mirror of https://github.com/status-im/nim-eth.git
553 lines
18 KiB
Nim
553 lines
18 KiB
Nim
#
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# Ethereum P2P
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# (c) Copyright 2018
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# Status Research & Development GmbH
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#
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# Licensed under either of
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# Apache License, version 2.0, (LICENSE-APACHEv2)
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# MIT license (LICENSE-MIT)
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#
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## This module implements Ethereum authentication
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{.push raises: [Defect].}
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import
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nimcrypto/[rijndael, keccak, utils], bearssl,
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stew/[byteutils, endians2, objects, results],
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".."/[keys, rlp],
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./ecies
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export results
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const
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SupportedRlpxVersion* = 4'u8
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PlainAuthMessageV4Length* = 194
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AuthMessageV4Length* = 307
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PlainAuthMessageEIP8Length = 169
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PlainAuthMessageMaxEIP8* = PlainAuthMessageEIP8Length + 255
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AuthMessageEIP8Length* = 282 + 2
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AuthMessageMaxEIP8* = AuthMessageEIP8Length + 255
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PlainAckMessageV4Length* = 97
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AckMessageV4Length* = 210
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PlainAckMessageEIP8Length* = 102
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PlainAckMessageMaxEIP8* = PlainAckMessageEIP8Length + 255
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AckMessageEIP8Length* = 215 + 2
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AckMessageMaxEIP8* = AckMessageEIP8Length + 255
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type
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Nonce* = array[KeyLength, byte]
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AuthMessageV4* {.packed.} = object
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signature: array[RawSignatureSize, byte]
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keyhash: array[keccak256.sizeDigest, byte]
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pubkey: array[RawPublicKeySize, byte]
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nonce: array[keccak256.sizeDigest, byte]
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flag: byte
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AckMessageV4* {.packed.} = object
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pubkey: array[RawPublicKeySize, byte]
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nonce: array[keccak256.sizeDigest, byte]
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flag: byte
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HandshakeFlag* = enum
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Initiator, ## `Handshake` owner is connection initiator
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Responder, ## `Handshake` owner is connection responder
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EIP8 ## Flag indicates that EIP-8 handshake is used
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AuthError* = enum
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EcdhError = "auth: ECDH shared secret could not be calculated"
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BufferOverrun = "auth: buffer overrun"
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SignatureError = "auth: signature could not be obtained"
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EciesError = "auth: ECIES encryption/decryption error"
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InvalidPubKey = "auth: invalid public key"
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InvalidAuth = "auth: invalid Authentication message"
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InvalidAck = "auth: invalid Authentication ACK message"
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RlpError = "auth: error while decoding RLP stream"
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IncompleteError = "auth: data incomplete"
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Handshake* = object
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version*: uint8 ## protocol version
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flags*: set[HandshakeFlag] ## handshake flags
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host*: KeyPair ## host keypair
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ephemeral*: KeyPair ## ephemeral host keypair
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remoteHPubkey*: PublicKey ## remote host public key
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remoteEPubkey*: PublicKey ## remote host ephemeral public key
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initiatorNonce*: Nonce ## initiator nonce
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responderNonce*: Nonce ## responder nonce
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expectedLength*: int ## expected incoming message length
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ConnectionSecret* = object
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aesKey*: array[aes256.sizeKey, byte]
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macKey*: array[KeyLength, byte]
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egressMac*: keccak256
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ingressMac*: keccak256
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AuthResult*[T] = Result[T, AuthError]
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template toa(a, b, c: untyped): untyped =
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toOpenArray((a), (b), (b) + (c) - 1)
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proc `xor`[N: static int](a, b: array[N, byte]): array[N, byte] =
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for i in 0 ..< len(a):
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result[i] = a[i] xor b[i]
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proc mapErrTo[T, E](r: Result[T, E], v: static AuthError): AuthResult[T] =
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r.mapErr(proc (e: E): AuthError = v)
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proc tryInit*(
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T: type Handshake, rng: var BrHmacDrbgContext, host: KeyPair,
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flags: set[HandshakeFlag] = {Initiator},
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version: uint8 = SupportedRlpxVersion): AuthResult[T] =
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## Create new `Handshake` object.
