19b50d902SRodney W. Grimes.\" Copyright (c) 1991, 1993 29b50d902SRodney W. Grimes.\" The Regents of the University of California. All rights reserved. 39b50d902SRodney W. Grimes.\" 49b50d902SRodney W. Grimes.\" This code is derived from software contributed to Berkeley by 59b50d902SRodney W. Grimes.\" the Institute of Electrical and Electronics Engineers, Inc. 69b50d902SRodney W. Grimes.\" 79b50d902SRodney W. Grimes.\" Redistribution and use in source and binary forms, with or without 89b50d902SRodney W. Grimes.\" modification, are permitted provided that the following conditions 99b50d902SRodney W. Grimes.\" are met: 109b50d902SRodney W. Grimes.\" 1. Redistributions of source code must retain the above copyright 119b50d902SRodney W. Grimes.\" notice, this list of conditions and the following disclaimer. 129b50d902SRodney W. Grimes.\" 2. Redistributions in binary form must reproduce the above copyright 139b50d902SRodney W. Grimes.\" notice, this list of conditions and the following disclaimer in the 149b50d902SRodney W. Grimes.\" documentation and/or other materials provided with the distribution. 15fbbd9655SWarner Losh.\" 3. Neither the name of the University nor the names of its contributors 169b50d902SRodney W. Grimes.\" may be used to endorse or promote products derived from this software 179b50d902SRodney W. Grimes.\" without specific prior written permission. 189b50d902SRodney W. Grimes.\" 199b50d902SRodney W. Grimes.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 209b50d902SRodney W. Grimes.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 219b50d902SRodney W. Grimes.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 229b50d902SRodney W. Grimes.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 239b50d902SRodney W. Grimes.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 249b50d902SRodney W. Grimes.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 259b50d902SRodney W. Grimes.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 269b50d902SRodney W. Grimes.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 279b50d902SRodney W. Grimes.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 289b50d902SRodney W. Grimes.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 299b50d902SRodney W. Grimes.\" SUCH DAMAGE. 309b50d902SRodney W. Grimes.\" 3170445a80SFernando Apesteguía.Dd January 18, 2024 329b50d902SRodney W. Grimes.Dt CKSUM 1 3362500372SRuslan Ermilov.Os 349b50d902SRodney W. Grimes.Sh NAME 35a684cccdSMike Pritchard.Nm cksum , 36a684cccdSMike Pritchard.Nm sum 379b50d902SRodney W. Grimes.Nd display file checksums and block counts 389b50d902SRodney W. Grimes.Sh SYNOPSIS 398fe908efSRuslan Ermilov.Nm 40f4ddfb38SRuslan Ermilov.Op Fl o Ar 1 | 2 | 3 41f74fd6ecSPhilippe Charnier.Op Ar 422cbd6933SBruce Evans.Nm sum 43f74fd6ecSPhilippe Charnier.Op Ar 449b50d902SRodney W. Grimes.Sh DESCRIPTION 459b50d902SRodney W. GrimesThe 46f74fd6ecSPhilippe Charnier.Nm 479b50d902SRodney W. Grimesutility writes to the standard output three whitespace separated 489b50d902SRodney W. Grimesfields for each input file. 499b50d902SRodney W. GrimesThese fields are a checksum 509b50d902SRodney W. Grimes.Tn CRC , 519b50d902SRodney W. Grimesthe total number of octets in the file and the file name. 529b50d902SRodney W. GrimesIf no file name is specified, the standard input is used and no file name 539b50d902SRodney W. Grimesis written. 