utils.go

package btcaddress

import (
	"hash"
	"crypto/sha256"
)

// paddedAppend appends the src byte slice to dst, returning the new slice.
// If the length of the source is smaller than the passed size, leading zero
// bytes are appended to the dst slice before appending src.
func paddedAppend(size uint, dst, src []byte) []byte {
	for i := 0; i < int(size)-len(src); i++ {
		dst = append(dst, 0)
	}
	return append(dst, src...)
}

// Calculate the hash of hasher over buf.
func calcHash(buf []byte, hasher hash.Hash) []byte {
	hasher.Write(buf)
	return hasher.Sum(nil)
}

// HashB calculates hash(b) and returns the resulting bytes.
func HashB(b []byte) []byte {
	hash := sha256.Sum256(b)
	return hash[:]
}

// HashH calculates hash(b) and returns the resulting bytes as a Hash.
func HashH(b []byte) [HashSize]byte {
	return Hash(sha256.Sum256(b))
}

// DoubleHashB calculates hash(hash(b)) and returns the resulting bytes.
func DoubleHashB(b []byte) []byte {
	first := sha256.Sum256(b)
	second := sha256.Sum256(first[:])
	return second[:]
}

// DoubleHashH calculates hash(hash(b)) and returns the resulting bytes as a
// Hash.
func DoubleHashH(b []byte) Hash {
	first := sha256.Sum256(b)
	return Hash(sha256.Sum256(first[:]))
}