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var
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initiatorNonce: Nonce
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responderNonce: Nonce
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expectedLength: int
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ephemeral = KeyPair.random(rng)
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if Initiator in flags:
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expectedLength = AckMessageV4Length
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brHmacDrbgGenerate(rng, initiatorNonce)
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else:
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expectedLength = AuthMessageV4Length
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brHmacDrbgGenerate(rng, responderNonce)
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return ok(T(
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version: version,
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flags: flags,
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host: host,
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ephemeral: ephemeral,
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initiatorNonce: initiatorNonce,
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responderNonce: responderNonce,
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expectedLength: expectedLength
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))
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proc authMessagePreEIP8(h: var Handshake,
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rng: var BrHmacDrbgContext,
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pubkey: PublicKey,
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output: var openArray[byte],
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outlen: var int,
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flag: byte = 0,
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encrypt: bool = true): AuthResult[void] =
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## Create plain pre-EIP8 authentication message.
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var
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buffer: array[PlainAuthMessageV4Length, byte]
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outlen = 0
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let header = cast[ptr AuthMessageV4](addr buffer[0])
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var secret = ecdhRaw(h.host.seckey, pubkey)
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secret.data = secret.data xor h.initiatorNonce
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let signature = sign(h.ephemeral.seckey, SkMessage(secret.data))
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secret.clear()
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h.remoteHPubkey = pubkey
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header.signature = signature.toRaw()
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header.keyhash = keccak256.digest(h.ephemeral.pubkey.toRaw()).data
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header.pubkey = h.host.pubkey.toRaw()
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header.nonce = h.initiatorNonce
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header.flag = flag
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if encrypt:
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if len(output) < AuthMessageV4Length:
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return err(BufferOverrun)
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if eciesEncrypt(rng, buffer, output, h.remoteHPubkey).isErr:
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return err(EciesError)
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outlen = AuthMessageV4Length
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else:
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if len(output) < PlainAuthMessageV4Length:
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return err(BufferOverrun)
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copyMem(addr output[0], addr buffer[0], PlainAuthMessageV4Length)
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outlen = PlainAuthMessageV4Length
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ok()
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proc authMessageEIP8(h: var Handshake,
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rng: var BrHmacDrbgContext,
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pubkey: PublicKey,
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output: var openArray[byte],
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outlen: var int,
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flag: byte = 0,
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encrypt: bool = true): AuthResult[void] =
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## Create EIP8 authentication message.
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var
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buffer: array[PlainAuthMessageMaxEIP8, byte]
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padsize: array[1, byte]
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doAssert(EIP8 in h.flags)
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outlen = 0
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var secret = ecdhRaw(h.host.seckey, pubkey)
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secret.data = secret.data xor h.initiatorNonce
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let signature = sign(h.ephemeral.seckey, SkMessage(secret.data))
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secret.clear()
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h.remoteHPubkey = pubkey
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var payload = rlp.encodeList(signature.toRaw(),
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h.host.pubkey.toRaw(),
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h.initiatorNonce,
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[byte(h.version)])
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doAssert(len(payload) == PlainAuthMessageEIP8Length)
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let
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pencsize = eciesEncryptedLength(len(payload))
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while true:
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brHmacDrbgGenerate(rng, padsize)
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if int(padsize[0]) > (AuthMessageV4Length - (pencsize + 2)):
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break
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# It is possible to make packet size constant by uncommenting this line
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# padsize = 24
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let wosize = pencsize + int(padsize[0])
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let fullsize = wosize + 2
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brHmacDrbgGenerate(
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rng, toa(buffer, PlainAuthMessageEIP8Length, int(padsize[0])))
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if encrypt:
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copyMem(addr buffer[0], addr payload[0], len(payload))
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if len(output) < fullsize:
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return err(BufferOverrun)
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let wosizeBE = uint16(wosize).toBytesBE()
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output[0..<2] = wosizeBE
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if eciesEncrypt(rng, toa(buffer, 0, len(payload) + int(padsize[0])),
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toa(output, 2, wosize), pubkey,
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toa(output, 0, 2)).isErr:
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return err(EciesError)
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outlen = fullsize
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else:
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let plainsize = len(payload) + int(padsize[0])
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if len(output) < plainsize:
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return err(BufferOverrun)
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copyMem(addr output[0], addr buffer[0], plainsize)
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outlen = plainsize
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ok()
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proc ackMessagePreEIP8(h: var Handshake,
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rng: var BrHmacDrbgContext,
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output: var openArray[byte],
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outlen: var int,
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flag: byte = 0,
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encrypt: bool = true): AuthResult[void] =
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## Create plain pre-EIP8 authentication ack message.
