Add functions to encode and decode payment addresses.

addrconvs.go

@@ -0,0 +1,78 @@
+package btcutil
+
+import (
+	"bytes"
+	"code.google.com/p/go.crypto/ripemd160"
+	"errors"
+	"github.com/conformal/btcwire"
+)
+
+// ErrAddrUnknownNet describes an error where the address identifier
+// byte is not recognized as belonging to neither the Bitcoin MainNet nor
+// TestNet.
+var ErrAddrUnknownNet = errors.New("unrecognized network identifier byte")
+
+// ErrMalformedAddress describes an error where an address is improperly
+// formatted, either due to an incorrect length of the hashed pubkey or
+// a non-matching checksum.
+var ErrMalformedAddress  = errors.New("malformed address")
+
+// Constants used to specify which network a payment address belongs
+// to.  Mainnet address cannot be used on the Testnet, and vice versa.
+const (
+	// MainNetAddr is the address identifier for MainNet
+	MainNetAddr = 0x00
+
+	// TestNetAddr is the address identifier for TestNet
+	TestNetAddr = 0x6f
+)
+
+// EncodeAddress takes a 20-byte raw payment address (hash160 of the
+// uncompressed pubkey) and a network identifying byte and encodes the
+// payment address in a human readable string.
+func EncodeAddress(addrHash []byte, netID byte) (encoded string, err error) {
+	if len(addrHash) != ripemd160.Size {
+		return "", ErrMalformedAddress
+	}
+	if netID != MainNetAddr && netID != TestNetAddr {
+		return "", ErrAddrUnknownNet
+	}
+
+	tosum := append([]byte{netID}, addrHash...)
+	cksum := btcwire.DoubleSha256(tosum)
+
+	a := append([]byte{netID}, addrHash...)
+	a = append(a, cksum[:4]...)
+
+	return Base58Encode(a), nil
+}
+
+// DecodeAddress decodes a human readable payment address string
+// returning the 20-byte decoded address, along with the network
+// identifying byte.
+func DecodeAddress(addr string) (addrHash []byte, netID byte, err error) {
+	decoded := Base58Decode(addr)
+
+	// Length of decoded address must be 20 bytes + 1 byte for a network
+	// identifier byte + 4 bytes of checksum.
+	if len(decoded) != ripemd160.Size+5 {
+		return nil, 0x00, ErrMalformedAddress
+	}
+
+	netID = decoded[0]
+	if netID != MainNetAddr && netID != TestNetAddr {
+		return nil, 0x00, ErrAddrUnknownNet
+	}
+	addrHash = decoded[1:21]
+
+	// Checksum is first four bytes of double SHA256 of the network byte
+	// and addrHash.  Verify this matches the final 4 bytes of the decoded
+	// address.
+	tosum := append([]byte{netID}, addrHash...)
+	cksum := btcwire.DoubleSha256(tosum)[:4]
+	if !bytes.Equal(cksum, decoded[len(decoded)-4:]) {
+		return nil, 0x00, ErrMalformedAddress
+	}
+
+	return addrHash, netID, nil
+}

addrconvs_test.go

@@ -0,0 +1,83 @@
+// Copyright (c) 2013 Conformal Systems LLC.
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+package btcutil_test
+
+import (
+	"bytes"
+	"github.com/conformal/btcutil"
+	"testing"
+)
+
+var encodeTests = []struct {
+	raw []byte
+	net byte
+	res string
+	err error
+}{
+	{[]byte{0xe3, 0x4c, 0xce, 0x70, 0xc8, 0x63, 0x73, 0x27, 0x3e, 0xfc, 0xc5, 0x4c, 0xe7, 0xd2, 0xa4, 0x91, 0xbb, 0x4a, 0x0e, 0x84},
+		btcutil.MainNetAddr, "1MirQ9bwyQcGVJPwKUgapu5ouK2E2Ey4gX", nil},
+	{[]byte{0x0e, 0xf0, 0x30, 0x10, 0x7f, 0xd2, 0x6e, 0x0b, 0x6b, 0xf4, 0x05, 0x12, 0xbc, 0xa2, 0xce, 0xb1, 0xdd, 0x80, 0xad, 0xaa},
+		btcutil.MainNetAddr, "12MzCDwodF9G1e7jfwLXfR164RNtx4BRVG", nil},
+	{[]byte{0x78, 0xb3, 0x16, 0xa0, 0x86, 0x47, 0xd5, 0xb7, 0x72, 0x83, 0xe5, 0x12, 0xd3, 0x60, 0x3f, 0x1f, 0x1c, 0x8d, 0xe6, 0x8f},
+		btcutil.TestNetAddr, "mrX9vMRYLfVy1BnZbc5gZjuyaqH3ZW2ZHz", nil},
+
+	// Raw address not 20 bytes (padded with leading 0s)
+	{[]byte{0x00, 0x0e, 0xf0, 0x30, 0x10, 0x7f, 0xd2, 0x6e, 0x0b, 0x6b, 0xf4, 0x05, 0x12, 0xbc, 0xa2, 0xce, 0xb1, 0xdd, 0x80, 0xad, 0xaa},
+		btcutil.MainNetAddr, "12MzCDwodF9G1e7jfwLXfR164RNtx4BRVG", btcutil.ErrMalformedAddress},
+
+	// Bad network byte
+	{make([]byte, 20), btcutil.MainNetAddr + 1, "", btcutil.ErrAddrUnknownNet},
+}
+
+func TestEncodeAddresses(t *testing.T) {
+	for i := range encodeTests {
+		res, err := btcutil.EncodeAddress(encodeTests[i].raw,
+			encodeTests[i].net)
+		if err != encodeTests[i].err {
+			t.Error(err)
+			continue
+		}
+		if err == nil && res != encodeTests[i].res {
+			t.Errorf("Results differ: Expected '%s', returned '%s'",
+				encodeTests[i].res, res)
+		}
+	}
+}
+
+var decodeTests = []struct {
+	addr string
+	res  []byte
+	net  byte
+	err  error
+}{
+	{"1MirQ9bwyQcGVJPwKUgapu5ouK2E2Ey4gX",
+		[]byte{0xe3, 0x4c, 0xce, 0x70, 0xc8, 0x63, 0x73, 0x27, 0x3e, 0xfc, 0xc5, 0x4c, 0xe7, 0xd2, 0xa4, 0x91, 0xbb, 0x4a, 0x0e, 0x84},
+		btcutil.MainNetAddr, nil},
+	{"mrX9vMRYLfVy1BnZbc5gZjuyaqH3ZW2ZHz",
+		[]byte{0x78, 0xb3, 0x16, 0xa0, 0x86, 0x47, 0xd5, 0xb7, 0x72, 0x83, 0xe5, 0x12, 0xd3, 0x60, 0x3f, 0x1f, 0x1c, 0x8d, 0xe6, 0x8f},
+		btcutil.TestNetAddr, nil},
+
+	// Wrong length
+	{"01MirQ9bwyQcGVJPwKUgapu5ouK2E2Ey4gX", nil, btcutil.MainNetAddr, btcutil.ErrMalformedAddress},
+
+	// Bad magic
+	{"2MirQ9bwyQcGVJPwKUgapu5ouK2E2Ey4gX", nil, btcutil.MainNetAddr, btcutil.ErrAddrUnknownNet},
+
+	// Bad checksum
+	{"1MirQ9bwyQcGVJPwKUgapu5ouK2E2dpuqz", nil, btcutil.MainNetAddr, btcutil.ErrMalformedAddress},
+}
+
+func TestDecodeAddresses(t *testing.T) {
+	for i := range decodeTests {
+		res, _, err := btcutil.DecodeAddress(decodeTests[i].addr)
+		if err != decodeTests[i].err {
+			t.Error(err)
+		}
+		if err == nil && !bytes.Equal(res, decodeTests[i].res) {
+			t.Errorf("Results differ: Expected '%v', returned '%v'",
+				decodeTests[i].res, res)
+		}
+	}
+}

