1.\" $FreeBSD$ 2.Dd July 31, 2012 3.Dt MD5 1 4.Os 5.Sh NAME 6.Nm md5 , sha1 , sha256 , sha512, rmd160 7.Nd calculate a message-digest fingerprint (checksum) for a file 8.Sh SYNOPSIS 9.Nm md5 10.Op Fl pqrtx 11.Op Fl c Ar string 12.Op Fl s Ar string 13.Op Ar 14.Nm sha1 15.Op Fl pqrtx 16.Op Fl c Ar string 17.Op Fl s Ar string 18.Op Ar 19.Nm sha256 20.Op Fl pqrtx 21.Op Fl c Ar string 22.Op Fl s Ar string 23.Op Ar 24.Nm sha512 25.Op Fl pqrtx 26.Op Fl c Ar string 27.Op Fl s Ar string 28.Op Ar 29.Nm rmd160 30.Op Fl pqrtx 31.Op Fl c Ar string 32.Op Fl s Ar string 33.Op Ar 34.Sh DESCRIPTION 35The 36.Nm md5 , sha1 , sha256 , sha512 37and 38.Nm rmd160 39utilities take as input a message of arbitrary length and produce as 40output a 41.Dq fingerprint 42or 43.Dq message digest 44of the input. 45It is conjectured that it is computationally infeasible to 46produce two messages having the same message digest, or to produce any 47message having a given prespecified target message digest. 48The 49.Tn MD5 , SHA-1 , SHA-256 , SHA-512 50and 51.Tn RIPEMD-160 52algorithms are intended for digital signature applications, where a 53large file must be 54.Dq compressed 55in a secure manner before being encrypted with a private 56(secret) 57key under a public-key cryptosystem such as 58.Tn RSA . 59.Pp 60.Tn MD5 61has been completely broken as far as finding collisions is 62concerned, and should not be relied upon to produce unique outputs. 63This also means that 64.Tn MD5 65should not be used as part of a cryptographic signature scheme. 66At the current time (2009-01-06) there is no publicly known method to 67.Dq reverse 68MD5, i.e., to find an input given a hash value. 69.Pp 70.Tn SHA-1 71currently (2009-01-06) has no known collisions, but an attack has been 72found which is faster than a brute-force search, placing the security of 73.Tn SHA-1 74in doubt. 75.Pp 76It is recommended that all new applications use 77.Tn SHA-256 78instead of one of the other hash functions. 79.Pp 80The following options may be used in any combination and must 81precede any files named on the command line. 82The hexadecimal checksum of each file listed on the command line is printed 83after the options are processed. 84.Bl -tag -width indent 85.It Fl c Ar string 86Compare files to this md5 string. 87(Note that this option is not yet useful if multiple files are specified.) 88.It Fl s Ar string 89Print a checksum of the given 90.Ar string . 91.It Fl p 92Echo stdin to stdout and append the checksum to stdout. 93.It Fl q 94Quiet mode - only the checksum is printed out. 95Overrides the 96.Fl r 97option. 98.It Fl r 99Reverses the format of the output. 100This helps with visual diffs. 101Does nothing 102when combined with the 103.Fl ptx 104options. 105.It Fl t 106Run a built-in time trial. 107.It Fl x 108Run a built-in test script. 109.El 110.Sh EXIT STATUS 111The 112.Nm md5 , sha1 , sha256 , sha512 113and 114.Nm rmd160 115utilities exit 0 on success, 1161 if at least one of the input files could not be read, 117and 2 if at least one file does not have the same hash as the -c option. 118.Sh SEE ALSO 119.Xr cksum 1 , 120.Xr md5 3 , 121.Xr ripemd 3 , 122.Xr sha 3 , 123.Xr sha256 3 , 124.Xr sha512 3 125.Rs 126.%A R. Rivest 127.%T The MD5 Message-Digest Algorithm 128.%O RFC1321 129.Re 130.Rs 131.%A J. Burrows 132.%T The Secure Hash Standard 133.%O FIPS PUB 180-2 134.Re 135.Rs 136.%A D. Eastlake and P. Jones 137.%T US Secure Hash Algorithm 1 138.%O RFC 3174 139.Re 140.Pp 141RIPEMD-160 is part of the ISO draft standard 142.Qq ISO/IEC DIS 10118-3 143on dedicated hash functions. 144.Pp 145Secure Hash Standard (SHS): 146.Pa http://csrc.nist.gov/cryptval/shs.html . 147.Pp 148The RIPEMD-160 page: 149.Pa http://www.esat.kuleuven.ac.be/~bosselae/ripemd160.html . 150.Sh ACKNOWLEDGMENTS 151This program is placed in the public domain for free general use by 152RSA Data Security. 153.Pp 154Support for SHA-1 and RIPEMD-160 has been added by 155.An Oliver Eikemeier Aq eik@FreeBSD.org . 156