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var buffer: array[PlainAckMessageV4Length, byte]
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outlen = 0
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let header = cast[ptr AckMessageV4](addr buffer[0])
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header.pubkey = h.ephemeral.pubkey.toRaw()
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header.nonce = h.responderNonce
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header.flag = flag
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if encrypt:
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if len(output) < AckMessageV4Length:
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return err(BufferOverrun)
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if eciesEncrypt(rng, buffer, output, h.remoteHPubkey).isErr:
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return err(EciesError)
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outlen = AckMessageV4Length
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else:
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if len(output) < PlainAckMessageV4Length:
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return err(BufferOverrun)
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copyMem(addr output[0], addr buffer[0], PlainAckMessageV4Length)
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outlen = PlainAckMessageV4Length
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ok()
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proc ackMessageEIP8(h: var Handshake,
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rng: var BrHmacDrbgContext,
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output: var openArray[byte],
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outlen: var int,
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flag: byte = 0,
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encrypt: bool = true): AuthResult[void] =
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## Create EIP8 authentication ack message.
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var
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buffer: array[PlainAckMessageMaxEIP8, byte]
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padsize: array[1, byte]
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doAssert(EIP8 in h.flags)
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var payload = rlp.encodeList(h.ephemeral.pubkey.toRaw(),
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h.responderNonce,
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[byte(h.version)])
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doAssert(len(payload) == PlainAckMessageEIP8Length)
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outlen = 0
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let pencsize = eciesEncryptedLength(len(payload))
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while true:
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brHmacDrbgGenerate(rng, padsize)
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if int(padsize[0]) > (AckMessageV4Length - (pencsize + 2)):
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break
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# It is possible to make packet size constant by uncommenting this line
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# padsize = 0
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let wosize = pencsize + int(padsize[0])
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let fullsize = wosize + 2
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if int(padsize[0]) > 0:
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brHmacDrbgGenerate(
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rng, toa(buffer, PlainAckMessageEIP8Length, int(padsize[0])))
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copyMem(addr buffer[0], addr payload[0], len(payload))
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if encrypt:
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if len(output) < fullsize:
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return err(BufferOverrun)
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output[0..<2] = uint16(wosize).toBytesBE()
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if eciesEncrypt(rng, toa(buffer, 0, len(payload) + int(padsize[0])),
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toa(output, 2, wosize), h.remoteHPubkey,
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toa(output, 0, 2)).isErr:
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return err(EciesError)
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outlen = fullsize
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else:
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let plainsize = len(payload) + int(padsize[0])
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if len(output) < plainsize:
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return err(BufferOverrun)
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copyMem(addr output[0], addr buffer[0], plainsize)
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outlen = plainsize
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ok()
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template authSize*(h: Handshake, encrypt: bool = true): int =
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## Get number of bytes needed to store AuthMessage.
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if EIP8 in h.flags:
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if encrypt: (AuthMessageMaxEIP8) else: (PlainAuthMessageMaxEIP8)
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else:
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if encrypt: (AuthMessageV4Length) else: (PlainAuthMessageV4Length)
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template ackSize*(h: Handshake, encrypt: bool = true): int =
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## Get number of bytes needed to store AckMessage.
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if EIP8 in h.flags:
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if encrypt: (AckMessageMaxEIP8) else: (PlainAckMessageMaxEIP8)
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else:
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if encrypt: (AckMessageV4Length) else: (PlainAckMessageV4Length)
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proc authMessage*(h: var Handshake, rng: var BrHmacDrbgContext,
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pubkey: PublicKey,
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output: var openArray[byte],
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outlen: var int, flag: byte = 0,
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encrypt: bool = true): AuthResult[void] =
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## Create new AuthMessage for specified `pubkey` and store it inside
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## of `output`, size of generated AuthMessage will stored in `outlen`.
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if EIP8 in h.flags:
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authMessageEIP8(h, rng, pubkey, output, outlen, flag, encrypt)
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else:
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authMessagePreEIP8(h, rng, pubkey, output, outlen, flag, encrypt)
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proc ackMessage*(h: var Handshake, rng: var BrHmacDrbgContext,
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output: var openArray[byte],
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outlen: var int, flag: byte = 0,
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encrypt: bool = true): AuthResult[void] =
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## Create new AckMessage and store it inside of `output`, size of generated
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## AckMessage will stored in `outlen`.
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if EIP8 in h.flags:
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ackMessageEIP8(h, rng, output, outlen, flag, encrypt)
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else:
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ackMessagePreEIP8(h, rng, output, outlen, flag, encrypt)
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proc decodeAuthMessageV4(h: var Handshake, m: openArray[byte]): AuthResult[void] =
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## Decodes V4 AuthMessage.
