43 lines
1.1 KiB
Go
43 lines
1.1 KiB
Go
package utils
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import (
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"crypto/sha256"
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"errors"
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"github.com/btcsuite/btcutil/base58"
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)
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var (
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// ErrChecksumMismatch describes an error where decoding failed due
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// to a bad checksum.
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ErrChecksumMismatch = errors.New("checksum mismatch")
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// ErrInvalidFormat describes an error where decoding failed due to invalid version
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ErrInvalidFormat = errors.New("invalid format: version and/or checksum bytes missing")
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)
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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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// 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 := base58.Decode(input)
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if len(decoded) < 5 {
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return nil, nil, ErrInvalidFormat
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}
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version = append(version, decoded[0:2]...)
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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, nil, ErrChecksumMismatch
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}
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payload := decoded[2 : len(decoded)-4]
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result = append(result, payload...)
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return
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}
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