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nim-eth/eth/keys.nim

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# Nim Ethereum Keys (nim-eth-keys)
# Copyright (c) 2020 Status Research & Development GmbH
# Licensed under either of
# - Apache License, version 2.0, (LICENSE-APACHEv2)
# - MIT license (LICENSE-MIT)
#
# This module contains adaptations of the general secp interface to help make
# working with keys and signatures as they appear in Ethereum in particular:
#
# * Public keys as serialized in uncompressed format without the initial byte
# * Shared secrets are serialized in raw format without the initial byte
# * distinct types are used to avoid confusion with the "standard" secp types
{.push raises: [Defect].}
import
std/strformat,
secp256k1, bearssl/hash as bhash, bearssl/rand,
stew/[byteutils, objects, results, ptrops],
./common/eth_hash
from nimcrypto/utils import burnMem
export secp256k1, results, rand
const
KeyLength* = SkEcdhSecretSize
## Ecdh shared secret key length without leading byte
## (publicKey * privateKey).x, where length of x is 32 bytes
FullKeyLength* = KeyLength + 1
## Ecdh shared secret with leading byte 0x02 or 0x03
RawPublicKeySize* = SkRawPublicKeySize - 1
## Size of uncompressed public key without format marker (0x04)
RawSignatureSize* = SkRawRecoverableSignatureSize
RawSignatureNRSize* = SkRawSignatureSize
type
PrivateKey* = distinct SkSecretKey
PublicKey* = distinct SkPublicKey
## Public key that's serialized to raw format without 0x04 marker
Signature* = distinct SkRecoverableSignature
## Ethereum uses recoverable signatures allowing some space savings
SignatureNR* = distinct SkSignature
## ...but ENR uses non-recoverable signatures!
SharedSecretFull* = object
## Representation of ECDH shared secret, with leading `y` byte
## (`y` is 0x02 when (publicKey * privateKey).y is even or 0x03 when odd)
data*: array[FullKeyLength, byte]
SharedSecret* = object
## Representation of ECDH shared secret, without leading `y` byte
data*: array[KeyLength, byte]
KeyPair* = distinct SkKeyPair
template pubkey*(v: KeyPair): PublicKey = PublicKey(SkKeyPair(v).pubkey)
template seckey*(v: KeyPair): PrivateKey = PrivateKey(SkKeyPair(v).seckey)
proc newRng*(): ref HmacDrbgContext =
# You should only create one instance of the RNG per application / library
# Ref is used so that it can be shared between components
HmacDrbgContext.new()
proc random*(T: type PrivateKey, rng: var HmacDrbgContext): T =
let rngPtr = unsafeAddr rng # doesn't escape
proc callRng(data: var openArray[byte]) =
generate(rngPtr[], data)
T(SkSecretKey.random(callRng))
func fromRaw*(T: type PrivateKey, data: openArray[byte]): SkResult[T] =
SkSecretKey.fromRaw(data).mapConvert(T)
func fromHex*(T: type PrivateKey, data: string): SkResult[T] =
SkSecretKey.fromHex(data).mapConvert(T)
func toRaw*(seckey: PrivateKey): array[SkRawSecretKeySize, byte] =
SkSecretKey(seckey).toRaw()
func toPublicKey*(seckey: PrivateKey): PublicKey {.borrow.}
func fromRaw*(T: type PublicKey, data: openArray[byte]): SkResult[T] =
if data.len() == SkRawCompressedPublicKeySize:
return SkPublicKey.fromRaw(data).mapConvert(T)
if len(data) < SkRawPublicKeySize - 1:
return err(static(
&"keys: raw eth public key should be {SkRawPublicKeySize - 1} bytes"))
var d: array[SkRawPublicKeySize, byte]
d[0] = 0x04'u8
copyMem(addr d[1], unsafeAddr data[0], 64)
SkPublicKey.fromRaw(d).mapConvert(T)
func fromHex*(T: type PublicKey, data: string): SkResult[T] =
T.fromRaw(? seq[byte].fromHex(data))
func toRaw*(pubkey: PublicKey): array[RawPublicKeySize, byte] =
let tmp = SkPublicKey(pubkey).toRaw()
copyMem(addr result[0], unsafeAddr tmp[1], 64)
func toRawCompressed*(pubkey: PublicKey): array[33, byte] {.borrow.}
proc random*(T: type KeyPair, rng: var HmacDrbgContext): T =
let seckey = SkSecretKey(PrivateKey.random(rng))
KeyPair(SkKeyPair(
seckey: seckey,
pubkey: seckey.toPublicKey()
))
func toKeyPair*(seckey: PrivateKey): KeyPair =
KeyPair(SkKeyPair(
seckey: SkSecretKey(seckey), pubkey: SkSecretKey(seckey).toPublicKey()))
func fromRaw*(T: type Signature, data: openArray[byte]): SkResult[T] =
SkRecoverableSignature.fromRaw(data).mapConvert(T)
func fromHex*(T: type Signature, data: string): SkResult[T] =
T.fromRaw(? seq[byte].fromHex(data))
func toRaw*(sig: Signature): array[RawSignatureSize, byte] {.borrow.}
func fromRaw*(T: type SignatureNR, data: openArray[byte]): SkResult[T] =
SkSignature.fromRaw(data).mapConvert(T)