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var
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buffer: array[PlainAuthMessageV4Length, byte]
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doAssert(Responder in h.flags)
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if eciesDecrypt(m, buffer, h.host.seckey).isErr:
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return err(EciesError)
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let
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header = cast[ptr AuthMessageV4](addr buffer[0])
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pubkey = ? PublicKey.fromRaw(header.pubkey).mapErrTo(InvalidPubKey)
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signature = ? Signature.fromRaw(header.signature).mapErrTo(SignatureError)
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var secret = ecdhRaw(h.host.seckey, pubkey)
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secret.data = secret.data xor header.nonce
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var recovered = recover(signature, SkMessage(secret.data))
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secret.clear()
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h.remoteEPubkey = ? recovered.mapErrTo(SignatureError)
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h.initiatorNonce = header.nonce
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h.remoteHPubkey = pubkey
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ok()
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proc decodeAuthMessageEIP8(h: var Handshake, m: openArray[byte]): AuthResult[void] =
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## Decodes EIP-8 AuthMessage.
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let size = uint16.fromBytesBE(m)
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h.expectedLength = int(size) + 2
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if h.expectedLength > len(m):
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return err(IncompleteError)
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var buffer = newSeq[byte](eciesDecryptedLength(int(size)))
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if eciesDecrypt(toa(m, 2, int(size)), buffer, h.host.seckey,
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toa(m, 0, 2)).isErr:
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return err(EciesError)
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try:
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var reader = rlpFromBytes(buffer)
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if not reader.isList() or reader.listLen() < 4:
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return err(InvalidAuth)
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if reader.listElem(0).blobLen != RawSignatureSize:
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return err(InvalidAuth)
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if reader.listElem(1).blobLen != RawPublicKeySize:
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return err(InvalidAuth)
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if reader.listElem(2).blobLen != KeyLength:
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return err(InvalidAuth)
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if reader.listElem(3).blobLen != 1:
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return err(InvalidAuth)
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let
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signatureBr = reader.listElem(0).toBytes()
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pubkeyBr = reader.listElem(1).toBytes()
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nonceBr = reader.listElem(2).toBytes()
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versionBr = reader.listElem(3).toBytes()
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let
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signature = ? Signature.fromRaw(signatureBr).mapErrTo(SignatureError)
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pubkey = ? PublicKey.fromRaw(pubkeyBr).mapErrTo(InvalidPubKey)
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nonce = toArray(KeyLength, nonceBr)
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var secret = ecdhRaw(h.host.seckey, pubkey)
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secret.data = secret.data xor nonce
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let recovered = recover(signature, SkMessage(secret.data))
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secret.clear()
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h.remoteEPubkey = ? recovered.mapErrTo(SignatureError)
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h.initiatorNonce = nonce
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h.remoteHPubkey = pubkey
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h.version = versionBr[0]
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ok()
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except CatchableError:
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err(RlpError)
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proc decodeAckMessageEIP8*(h: var Handshake, m: openArray[byte]): AuthResult[void] =
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## Decodes EIP-8 AckMessage.
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let size = uint16.fromBytesBE(m)
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h.expectedLength = 2 + int(size)
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if h.expectedLength > len(m):
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return err(IncompleteError)
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var buffer = newSeq[byte](eciesDecryptedLength(int(size)))
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if eciesDecrypt(toa(m, 2, int(size)), buffer, h.host.seckey,
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toa(m, 0, 2)).isErr:
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return err(EciesError)
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try:
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var reader = rlpFromBytes(buffer)
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if not reader.isList() or reader.listLen() < 3:
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return err(InvalidAck)
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if reader.listElem(0).blobLen != RawPublicKeySize:
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return err(InvalidAck)
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if reader.listElem(1).blobLen != KeyLength:
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return err(InvalidAck)
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if reader.listElem(2).blobLen != 1:
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return err(InvalidAck)
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let
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pubkeyBr = reader.listElem(0).toBytes()
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nonceBr = reader.listElem(1).toBytes()
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versionBr = reader.listElem(2).toBytes()
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h.remoteEPubkey = ? PublicKey.fromRaw(pubkeyBr).mapErrTo(InvalidPubKey)
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h.responderNonce = toArray(KeyLength, nonceBr)
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h.version = versionBr[0]
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ok()
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except CatchableError:
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err(RlpError)
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proc decodeAckMessageV4(h: var Handshake, m: openArray[byte]): AuthResult[void] =
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## Decodes V4 AckMessage.
