diff --git a/quic/core/crypto/crypto_protocol.h b/quic/core/crypto/crypto_protocol.h
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+++ b/quic/core/crypto/crypto_protocol.h
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+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef QUICHE_QUIC_CORE_CRYPTO_CRYPTO_PROTOCOL_H_
+#define QUICHE_QUIC_CORE_CRYPTO_CRYPTO_PROTOCOL_H_
+
+#include <cstddef>
+
+#include "net/third_party/quiche/src/quic/core/quic_tag.h"
+#include "net/third_party/quiche/src/quic/platform/api/quic_string.h"
+
+// Version and Crypto tags are written to the wire with a big-endian
+// representation of the name of the tag.  For example
+// the client hello tag (CHLO) will be written as the
+// following 4 bytes: 'C' 'H' 'L' 'O'.  Since it is
+// stored in memory as a little endian uint32_t, we need
+// to reverse the order of the bytes.
+//
+// We use a macro to ensure that no static initialisers are created. Use the
+// MakeQuicTag function in normal code.
+#define TAG(a, b, c, d) \
+  static_cast<QuicTag>((d << 24) + (c << 16) + (b << 8) + a)
+
+namespace quic {
+
+typedef QuicString ServerConfigID;
+
+// clang-format off
+const QuicTag kCHLO = TAG('C', 'H', 'L', 'O');   // Client hello
+const QuicTag kSHLO = TAG('S', 'H', 'L', 'O');   // Server hello
+const QuicTag kSCFG = TAG('S', 'C', 'F', 'G');   // Server config
+const QuicTag kREJ  = TAG('R', 'E', 'J', '\0');  // Reject
+const QuicTag kSREJ = TAG('S', 'R', 'E', 'J');   // Stateless reject
+const QuicTag kCETV = TAG('C', 'E', 'T', 'V');   // Client encrypted tag-value
+                                                 // pairs
+const QuicTag kPRST = TAG('P', 'R', 'S', 'T');   // Public reset
+const QuicTag kSCUP = TAG('S', 'C', 'U', 'P');   // Server config update
+const QuicTag kALPN = TAG('A', 'L', 'P', 'N');   // Application-layer protocol
+
+// Key exchange methods
+const QuicTag kP256 = TAG('P', '2', '5', '6');   // ECDH, Curve P-256
+const QuicTag kC255 = TAG('C', '2', '5', '5');   // ECDH, Curve25519
+
+// AEAD algorithms
+const QuicTag kAESG = TAG('A', 'E', 'S', 'G');   // AES128 + GCM-12
+const QuicTag kCC20 = TAG('C', 'C', '2', '0');   // ChaCha20 + Poly1305 RFC7539
+
+// Congestion control feedback types
+const QuicTag kQBIC = TAG('Q', 'B', 'I', 'C');   // TCP cubic
+
+// Connection options (COPT) values
+const QuicTag kAFCW = TAG('A', 'F', 'C', 'W');   // Auto-tune flow control
+                                                 // receive windows.
+const QuicTag kIFW5 = TAG('I', 'F', 'W', '5');   // Set initial size
+                                                 // of stream flow control
+                                                 // receive window to
+                                                 // 32KB. (2^5 KB).
+const QuicTag kIFW6 = TAG('I', 'F', 'W', '6');   // Set initial size
+                                                 // of stream flow control
+                                                 // receive window to
+                                                 // 64KB. (2^6 KB).
+const QuicTag kIFW7 = TAG('I', 'F', 'W', '7');   // Set initial size
+                                                 // of stream flow control
+                                                 // receive window to
+                                                 // 128KB. (2^7 KB).
+const QuicTag kIFW8 = TAG('I', 'F', 'W', '8');   // Set initial size
+                                                 // of stream flow control
+                                                 // receive window to
+                                                 // 256KB. (2^8 KB).
+const QuicTag kIFW9 = TAG('I', 'F', 'W', '9');   // Set initial size
+                                                 // of stream flow control
+                                                 // receive window to
+                                                 // 512KB. (2^9 KB).
+const QuicTag kIFWA = TAG('I', 'F', 'W', 'a');   // Set initial size
+                                                 // of stream flow control
+                                                 // receive window to
+                                                 // 1MB. (2^0xa KB).