549b50d902SRodney W. Grimes.Pp 552cbd6933SBruce EvansThe 562cbd6933SBruce Evans.Nm sum 572cbd6933SBruce Evansutility is identical to the 58f74fd6ecSPhilippe Charnier.Nm 592cbd6933SBruce Evansutility, except that it defaults to using historic algorithm 1, as 602cbd6933SBruce Evansdescribed below. 612cbd6933SBruce EvansIt is provided for compatibility only. 622cbd6933SBruce Evans.Pp 639b50d902SRodney W. GrimesThe options are as follows: 649b50d902SRodney W. Grimes.Bl -tag -width indent 659b50d902SRodney W. Grimes.It Fl o 669b50d902SRodney W. GrimesUse historic algorithms instead of the (superior) default one. 679b50d902SRodney W. Grimes.Pp 689b50d902SRodney W. GrimesAlgorithm 1 is the algorithm used by historic 699b50d902SRodney W. Grimes.Bx 709b50d902SRodney W. Grimessystems as the 719b50d902SRodney W. Grimes.Xr sum 1 729b50d902SRodney W. Grimesalgorithm and by historic 739b50d902SRodney W. Grimes.At V 749b50d902SRodney W. Grimessystems as the 75f74fd6ecSPhilippe Charnier.Xr sum 1 769b50d902SRodney W. Grimesalgorithm when using the 779b50d902SRodney W. Grimes.Fl r 789b50d902SRodney W. Grimesoption. 799b50d902SRodney W. GrimesThis is a 16-bit checksum, with a right rotation before each addition; 809b50d902SRodney W. Grimesoverflow is discarded. 819b50d902SRodney W. Grimes.Pp 829b50d902SRodney W. GrimesAlgorithm 2 is the algorithm used by historic 839b50d902SRodney W. Grimes.At V 849b50d902SRodney W. Grimessystems as the 859b50d902SRodney W. Grimesdefault 86f74fd6ecSPhilippe Charnier.Xr sum 1 879b50d902SRodney W. Grimesalgorithm. 889b50d902SRodney W. GrimesThis is a 32-bit checksum, and is defined as follows: 899b50d902SRodney W. Grimes.Bd -unfilled -offset indent 909b50d902SRodney W. Grimess = sum of all bytes; 919b50d902SRodney W. Grimesr = s % 2^16 + (s % 2^32) / 2^16; 929b50d902SRodney W. Grimescksum = (r % 2^16) + r / 2^16; 939b50d902SRodney W. Grimes.Ed 949b50d902SRodney W. Grimes.Pp 9568d8bb38SPoul-Henning KampAlgorithm 3 is what is commonly called the 9668d8bb38SPoul-Henning Kamp.Ql 32bit CRC 9768d8bb38SPoul-Henning Kampalgorithm. 9868d8bb38SPoul-Henning KampThis is a 32-bit checksum. 9968d8bb38SPoul-Henning Kamp.Pp 1009b50d902SRodney W. GrimesBoth algorithm 1 and 2 write to the standard output the same fields as 1019b50d902SRodney W. Grimesthe default algorithm except that the size of the file in bytes is 1029b50d902SRodney W. Grimesreplaced with the size of the file in blocks. 1039b50d902SRodney W. GrimesFor historic reasons, the block size is 1024 for algorithm 1 and 512 1049b50d902SRodney W. Grimesfor algorithm 2. 1059b50d902SRodney W. GrimesPartial blocks are rounded up. 1069b50d902SRodney W. Grimes.El 1079b50d902SRodney W. Grimes.Pp 1089b50d902SRodney W. GrimesThe default 1099b50d902SRodney W. Grimes.Tn CRC 1109b50d902SRodney W. Grimesused is based on the polynomial used for 1119b50d902SRodney W. Grimes.Tn CRC 1129b50d902SRodney W. Grimeserror checking 1139b50d902SRodney W. Grimesin the networking standard 114f74fd6ecSPhilippe Charnier.St -iso8802-3 . 1159b50d902SRodney W. GrimesThe 1169b50d902SRodney W. Grimes.Tn CRC 1179b50d902SRodney W. Grimeschecksum encoding is defined by the generating polynomial: 1189b50d902SRodney W. Grimes.Bd -unfilled -offset indent 1199b50d902SRodney W. GrimesG(x) = x^32 + x^26 + x^23 + x^22 + x^16 + x^12 + 1209b50d902SRodney W. Grimes x^11 + x^10 + x^8 + x^7 + x^5 + x^4 + x^2 + x + 1 1219b50d902SRodney W. Grimes.Ed 1229b50d902SRodney W. Grimes.Pp 1239b50d902SRodney W. GrimesMathematically, the 1249b50d902SRodney W. Grimes.Tn CRC 1259b50d902SRodney W. Grimesvalue corresponding to a given file is defined by 1269b50d902SRodney W. Grimesthe following procedure: 12746eea498SRuslan Ermilov.Bd -ragged -offset indent 1289b50d902SRodney W. GrimesThe 1299b50d902SRodney W. Grimes.Ar n 1309b50d902SRodney W. Grimesbits to be evaluated are considered to be the coefficients of a mod 2 1319b50d902SRodney W. Grimespolynomial M(x) of degree 1329b50d902SRodney W. Grimes.Ar n Ns \-1 . 