Function pHash

tls12/tls12.go:25–42

pHash implements the P_hash function, as defined in RFC 5246, Section 5.

(hash1 func() H, result, secret, seed []byte)

// pHash implements the P_hash function, as defined in RFC 5246, Section 5.
func pHash[H hash.Hash](hash1 func() H, result, secret, seed []byte) {
	h := hmac.New(any(hash1).(func() hash.Hash), secret)
	h.Write(seed)
	a := h.Sum(nil)

	for len(result) > 0 {
		h.Reset()
		h.Write(a)
		h.Write(seed)
		b := h.Sum(nil)
		n := copy(result, b)
		result = result[n:]

		h.Reset()
		h.Write(a)
		a = h.Sum(nil)
	}
}

const masterSecretLength = 48
const extendedMasterSecretLabel = "extended master secret"