seed []byte, keyLen int) []byte { labelAndSeed := make([]byte, len(label)+len(seed)) copy(labelAndSeed, label) copy(labelAndSeed[len(label):], seed) result := make([]byte, keyLen) pHash(hash, result, secret, labelAndSeed) return result } // pHash implements the P_hash function, as defined in RFC 5246, Section 5. func pHash[H fips140.Hash](hash func() H, result, secret, seed []byte) { h := hmac.New(hash, secret) h.Write(seed) a := h.Sum(nil) for len(result) > 0 { h.Reset() h.Write(a) h.Write(seed) b...