* Shorten SHA-256 hashes used in store path name generation to 160

  bits, then encode them in a radix-32 representation (using digits
  and letters except e, o, u, and t).  This produces store paths like
  /nix/store/4i0zb0z7f88mwghjirkz702a71dcfivn-aterm-2.3.1.  The nice
  thing about this is that the hash part of the file name is still 32
  characters, as before with MD5.

  (Of course, shortening SHA-256 to 160 bits makes it no better than
  SHA-160 in theory, but hopefully it's a bit more resistant to
  attacks; it's certainly a lot slower.)

1 files changed, 2 insertions, 6 deletions

diff --git a/src/nix-env/main.cc b/src/nix-env/main.cc
index fc65dcfc3b60..0143c1d24e44 100644
--- a/src/nix-env/main.cc
+++ b/src/nix-env/main.cc
@@ -34,10 +34,6 @@ struct DrvInfo
     Path drvPath;
     Path outPath;
     Hash drvHash;
-
-    DrvInfo() : drvHash(htMD5)
-    {
-    }
 };
 
 typedef map<Path, DrvInfo> DrvInfos;
@@ -74,7 +70,7 @@ bool parseDerivation(EvalState & state, Expr e, DrvInfo & drv)
 
     a = queryAttr(e, "drvHash");
     if (!a) throw badTerm("derivation hash missing", e);
-    drv.drvHash = parseHash(evalString(state, a));
+    drv.drvHash = parseHash(htMD5, evalString(state, a));
 
     a = queryAttr(e, "outPath");
     if (!a) throw badTerm("output path missing", e);
@@ -205,7 +201,7 @@ void createUserEnv(EvalState & state, const DrvInfos & drvs,
             makeBind(toATerm("drvPath"),
                 makePath(toATerm(i->second.drvPath)), makeNoPos()),
             makeBind(toATerm("drvHash"),
-                makeStr(toATerm((string) i->second.drvHash)), makeNoPos()),
+                makeStr(toATerm(printHash(i->second.drvHash))), makeNoPos()),
             makeBind(toATerm("outPath"),
                 makePath(toATerm(i->second.outPath)), makeNoPos())
             ));