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var
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buffer: array[PlainAckMessageV4Length, byte]
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doAssert(Initiator in h.flags)
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if eciesDecrypt(m, buffer, h.host.seckey).isErr:
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return err(EciesError)
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var header = cast[ptr AckMessageV4](addr buffer[0])
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h.remoteEPubkey = ? PublicKey.fromRaw(header.pubkey).mapErrTo(InvalidPubKey)
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h.responderNonce = header.nonce
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ok()
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proc decodeAuthMessage*(h: var Handshake, input: openArray[byte]): AuthResult[void] =
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## Decodes AuthMessage from `input`.
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if len(input) < AuthMessageV4Length:
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return err(IncompleteError)
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if len(input) == AuthMessageV4Length:
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let res = h.decodeAuthMessageV4(input)
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if res.isOk(): return res
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let res = h.decodeAuthMessageEIP8(input)
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if res.isOk():
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h.flags.incl(EIP8)
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res
|
|
|
|
proc decodeAckMessage*(h: var Handshake, input: openArray[byte]): AuthResult[void] =
|
|
## Decodes AckMessage from `input`.
|
|
if len(input) < AckMessageV4Length:
|
|
return err(IncompleteError)
|
|
if len(input) == AckMessageV4Length:
|
|
let res = h.decodeAckMessageV4(input)
|
|
if res.isOk(): return res
|
|
|
|
let res = h.decodeAckMessageEIP8(input)
|
|
if res.isOk(): h.flags.incl(EIP8)
|
|
res
|
|
|
|
proc getSecrets*(
|
|
h: Handshake, authmsg: openArray[byte],
|
|
ackmsg: openArray[byte]): ConnectionSecret =
|
|
## Derive secrets from handshake `h` using encrypted AuthMessage `authmsg` and
|
|
## encrypted AckMessage `ackmsg`.
|
|
var
|
|
ctx0: keccak256
|
|
ctx1: keccak256
|
|
mac1: MDigest[256]
|
|
secret: ConnectionSecret
|
|
|
|
# ecdhe-secret = ecdh.agree(ephemeral-privkey, remote-ephemeral-pubk)
|
|
var shsec = ecdhRaw(h.ephemeral.seckey, h.remoteEPubkey)
|
|
|
|
# shared-secret = keccak(ecdhe-secret || keccak(nonce || initiator-nonce))
|
|
ctx0.init()
|
|
ctx1.init()
|
|
ctx1.update(h.responderNonce)
|
|
ctx1.update(h.initiatorNonce)
|
|
mac1 = ctx1.finish()
|
|
ctx1.clear()
|
|
ctx0.update(shsec.data)
|
|
ctx0.update(mac1.data)
|
|
mac1 = ctx0.finish()
|
|
|
|
# aes-secret = keccak(ecdhe-secret || shared-secret)
|
|
ctx0.init()
|
|
ctx0.update(shsec.data)
|
|
ctx0.update(mac1.data)
|
|
mac1 = ctx0.finish()
|
|
|
|
# mac-secret = keccak(ecdhe-secret || aes-secret)
|
|
ctx0.init()
|
|
ctx0.update(shsec.data)
|
|
ctx0.update(mac1.data)
|
|
secret.aesKey = mac1.data
|
|
mac1 = ctx0.finish()
|
|
secret.macKey = mac1.data
|
|
|
|
clear(shsec)
|
|
|
|
# egress-mac = keccak256(mac-secret ^ recipient-nonce || auth-sent-init)
|
|
|
|
var xornonce = mac1.data xor h.responderNonce
|
|
ctx0.init()
|
|
ctx0.update(xornonce)
|
|
ctx0.update(authmsg)
|
|
|
|
# ingress-mac = keccak256(mac-secret ^ initiator-nonce || auth-recvd-ack)
|
|
xornonce = secret.macKey xor h.initiatorNonce
|
|
|
|
ctx1.init()
|
|
ctx1.update(xornonce)
|
|
ctx1.update(ackmsg)
|
|
burnMem(xornonce)
|
|
|
|
if Initiator in h.flags:
|
|
secret.egressMac = ctx0
|
|
secret.ingressMac = ctx1
|
|
else:
|
|
secret.ingressMac = ctx0
|
|
secret.egressMac = ctx1
|
|
|
|
ctx0.clear()
|
|
ctx1.clear()
|
|
|
|
secret
|