542 lines
19 KiB
Nim
542 lines
19 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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# See the file "LICENSE", included in this
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# distribution, for details about the copyright.
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#
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## This module implements Ethereum authentication
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import endians
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import eth_keys, ecies, rlp
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import nimcrypto/sysrand, nimcrypto/hash, nimcrypto/utils, nimcrypto/hmac
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import nimcrypto/rijndael, nimcrypto/keccak, nimcrypto/sha2
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const
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SupportedRlpxVersion* = 4
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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* = object {.packed.}
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signature: array[RawSignatureSize, byte]
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keyhash: array[keccak256.sizeDigest, byte]
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pubkey: PublicKey
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nonce: array[keccak256.sizeDigest, byte]
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flag: byte
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AckMessageV4* = object {.packed.}
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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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AuthStatus* = enum
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Success, ## Operation was successful
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RandomError, ## Could not obtain random data
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EcdhError, ## ECDH shared secret could not be calculated
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BufferOverrun, ## Buffer overrun error
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SignatureError, ## Signature could not be obtained
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EciesError, ## ECIES encryption/decryption error
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InvalidPubKey, ## Invalid public key
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InvalidAuth, ## Invalid Authentication message
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InvalidAck, ## Invalid Authentication ACK message
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RlpError, ## Error while decoding RLP stream
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IncompleteError ## Data incomplete error
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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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ConnectionSecret* = object
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aesKey*: array[aes256.sizeKey, byte]
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macKey*: array[KeyLength, byte]
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egressMac*: array[keccak256.sizeDigest, byte]
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ingressMac*: array[keccak256.sizeDigest, byte]
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AuthException* = object of Exception
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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 sxor[T](a: var openarray[T], b: openarray[T]) =
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assert(len(a) == len(b))
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for i in 0 ..< len(a):
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a[i] = a[i] xor b[i]
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proc newHandshake*(flags: set[HandshakeFlag] = {Initiator},
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version: int = SupportedRlpxVersion): Handshake =
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## Create new `Handshake` object.
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result.version = byte(version and 0xFF)
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result.flags = flags
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result.ephemeral = newKeyPair()
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if Initiator in flags:
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if randomBytes(result.initiatorNonce) != len(result.initiatorNonce):
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raise newException(AuthException, "Could not obtain random data!")
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else:
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if randomBytes(result.responderNonce) != len(result.responderNonce):
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raise newException(AuthException, "Could not obtain random data!")
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proc authMessagePreEIP8(h: var Handshake,
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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: int = 0,
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encrypt: bool = true): AuthStatus =
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## Create plain pre-EIP8 authentication message.
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var
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secret: SharedSecret
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signature: Signature
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buffer: array[PlainAuthMessageV4Length, byte]
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flagb: byte
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header: ptr AuthMessageV4
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outlen = 0
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flagb = byte(flag)
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header = cast[ptr AuthMessageV4](addr buffer[0])
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if ecdhAgree(h.host.seckey, pubkey, secret) != EthKeysStatus.Success:
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return(EcdhError)
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var xornonce = h.initiatorNonce
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xornonce.sxor(secret.data)
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if signRawMessage(xornonce, h.ephemeral.seckey,
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signature) != EthKeysStatus.Success:
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return(SignatureError)
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h.remoteHPubkey = pubkey
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header.signature = signature.getRaw()
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header.keyhash = keccak256.digest(h.ephemeral.pubkey.getRaw()).data
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header.pubkey = cast[PublicKey](h.host.pubkey.getRaw())
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header.nonce = h.initiatorNonce
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header.flag = flagb
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if encrypt:
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if len(output) < AuthMessageV4Length:
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return(BufferOverrun)
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if eciesEncrypt(buffer, output, h.remoteHPubkey) != EciesStatus.Success:
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return(EciesError)
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outlen = AuthMessageV4Length
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result = Success
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else:
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if len(output) < PlainAuthMessageV4Length:
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return(BufferOverrun)
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copyMem(addr output[0], addr buffer[0], PlainAuthMessageV4Length)
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outlen = PlainAuthMessageV4Length
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result = Success
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proc authMessageEIP8(h: var Handshake,
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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: int = 0,
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encrypt: bool = true): AuthStatus =
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## Create EIP8 authentication message.
