Fix: Digest::HalfSipHash to generate 64-bit hashes

So Crystal::Hasher#result always returns an UInt64 across systems. Generating 8-bytes instead of 4-bytes hashes doubles the finalization rounds but is still significantly faster in 32-bit systems than Digest::SipHash.
crystal-lang · Oct 13, 2017 · a2af730 · a2af730
1 parent 4a4f447
commit a2af730
Show file tree

Hide file tree

Showing 4 changed files with 85 additions and 78 deletions.
diff --git a/spec/std/digest/halfsiphash_spec.cr b/spec/std/digest/halfsiphash_spec.cr
@@ -1,79 +1,79 @@
 require "spec"
 require "digest/halfsiphash"
 
-private VECTORS_HSIP32 = [
-  UInt8.static_array(0xa9, 0x35, 0x9f, 0x5b),
-  UInt8.static_array(0x27, 0x47, 0x5a, 0xb8),
-  UInt8.static_array(0xfa, 0x62, 0xa6, 0x03),
-  UInt8.static_array(0x8a, 0xfe, 0xe7, 0x04),
-  UInt8.static_array(0x2a, 0x6e, 0x46, 0x89),
-  UInt8.static_array(0xc5, 0xfa, 0xb6, 0x69),
-  UInt8.static_array(0x58, 0x63, 0xfc, 0x23),
-  UInt8.static_array(0x8b, 0xcf, 0x63, 0xc5),
-  UInt8.static_array(0xd0, 0xb8, 0x84, 0x8f),
-  UInt8.static_array(0xf8, 0x06, 0xe7, 0x79),
-  UInt8.static_array(0x94, 0xb0, 0x79, 0x34),
-  UInt8.static_array(0x08, 0x08, 0x30, 0x50),
-  UInt8.static_array(0x57, 0xf0, 0x87, 0x2f),
-  UInt8.static_array(0x77, 0xe6, 0x63, 0xff),
-  UInt8.static_array(0xd6, 0xff, 0xf8, 0x7c),
-  UInt8.static_array(0x74, 0xfe, 0x2b, 0x97),
-  UInt8.static_array(0xd9, 0xb5, 0xac, 0x84),
-  UInt8.static_array(0xc4, 0x74, 0x64, 0x5b),
-  UInt8.static_array(0x46, 0x5b, 0x8d, 0x9b),
-  UInt8.static_array(0x7b, 0xef, 0xe3, 0x87),
-  UInt8.static_array(0xe3, 0x4d, 0x10, 0x45),
-  UInt8.static_array(0x61, 0x3f, 0x62, 0xb3),
-  UInt8.static_array(0x70, 0xf3, 0x67, 0xfe),
-  UInt8.static_array(0xe6, 0xad, 0xb8, 0xbd),
-  UInt8.static_array(0x27, 0x40, 0x0c, 0x63),
-  UInt8.static_array(0x26, 0x78, 0x78, 0x75),
-  UInt8.static_array(0x4f, 0x56, 0x7b, 0x5f),
-  UInt8.static_array(0x3a, 0xb0, 0xe6, 0x69),
-  UInt8.static_array(0xb0, 0x64, 0x40, 0x00),
-  UInt8.static_array(0xff, 0x67, 0x0f, 0xb4),