+const QuicTag kTBBR = TAG('T', 'B', 'B', 'R');   // Reduced Buffer Bloat TCP
+const QuicTag k1RTT = TAG('1', 'R', 'T', 'T');   // STARTUP in BBR for 1 RTT
+const QuicTag k2RTT = TAG('2', 'R', 'T', 'T');   // STARTUP in BBR for 2 RTTs
+const QuicTag kLRTT = TAG('L', 'R', 'T', 'T');   // Exit STARTUP in BBR on loss
+const QuicTag kBBS1 = TAG('B', 'B', 'S', '1');   // Rate-based recovery in
+                                                 // BBR STARTUP
+const QuicTag kBBS2 = TAG('B', 'B', 'S', '2');   // More aggressive packet
+                                                 // conservation in BBR STARTUP
+const QuicTag kBBS3 = TAG('B', 'B', 'S', '3');   // Slowstart packet
+                                                 // conservation in BBR STARTUP
+const QuicTag kBBS4 = TAG('B', 'B', 'S', '4');   // Reduce rate in STARTUP by
+                                                 // bytes_lost / CWND.
+const QuicTag kBBS5 = TAG('B', 'B', 'S', '5');   // Reduce rate in STARTUP by
+                                                 // 2 * bytes_lost / CWND.
+const QuicTag kBBRR = TAG('B', 'B', 'R', 'R');   // Rate-based recovery in BBR
+const QuicTag kBBR1 = TAG('B', 'B', 'R', '1');   // DEPRECATED
+const QuicTag kBBR2 = TAG('B', 'B', 'R', '2');   // DEPRECATED
+const QuicTag kBBR3 = TAG('B', 'B', 'R', '3');   // Fully drain the queue once
+                                                 // per cycle
+const QuicTag kBBR4 = TAG('B', 'B', 'R', '4');   // 20 RTT ack aggregation
+const QuicTag kBBR5 = TAG('B', 'B', 'R', '5');   // 40 RTT ack aggregation
+const QuicTag kBBR6 = TAG('B', 'B', 'R', '6');   // PROBE_RTT with 0.75 * BDP
+const QuicTag kBBR7 = TAG('B', 'B', 'R', '7');   // Skip PROBE_RTT if rtt has
+                                                 // not changed 12.5%
+const QuicTag kBBR8 = TAG('B', 'B', 'R', '8');   // Disable PROBE_RTT when
+                                                 // recently app-limited
+const QuicTag kBBR9 = TAG('B', 'B', 'R', '9');   // Ignore app-limited calls in
+                                                 // BBR if enough inflight.
+const QuicTag kBBRS = TAG('B', 'B', 'R', 'S');   // Use 1.5x pacing in startup
+                                                 // after a loss has occurred.
+const QuicTag kBBQ1 = TAG('B', 'B', 'Q', '1');   // BBR with lower 2.77 STARTUP
+                                                 // pacing and CWND gain.
+const QuicTag kBBQ2 = TAG('B', 'B', 'Q', '2');   // BBR with lower 2.0 STARTUP
+                                                 // CWND gain.
+const QuicTag kBBQ3 = TAG('B', 'B', 'Q', '3');   // BBR with ack aggregation
+                                                 // compensation in STARTUP.
+const QuicTag kBBQ4 = TAG('B', 'B', 'Q', '4');   // Drain gain of 0.75.
+const QuicTag kBBQ5 = TAG('B', 'B', 'Q', '5');   // Expire ack aggregation upon
+                                                 // bandwidth increase in
+                                                 // STARTUP.
