Update README with examples; Add signature test

README.md

@@ -4,3 +4,18 @@ go-crypto is the cryptographic package adapted for Tendermint's uses
 
 ## Importing it
 `import "github.com/tendermint/go-crypto"`
+
+## Binary encoding
+
+go-crypto `.Bytes()` uses Amino:binary encoding, but Amino:JSON is also supported.
+
+```go
+Example Amino:JSON encodings:
+
+crypto.PrivKeyEd25519     - {"type":"954568A3288910","value":"EVkqJO/jIXp3rkASXfh9YnyToYXRXhBr6g9cQVxPFnQBP/5povV4HTjvsy530kybxKHwEi85iU8YL0qQhSYVoQ=="}
+crypto.SignatureEd25519   - {"type":"6BF5903DA1DB28","value":"77sQNZOrf7ltExpf7AV1WaYPCHbyRLgjBsoWVzcduuLk+jIGmYk+s5R6Emm29p12HeiNAuhUJgdFGmwkpeGJCA=="}
+crypto.PubKeyEd25519      - {"type":"AC26791624DE60","value":"AT/+aaL1eB0477Mud9JMm8Sh8BIvOYlPGC9KkIUmFaE="}
+crypto.PrivKeySecp256k1   - {"type":"019E82E1B0F798","value":"zx4Pnh67N+g2V+5vZbQzEyRerX9c4ccNZOVzM9RvJ0Y="}
+crypto.SignatureSecp256k1 - {"type":"6D1EA416E1FEE8","value":"MEUCIQCIg5TqS1l7I+MKTrSPIuUN2+4m5tA29dcauqn3NhEJ2wIgICaZ+lgRc5aOTVahU/XoLopXKn8BZcl0bnuYWLvohR8="}
+crypto.PubKeySecp256k1    - {"type":"F8CCEAEB5AE980","value":"A8lPKJXcNl5VHt1FK8a244K9EJuS4WX1hFBnwisi0IJx"}
+```

encode_test.go

@@ -18,7 +18,9 @@ func checkAminoBinary(t *testing.T, src byter, dst interface{}, size int) {
 	// Make sure this is compatible with current (Bytes()) encoding.
 	assert.Equal(t, src.Bytes(), bz, "Amino binary vs Bytes() mismatch")
 	// Make sure we have the expected length.
-	assert.Equal(t, size, len(bz), "Amino binary size mismatch")
+	if size != -1 {
+		assert.Equal(t, size, len(bz), "Amino binary size mismatch")
+	}
 	// Unmarshal.
 	err = cdc.UnmarshalBinaryBare(bz, dst)
 	require.Nil(t, err, "%+v", err)
@@ -41,9 +43,8 @@ func checkAminoJSON(t *testing.T, src interface{}, dst interface{}, isNil bool)
 
 func TestKeyEncodings(t *testing.T) {
 	cases := []struct {
-		privKey PrivKey
-		// 1 (type byte) + size of byte array
-		privSize, pubSize int
+		privKey           PrivKey
+		privSize, pubSize int // binary sizes
 	}{
 		{
 			privKey:  GenPrivKeyEd25519(),
@@ -58,6 +59,7 @@ func TestKeyEncodings(t *testing.T) {
 	}
 
 	for _, tc := range cases {
+
 		// Check (de/en)codings of PrivKeys.
 		var priv2, priv3 PrivKey
 		checkAminoBinary(t, tc.privKey, &priv2, tc.privSize)
@@ -65,6 +67,14 @@ func TestKeyEncodings(t *testing.T) {
 		checkAminoJSON(t, tc.privKey, &priv3, false) // TODO also check Prefix bytes.
 		assert.EqualValues(t, tc.privKey, priv3)
 
+		// Check (de/en)codings of Signatures.
+		var sig1, sig2, sig3 Signature
+		sig1 = tc.privKey.Sign([]byte("something"))
+		checkAminoBinary(t, sig1, &sig2, -1) // Siganture size changes for Secp anyways.
+		assert.EqualValues(t, sig1, sig2)
+		checkAminoJSON(t, sig1, &sig3, false) // TODO also check Prefix bytes.
+		assert.EqualValues(t, sig1, sig3)
+
 		// Check (de/en)codings of PubKeys.
 		pubKey := tc.privKey.PubKey()
 		var pub2, pub3 PubKey