When computers talk to each other, they make sure that
what they heard is correct by using error correction such
as CRC, or various hash functions like SHA or MD5.
Humans should also benefit. And they can, doing so is
easy, all it requires is a bit of a social convention and
readily accessible
tools. Let's say Alice and Bob are
talking on a poor quality radio link.
Alice: The password is g7B1*bgLp .... Hold for MD5
Bob: Roger
*Alice*: Types in into MD5 tool, sees
bc3ad93663281aab366c3218b34296cb and reads first 3
letters (bc3)
Alice: Bravo Charlie Three
Bob: Roger Bravo Charlie Three
*Bob*: Types the password he thought he heard into MD5
tool and sees hash code starting with 8d7 ...
unfortunately he heard g7B1*bgLb instead of g7B1*bgLp
(he doesn't know what he got wrong, but he's 99.9% sure
he heard wrong)
Bob: Please repeat password, MD5 mismatch for
Bravo Charlie Three
Alice: The password is g7B1*bgLp
Bob: Roger
*Bob*: Types the password he thought he heard into MD5
tool and sees hash code starting with bc3
Bob: MD5 confirmed Bravo Charlie Three
Alice: Awesome! Alice Out.
If Alice and Bob want to get really fancy, they can agree
on a erasure code standard and that way the information
Bob thinks he heard will self correct.