1339b50d902SRodney W. GrimesThese 1349b50d902SRodney W. Grimes.Ar n 1359b50d902SRodney W. Grimesbits are the bits from the file, with the most significant bit being the most 1369b50d902SRodney W. Grimessignificant bit of the first octet of the file and the last bit being the least 1379b50d902SRodney W. Grimessignificant bit of the last octet, padded with zero bits (if necessary) to 1389b50d902SRodney W. Grimesachieve an integral number of octets, followed by one or more octets 1399b50d902SRodney W. Grimesrepresenting the length of the file as a binary value, least significant octet 1409b50d902SRodney W. Grimesfirst. 1419b50d902SRodney W. GrimesThe smallest number of octets capable of representing this integer are used. 1429b50d902SRodney W. Grimes.Pp 1439b50d902SRodney W. GrimesM(x) is multiplied by x^32 (i.e., shifted left 32 bits) and divided by 1449b50d902SRodney W. GrimesG(x) using mod 2 division, producing a remainder R(x) of degree <= 31. 1459b50d902SRodney W. Grimes.Pp 1469b50d902SRodney W. GrimesThe coefficients of R(x) are considered to be a 32-bit sequence. 1479b50d902SRodney W. Grimes.Pp 1489b50d902SRodney W. GrimesThe bit sequence is complemented and the result is the CRC. 1499b50d902SRodney W. Grimes.Ed 150a866e170SRuslan Ermilov.Sh EXIT STATUS 151d628d776SRuslan Ermilov.Ex -std cksum sum 15270445a80SFernando Apesteguía.Sh EXAMPLES 15370445a80SFernando ApesteguíaCompute the checksum for all available algorithms. 15470445a80SFernando ApesteguíaNotice the difference in the size representation (in bytes for algorithm 1 and 2 15570445a80SFernando Apesteguíaand in blocks for 3 and the default algorithm): 15670445a80SFernando Apesteguía.Bd -literal -offset indent 15770445a80SFernando Apesteguía$ echo "hello" | cksum 15870445a80SFernando Apesteguía3015617425 6 15970445a80SFernando Apesteguía$ echo "hello" | cksum -o 1 16070445a80SFernando Apesteguía36979 1 16170445a80SFernando Apesteguía$ echo "hello" | cksum -o 2 16270445a80SFernando Apesteguía542 1 16370445a80SFernando Apesteguía$ echo "hello" | cksum -o 3 16470445a80SFernando Apesteguía909783072 6 16570445a80SFernando Apesteguía.Ed 1669b50d902SRodney W. Grimes.Sh SEE ALSO 1672c0d39adSJohn-Mark Gurney.Xr md5 1 16898849115SRuslan Ermilov.Pp 1699b50d902SRodney W. GrimesThe default calculation is identical to that given in pseudo-code 1709b50d902SRodney W. Grimesin the following 1719b50d902SRodney W. Grimes.Tn ACM 1729b50d902SRodney W. Grimesarticle. 1739b50d902SRodney W. Grimes.Rs 1749b50d902SRodney W. Grimes.%T "Computation of Cyclic Redundancy Checks Via Table Lookup" 1759b50d902SRodney W. Grimes.%A Dilip V. Sarwate 1769b88faecSRuslan Ermilov.%J "Communications of the" Tn ACM 1779b50d902SRodney W. Grimes.%D "August 1988" 1789b50d902SRodney W. Grimes.Re 1799b50d902SRodney W. Grimes.Sh STANDARDS 1809b50d902SRodney W. GrimesThe 181f74fd6ecSPhilippe Charnier.Nm 182f8a42d82SPhilippe Charnierutility is expected to conform to 183f8a42d82SPhilippe Charnier.St -p1003.2-92 . 1849b50d902SRodney W. Grimes.Sh HISTORY 1859b50d902SRodney W. GrimesThe 186f74fd6ecSPhilippe Charnier.Nm 18793e0d62dSJohn-Mark Gurneyutility appeared in 1889b50d902SRodney W. Grimes.Bx 4.4 . 189