-  UInt8.static_array(0x50, 0x9e, 0x33, 0x8b),
-  UInt8.static_array(0x5d, 0x58, 0x9f, 0x1a),
-  UInt8.static_array(0xfe, 0xe7, 0x21, 0x12),
-  UInt8.static_array(0x33, 0x75, 0x32, 0x59),
-  UInt8.static_array(0x6a, 0x43, 0x4f, 0x8c),
-  UInt8.static_array(0xfe, 0x28, 0xb7, 0x29),
-  UInt8.static_array(0xe7, 0x5c, 0xc6, 0xec),
-  UInt8.static_array(0x69, 0x7e, 0x8d, 0x54),
-  UInt8.static_array(0x63, 0x68, 0x8b, 0x0f),
-  UInt8.static_array(0x65, 0x0b, 0x62, 0xb4),
-  UInt8.static_array(0xb6, 0xbc, 0x18, 0x40),
-  UInt8.static_array(0x5d, 0x07, 0x45, 0x05),
-  UInt8.static_array(0x24, 0x42, 0xfd, 0x2e),
-  UInt8.static_array(0x7b, 0xb7, 0x86, 0x3a),
-  UInt8.static_array(0x77, 0x05, 0xd5, 0x48),
-  UInt8.static_array(0xd7, 0x52, 0x08, 0xb1),
-  UInt8.static_array(0xb6, 0xd4, 0x99, 0xc8),
-  UInt8.static_array(0x08, 0x92, 0x20, 0x2e),
-  UInt8.static_array(0x69, 0xe1, 0x2c, 0xe3),
-  UInt8.static_array(0x8d, 0xb5, 0x80, 0xe5),
-  UInt8.static_array(0x36, 0x97, 0x64, 0xc6),
-  UInt8.static_array(0x01, 0x6e, 0x02, 0x04),
-  UInt8.static_array(0x3b, 0x85, 0xf3, 0xd4),
-  UInt8.static_array(0xfe, 0xdb, 0x66, 0xbe),
-  UInt8.static_array(0x1e, 0x69, 0x2a, 0x3a),
-  UInt8.static_array(0xc6, 0x89, 0x84, 0xc0),
-  UInt8.static_array(0xa5, 0xc5, 0xb9, 0x40),
-  UInt8.static_array(0x9b, 0xe9, 0xe8, 0x8c),
-  UInt8.static_array(0x7d, 0xbc, 0x81, 0x40),
-  UInt8.static_array(0x7c, 0x07, 0x8e, 0xc5),
-  UInt8.static_array(0xd4, 0xe7, 0x6c, 0x73),
-  UInt8.static_array(0x42, 0x8f, 0xcb, 0xb9),
-  UInt8.static_array(0xbd, 0x83, 0x99, 0x7a),
-  UInt8.static_array(0x59, 0xea, 0x4a, 0x74),
+private VECTORS_HSIP64 = [
+  UInt8.static_array(0x21, 0x8d, 0x1f, 0x59, 0xb9, 0xb8, 0x3c, 0xc8),
+  UInt8.static_array(0xbe, 0x55, 0x24, 0x12, 0xf8, 0x38, 0x73, 0x15),
+  UInt8.static_array(0x06, 0x4f, 0x39, 0xef, 0x7c, 0x50, 0xeb, 0x57),
+  UInt8.static_array(0xce, 0x0f, 0x1a, 0x45, 0xf7, 0x06, 0x06, 0x79),
+  UInt8.static_array(0xd5, 0xe7, 0x8a, 0x17, 0x5b, 0xe5, 0x2e, 0xa1),
+  UInt8.static_array(0xcb, 0x9d, 0x7c, 0x3f, 0x2f, 0x3d, 0xb5, 0x80),
