e911666b5d
fixed make lint warnings cleared linter_exclude_list.txt removed some commented code fixed comments from #388
53 lines
1.4 KiB
Go
53 lines
1.4 KiB
Go
package extkeys
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import (
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"crypto/hmac"
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"crypto/sha512"
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"errors"
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"math/big"
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"github.com/btcsuite/btcd/btcec"
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)
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// errors
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var (
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ErrInvalidSecretKey = errors.New("generated secret key cannot be used")
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)
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func splitHMAC(seed, salt []byte) (secretKey, chainCode []byte, err error) {
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data := hmac.New(sha512.New, salt)
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if _, err = data.Write(seed); err != nil {
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return
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}
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I := data.Sum(nil)
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// Split I into two 32-byte sequences, IL and IR.
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// IL = master secret key
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// IR = master chain code
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secretKey = I[:32]
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chainCode = I[32:]
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// IL (secretKey) is expected to be a 256-bit integer (it is used as parse256(IL)),
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// and consequently that integer must be within range for SECP256k1 private key.
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//
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// There's tiny possibility (<1 in 2^127) this invariant is violated:
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// error is returned in that case, and simple resolution is to request another child with i incremented.
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keyBigInt := new(big.Int).SetBytes(secretKey)
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if keyBigInt.Cmp(btcec.S256().N) >= 0 || keyBigInt.Sign() == 0 {
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err = ErrInvalidSecretKey
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}
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return
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}
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// paddedAppend appends the src byte slice to dst, returning the new slice.
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// If the length of the source is smaller than the passed size, leading zero
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// bytes are appended to the dst slice before appending src.
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// nolint: unparam
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func paddedAppend(size uint, dst, src []byte) []byte {
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for i := 0; i < int(size)-len(src); i++ {
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dst = append(dst, 0)
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}
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return append(dst, src...)
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}
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