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var
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secret: SharedSecret
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signature: Signature
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buffer: array[PlainAuthMessageMaxEIP8, byte]
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padsize: byte
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assert(EIP8 in h.flags)
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outlen = 0
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if ecdhAgree(h.host.seckey, pubkey, secret) != EthKeysStatus.Success:
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return(EcdhError)
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var xornonce = h.initiatorNonce
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xornonce.sxor(secret.data)
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if signRawMessage(xornonce, h.ephemeral.seckey,
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signature) != EthKeysStatus.Success:
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return(SignatureError)
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h.remoteHPubkey = pubkey
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var payload = rlp.encodeList(signature.getRaw(),
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h.host.pubkey.getRaw(),
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h.initiatorNonce,
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[byte(h.version)])
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assert(len(payload) == PlainAuthMessageEIP8Length)
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let pencsize = eciesEncryptedLength(len(payload))
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while true:
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if randomBytes(addr padsize, 1) != 1:
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return(RandomError)
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if int(padsize) > (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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var wosize = pencsize + int(padsize)
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let fullsize = wosize + 2
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if randomBytes(toa(buffer, PlainAuthMessageEIP8Length,
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int(padsize))) != int(padsize):
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return(RandomError)
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if encrypt:
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copyMem(addr buffer[0], payload.baseAddr, len(payload))
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if len(output) < fullsize:
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return(BufferOverrun)
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bigEndian16(addr output, addr wosize)
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if eciesEncrypt(toa(buffer, 0, len(payload) + int(padsize)),
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toa(output, 2, wosize), pubkey,
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toa(output, 0, 2)) != EciesStatus.Success:
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return(EciesError)
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outlen = fullsize
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else:
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let plainsize = len(payload) + int(padsize)
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if len(output) < plainsize:
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return(BufferOverrun)
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copyMem(addr output[0], addr buffer[0], plainsize)
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outlen = plainsize
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result = Success
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proc ackMessagePreEIP8(h: var Handshake,
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output: var openarray[byte],
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outlen: var int,
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flag: int = 0,
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encrypt: bool = true): AuthStatus =
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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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var header = cast[ptr AckMessageV4](addr buffer[0])
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header.pubkey = h.ephemeral.pubkey.getRaw()
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header.nonce = h.responderNonce
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header.flag = byte(flag)
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if encrypt:
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if len(output) < AckMessageV4Length:
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return(BufferOverrun)
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if eciesEncrypt(buffer, output, h.remoteHPubkey) != EciesStatus.Success:
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return(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(BufferOverrun)
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copyMem(addr output[0], addr buffer[0], PlainAckMessageV4Length)
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outlen = PlainAckMessageV4Length
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result = Success
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proc ackMessageEIP8(h: var Handshake,
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output: var openarray[byte],
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outlen: var int,
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flag: int = 0,
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encrypt: bool = true): AuthStatus =
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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: byte
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assert(EIP8 in h.flags)
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var payload = rlp.encodeList(h.ephemeral.pubkey.getRaw(),
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h.responderNonce,
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[byte(h.version)])
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assert(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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if randomBytes(addr padsize, 1) != 1:
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return(RandomError)
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if int(padsize) > (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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var wosize = pencsize + int(padsize)
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let fullsize = wosize + 2
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if int(padsize) > 0:
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if randomBytes(toa(buffer, PlainAckMessageEIP8Length,
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int(padsize))) != int(padsize):
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return(RandomError)
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copyMem(addr buffer[0], payload.baseAddr, len(payload))
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if encrypt:
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if len(output) < fullsize:
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return(BufferOverrun)
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bigEndian16(addr output, addr wosize)
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if eciesEncrypt(toa(buffer, 0, len(payload) + int(padsize)),
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toa(output, 2, wosize), h.remoteHPubkey,
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toa(output, 0, 2)) != EciesStatus.Success:
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return(EciesError)
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outlen = fullsize
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else:
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let plainsize = len(payload) + int(padsize)
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if len(output) < plainsize:
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return(BufferOverrun)
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copyMem(addr output[0], addr buffer[0], plainsize)
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outlen = plainsize
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result = Success
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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, pubkey: PublicKey,
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output: var openarray[byte],
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outlen: var int, flag: int = 0,
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encrypt: bool = true): AuthStatus {.inline.} =
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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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result = authMessageEIP8(h, pubkey, output, outlen, flag, encrypt)
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else:
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result = authMessagePreEIP8(h, pubkey, output, outlen, flag, encrypt)
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proc ackMessage*(h: var Handshake, output: var openarray[byte],
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outlen: var int, flag: int = 0,
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encrypt: bool = true): AuthStatus =
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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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result = ackMessageEIP8(h, output, outlen, flag, encrypt)
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else:
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result = ackMessagePreEIP8(h, output, outlen, flag, encrypt)
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proc decodeAuthMessageV4(h: var Handshake, m: openarray[byte]): AuthStatus =
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## Decodes V4 AuthMessage.
