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NAMEmd5 , sha1 ,
sha224 , sha256 ,
sha384 , sha512 ,
sha512t256 , rmd160 ,
skein256 , skein512 ,
skein1024 , md5sum ,
sha1sum , sha224sum ,
sha256sum , sha384sum ,
sha512sum , sha512t256sum ,
rmd160sum , skein256sum ,
skein512sum , skein1024sum
—
calculate a message-digest fingerprint (checksum) for a
file
SYNOPSIS
DESCRIPTIONThemd5 , sha1 ,
sha224 , sha256 ,
sha384 , sha512 ,
sha512t256 , rmd160 ,
skein256 , skein512 , and
skein1024 utilities take as input a message of
arbitrary length and produce as output a “fingerprint” or
“message digest” of the input. The
md5sum , sha1sum ,
sha224sum , sha256sum ,
sha384sum , sha512sum ,
sha512t256sum , rmd160sum ,
skein256sum , skein512sum , and
skein1024sum utilities do the same, but default to the
reversed format of the -r flag. It is conjectured that
it is computationally infeasible to produce two messages having the same
message digest, or to produce any message having a given prespecified target
message digest. The SHA-224 , SHA-256 , SHA-384 , SHA-512, RIPEMD-160, and
SKEIN algorithms are intended for digital signature applications, where a
large file must be “compressed” in a secure manner before being
encrypted with a private (secret) key under a public-key cryptosystem such as
RSA.
The MD5 and SHA-1 algorithms have been proven to be vulnerable to practical collision attacks and should not be relied upon to produce unique outputs, nor should they be used as part of a cryptographic signature scheme. As of 2017-03-02, there is no publicly known method to reverse either algorithm, i.e., to find an input that produces a specific output. SHA-512t256 is a version of SHA-512 truncated to only 256 bits. On 64-bit hardware, this algorithm is approximately 50% faster than SHA-256 but with the same level of security. The hashes are not interchangeable. It is recommended that all new applications use SHA-512 or SKEIN-512 instead of one of the other hash functions. The following options may be used in any combination and must precede any files named on the command line. The hexadecimal checksum of each file listed on the command line is printed after the options are processed.
EXIT STATUSThemd5 , sha1 ,
sha224 , sha256 ,
sha512 , sha512t256 ,
rmd160 , skein256 ,
skein512 , and skein1024
utilities exit 0 on success, 1 if at least one of the input files could not be
read, and 2 if at least one file does not have the same hash as the
-c option.
EXAMPLESCalculate the MD5 checksum of the string “Hello”.$ md5 -s Hello MD5 ("Hello") = 8b1a9953c4611296a827abf8c47804d7 Same as above, but note the absence of the newline character in the input string: $ echo -n Hello | md5 8b1a9953c4611296a827abf8c47804d7 Calculate the checksum of multiple files reversing the output:
$ md5 -r /boot/loader.conf /etc/rc.conf
ada5f60f23af88ff95b8091d6d67bef6 /boot/loader.conf
d80bf36c332dc0fdc479366ec3fa44cd /etc/rc.conf
The
Write the digest for /boot/loader.conf in a file named digest. Then calculate the checksum again and validate it against the checksum string extracted from the digest file: $ md5 /boot/loader.conf > digest && md5 -c $(cut -f2 -d= digest) /boot/loader.conf MD5 (/boot/loader.conf) = ada5f60f23af88ff95b8091d6d67bef6 Same as above but comparing the digest against an invalid string (“randomstring”), which results in a failure. $ md5 -c randomstring /boot/loader.conf MD5 (/boot/loader.conf) = ada5f60f23af88ff95b8091d6d67bef6 [ Failed ] If invoked with a name ending in $ md5 -c digest /boot/loader.conf /boot/loader.conf: OK The digest file may contain any number of lines in the format
generated with or without the SEE ALSOcksum(1), md5(3), ripemd(3), sha(3), sha256(3), sha384(3), sha512(3), skein(3)R. Rivest, The MD5 Message-Digest Algorithm, RFC1321. J. Burrows, The Secure Hash Standard, FIPS PUB 180-2. D. Eastlake and P. Jones, US Secure Hash Algorithm 1, RFC 3174. RIPEMD-160 is part of the ISO draft standard “ISO/IEC DIS 10118-3” on dedicated hash functions. Secure Hash Standard (SHS): http://csrc.nist.gov/cryptval/shs.html. The RIPEMD-160 page: http://www.esat.kuleuven.ac.be/~bosselae/ripemd160.html. BUGSAll of the utilities that end in ‘sum’ are intended to be compatible with the GNU coreutils programs. However, the long option functionality is not provided.ACKNOWLEDGMENTSThis program is placed in the public domain for free general use by RSA Data Security.Support for SHA-1 and RIPEMD-160 has been added by Oliver Eikemeier <eik@FreeBSD.org>.
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