fix(bcrypt): require version 2 for sha256 digests

algorithm/bcrypt/const.go

@@ -55,6 +55,8 @@ const (
 )
 
 const (
+	versionSHA256 = "2"
+
 	oV = "v"
 	oT = "t"
 	oR = "r"

algorithm/bcrypt/decoder.go

@@ -170,7 +170,10 @@ func decode(variant Variant, parts []string) (digest algorithm.Digest, err error
 			return nil, fmt.Errorf("%w: key is expected to be %d bytes but it has %d bytes", algorithm.ErrEncodedHashKeyEncoding, bcrypt.EncodedHashSize, n)
 		}
 
-		var params []encoding.Parameter
+		var (
+			params  []encoding.Parameter
+			version bool
+		)
 
 		if params, err = encoding.DecodeParameterStr(parts[0]); err != nil {
 			return nil, err
@@ -179,7 +182,11 @@ func decode(variant Variant, parts []string) (digest algorithm.Digest, err error
 		for _, param := range params {
 			switch param.Key {
 			case oV:
-				break
+				if param.Value != versionSHA256 {
+					return nil, fmt.Errorf("%w: version %s is supported but encoded hash is version %s", algorithm.ErrEncodedHashInvalidVersion, versionSHA256, param.Value)
+				}
+
+				version = true
 			case oT:
 				decoded.version = param.Value
 			case oR:
@@ -193,6 +200,10 @@ func decode(variant Variant, parts []string) (digest algorithm.Digest, err error
 			}
 		}
 
+		if !version {
+			return nil, fmt.Errorf("%w: version %s is supported but encoded hash has no version", algorithm.ErrEncodedHashInvalidVersion, versionSHA256)
+		}
+
 		if err = validateCost(decoded.iterations); err != nil {
 			return nil, err
 		}

algorithm/bcrypt/regression_test.go

@@ -218,3 +218,36 @@ func TestSHA256VariantVersion2xMatches(t *testing.T) {
 	assert.NoError(t, err)
 	assert.False(t, match)
 }
+
+func TestDecodeSHA256VariantRequiresVersion2(t *testing.T) {
+	testCases := []struct {
+		name   string
+		digest string
+		err    string
+	}{
+		{"Version1", "$bcrypt-sha256$v=1,t=2b,r=10$oYmTNJVOBi3hdhUYy4JqOe$jCuMDm.Pw9hhoF/FDC6sOi48yBAoWvC", "bcrypt decode error: provided encoded hash has an invalid version: version 2 is supported but encoded hash is version 1"},
+		{"Version3", "$bcrypt-sha256$v=3,t=2b,r=10$oYmTNJVOBi3hdhUYy4JqOe$jCuMDm.Pw9hhoF/FDC6sOi48yBAoWvC", "bcrypt decode error: provided encoded hash has an invalid version: version 2 is supported but encoded hash is version 3"},
+		{"VersionEmpty", "$bcrypt-sha256$v=,t=2b,r=10$oYmTNJVOBi3hdhUYy4JqOe$jCuMDm.Pw9hhoF/FDC6sOi48yBAoWvC", "bcrypt decode error: provided encoded hash has an invalid version: version 2 is supported but encoded hash is version "},
+		{"VersionMissing", "$bcrypt-sha256$t=2b,r=10$oYmTNJVOBi3hdhUYy4JqOe$jCuMDm.Pw9hhoF/FDC6sOi48yBAoWvC", "bcrypt decode error: provided encoded hash has an invalid version: version 2 is supported but encoded hash has no version"},
+		{"PasslibVersion1Format", "$bcrypt-sha256$2a,12$LrmaIX5x4TRtAwEfwJZa1.$2ehnw6LvuIUTM0iz4iz9hTxv21B6KFO", "bcrypt decode error: parameter pair '2a' is not properly encoded: does not contain kv separator '='"},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			digest, err := Decode(tc.digest)
+
+			assert.Nil(t, digest)
+			assert.EqualError(t, err, tc.err)
+		})
+	}
+}
+
+func TestDecodeSHA256VariantAcceptsVersion2(t *testing.T) {
+	const encoded = "$bcrypt-sha256$v=2,t=2b,r=10$oYmTNJVOBi3hdhUYy4JqOe$jCuMDm.Pw9hhoF/FDC6sOi48yBAoWvC"
+
+	digest, err := Decode(encoded)
+	require.NoError(t, err)
+
+	assert.Equal(t, encoded, digest.Encode())
+	assert.True(t, digest.Match("password"))
+}