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var
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secret: SharedSecret
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buffer: array[PlainAuthMessageV4Length, byte]
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pubkey: PublicKey
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assert(Responder in h.flags)
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if eciesDecrypt(m, buffer, h.host.seckey) != EciesStatus.Success:
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return(EciesError)
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var header = cast[ptr AuthMessageV4](addr buffer[0])
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if recoverPublicKey(header.pubkey.data, pubkey) != EthKeysStatus.Success:
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return(InvalidPubKey)
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if ecdhAgree(h.host.seckey, pubkey, secret) != EthKeysStatus.Success:
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return(EcdhError)
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var xornonce = header.nonce
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xornonce.sxor(secret.data)
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if recoverSignatureKey(header.signature, xornonce,
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h.remoteEPubkey) != EthKeysStatus.Success:
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return(SignatureError)
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h.initiatorNonce = header.nonce
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h.remoteHPubkey = pubkey
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result = Success
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proc decodeAuthMessageEip8(h: var Handshake, m: openarray[byte]): AuthStatus =
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## Decodes EIP-8 AuthMessage.
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var
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pubkey: PublicKey
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nonce: Nonce
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size: uint16
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secret: SharedSecret
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bigEndian16(addr size, unsafeAddr m[0])
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if 2 + int(size) > len(m):
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return(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)) != EciesStatus.Success:
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return(EciesError)
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try:
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var reader = rlpFromBytes(buffer.toRange())
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if not reader.isList() or reader.listLen() < 4:
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return(InvalidAuth)
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if reader.listElem(0).blobLen != RawSignatureSize:
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return(InvalidAuth)
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if reader.listElem(1).blobLen != RawPublicKeySize:
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return(InvalidAuth)
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if reader.listElem(2).blobLen != KeyLength:
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return(InvalidAuth)
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if reader.listElem(3).blobLen != 1:
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return(InvalidAuth)
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var signatureBr = reader.listElem(0).toBytes()
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var pubkeyBr = reader.listElem(1).toBytes()
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var nonceBr = reader.listElem(2).toBytes()
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var versionBr = reader.listElem(3).toBytes()
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if recoverPublicKey(pubkeyBr.toOpenArray(),
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pubkey) != EthKeysStatus.Success:
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return(InvalidPubKey)
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copyMem(addr nonce[0], nonceBr.baseAddr, KeyLength)
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if ecdhAgree(h.host.seckey, pubkey, secret) != EthKeysStatus.Success:
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return(EcdhError)
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var xornonce = nonce
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xornonce.sxor(secret.data)
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if recoverSignatureKey(signatureBr.toOpenArray(),
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xornonce,
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h.remoteEPubkey) != EthKeysStatus.Success:
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return(SignatureError)
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h.initiatorNonce = nonce
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h.remoteHPubkey = pubkey
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h.version = cast[ptr byte](versionBr.baseAddr)[]
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result = Success
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except:
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result = RlpError
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proc decodeAckMessageEip8*(h: var Handshake, m: openarray[byte]): AuthStatus =
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## Decodes EIP-8 AckMessage.
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var size: uint16
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assert(len(m) > 2)
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bigEndian16(addr size, unsafeAddr m[0])
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if 2 + int(size) > len(m):
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return(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)) != EciesStatus.Success:
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return(EciesError)
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try:
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var reader = rlpFromBytes(buffer.toRange())
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if not reader.isList() or reader.listLen() < 3:
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return(InvalidAck)
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if reader.listElem(0).blobLen != RawPublicKeySize:
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return(InvalidAck)
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if reader.listElem(1).blobLen != KeyLength:
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return(InvalidAck)
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if reader.listElem(2).blobLen != 1:
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return(InvalidAck)
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let pubkeyBr = reader.listElem(0).toBytes()
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let nonceBr = reader.listElem(1).toBytes()
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let versionBr = reader.listElem(2).toBytes()
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if recoverPublicKey(pubkeyBr.toOpenArray(),
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h.remoteEPubkey) != EthKeysStatus.Success:
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return(InvalidPubKey)
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copyMem(addr h.responderNonce[0], nonceBr.baseAddr, KeyLength)
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h.version = cast[ptr byte](versionBr.baseAddr)[]
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result = Success
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except:
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result = RlpError
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proc decodeAckMessageV4(h: var Handshake, m: openarray[byte]): AuthStatus =
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## Decodes V4 AckMessage.