+  UInt8.static_array(0xce, 0x3e, 0x91, 0x35, 0x8a, 0xa2, 0xbc, 0x25),
+  UInt8.static_array(0xff, 0x20, 0x27, 0x28, 0xb0, 0x7b, 0xc6, 0x84),
+  UInt8.static_array(0xed, 0xfe, 0xe8, 0x20, 0xbc, 0xe4, 0x85, 0x8c),
+  UInt8.static_array(0x5b, 0x51, 0xcc, 0xcc, 0x13, 0x88, 0x83, 0x07),
+  UInt8.static_array(0x95, 0xb0, 0x46, 0x9f, 0x06, 0xa6, 0xf2, 0xee),
+  UInt8.static_array(0xae, 0x26, 0x33, 0x39, 0x94, 0xdd, 0xcd, 0x48),
+  UInt8.static_array(0x7b, 0xc7, 0x1f, 0x9f, 0xae, 0xf5, 0xc7, 0x99),
+  UInt8.static_array(0x5a, 0x23, 0x52, 0xd7, 0x5a, 0x0c, 0x37, 0x44),
+  UInt8.static_array(0x3b, 0xb1, 0xa8, 0x70, 0xea, 0xe8, 0xe6, 0x58),
+  UInt8.static_array(0x21, 0x7d, 0x0b, 0xcb, 0x4e, 0x81, 0xc9, 0x02),
+  UInt8.static_array(0x73, 0x36, 0xaa, 0xd2, 0x5f, 0x7b, 0xf3, 0xb5),
+  UInt8.static_array(0x37, 0xad, 0xc0, 0x64, 0x1c, 0x4c, 0x4f, 0x6a),
+  UInt8.static_array(0xc9, 0xb2, 0xdb, 0x2b, 0x9a, 0x3e, 0x42, 0xf9),
+  UInt8.static_array(0xf9, 0x10, 0xe4, 0x80, 0x20, 0xab, 0x36, 0x3c),
+  UInt8.static_array(0x1b, 0xf5, 0x2b, 0x0a, 0x6f, 0xee, 0xa7, 0xdb),
+  UInt8.static_array(0x00, 0x74, 0x1d, 0xc2, 0x69, 0xe8, 0xb3, 0xef),
+  UInt8.static_array(0xe2, 0x01, 0x03, 0xfa, 0x1b, 0xa7, 0x76, 0xef),
+  UInt8.static_array(0x4c, 0x22, 0x10, 0xe5, 0x4b, 0x68, 0x1d, 0x73),
+  UInt8.static_array(0x70, 0x74, 0x10, 0x45, 0xae, 0x3f, 0xa6, 0xf1),
+  UInt8.static_array(0x0c, 0x86, 0x40, 0x37, 0x39, 0x71, 0x40, 0x38),
+  UInt8.static_array(0x0d, 0x89, 0x9e, 0xd8, 0x11, 0x29, 0x23, 0xf0),
+  UInt8.static_array(0x22, 0x6b, 0xf5, 0xfa, 0xb8, 0x1e, 0xe1, 0xb8),
+  UInt8.static_array(0x2d, 0x92, 0x5f, 0xfb, 0x1e, 0x00, 0x16, 0xb5),
+  UInt8.static_array(0x36, 0x19, 0x58, 0xd5, 0x2c, 0xee, 0x10, 0xf1),
+  UInt8.static_array(0x29, 0x1a, 0xaf, 0x86, 0x48, 0x98, 0x17, 0x9d),
+  UInt8.static_array(0x86, 0x3c, 0x7f, 0x15, 0x5c, 0x34, 0x11, 0x7c),
+  UInt8.static_array(0x28, 0x70, 0x9d, 0x46, 0xd8, 0x11, 0x62, 0x6c),
+  UInt8.static_array(0x24, 0x84, 0x77, 0x68, 0x1d, 0x28, 0xf8, 0x9c),
+  UInt8.static_array(0x83, 0x24, 0xe4, 0xd7, 0x52, 0x8f, 0x98, 0x30),
