Initial commit

third_party/official/gosdk_demo/zxsdk/wallet_sdk/mnemonics/mnemonics.go

@@ -0,0 +1,134 @@
+package mnemonics
+
+import (
+	"crypto/rand"
+	"encoding/binary"
+	"fmt"
+	"math/big"
+	"strings"
+	"wallet_sdk/mnemonics/wordlists"
+
+	"github.com/tjfoc/gmsm/sm3"
+)
+
+var (
+	// Some bitwise operands for working with big.Ints.
+	last11BitsMask  = big.NewInt(2047)
+	shift11BitsMask = big.NewInt(2048)
+	bigOne          = big.NewInt(1)
+	bigTwo          = big.NewInt(2)
+
+	wordList []string
+)
+
+func init() {
+	wordList = wordlists.English
+}
+
+func validateEntropyBitSize(bitSize int) error {
+	if (bitSize%32) != 0 || bitSize < 128 || bitSize > 256 {
+		return fmt.Errorf("invalid entropy length")
+	}
+
+	return nil
+}
+
+func computeChecksum(data []byte) []byte {
+	hasher := sm3.New()
+	_, _ = hasher.Write(data) // This error is guaranteed to be nil
+
+	return hasher.Sum(nil)
+}
+
+func addChecksum(data []byte) []byte {
+	// Get first byte of sha256
+	hash := computeChecksum(data)
+	firstChecksumByte := hash[0]
+
+	// len() is in bytes so we divide by 4
+	checksumBitLength := uint(len(data) / 4)
+
+	// For each bit of check sum we want we shift the data one the left
+	// and then set the (new) right most bit equal to checksum bit at that index
+	// staring from the left
+	dataBigInt := new(big.Int).SetBytes(data)
+
+	for i := uint(0); i < checksumBitLength; i++ {
+		// Bitshift 1 left
+		dataBigInt.Mul(dataBigInt, bigTwo)
+
+		// Set rightmost bit if leftmost checksum bit is set
+		if firstChecksumByte&(1<<(7-i)) > 0 {
+			dataBigInt.Or(dataBigInt, bigOne)
+		}
+	}
+
+	return dataBigInt.Bytes()
+}
+
+func padByteSlice(slice []byte, length int) []byte {
+	offset := length - len(slice)
+	if offset <= 0 {
+		return slice
+	}
+
+	newSlice := make([]byte, length)
+	copy(newSlice[offset:], slice)
+
+	return newSlice
+}
+
+func NewEntropy(bitSize int) ([]byte, error) {
+	if err := validateEntropyBitSize(bitSize); err != nil {
+		return nil, err
+	}
+
+	entropy := make([]byte, bitSize/8)
+	_, _ = rand.Read(entropy) // err is always nil
+
+	return entropy, nil
+}
+
+func NewMnemonic(entropy []byte) (string, error) {
+	// Compute some lengths for convenience.
+	entropyBitLength := len(entropy) * 8
+	checksumBitLength := entropyBitLength / 32
+	sentenceLength := (entropyBitLength + checksumBitLength) / 11
+
+	// Validate that the requested size is supported.
+	err := validateEntropyBitSize(entropyBitLength)
+	if err != nil {
+		return "", err
+	}
+
+	// Add checksum to entropy.
+	entropy = addChecksum(entropy)
+
+	// Break entropy up into sentenceLength chunks of 11 bits.
+	// For each word AND mask the rightmost 11 bits and find the word at that index.
+	// Then bitshift entropy 11 bits right and repeat.
+	// Add to the last empty slot so we can work with LSBs instead of MSB.
+
+	// Entropy as an int so we can bitmask without worrying about bytes slices.
+	entropyInt := new(big.Int).SetBytes(entropy)
+
+	// Slice to hold words in.
+	words := make([]string, sentenceLength)
+
+	// Throw away big.Int for AND masking.
+	word := big.NewInt(0)
+
+	for i := sentenceLength - 1; i >= 0; i-- {
+		// Get 11 right most bits and bitshift 11 to the right for next time.
+		word.And(entropyInt, last11BitsMask)
+		entropyInt.Div(entropyInt, shift11BitsMask)
+
+		// Get the bytes representing the 11 bits as a 2 byte slice.
+		wordBytes := padByteSlice(word.Bytes(), 2)
+
+		// Convert bytes to an index and add that word to the list.
+		words[i] = wordList[binary.BigEndian.Uint16(wordBytes)]
+	}
+
+	return strings.Join(words, " "), nil
+}