package tz import ( "github.com/nspcc-dev/tzhash/gogf127" ) type digestp struct { x [4]gogf127.GF127 } // New returns a new hash.Hash computing the Tillich-ZĂ©mor checksum. func newPure() *digestp { d := new(digestp) d.Reset() return d } func (d *digestp) Sum(in []byte) []byte { // Make a copy of d so that caller can keep writing and summing. d0 := *d h := d0.checkSum() return append(in, h[:]...) } func (d *digestp) checkSum() [hashSize]byte { return d.byteArray() } func (d *digestp) byteArray() (b [hashSize]byte) { for i := 0; i < 4; i++ { t := d.x[i].ByteArray() copy(b[i*16:], t[:]) } return } func (d *digestp) Reset() { d.x[0] = gogf127.GF127{1, 0} d.x[1] = gogf127.GF127{0, 0} d.x[2] = gogf127.GF127{0, 0} d.x[3] = gogf127.GF127{1, 0} } func (d *digestp) Write(data []byte) (n int, err error) { n = len(data) for _, b := range data { mulBitRightPure(&d.x[0], &d.x[1], &d.x[2], &d.x[3], b&0x80 != 0) mulBitRightPure(&d.x[0], &d.x[1], &d.x[2], &d.x[3], b&0x40 != 0) mulBitRightPure(&d.x[0], &d.x[1], &d.x[2], &d.x[3], b&0x20 != 0) mulBitRightPure(&d.x[0], &d.x[1], &d.x[2], &d.x[3], b&0x10 != 0) mulBitRightPure(&d.x[0], &d.x[1], &d.x[2], &d.x[3], b&0x08 != 0) mulBitRightPure(&d.x[0], &d.x[1], &d.x[2], &d.x[3], b&0x04 != 0) mulBitRightPure(&d.x[0], &d.x[1], &d.x[2], &d.x[3], b&0x02 != 0) mulBitRightPure(&d.x[0], &d.x[1], &d.x[2], &d.x[3], b&0x01 != 0) } return } func (d *digestp) Size() int { return hashSize } func (d *digestp) BlockSize() int { return hashBlockSize } func mulBitRightPure(c00, c01, c10, c11 *gogf127.GF127, bit bool) { var tmp gogf127.GF127 if bit { tmp = *c00 gogf127.Mul10(c00, c00) gogf127.Add(c00, c01, c00) gogf127.Mul11(&tmp, &tmp) gogf127.Add(c01, &tmp, c01) tmp = *c10 gogf127.Mul10(c10, c10) gogf127.Add(c10, c11, c10) gogf127.Mul11(&tmp, &tmp) gogf127.Add(c11, &tmp, c11) } else { tmp = *c00 gogf127.Mul10(c00, c00) gogf127.Add(c00, c01, c00) *c01 = tmp tmp = *c10 gogf127.Mul10(c10, c10) gogf127.Add(c10, c11, c10) *c11 = tmp } }