SHA1(1) BSD Reference Manual SHA1(1)
sha1 - calculate a message-digest fingerprint (checksum) for a file
sha1 [-b] [-p | -s string | file ...] sha1 -G [file ...] sha1 -t | -x | -c [checklist ...] sha1sum [-b | -t] [file ...]
sha1 takes as input a message of arbitrary length and produces as output a 160-bit "fingerprint" or "message digest" of the input. It is conjec- tured that it is computationally infeasible to produce two messages hav- ing the same message digest, or to produce any message having a given prespecified target message digest. The SHA-1 algorithm is intended for digital signature applications, where a large file must be "compressed" in a secure manner before being en- crypted with a private (secret) key under a public-key cryptosystem such as RSA. However, recently the SHA family's (SHA-0, SHA-1, SHA-2 (SHA-384 and SHA-512) all share the same design) weakness has been proven in re- duced versions of SHA-1 and partially SHA-2 and collisions for SHA-1 can be found. The use of other hash functions is encouraged; however, as RIPEMD-160 is only little more secure, combining hashes from different families or, better, different approaches (Tiger, Whirlpool) is recom- mended. The options are as follows: -b Print the checksum as binary to stdout. Ignored in GNU mode. -c [checklist ...] Compares all checksums contained in the file checklist with newly computed checksums for the corresponding files. Output consists of the digest used, the file name, and an OK or FAILED for the result of the comparison. This will validate any of the supported checksums (see cksum(1)). If no file is given, stdin is used. -G Enable GNU md5sum compatible output mode. Can also be enabled by calling this programme as sha1sum. -p Echoes stdin to stdout and appends the SHA-1 sum to stdout. -s string Prints a checksum of the given string. -t Runs a built-in time trial. Ignored in GNU mode. -x Runs a built-in test script. The SHA-1 sum of each file listed on the command line is printed after the options are processed. The sha1 command is shorthand for cksum -a sha1 The cksum(1) command can also be used to compute digests from the SHA-2 family: sha256, sha384 and sha512.
cksum(1), md5(1), rmd160(1) J. Burrows, The Secure Hash Standard, FIPS PUB 180-1. D. Eastlake and P. Jones, US Secure Hash Algorithm 1, RFC 3174. MirOS BSD #10-current November 17, 2009 1
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