+  UInt8.static_array(0xf9, 0xef, 0xd4, 0xe1, 0x3a, 0xea, 0x6b, 0xd8),
+  UInt8.static_array(0x86, 0xd6, 0x7a, 0x40, 0xec, 0x42, 0x76, 0xdc),
+  UInt8.static_array(0x3f, 0x62, 0x92, 0xec, 0xcc, 0xa9, 0x7e, 0x35),
+  UInt8.static_array(0xcb, 0xd9, 0x2e, 0xe7, 0x24, 0xd4, 0x21, 0x09),
+  UInt8.static_array(0x36, 0x8d, 0xf6, 0x80, 0x8d, 0x40, 0x3d, 0x79),
+  UInt8.static_array(0x5b, 0x38, 0xc8, 0x1c, 0x67, 0xc8, 0xae, 0x4c),
+  UInt8.static_array(0x95, 0xab, 0x71, 0x89, 0xd4, 0x39, 0xac, 0xb3),
+  UInt8.static_array(0xa9, 0x1a, 0x52, 0xc0, 0x25, 0x32, 0x70, 0x24),
+  UInt8.static_array(0x5b, 0x00, 0x87, 0xc6, 0x95, 0x28, 0xac, 0xea),
+  UInt8.static_array(0x1e, 0x30, 0xf3, 0xad, 0x27, 0xdc, 0xb1, 0x5a),
+  UInt8.static_array(0x69, 0x7f, 0x5c, 0x9a, 0x90, 0x32, 0x4e, 0xd4),
+  UInt8.static_array(0x49, 0x5c, 0x0f, 0x99, 0x55, 0x57, 0xdc, 0x38),
+  UInt8.static_array(0x94, 0x27, 0x20, 0x2a, 0x3c, 0x29, 0xf9, 0x4d),
+  UInt8.static_array(0xa9, 0xea, 0xa8, 0xc0, 0x4b, 0xa9, 0x3e, 0x3e),
+  UInt8.static_array(0xee, 0xa4, 0xc1, 0x73, 0x7d, 0x01, 0x12, 0x18),
+  UInt8.static_array(0x91, 0x2d, 0x56, 0x8f, 0xd8, 0xf6, 0x5a, 0x49),
+  UInt8.static_array(0x56, 0x91, 0x95, 0x96, 0xb0, 0xff, 0x5c, 0x97),
+  UInt8.static_array(0x02, 0x44, 0x5a, 0x79, 0x98, 0xf5, 0x50, 0xe1),
+  UInt8.static_array(0x86, 0xec, 0x46, 0x6c, 0xe7, 0x1d, 0x1f, 0xb2),
+  UInt8.static_array(0x35, 0x95, 0x69, 0xe7, 0xd2, 0x89, 0xe3, 0xbc),
+  UInt8.static_array(0x87, 0x1b, 0x05, 0xca, 0x62, 0xbb, 0x7c, 0x96),
+  UInt8.static_array(0xa1, 0xa4, 0x92, 0xf9, 0x42, 0xf1, 0x5f, 0x1d),
+  UInt8.static_array(0x12, 0xec, 0x26, 0x7f, 0xf6, 0x09, 0x5b, 0x6e),
+  UInt8.static_array(0x5d, 0x1b, 0x5e, 0xa1, 0xb2, 0x31, 0xd8, 0x9d),
+  UInt8.static_array(0xd8, 0xcf, 0xb4, 0x45, 0x3f, 0x92, 0xee, 0x54),
+  UInt8.static_array(0xd6, 0x76, 0x28, 0x90, 0xbf, 0x26, 0xe4, 0x60),
+  UInt8.static_array(0x31, 0x35, 0x63, 0xa4, 0xb7, 0xed, 0x5c, 0xf3),
+  UInt8.static_array(0xf9, 0x0b, 0x3a, 0xb5, 0x72, 0xd4, 0x66, 0x93),
+  UInt8.static_array(0x2e, 0xa6, 0x3c, 0x71, 0xbf, 0x32, 0x60, 0x87),
 ]
 
