Merge pull request #34 from multiformats/feat/dbl-sha

add a double sha256 hash method for supporting bitcoin
multiformats · Nov 10, 2016 · 3922c53 · 3922c53
2 parents 5c64ea9 + afd20e6
commit 3922c53
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Showing 4 changed files with 27 additions and 18 deletions.
diff --git a/multihash.go b/multihash.go
@@ -34,36 +34,41 @@ const (
 	SHA3     = 0x14
 	BLAKE2B  = 0x40
 	BLAKE2S  = 0x41
+
+	DBL_SHA2_256 = 0x56
 )
 
 // Names maps the name of a hash to the code
 var Names = map[string]int{
-	"sha1":     SHA1,
-	"sha2-256": SHA2_256,
-	"sha2-512": SHA2_512,
-	"sha3":     SHA3,
-	"blake2b":  BLAKE2B,
-	"blake2s":  BLAKE2S,
+	"sha1":         SHA1,
+	"sha2-256":     SHA2_256,
+	"sha2-512":     SHA2_512,
+	"sha3":         SHA3,
+	"blake2b":      BLAKE2B,
+	"blake2s":      BLAKE2S,
+	"dbl-sha2-256": DBL_SHA2_256,
 }
 
 // Codes maps a hash code to it's name
 var Codes = map[int]string{
-	SHA1:     "sha1",
-	SHA2_256: "sha2-256",
-	SHA2_512: "sha2-512",
-	SHA3:     "sha3",
-	BLAKE2B:  "blake2b",
-	BLAKE2S:  "blake2s",
+	SHA1:         "sha1",
+	SHA2_256:     "sha2-256",
+	SHA2_512:     "sha2-512",
+	SHA3:         "sha3",
+	BLAKE2B:      "blake2b",
+	BLAKE2S:      "blake2s",
+	DBL_SHA2_256: "dbl-sha2-256",
 }
 
 // DefaultLengths maps a hash code to it's default length
 var DefaultLengths = map[int]int{
-	SHA1:     20,
-	SHA2_256: 32,
-	SHA2_512: 64,
-	SHA3:     64,
-	BLAKE2B:  64,
-	BLAKE2S:  32,
+	SHA1:         20,
+	SHA2_256:     32,
+	SHA2_512:     64,
+	SHA3:         64,
+	BLAKE2B:      64,
+	BLAKE2S:      32,
+	DBL_SHA2_256: 32,
 }
 
 type DecodedMultihash struct {

diff --git a/multihash_test.go b/multihash_test.go
@@ -16,6 +16,7 @@ var tCodes = map[int]string{
 	0x14: "sha3",
 	0x40: "blake2b",
 	0x41: "blake2s",
+	0x56: "dbl-sha2-256",
 }
 
 type TestCase struct {

diff --git a/sum.go b/sum.go
@@ -29,6 +29,8 @@ func Sum(data []byte, code int, length int) (Multihash, error) {
 		d = sumSHA512(data)
 	case SHA3:
 		d, err = sumSHA3(data)
+	case DBL_SHA2_256:
+		d = sumSHA256(sumSHA256(data))
 	default:
 		return m, ErrSumNotSupported
 	}

diff --git a/sum_test.go b/sum_test.go
@@ -21,6 +21,7 @@ var sumTestCases = []SumTestCase{
 	SumTestCase{SHA2_512, 32, "foo", "1320f7fbba6e0636f890e56fbbf3283e524c6fa3204ae298382d624741d0dc663832"},
 	SumTestCase{SHA3, -1, "foo", "14404bca2b137edc580fe50a88983ef860ebaca36c857b1f492839d6d7392452a63c82cbebc68e3b70a2a1480b4bb5d437a7cba6ecf9d89f9ff3ccd14cd6146ea7e7"},
 	SumTestCase{SHA3, 32, "foo", "14204bca2b137edc580fe50a88983ef860ebaca36c857b1f492839d6d7392452a63c"},
+	SumTestCase{DBL_SHA2_256, 32, "foo", "5620c7ade88fc7a21498a6a5e5c385e1f68bed822b72aa63c4a9a48a02c2466ee29e"},
 }
 
 func TestSum(t *testing.T) {