添加 github.com/pion/dtls 代码

dtls-2.0.9/pkg/crypto/prf/prf.go

@@ -0,0 +1,224 @@
+// Package prf implements TLS 1.2 Pseudorandom functions
+package prf
+
+import ( //nolint:gci
+	ellipticStdlib "crypto/elliptic"
+	"crypto/hmac"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"hash"
+	"math"
+
+	"github.com/pion/dtls/v2/pkg/crypto/elliptic"
+	"github.com/pion/dtls/v2/pkg/protocol"
+	"golang.org/x/crypto/curve25519"
+)
+
+const (
+	masterSecretLabel         = "master secret"
+	extendedMasterSecretLabel = "extended master secret"
+	keyExpansionLabel         = "key expansion"
+	verifyDataClientLabel     = "client finished"
+	verifyDataServerLabel     = "server finished"
+)
+
+// HashFunc allows callers to decide what hash is used in PRF
+type HashFunc func() hash.Hash
+
+// EncryptionKeys is all the state needed for a TLS CipherSuite
+type EncryptionKeys struct {
+	MasterSecret   []byte
+	ClientMACKey   []byte
+	ServerMACKey   []byte
+	ClientWriteKey []byte
+	ServerWriteKey []byte
+	ClientWriteIV  []byte
+	ServerWriteIV  []byte
+}
+
+var errInvalidNamedCurve = &protocol.FatalError{Err: errors.New("invalid named curve")} //nolint:goerr113
+
+func (e *EncryptionKeys) String() string {
+	return fmt.Sprintf(`encryptionKeys:
+- masterSecret: %#v
+- clientMACKey: %#v
+- serverMACKey: %#v
+- clientWriteKey: %#v
+- serverWriteKey: %#v
+- clientWriteIV: %#v
+- serverWriteIV: %#v
+`,
+		e.MasterSecret,
+		e.ClientMACKey,
+		e.ServerMACKey,
+		e.ClientWriteKey,
+		e.ServerWriteKey,
+		e.ClientWriteIV,
+		e.ServerWriteIV)
+}
+
+// PSKPreMasterSecret generates the PSK Premaster Secret
+// The premaster secret is formed as follows: if the PSK is N octets
+// long, concatenate a uint16 with the value N, N zero octets, a second
+// uint16 with the value N, and the PSK itself.
+//
+// https://tools.ietf.org/html/rfc4279#section-2
+func PSKPreMasterSecret(psk []byte) []byte {
+	pskLen := uint16(len(psk))
+
+	out := append(make([]byte, 2+pskLen+2), psk...)
+	binary.BigEndian.PutUint16(out, pskLen)
+	binary.BigEndian.PutUint16(out[2+pskLen:], pskLen)
+
+	return out
+}
+
+// PreMasterSecret implements TLS 1.2 Premaster Secret generation given a keypair and a curve
+func PreMasterSecret(publicKey, privateKey []byte, curve elliptic.Curve) ([]byte, error) {
+	switch curve {
+	case elliptic.X25519:
+		return curve25519.X25519(privateKey, publicKey)
+	case elliptic.P256:
+		return ellipticCurvePreMasterSecret(publicKey, privateKey, ellipticStdlib.P256(), ellipticStdlib.P256())
+	case elliptic.P384:
+		return ellipticCurvePreMasterSecret(publicKey, privateKey, ellipticStdlib.P384(), ellipticStdlib.P384())
+	default:
+		return nil, errInvalidNamedCurve
+	}
+}
+
+func ellipticCurvePreMasterSecret(publicKey, privateKey []byte, c1, c2 ellipticStdlib.Curve) ([]byte, error) {
+	x, y := ellipticStdlib.Unmarshal(c1, publicKey)
+	if x == nil || y == nil {
+		return nil, errInvalidNamedCurve
+	}
+
+	result, _ := c2.ScalarMult(x, y, privateKey)
+	preMasterSecret := make([]byte, (c2.Params().BitSize+7)>>3)
+	resultBytes := result.Bytes()
+	copy(preMasterSecret[len(preMasterSecret)-len(resultBytes):], resultBytes)
+	return preMasterSecret, nil
+}
+
+// PHash is PRF is the SHA-256 hash function is used for all cipher suites
+// defined in this TLS 1.2 document and in TLS documents published prior to this
+// document when TLS 1.2 is negotiated.  New cipher suites MUST explicitly
+// specify a PRF and, in general, SHOULD use the TLS PRF with SHA-256 or a
+// stronger standard hash function.
+//
+//    P_hash(secret, seed) = HMAC_hash(secret, A(1) + seed) +
+//                           HMAC_hash(secret, A(2) + seed) +
+//                           HMAC_hash(secret, A(3) + seed) + ...
