in place and
its return value is always mem.
memfrob a second time on the same data structure
returns it to its original state.
This is a good function for hiding information from someone who doesn’t want to see it or doesn’t want to see it very much. To really prevent people from retrieving the information, use stronger encryption such as that described in See Cryptographic Functions.
Portability Note: This function is unique to the GNU C Library.