mirror of
https://github.com/cryb-to/cryb-to.git
synced 2024-11-22 22:02:03 +00:00
94 lines
3.2 KiB
Groff
94 lines
3.2 KiB
Groff
|
.\"-
|
||
|
|
.\" Copyright (c) 2016 Dag-Erling Smørgrav
|
||
|
|
.\" All rights reserved.
|
||
|
|
.\"
|
||
|
|
.\" Redistribution and use in source and binary forms, with or without
|
||
|
|
.\" modification, are permitted provided that the following conditions
|
||
|
|
.\" are met:
|
||
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
||
|
|
.\" notice, this list of conditions and the following disclaimer.
|
||
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
||
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
||
|
|
.\" documentation and/or other materials provided with the distribution.
|
||
|
|
.\" 3. The name of the author may not be used to endorse or promote
|
||
|
|
.\" products derived from this software without specific prior written
|
||
|
|
.\" permission.
|
||
|
|
.\"
|
||
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
||
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
||
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
||
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
||
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
||
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
||
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
||
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
||
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
||
|
|
.\" SUCH DAMAGE.
|
||
|
|
.\"
|
||
|
|
.Dd January 8, 2016
|
||
|
|
.Dt CRYB_FLETCHER 3
|
||
|
|
.Os
|
||
|
|
.Sh NAME
|
||
|
|
.Nm cryb_fletcher16_hash ,
|
||
|
|
.Nm cryb_fletcher32_hash ,
|
||
|
|
.Nm cryb_fletcher64_hash
|
||
|
|
.Nd hash functions
|
||
|
|
.Sh LIBRARY
|
||
|
|
.Lb libcryb-hash
|
||
|
|
.Sh SYNOPSIS
|
||
|
|
.In stdint.h
|
||
|
|
.In cryb/hash.h
|
||
|
|
.Ft uint16_t
|
||
|
|
.Fn fletcher16_hash "const void *data" "size_t len"
|
||
|
|
.Ft uint32_t
|
||
|
|
.Fn fletcher32_hash "const void *data" "size_t len"
|
||
|
|
.Ft uint64_t
|
||
|
|
.Fn fletcher64_hash "const void *data" "size_t len"
|
||
|
|
.Sh DESCRIPTION
|
||
|
|
The
|
||
|
|
.Fn cryb_fletcher16_hash ,
|
||
|
|
.Fn cryb_fletcher32_hash
|
||
|
|
and
|
||
|
|
.Fn cryb_fletcher64_hash
|
||
|
|
function return a 16-bit, 32-bit or 64-bit checksum of the
|
||
|
|
.Va len
|
||
|
|
first bytes of the object pointed to by
|
||
|
|
.Va data .
|
||
|
|
.Pp
|
||
|
|
Unlike the Pearson hash implemented by
|
||
|
|
.Fn cryb_hash
|
||
|
|
or cryptographic message digests such as the SHA family, these
|
||
|
|
checksums are suitable for error detection.
|
||
|
|
.Sh IMPLEMENTATION NOTES
|
||
|
|
Fletcher's paper assumes that the length of the input is a multiple of
|
||
|
|
the algorithm's word size (half the output size), and does not specify
|
||
|
|
or suggest how to handle odd-length input.
|
||
|
|
This implementation zero-pads the input up to the nearest multiple of
|
||
|
|
the word size.
|
||
|
|
If strict compatibility with other implementations is required, the
|
||
|
|
caller should take care to either pad the input or truncate the
|
||
|
|
.Va len
|
||
|
|
argument before calling the checksum function.
|
||
|
|
.Sh SEE ALSO
|
||
|
|
.Xr cryb_hash 3
|
||
|
|
.\".Sh REFERENCES
|
||
|
|
.Rs
|
||
|
|
.%A "Fletcher, John G."
|
||
|
|
.%D "January 1982"
|
||
|
|
.%T "An Arithmetic Checksum for Serial Transmissions"
|
||
|
|
.%J "IEEE Transactions on Communications"
|
||
|
|
.%V "30"
|
||
|
|
.%N "1"
|
||
|
|
.%P "247-252"
|
||
|
|
.%O "doi:10.1109/tcom.1982.1095369"
|
||
|
|
.Re
|
||
|
|
.Sh AUTHORS
|
||
|
|
The
|
||
|
|
.Fn cryb_fletcher16 ,
|
||
|
|
.Fn cryb_fletcher32
|
||
|
|
and
|
||
|
|
.Fn cryb_fletcher64
|
||
|
|
functions and this manual page were written by
|
||
|
|
.An Dag-Erling Sm\(/orgrav Aq Mt des@des.no .
|