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var
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buffer: array[PlainAckMessageV4Length, byte]
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assert(Initiator in h.flags)
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if eciesDecrypt(m, buffer, h.host.seckey) != EciesStatus.Success:
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return(EciesError)
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var header = cast[ptr AckMessageV4](addr buffer[0])
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if recoverPublicKey(header.pubkey, h.remoteEPubkey) != EthKeysStatus.Success:
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return(InvalidPubKey)
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h.responderNonce = header.nonce
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result = Success
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proc decodeAuthMessage*(h: var Handshake, input: openarray[byte]): AuthStatus =
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## Decodes AuthMessage from `input`.
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if len(input) < AuthMessageV4Length:
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result = IncompleteError
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elif len(input) == AuthMessageV4Length:
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let res = h.decodeAuthMessageV4(input)
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if res != Success:
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if h.decodeAuthMessageEip8(input) != Success:
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result = res
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else:
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h.flags.incl(EIP8)
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result = Success
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else:
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result = Success
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else:
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result = h.decodeAuthMessageEip8(input)
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if result == Success:
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h.flags.incl(EIP8)
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proc decodeAckMessage*(h: var Handshake, input: openarray[byte]): AuthStatus =
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## Decodes AckMessage from `input`.
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if len(input) < AckMessageV4Length:
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return(IncompleteError)
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elif len(input) == AckMessageV4Length:
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let res = h.decodeAckMessageV4(input)
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if res != Success:
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if h.decodeAckMessageEip8(input) != Success:
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result = res
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else:
|
|
h.flags.incl(EIP8)
|
|
result = Success
|
|
else:
|
|
result = Success
|
|
else:
|
|
result = h.decodeAckMessageEip8(input)
|
|
if result == Success:
|
|
h.flags.incl(EIP8)
|
|
|
|
proc getSecrets*(h: Handshake, authmsg: openarray[byte],
|
|
ackmsg: openarray[byte],
|
|
secret: var ConnectionSecret): AuthStatus =
|
|
## Derive secrets from handshake `h` using encrypted AuthMessage `authmsg` and
|
|
## encrypted AckMessage `ackmsg`.
|
|
var
|
|
shsec: SharedSecret
|
|
ctx0: keccak256
|
|
ctx1: keccak256
|
|
mac1: MDigest[256]
|
|
mac2: MDigest[256]
|
|
xornonce: Nonce
|
|
|
|
# ecdhe-secret = ecdh.agree(ephemeral-privkey, remote-ephemeral-pubk)
|
|
if ecdhAgree(h.ephemeral.seckey, h.remoteEPubkey,
|
|
shsec) != EthKeysStatus.Success:
|
|
return(EcdhError)
|
|
|
|
# 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
|
|
|
|
burnMem(shsec)
|
|
# egress-mac = keccak256(mac-secret ^ recipient-nonce || auth-sent-init)
|
|
xornonce = mac1.data
|
|
xornonce.sxor(h.responderNonce)
|
|
ctx0.init()
|
|
ctx0.update(xornonce)
|
|
ctx0.update(authmsg)
|
|
mac1 = ctx0.finish()
|
|
|
|
# ingress-mac = keccak256(mac-secret ^ initiator-nonce || auth-recvd-ack)
|
|
xornonce = secret.macKey
|
|
xornonce.sxor(h.initiatorNonce)
|
|
ctx0.init()
|
|
ctx0.update(xornonce)
|
|
ctx0.update(ackmsg)
|
|
mac2 = ctx0.finish()
|
|
|
|
ctx0.init() # clean keccak256 context
|
|
zeroMem(addr xornonce[0], sizeof(Nonce)) # clean xornonce
|
|
|
|
if Initiator in h.flags:
|
|
secret.egressMac = mac1.data
|
|
secret.ingressMac = mac2.data
|
|
else:
|
|
secret.ingressMac = mac1.data
|
|
secret.egressMac = mac2.data
|
|
|
|
burnMem(mac1)
|
|
burnMem(mac2)
|
|
result = Success
|