It can be difficult to copy or read (e.g. over a telephone) a long sequence of characters, even if the sequence is punctuated into several chunks of uniform length.
Page 4 of <https://www.cl.cam.ac.uk/~rja14/Papers/prepay-meters.pdf> reports that breaking a 20-character sequence non-uniformly across two lines reduced users' copying error rate significantly. Unfortunately, not every application can rely on line breaks to improve readability. I have experimented with using pseudo-words of non-uniform length on a single line; varying chunk lengths does seem to improve my ability to read and copy strings. Here are some chunk-size sequences that I have found effective for a few sizes of base32 strings, in roughly the order that I produced them: 160 bits (32 chars): [6,5,4,3,7,2,5] 255 bits (51 chars): [6,5,4,3,7,2,5,4,7,3,5] 205 bits (41 chars): [6,5,4,3,7,2,5,2,4,3] 195 bits (39 chars): [6,5,4,3,7,2,5,4,3] 130 bits (26 chars): [5,3,2,7,5,4] 160-bit and 130-bit sequences may be useful for symmetric crypto (e.g. file encryption passwords, keys for PSK-style authentication, hashes). 195-bit, 205-bit, and 255-bit sequences are roughly the right size for group elements in EC groups over 195-bit, 206-bit, and 255-bit coordinate fields. Robert Ransom _______________________________________________ Curves mailing list [email protected] https://moderncrypto.org/mailman/listinfo/curves
