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53 lines
1.5 KiB
53 lines
1.5 KiB
// Copyright (c) 2013-2014 The btcsuite developers |
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// Use of this source code is governed by an ISC |
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// license that can be found in the LICENSE file. |
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package base58 |
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import ( |
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"errors" |
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"github.com/minio/sha256-simd" |
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) |
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// ErrChecksum indicates that the checksum of a check-encoded string does not verify against |
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// the checksum. |
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var ErrChecksum = errors.New("checksum error") |
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// ErrInvalidFormat indicates that the check-encoded string has an invalid format. |
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var ErrInvalidFormat = errors.New("invalid format: version and/or checksum bytes missing") |
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// checksum: first four bytes of sha256^2 |
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func checksum(input []byte) (cksum [4]byte) { |
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h := sha256.Sum256(input) |
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h2 := sha256.Sum256(h[:]) |
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copy(cksum[:], h2[:4]) |
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return |
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} |
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// CheckEncode prepends a version byte and appends a four byte checksum. |
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func CheckEncode(input []byte, version byte) string { |
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b := make([]byte, 0, 1+len(input)+4) |
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b = append(b, version) |
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b = append(b, input...) |
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cksum := checksum(b) |
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b = append(b, cksum[:]...) |
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return Encode(b) |
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} |
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// CheckDecode decodes a string that was encoded with CheckEncode and verifies the checksum. |
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func CheckDecode(input string) (result []byte, version byte, err error) { |
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decoded := Decode(input) |
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if len(decoded) < 5 { |
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return nil, 0, ErrInvalidFormat |
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} |
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version = decoded[0] |
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var cksum [4]byte |
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copy(cksum[:], decoded[len(decoded)-4:]) |
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if checksum(decoded[:len(decoded)-4]) != cksum { |
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return nil, 0, ErrChecksum |
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} |
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payload := decoded[1 : len(decoded)-4] |
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result = append(result, payload...) |
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return |
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}
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