Reads a passphrase using readpassphrase(3), returning it as a String.
Internally uses a buffer of PASSWORD_LEN bytes, allowing for passwords
up to PASSWORD_LEN - 1 characters (including the null terminator.)
Reads a passphrase using readpassphrase(3) into the passed buffer.
Returns a String consisting of the same memory from the buffer, or
else zeroes the buffer on error.
Reads a passphrase using readpassphrase(3) info the passed buffer.
Returns a string slice from that buffer. Does not zero memory; this
should be done out of band, for example by using Zeroizing<Vec<u8>>.