require strkey length is divisible by 8

build/asset_test.go

@@ -55,7 +55,7 @@ func TestAsset_ToXDR(t *testing.T) {
 		{
 			Name:        "bad issuer",
 			Asset:       CreditAsset("USD", "FUNK"),
-			ExpectedErr: "base32 decode failed: illegal base32 data at input byte 0",
+			ExpectedErr: "length has to be a multiple of 8",
 		},
 		{
 			Name:        "bad code",

build/set_options_test.go

@@ -35,7 +35,7 @@ func TestSetOptions_Signer(t *testing.T) {
 			Name:    "Bad",
 			Address: "foo",
 			Weight:  1,
-			Error:   "base32 decode failed",
+			Error:   "length has to be a multiple of 8",
 		},
 	}
 

strkey/decode_test.go

@@ -86,3 +86,10 @@ func TestDecode(t *testing.T) {
 	_, err = Decode(VersionByteAccountID, "GA3D5KRYM6CB7OWOOOORR3Z4T7GNZLKERYNZGGA5SOAOPIFY6YQHES5")
 	assert.Error(t, err)
 }
+
+func TestDecodeDisallowPadding(t *testing.T) {
+	invalidKey := "GDWZCOEQRODFCH6ISYQPWY67L3ULLWS5ISXYYL5GH43W7Y"
+	_, err := Decode(VersionByteAccountID /* XXX */, invalidKey)
+
+	assert.Error(t, err, "Padding is disallowed")
+}

strkey/main.go

@@ -13,6 +13,10 @@ import (
 // strkey-encoded string is not one of the valid values.
 var ErrInvalidVersionByte = errors.New("invalid version byte")
 
+// ErrLengthIsNotDivisibleBy8 is returned when the length of a
+// strkey-encoded string is not a multiple of 8.
+var ErrLengthIsNotDivisibleBy8 = errors.New("length has to be a multiple of 8")
+
 // VersionByte represents one of the possible prefix values for a StrKey base
 // string--the string the when encoded using base32 yields a final StrKey.
 type VersionByte byte
@@ -178,6 +182,11 @@ func checkValidVersionByte(version VersionByte) error {
 // potentially be strkey encoded (i.e. it has both a version byte and a
 // checksum, neither of which are explicitly checked by this func)
 func decodeString(src string) ([]byte, error) {
+	// base 32 data size is (s * 5)/8 => has to be a multiple of 8
+	if (len(src) & 0x07) != 0 {
+		return nil, ErrLengthIsNotDivisibleBy8
+	}
+
 	raw, err := base32.StdEncoding.DecodeString(src)
 	if err != nil {
 		return nil, errors.Wrap(err, "base32 decode failed")

txnbuild/asset_test.go

@@ -99,6 +99,6 @@ func TestBadIssuer(t *testing.T) {
 	var xdrAssetCode [4]byte
 	copy(xdrAssetCode[:], asset.Code)
 	var xdrIssuer xdr.AccountId
-	expectedErrMsg := "base32 decode failed: illegal base32 data at input byte 16"
+	expectedErrMsg := "length has to be a multiple of 8"
 	require.EqualError(t, xdrIssuer.SetAddress(asset.Issuer), expectedErrMsg, "Issuer address should be validated")
 }