 describe Digest::HalfSipHash(2, 4) do
   key = UInt8.static_array(0, 1, 2, 3, 4, 5, 6, 7)
 
   it "generates official halfsiphash2-4 32-bit test vectors" do
     input = uninitialized UInt8[64]
-    output = uninitialized UInt8[4]
+    output = uninitialized UInt8[8]
 
     64.times do |i|
       input[i] = i.to_u8
@@ -82,14 +82,14 @@ describe Digest::HalfSipHash(2, 4) do
       hasher.update(input.to_slice[0, i])
       hasher.result(output.to_slice)
 
-      output.should eq(VECTORS_HSIP32[i])
+      output.should eq(VECTORS_HSIP64[i])
     end
   end
 
   it "generates 32-bit hash in chunks" do
     input = StaticArray(UInt8, 64).new { |i| i.to_u8 }
-    expected = uninitialized UInt8[4]
-    got = uninitialized UInt8[4]
+    expected = uninitialized UInt8[8]
+    got = uninitialized UInt8[8]
 
     hasher = Digest::HalfSipHash(2, 4).new(key)
     hasher.update(input.to_slice)
@@ -109,7 +109,7 @@ describe Digest::HalfSipHash(2, 4) do
   it "returns a 32-bit hash" do
     hasher = Digest::HalfSipHash(2, 4).new(key)
     hasher.update("fixed data")
-    typeof(hasher.result).should eq(UInt32)
-    hasher.result.should eq(1533225208_u32)
+    typeof(hasher.result).should eq(UInt64)
+    hasher.result.should eq(13596912907759364473_u64)
   end
 end
diff --git a/src/crystal/hasher.cr b/src/crystal/hasher.cr
@@ -23,10 +23,8 @@ struct Crystal::Hasher
   # TODO: use flag?(:bits64) for Crystal > 0.23.1
   {% if flag?(:x86_64) || flag?(:aarch64) %}
     alias SipHash = Digest::SipHash
-    alias HashType = UInt64
   {% else %}
     alias SipHash = Digest::HalfSipHash
-    alias HashType = UInt32
   {% end %}
 
   @@seed = uninitialized SipHash::Key
@@ -36,7 +34,7 @@ struct Crystal::Hasher
     @siphash = SipHash(1, 3).new(@@seed)
   end
 
-  def result : HashType
+  def result : UInt64
     @siphash.result
   end
 

diff --git a/src/digest/halfsiphash.cr b/src/digest/halfsiphash.cr
@@ -56,6 +56,8 @@ struct Digest::HalfSipHash(CROUNDS, DROUNDS)
     @v2 ^= k0
     @v1 ^= k1
     @v0 ^= k0
+
+    @v1 ^= 0xee
   end
 
   def update(data : String) : Nil
@@ -116,13 +118,13 @@ struct Digest::HalfSipHash(CROUNDS, DROUNDS)
   end
 
   def result
-    output = uninitialized UInt32
+    output = uninitialized UInt64
     result(@buf.to_unsafe, @buf_index, pointerof(output).as(UInt8*))
     output
   end
 
   def result(output : Bytes) : Nil
-    raise ArgumentError.new("Digest::HalfSipHash can only generate 4 bytes hashes.") unless output.size == 4
+    raise ArgumentError.new("Digest::HalfSipHash can only generate 8 bytes hashes.") unless output.size == 8
     result(@buf.to_unsafe, @buf_index, output.to_unsafe)
   end
 
@@ -147,12 +149,19 @@ struct Digest::HalfSipHash(CROUNDS, DROUNDS)
     CROUNDS.times { sipround }
 
     v0 ^= b
-    v2 ^= 0xff
+    v2 ^= 0xee
 
     DROUNDS.times { sipround }
 
     b = v1 ^ v3
     u32to8_le(output, b)
+
+    v1 ^= 0xdd
+
+    DROUNDS.times { sipround }
+
+    b = v1 ^ v3
+    u32to8_le(output + 4, b)
   end
 
   private def rotl(x, b)

diff --git a/src/string_pool.cr b/src/string_pool.cr
@@ -178,6 +178,6 @@ class StringPool
     hasher = Crystal::Hasher.new
     hasher = str.to_slice(len).hash(hasher)
     # hash should be non-zero, so `or` it with high bit
-    hasher.result.to_u64 | 0x8000_0000_0000_0000_u64
+    hasher.result | 0x8000000000000000_u64
   end
 end