SHA-1 or SHA1 is a one-way hash function;
it computes a 160-bit message digest.
SHA-1 often appears in security protocols; for example,
many HTTPS websites use RSA with SHA-1 to secure their connections.
BitTorrent uses SHA-1 to verify downloads.
Git and Mercurial use SHA-1 digests to identify commits.

A US government standard, FIPS 180-1, defines SHA-1.

Find the SHA-1 message digest for a string of octets. You may either call a SHA-1 library, or implement SHA-1 in your language. Both approaches interest Rosetta Code.



 Warning: SHA-1 has known weaknesses. Theoretical attacks may find a collision after 252 operations, or perhaps fewer.
This is much faster than a brute force attack of 280 operations. USgovernment deprecated SHA-1.
For production-grade cryptography, users may consider a stronger alternative, such as SHA-256 (from the SHA-2 family) or the upcoming SHA-3.


$ zkl // run the REPL
zkl: var MsgHash=Import("zklMsgHash")
MsgHash
zkl: MsgHash.SHA1("Rosetta Code")
48c98f7e5a6e736d790ab740dfc3f51a61abe2b5
 
zkl: var hash=MsgHash.SHA1("Rosetta Code",1,False)  // hash once, return hash as bytes
Data(20)
zkl:  hash.bytes()
L(72,201,143,126,90,110,115,109,121,10,183,64,223,195,245,26,97,171,226,181)
zkl: hash.bytes().apply("toString",16).concat()
48c98f7e5a6e736d79ab740dfc3f51a61abe2b5
 
zkl: MsgHash.SHA1("a"*1000,1000); // hash 1000 a's 1000 times
34aa973cd4c4daa4f61eeb2bdbad27316534016f