+//
+// A() is defined as:
+//
+//    A(0) = seed
+//    A(i) = HMAC_hash(secret, A(i-1))
+//
+// P_hash can be iterated as many times as necessary to produce the
+// required quantity of data.  For example, if P_SHA256 is being used to
+// create 80 bytes of data, it will have to be iterated three times
+// (through A(3)), creating 96 bytes of output data; the last 16 bytes
+// of the final iteration will then be discarded, leaving 80 bytes of
+// output data.
+//
+// https://tools.ietf.org/html/rfc4346w
+func PHash(secret, seed []byte, requestedLength int, h HashFunc) ([]byte, error) {
+	hmacSHA256 := func(key, data []byte) ([]byte, error) {
+		mac := hmac.New(h, key)
+		if _, err := mac.Write(data); err != nil {
+			return nil, err
+		}
+		return mac.Sum(nil), nil
+	}
+
+	var err error
+	lastRound := seed
+	out := []byte{}
+
+	iterations := int(math.Ceil(float64(requestedLength) / float64(h().Size())))
+	for i := 0; i < iterations; i++ {
+		lastRound, err = hmacSHA256(secret, lastRound)
+		if err != nil {
+			return nil, err
+		}
+		withSecret, err := hmacSHA256(secret, append(lastRound, seed...))
+		if err != nil {
+			return nil, err
+		}
+		out = append(out, withSecret...)
+	}
+
+	return out[:requestedLength], nil
+}
+
+// ExtendedMasterSecret generates a Extended MasterSecret as defined in
+// https://tools.ietf.org/html/rfc7627
+func ExtendedMasterSecret(preMasterSecret, sessionHash []byte, h HashFunc) ([]byte, error) {
+	seed := append([]byte(extendedMasterSecretLabel), sessionHash...)
+	return PHash(preMasterSecret, seed, 48, h)
+}
+
+// MasterSecret generates a TLS 1.2 MasterSecret
+func MasterSecret(preMasterSecret, clientRandom, serverRandom []byte, h HashFunc) ([]byte, error) {
+	seed := append(append([]byte(masterSecretLabel), clientRandom...), serverRandom...)
+	return PHash(preMasterSecret, seed, 48, h)
+}
+
+// GenerateEncryptionKeys is the final step TLS 1.2 PRF. Given all state generated so far generates
+// the final keys need for encryption
+func GenerateEncryptionKeys(masterSecret, clientRandom, serverRandom []byte, macLen, keyLen, ivLen int, h HashFunc) (*EncryptionKeys, error) {
+	seed := append(append([]byte(keyExpansionLabel), serverRandom...), clientRandom...)
+	keyMaterial, err := PHash(masterSecret, seed, (2*macLen)+(2*keyLen)+(2*ivLen), h)
+	if err != nil {
+		return nil, err
+	}
+
+	clientMACKey := keyMaterial[:macLen]
+	keyMaterial = keyMaterial[macLen:]
+
+	serverMACKey := keyMaterial[:macLen]
+	keyMaterial = keyMaterial[macLen:]
+
+	clientWriteKey := keyMaterial[:keyLen]
+	keyMaterial = keyMaterial[keyLen:]
+
+	serverWriteKey := keyMaterial[:keyLen]
+	keyMaterial = keyMaterial[keyLen:]
+
+	clientWriteIV := keyMaterial[:ivLen]
+	keyMaterial = keyMaterial[ivLen:]
+
+	serverWriteIV := keyMaterial[:ivLen]
+
+	return &EncryptionKeys{
+		MasterSecret:   masterSecret,
+		ClientMACKey:   clientMACKey,
+		ServerMACKey:   serverMACKey,
+		ClientWriteKey: clientWriteKey,
+		ServerWriteKey: serverWriteKey,
+		ClientWriteIV:  clientWriteIV,
+		ServerWriteIV:  serverWriteIV,
+	}, nil
+}
+
+func prfVerifyData(masterSecret, handshakeBodies []byte, label string, hashFunc HashFunc) ([]byte, error) {
+	h := hashFunc()
+	if _, err := h.Write(handshakeBodies); err != nil {
+		return nil, err
+	}
+
+	seed := append([]byte(label), h.Sum(nil)...)
+	return PHash(masterSecret, seed, 12, hashFunc)
+}
+
+// VerifyDataClient is caled on the Client Side to either verify or generate the VerifyData message
+func VerifyDataClient(masterSecret, handshakeBodies []byte, h HashFunc) ([]byte, error) {
+	return prfVerifyData(masterSecret, handshakeBodies, verifyDataClientLabel, h)
+}
+
+// VerifyDataServer is caled on the Server Side to either verify or generate the VerifyData message
+func VerifyDataServer(masterSecret, handshakeBodies []byte, h HashFunc) ([]byte, error) {
+	return prfVerifyData(masterSecret, handshakeBodies, verifyDataServerLabel, h)
+}