+const QuicTag kRENO = TAG('R', 'E', 'N', 'O');   // Reno Congestion Control
+const QuicTag kTPCC = TAG('P', 'C', 'C', '\0');  // Performance-Oriented
+                                                 // Congestion Control
+const QuicTag kBYTE = TAG('B', 'Y', 'T', 'E');   // TCP cubic or reno in bytes
+const QuicTag kIW03 = TAG('I', 'W', '0', '3');   // Force ICWND to 3
+const QuicTag kIW10 = TAG('I', 'W', '1', '0');   // Force ICWND to 10
+const QuicTag kIW20 = TAG('I', 'W', '2', '0');   // Force ICWND to 20
+const QuicTag kIW50 = TAG('I', 'W', '5', '0');   // Force ICWND to 50
+const QuicTag k1CON = TAG('1', 'C', 'O', 'N');   // Emulate a single connection
+const QuicTag kNTLP = TAG('N', 'T', 'L', 'P');   // No tail loss probe
+const QuicTag k1TLP = TAG('1', 'T', 'L', 'P');   // 1 tail loss probe
+const QuicTag k1RTO = TAG('1', 'R', 'T', 'O');   // Send 1 packet upon RTO
+const QuicTag kNRTO = TAG('N', 'R', 'T', 'O');   // CWND reduction on loss
+const QuicTag kTIME = TAG('T', 'I', 'M', 'E');   // Time based loss detection
+const QuicTag kATIM = TAG('A', 'T', 'I', 'M');   // Adaptive time loss detection
+const QuicTag kMIN1 = TAG('M', 'I', 'N', '1');   // Min CWND of 1 packet
+const QuicTag kMIN4 = TAG('M', 'I', 'N', '4');   // Min CWND of 4 packets,
+                                                 // with a min rate of 1 BDP.
+const QuicTag kTLPR = TAG('T', 'L', 'P', 'R');   // Tail loss probe delay of
+                                                 // 0.5RTT.
+const QuicTag kMAD0 = TAG('M', 'A', 'D', '0');   // Ignore ack delay
+const QuicTag kMAD1 = TAG('M', 'A', 'D', '1');   // 25ms initial max ack delay
+const QuicTag kMAD2 = TAG('M', 'A', 'D', '2');   // No min TLP
+const QuicTag kMAD3 = TAG('M', 'A', 'D', '3');   // No min RTO
+const QuicTag kMAD4 = TAG('M', 'A', 'D', '4');   // IETF style TLP
+const QuicTag kMAD5 = TAG('M', 'A', 'D', '5');   // IETF style TLP with 2x mult
+const QuicTag kACD0 = TAG('A', 'D', 'D', '0');   // Disable ack decimation
+const QuicTag kACKD = TAG('A', 'C', 'K', 'D');   // Ack decimation style acking.
+const QuicTag kAKD2 = TAG('A', 'K', 'D', '2');   // Ack decimation tolerating
+                                                 // out of order packets.
+const QuicTag kAKD3 = TAG('A', 'K', 'D', '3');   // Ack decimation style acking
+                                                 // with 1/8 RTT acks.
+const QuicTag kAKD4 = TAG('A', 'K', 'D', '4');   // Ack decimation with 1/8 RTT
+                                                 // tolerating out of order.
+const QuicTag kAKDU = TAG('A', 'K', 'D', 'U');   // Unlimited number of packets
+                                                 // received before acking
+const QuicTag kACKQ = TAG('A', 'C', 'K', 'Q');   // Send an immediate ack after
+                                                 // 1 RTT of not receiving.
+const QuicTag kSSLR = TAG('S', 'S', 'L', 'R');   // Slow Start Large Reduction.
+const QuicTag kNPRR = TAG('N', 'P', 'R', 'R');   // Pace at unity instead of PRR
+const QuicTag k5RTO = TAG('5', 'R', 'T', 'O');   // Close connection on 5 RTOs
+const QuicTag kCONH = TAG('C', 'O', 'N', 'H');   // Conservative Handshake
+                                                 // Retransmissions.
+const QuicTag kLFAK = TAG('L', 'F', 'A', 'K');   // Don't invoke FACK on the
+                                                 // first ack.
+const QuicTag kSTMP = TAG('S', 'T', 'M', 'P');   // Send and process timestamps
+// TODO(fayang): Remove this connection option when QUIC_VERSION_35, is removed
+// Since MAX_HEADER_LIST_SIZE settings frame is supported instead.
+const QuicTag kSMHL = TAG('S', 'M', 'H', 'L');   // Support MAX_HEADER_LIST_SIZE
+                                                 // settings frame.
+const QuicTag kNSTP = TAG('N', 'S', 'T', 'P');   // No stop waiting frames.
+const QuicTag kNRTT = TAG('N', 'R', 'T', 'T');   // Ignore initial RTT
+
+// Optional support of truncated Connection IDs.  If sent by a peer, the value
+// is the minimum number of bytes allowed for the connection ID sent to the
+// peer.
