From b069ed5e7fdab56024bc8e63575d942723b2ce31 Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira@intel.com>
Date: Wed, 30 Aug 2017 23:52:52 -0700
Subject: Revert "QCryptographicHash: make SHA3 calculate SHA3, not Keccak"

This reverts commit a647004d9f349e0edc4254dcfe672ccf18f98ea7 (which
is a backport of 88a8feeacb9bdaff9ee06164424e407eb904cd10). After the
5.9.0 release, we've found that changing the algorithm is a bad
idea. It's true that Qt hasn't calculated SHA-3, but it's calculated
something and people may be using it. Keeping a consistent calculation
is better for the 5.6 LTS.

Discussed-on: http://lists.qt-project.org/pipermail/development/2017-August/030786.html
Change-Id: I38341f8155354cc4a776fffd14dfdbcdc7d0f039
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
---
 src/corelib/tools/qcryptographichash.cpp | 52 ++++++++------------------------
 1 file changed, 12 insertions(+), 40 deletions(-)

(limited to 'src/corelib/tools/qcryptographichash.cpp')

diff --git a/src/corelib/tools/qcryptographichash.cpp b/src/corelib/tools/qcryptographichash.cpp
index db2ee978e8..d9f59b82fa 100644
--- a/src/corelib/tools/qcryptographichash.cpp
+++ b/src/corelib/tools/qcryptographichash.cpp
@@ -174,45 +174,9 @@ public:
         SHA3Context sha3Context;
 #endif
     };
-#ifndef QT_CRYPTOGRAPHICHASH_ONLY_SHA1
-    void sha3Finish(int bitCount);
-#endif
     QByteArray result;
 };
 
-#ifndef QT_CRYPTOGRAPHICHASH_ONLY_SHA1
-void QCryptographicHashPrivate::sha3Finish(int bitCount)
-{
-    /*
-        FIPS 202 §6.1 defines SHA-3 in terms of calculating the Keccak function
-        over the original message with the two-bit suffix "01" appended to it.
-        This variable stores that suffix (and it's fed into the calculations
-        when the hash is returned to users).
-
-        Only 2 bits of this variable are actually used (see the call to sha3Update
-        below). The Keccak implementation we're using will actually use the
-        *leftmost* 2 bits, and interpret them right-to-left. In other words, the
-        bits must appear in order of *increasing* significance; and as the two most
-        significant bits of the byte -- the rightmost 6 are ignored. (Yes, this
-        seems self-contradictory, but it's the way it is...)
-
-        Overall, this means:
-        * the leftmost two bits must be "10" (not "01"!);
-        * we don't care what the other six bits are set to (they can be set to
-        any value), but we arbitrarily set them to 0;
-
-        and for an unsigned char this gives us 0b10'00'00'00, or 0x80.
-    */
-    static const unsigned char sha3FinalSuffix = 0x80;
-
-    result.resize(bitCount / 8);
-
-    SHA3Context copy = sha3Context;
-    sha3Update(&copy, reinterpret_cast<const BitSequence *>(&sha3FinalSuffix), 2);
-    sha3Final(&copy, reinterpret_cast<BitSequence *>(result.data()));
-}
-#endif
-
 /*!
   \class QCryptographicHash
   \inmodule QtCore
@@ -457,19 +421,27 @@ QByteArray QCryptographicHash::result() const
         break;
     }
     case Sha3_224: {
-        d->sha3Finish(224);
+        SHA3Context copy = d->sha3Context;
+        d->result.resize(224/8);
+        sha3Final(&copy, reinterpret_cast<BitSequence *>(d->result.data()));
         break;
     }
     case Sha3_256: {
-        d->sha3Finish(256);
+        SHA3Context copy = d->sha3Context;
+        d->result.resize(256/8);
+        sha3Final(&copy, reinterpret_cast<BitSequence *>(d->result.data()));
         break;
     }
     case Sha3_384: {
-        d->sha3Finish(384);
+        SHA3Context copy = d->sha3Context;
+        d->result.resize(384/8);
+        sha3Final(&copy, reinterpret_cast<BitSequence *>(d->result.data()));
         break;
     }
     case Sha3_512: {
-        d->sha3Finish(512);
+        SHA3Context copy = d->sha3Context;
+        d->result.resize(512/8);
+        sha3Final(&copy, reinterpret_cast<BitSequence *>(d->result.data()));
         break;
     }
 #endif
-- 
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