mirror of
https://github.com/cryptonote-social/csminer.git
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101 lines
2.5 KiB
Go
101 lines
2.5 KiB
Go
// Copyright 2020 cryptonote.social. All rights reserved. Use of this source code is governed by
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// the license found in the LICENSE file.
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package blockchain
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// blockchain/base58.go implements "bitcoin style" base58 encoding/decoding of large ints
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import (
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"fmt"
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"math/big"
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)
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var (
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alphabet [58]byte
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decoder [256]int
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radix *big.Int
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zero *big.Int
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)
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func init() {
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alphabet = [58]byte{
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'1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F',
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'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
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'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'm',
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'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'}
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radix = big.NewInt(58)
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for i := range decoder {
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decoder[i] = -1
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}
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for i, b := range alphabet[:] {
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decoder[b] = i
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}
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radix = big.NewInt(58)
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zero = big.NewInt(0)
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}
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// given a bitcoin-base58 encoded string, returns the decoded string, or error if the input string
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// was not bitcoin-base58 format
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func DecodeBitcoinBase58(b58 string) (string, error) {
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if len(b58) == 0 {
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return "", nil
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}
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// handle leading zeros
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var zeros []byte
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for i := 0; i < len(b58)-1; i++ {
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if b58[i] != alphabet[0] {
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break
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}
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zeros = append(zeros, '0')
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}
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// now decode the rest
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bigOutput := new(big.Int)
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var decoded int
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for i := len(zeros); i < len(b58); i++ {
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c := b58[i]
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if decoded = decoder[c]; decoded < 0 {
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return "", fmt.Errorf("found invalid char [%c] while decoding base58 string [%v] at byte offset %v", c, b58, i)
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}
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bigOutput.Add(bigOutput.Mul(bigOutput, radix), big.NewInt(int64(decoded)))
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}
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return string(bigOutput.Append(zeros, 10)), nil
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}
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// given a base-10 integer string, returns the bitcoin-base58 encoded string of that integer, or
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// error if the input was not a base-10 integer.
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func EncodeBitcoinBase58(dec string) (string, error) {
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if len(dec) == 0 {
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return "", nil
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}
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bigInput, ok := new(big.Int).SetString(dec, 10)
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if !ok {
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return "", fmt.Errorf("expected a base10 string but got %s", dec)
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}
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// handle leading zeros
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output := []byte{}
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for i := 0; i < len(dec); i++ {
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if dec[i] != '0' {
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break
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}
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output = append(output, alphabet[0])
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}
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zeros := len(output)
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// now encode the rest
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var mod big.Int
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for bigInput.Cmp(zero) == 1 {
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bigInput.DivMod(bigInput, radix, &mod)
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output = append(output, alphabet[mod.Int64()])
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}
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reverse(output[zeros:])
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return string(output), nil
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}
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func reverse(b []byte) {
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for i, j := 0, len(b)-1; i < j; i, j = i+1, j-1 {
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b[i], b[j] = b[j], b[i]
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}
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}
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