+const QuicTag kTCID = TAG('T', 'C', 'I', 'D');   // Connection ID truncation.
+
+// Multipath option.
+const QuicTag kMPTH = TAG('M', 'P', 'T', 'H');   // Enable multipath.
+
+const QuicTag kNCMR = TAG('N', 'C', 'M', 'R');   // Do not attempt connection
+                                                 // migration.
+
+// Disable Pacing offload option.
+const QuicTag kNPCO = TAG('N', 'P', 'C', 'O');    // No pacing offload.
+
+// Enable bandwidth resumption experiment.
+const QuicTag kBWRE = TAG('B', 'W', 'R', 'E');  // Bandwidth resumption.
+const QuicTag kBWMX = TAG('B', 'W', 'M', 'X');  // Max bandwidth resumption.
+const QuicTag kBWRS = TAG('B', 'W', 'R', 'S');  // Server bandwidth resumption.
+const QuicTag kBWS2 = TAG('B', 'W', 'S', '2');  // Server bw resumption v2.
+
+// Enable path MTU discovery experiment.
+const QuicTag kMTUH = TAG('M', 'T', 'U', 'H');  // High-target MTU discovery.
+const QuicTag kMTUL = TAG('M', 'T', 'U', 'L');  // Low-target MTU discovery.
+
+// Proof types (i.e. certificate types)
+// NOTE: although it would be silly to do so, specifying both kX509 and kX59R
+// is allowed and is equivalent to specifying only kX509.
+const QuicTag kX509 = TAG('X', '5', '0', '9');   // X.509 certificate, all key
+                                                 // types
+const QuicTag kX59R = TAG('X', '5', '9', 'R');   // X.509 certificate, RSA keys
+                                                 // only
+const QuicTag kCHID = TAG('C', 'H', 'I', 'D');   // Channel ID.
+
+// Client hello tags
+const QuicTag kVER  = TAG('V', 'E', 'R', '\0');  // Version
+const QuicTag kNONC = TAG('N', 'O', 'N', 'C');   // The client's nonce
+const QuicTag kNONP = TAG('N', 'O', 'N', 'P');   // The client's proof nonce
+const QuicTag kKEXS = TAG('K', 'E', 'X', 'S');   // Key exchange methods
+const QuicTag kAEAD = TAG('A', 'E', 'A', 'D');   // Authenticated
+                                                 // encryption algorithms
+const QuicTag kCOPT = TAG('C', 'O', 'P', 'T');   // Connection options
+const QuicTag kCLOP = TAG('C', 'L', 'O', 'P');   // Client connection options
+const QuicTag kICSL = TAG('I', 'C', 'S', 'L');   // Idle network timeout
+const QuicTag kSCLS = TAG('S', 'C', 'L', 'S');   // Silently close on timeout
+const QuicTag kMIDS = TAG('M', 'I', 'D', 'S');   // Max incoming dynamic streams
+const QuicTag kIRTT = TAG('I', 'R', 'T', 'T');   // Estimated initial RTT in us.
+const QuicTag kSNI  = TAG('S', 'N', 'I', '\0');  // Server name
+                                                 // indication
+const QuicTag kPUBS = TAG('P', 'U', 'B', 'S');   // Public key values
+const QuicTag kSCID = TAG('S', 'C', 'I', 'D');   // Server config id
+const QuicTag kORBT = TAG('O', 'B', 'I', 'T');   // Server orbit.
+const QuicTag kPDMD = TAG('P', 'D', 'M', 'D');   // Proof demand.
+const QuicTag kPROF = TAG('P', 'R', 'O', 'F');   // Proof (signature).
+const QuicTag kCCS  = TAG('C', 'C', 'S', 0);     // Common certificate set
+const QuicTag kCCRT = TAG('C', 'C', 'R', 'T');   // Cached certificate
+const QuicTag kEXPY = TAG('E', 'X', 'P', 'Y');   // Expiry
+const QuicTag kSTTL = TAG('S', 'T', 'T', 'L');   // Server Config TTL
+const QuicTag kSFCW = TAG('S', 'F', 'C', 'W');   // Initial stream flow control
+                                                 // receive window.
