Add crc16 support

glide.lock

@@ -1,5 +1,5 @@
-hash: 3bcee9fbccf29d21217b24b6a83ec51e1514f37b2ae5d8718cf6c5df80f4fb2c
-updated: 2017-06-19T17:16:58.037568333+02:00
+hash: c0a2db1b80c6b1b8aab31c526ce43e22e49b23c893c78b8fdb8546aa2e7b7cc6
+updated: 2017-07-22T05:24:42.82932575-04:00
 imports:
 - name: github.com/bgentry/speakeasy
   version: 4aabc24848ce5fd31929f7d1e4ea74d3709c14cd
@@ -38,11 +38,11 @@ imports:
 - name: github.com/gorilla/context
   version: 08b5f424b9271eedf6f9f0ce86cb9396ed337a42
 - name: github.com/gorilla/handlers
-  version: 3a5767ca75ece5f7f1440b1d16975247f8d8b221
+  version: a4043c62cc2329bacda331d33fc908ab11ef0ec3
 - name: github.com/gorilla/mux
-  version: 392c28fe23e1c45ddba891b0320b3b5df220beea
+  version: bcd8bc72b08df0f70df986b97f95590779502d31
 - name: github.com/hashicorp/hcl
-  version: a4b07c25de5ff55ad3b8936cea69a79a3d95a855
+  version: 392dba7d905ed5d04a5794ba89f558b27e2ba1ca
   subpackages:
   - hcl/ast
   - hcl/parser
@@ -52,6 +52,8 @@ imports:
   - json/parser
   - json/scanner
   - json/token
+- name: github.com/howeyc/crc16
+  version: 58da63c846043d0bea709c8d47039df06577d6d9
 - name: github.com/inconshreveable/mousetrap
   version: 76626ae9c91c4f2a10f34cad8ce83ea42c93bb75
 - name: github.com/kr/logfmt
@@ -67,7 +69,7 @@ imports:
 - name: github.com/pelletier/go-toml
   version: 13d49d4606eb801b8f01ae542b4afc4c6ee3d84a
 - name: github.com/pkg/errors
-  version: ff09b135c25aae272398c51a07235b90a75aa4f0
+  version: 645ef00459ed84a119197bfb8d8205042c6df63d
 - name: github.com/spf13/afero
   version: 9be650865eab0c12963d8753212f4f9c66cdcf12
   subpackages:
@@ -75,11 +77,11 @@ imports:
 - name: github.com/spf13/cast
   version: acbeb36b902d72a7a4c18e8f3241075e7ab763e4
 - name: github.com/spf13/cobra
-  version: db6b9a8b3f3f400c8ecb4a4d7d02245b8facad66
+  version: 4cdb38c072b86bf795d2c81de50784d9fdd6eb77
 - name: github.com/spf13/jwalterweatherman
-  version: fa7ca7e836cf3a8bb4ebf799f472c12d7e903d66
+  version: 8f07c835e5cc1450c082fe3a439cf87b0cbb2d99
 - name: github.com/spf13/pflag
-  version: 80fe0fb4eba54167e2ccae1c6c950e72abf61b73
+  version: e57e3eeb33f795204c1ca35f56c44f83227c6e66
 - name: github.com/spf13/viper
   version: 0967fc9aceab2ce9da34061253ac10fb99bba5b2
 - name: github.com/tendermint/ed25519
@@ -93,7 +95,7 @@ imports:
   - data
   - data/base58
 - name: github.com/tendermint/tmlibs
-  version: bd9d0d1637dadf1330e167189d5e5031aadcda6f
+  version: 2f6f3e6aa70bb19b70a6e73210273fa127041070
   subpackages:
   - cli
   - common
@@ -111,7 +113,7 @@ imports:
   - ripemd160
   - salsa20/salsa
 - name: golang.org/x/sys
-  version: 9ccfe848b9db8435a24c424abbc07a921adf1df5
+  version: e62c3de784db939836898e5c19ffd41bece347da
   subpackages:
   - unix
 - name: golang.org/x/text

glide.yaml

@@ -29,6 +29,7 @@ import:
 - package: github.com/spf13/cobra
 - package: github.com/spf13/viper
 - package: gopkg.in/go-playground/validator.v9
+- package: github.com/howeyc/crc16
 testImport:
 - package: github.com/mndrix/btcutil
 - package: github.com/stretchr/testify

keys/ecc.go

@@ -5,6 +5,8 @@ import (
 	"errors"
 	"hash/crc32"
 	"hash/crc64"
+
+	"github.com/howeyc/crc16"
 )
 
 // ECC is used for anything that calculates an error-correcting code
@@ -26,6 +28,67 @@ var _ ECC = NoECC{}
 func (_ NoECC) AddECC(input []byte) []byte            { return input }
 func (_ NoECC) CheckECC(input []byte) ([]byte, error) { return input, nil }
 
+// CRC16 does the ieee crc16 polynomial check
+type CRC16 struct {
+	Poly  uint16
+	table *crc16.Table
+}
+
+var _ ECC = &CRC16{}
+
+const crc16Size = 2
+
+func NewIBMCRC16() *CRC16 {
+	return &CRC16{Poly: crc16.IBM}
+}
+
+func NewSCSICRC16() *CRC16 {
+	return &CRC16{Poly: crc16.SCSI}
+}
+
+func NewCCITTCRC16() *CRC16 {
+	return &CRC16{Poly: crc16.CCITT}
+}
+
+func (c *CRC16) AddECC(input []byte) []byte {
+	table := c.getTable()
+
+	// get crc and convert to some bytes...
+	crc := crc16.Checksum(input, table)
+	check := make([]byte, crc16Size)
+	binary.BigEndian.PutUint16(check, crc)
+
+	// append it to the input
+	output := append(input, check...)
+	return output
+}
+
+func (c *CRC16) CheckECC(input []byte) ([]byte, error) {
+	table := c.getTable()
+
+	if len(input) <= crc16Size {
+		return nil, errors.New("input too short, no checksum present")
+	}
+	cut := len(input) - crc16Size
+	data, check := input[:cut], input[cut:]
+	crc := binary.BigEndian.Uint16(check)
+	calc := crc16.Checksum(data, table)
+	if crc != calc {
+		return nil, errors.New("Checksum does not match")
+	}
+	return data, nil
+}
+
+func (c *CRC16) getTable() *crc16.Table {
+	if c.table == nil {
+		if c.Poly == 0 {
+			c.Poly = crc16.IBM
+		}
+		c.table = crc16.MakeTable(c.Poly)
+	}
+	return c.table
+}
+
 // CRC32 does the ieee crc32 polynomial check
 type CRC32 struct {
 	Poly  uint32

keys/ecc_test.go

@@ -14,6 +14,9 @@ func TestECCPasses(t *testing.T) {
 
 	checks := []ECC{
 		NoECC{},
+		NewIBMCRC16(),
+		NewSCSICRC16(),
+		NewCCITTCRC16(),
 		NewIEEECRC32(),
 		NewCastagnoliCRC32(),
 		NewKoopmanCRC32(),
@@ -40,6 +43,9 @@ func TestECCFails(t *testing.T) {
 	assert := assert.New(t)
 
 	checks := []ECC{
+		NewIBMCRC16(),
+		NewSCSICRC16(),
+		NewCCITTCRC16(),
 		NewIEEECRC32(),
 		NewCastagnoliCRC32(),
 		NewKoopmanCRC32(),