test_coverage.txt

@@ -1,18 +1,19 @@
 
-github.com/conformal/btcutil/base58.go	 Base58Decode			 100.00% (20/20)
-github.com/conformal/btcutil/block.go	 Block.TxSha			 100.00% (11/11)
-github.com/conformal/btcutil/block.go	 Block.TxShas			 100.00% (10/10)
-github.com/conformal/btcutil/block.go	 NewBlockFromBytes		 100.00% (7/7)
-github.com/conformal/btcutil/block.go	 Block.Sha			 100.00% (5/5)
-github.com/conformal/btcutil/block.go	 NewBlockFromBlockAndBytes	 100.00% (1/1)
-github.com/conformal/btcutil/block.go	 OutOfRangeError.Error		 100.00% (1/1)
-github.com/conformal/btcutil/block.go	 Block.Height			 100.00% (1/1)
-github.com/conformal/btcutil/block.go	 Block.SetHeight		 100.00% (1/1)
-github.com/conformal/btcutil/block.go	 NewBlock			 100.00% (1/1)
-github.com/conformal/btcutil/block.go	 Block.ProtocolVersion		 100.00% (1/1)
-github.com/conformal/btcutil/block.go	 Block.MsgBlock			 100.00% (1/1)
-github.com/conformal/btcutil/base58.go	 Base58Encode			 93.33% (14/15)
-github.com/conformal/btcutil/block.go	 Block.TxLoc			 88.89% (8/9)
-github.com/conformal/btcutil/block.go	 Block.Bytes			 88.89% (8/9)
-github.com/conformal/btcutil		 -------------------------	 96.77% (90/93)
+github.com/conformal/btcutil/base58.go		 Base58Decode			 100.00% (20/20)
+github.com/conformal/btcutil/base58.go		 Base58Encode			 100.00% (15/15)
+github.com/conformal/btcutil/addrconvs.go	 DecodeAddress			 100.00% (12/12)
+github.com/conformal/btcutil/block.go		 Block.TxSha			 100.00% (11/11)
+github.com/conformal/btcutil/block.go		 Block.TxShas			 100.00% (10/10)
+github.com/conformal/btcutil/addrconvs.go	 EncodeAddress			 100.00% (9/9)
+github.com/conformal/btcutil/block.go		 NewBlockFromBytes		 100.00% (7/7)
+github.com/conformal/btcutil/block.go		 Block.Sha			 100.00% (5/5)
+github.com/conformal/btcutil/block.go		 OutOfRangeError.Error		 100.00% (1/1)
+github.com/conformal/btcutil/block.go		 Block.Height			 100.00% (1/1)
+github.com/conformal/btcutil/block.go		 Block.SetHeight		 100.00% (1/1)
+github.com/conformal/btcutil/block.go		 NewBlock			 100.00% (1/1)
+github.com/conformal/btcutil/block.go		 NewBlockFromBlockAndBytes	 100.00% (1/1)
+github.com/conformal/btcutil/block.go		 Block.MsgBlock			 100.00% (1/1)
+github.com/conformal/btcutil/block.go		 Block.TxLoc			 88.89% (8/9)
+github.com/conformal/btcutil/block.go		 Block.Bytes			 88.89% (8/9)
+github.com/conformal/btcutil			 -------------------------	 98.23% (111/113)