+const QuicTag kCFCW = TAG('C', 'F', 'C', 'W');   // Initial session/connection
+                                                 // flow control receive window.
+const QuicTag kUAID = TAG('U', 'A', 'I', 'D');   // Client's User Agent ID.
+const QuicTag kXLCT = TAG('X', 'L', 'C', 'T');   // Expected leaf certificate.
+const QuicTag kTBKP = TAG('T', 'B', 'K', 'P');   // Token Binding key params.
+
+// Token Binding tags
+const QuicTag kTB10 = TAG('T', 'B', '1', '0');   // TB draft 10 with P256.
+
+// Rejection tags
+const QuicTag kRREJ = TAG('R', 'R', 'E', 'J');   // Reasons for server sending
+// Stateless Reject tags
+const QuicTag kRCID = TAG('R', 'C', 'I', 'D');   // Server-designated
+                                                 // connection ID
+// Server hello tags
+const QuicTag kCADR = TAG('C', 'A', 'D', 'R');   // Client IP address and port
+const QuicTag kASAD = TAG('A', 'S', 'A', 'D');   // Alternate Server IP address
+                                                 // and port.
+const QuicTag kSRST = TAG('S', 'R', 'S', 'T');   // Stateless reset token used
+                                                 // in IETF public reset packet
+
+// CETV tags
+const QuicTag kCIDK = TAG('C', 'I', 'D', 'K');   // ChannelID key
+const QuicTag kCIDS = TAG('C', 'I', 'D', 'S');   // ChannelID signature
+
+// Public reset tags
+const QuicTag kRNON = TAG('R', 'N', 'O', 'N');   // Public reset nonce proof
+const QuicTag kRSEQ = TAG('R', 'S', 'E', 'Q');   // Rejected packet number
+
+// Universal tags
+const QuicTag kPAD  = TAG('P', 'A', 'D', '\0');  // Padding
+
+// Stats collection tags
+const QuicTag kEPID = TAG('E', 'P', 'I', 'D');  // Endpoint identifier.
+
+// clang-format on
+
+// These tags have a special form so that they appear either at the beginning
+// or the end of a handshake message. Since handshake messages are sorted by
+// tag value, the tags with 0 at the end will sort first and those with 255 at
+// the end will sort last.
+//
+// The certificate chain should have a tag that will cause it to be sorted at
+// the end of any handshake messages because it's likely to be large and the
+// client might be able to get everything that it needs from the small values at
+// the beginning.
+//
+// Likewise tags with random values should be towards the beginning of the
+// message because the server mightn't hold state for a rejected client hello
+// and therefore the client may have issues reassembling the rejection message
+// in the event that it sent two client hellos.
+const QuicTag kServerNonceTag = TAG('S', 'N', 'O', 0);  // The server's nonce
+const QuicTag kSourceAddressTokenTag =
+    TAG('S', 'T', 'K', 0);  // Source-address token
+const QuicTag kCertificateTag = TAG('C', 'R', 'T', 255);  // Certificate chain
+const QuicTag kCertificateSCTTag =
+    TAG('C', 'S', 'C', 'T');  // Signed cert timestamp (RFC6962) of leaf cert.
+
+#undef TAG
+
+const size_t kMaxEntries = 128;  // Max number of entries in a message.
+
+const size_t kNonceSize = 32;  // Size in bytes of the connection nonce.
+
+const size_t kOrbitSize = 8;  // Number of bytes in an orbit value.
+
+// kProofSignatureLabel is prepended to the CHLO hash and server configs before
+// signing to avoid any cross-protocol attacks on the signature.
+const char kProofSignatureLabel[] = "QUIC CHLO and server config signature";
+
+// kClientHelloMinimumSize is the minimum size of a client hello. Client hellos
+// will have PAD tags added in order to ensure this minimum is met and client
+// hellos smaller than this will be an error. This minimum size reduces the
+// amplification factor of any mirror DoS attack.
+//
+// A client may pad an inchoate client hello to a size larger than
+// kClientHelloMinimumSize to make it more likely to receive a complete
+// rejection message.
+const size_t kClientHelloMinimumSize = 1024;
+
+}  // namespace quic
+
+#endif  // QUICHE_QUIC_CORE_CRYPTO_CRYPTO_PROTOCOL_H_