func toRaw*(sig: SignatureNR): array[RawSignatureNRSize, byte] {.borrow.}
func toAddress*(pubkey: PublicKey, with0x = true): string =
## Convert public key to hexadecimal string address.
var hash = keccakHash(pubkey.toRaw())
result = if with0x: "0x" else: ""
result.add(toHex(toOpenArray(hash.data, 12, len(hash.data) - 1)))
func toChecksumAddress*(pubkey: PublicKey, with0x = true): string =
## Convert public key to checksumable mixed-case address (EIP-55).
result = if with0x: "0x" else: ""
var hash1 = keccakHash(pubkey.toRaw())
var hhash1 = toHex(toOpenArray(hash1.data, 12, len(hash1.data) - 1))
var hash2 = keccakHash(hhash1)
var hhash2 = toHex(hash2.data)
for i in 0..<len(hhash1):
if hhash2[i] >= '0' and hhash2[i] <= '7':
result.add(hhash1[i])
else:
if hhash1[i] >= '0' and hhash1[i] <= '9':
result.add(hhash1[i])
else:
let ch = chr(ord(hhash1[i]) - ord('a') + ord('A'))
result.add(ch)
func validateChecksumAddress*(a: string): bool =
## Validate checksumable mixed-case address (EIP-55).
var address = ""
var check = "0x"
if len(a) != 42:
return false
if a[0] != '0' and a[1] != 'x':
return false
for i in 2..41:
let ch = a[i]
if ch in {'0'..'9'} or ch in {'a'..'f'}:
address &= ch
elif ch in {'A'..'F'}:
address &= chr(ord(ch) - ord('A') + ord('a'))
else:
return false
var hash = keccakHash(address)
var hexhash = toHex(hash.data)
for i in 0..<len(address):
if hexhash[i] >= '0' and hexhash[i] <= '7':
check.add(address[i])
else:
if address[i] >= '0' and address[i] <= '9':
check.add(address[i])
else:
let ch = chr(ord(address[i]) - ord('a') + ord('A'))
check.add(ch)
result = (check == a)
func toCanonicalAddress*(pubkey: PublicKey): array[20, byte] =
## Convert public key to canonical address.
var hash = keccakHash(pubkey.toRaw())
copyMem(addr result[0], addr hash.data[12], 20)
func `$`*(pubkey: PublicKey): string =
## Convert public key to hexadecimal string representation.
toHex(pubkey.toRaw())
func `$`*(sig: Signature): string =
## Convert signature to hexadecimal string representation.
toHex(sig.toRaw())
func `$`*(seckey: PrivateKey): string =
## Convert private key to hexadecimal string representation
toHex(seckey.toRaw())
func `==`*(lhs, rhs: PublicKey): bool {.borrow.}
func `==`*(lhs, rhs: Signature): bool {.borrow.}
func `==`*(lhs, rhs: SignatureNR): bool {.borrow.}
func clear*(v: var PrivateKey) {.borrow.}
func clear*(v: var KeyPair) =
v.seckey.clear()
func clear*(v: var SharedSecret) = burnMem(v.data)
func clear*(v: var SharedSecretFull) = burnMem(v.data)
func sign*(seckey: PrivateKey, msg: SkMessage): Signature =
Signature(signRecoverable(SkSecretKey(seckey), msg))
func sign*(seckey: PrivateKey, msg: openArray[byte]): Signature =
let hash = keccakHash(msg)
sign(seckey, SkMessage(hash.data))
func signNR*(seckey: PrivateKey, msg: SkMessage): SignatureNR =
SignatureNR(sign(SkSecretKey(seckey), msg))
func signNR*(seckey: PrivateKey, msg: openArray[byte]): SignatureNR =
let hash = keccakHash(msg)
signNR(seckey, SkMessage(hash.data))
func recover*(sig: Signature, msg: SkMessage): SkResult[PublicKey] =
recover(SkRecoverableSignature(sig), msg).mapConvert(PublicKey)
func recover*(sig: Signature, msg: openArray[byte]): SkResult[PublicKey] =
let hash = keccakHash(msg)
recover(sig, SkMessage(hash.data))
func verify*(sig: SignatureNR, msg: SkMessage, key: PublicKey): bool =
verify(SkSignature(sig), msg, SkPublicKey(key))
func verify*(sig: SignatureNR, msg: openArray[byte], key: PublicKey): bool =
let hash = keccakHash(msg)
verify(sig, SkMessage(hash.data), key)
proc ecdhSharedSecretHash(output: ptr byte, x32, y32: ptr byte, data: pointer): cint
{.cdecl, raises: [].} =
## Hash function used by `ecdhSharedSecret` below
# `x32` and `y32` are result of scalar multiplication of publicKey * privateKey.
# Both `x32` and `y32` are 32 bytes length.
# Take the `x32` part as ecdh shared secret.
# output length is derived from x32 length and taken from ecdh
# generic parameter `KeyLength`
copyMem(output, x32, KeyLength)
return 1
func ecdhSharedSecret*(seckey: PrivateKey, pubkey: PublicKey): SharedSecret =
## Compute ecdh agreed shared secret.
let res = ecdh[KeyLength](SkSecretKey(seckey), SkPublicKey(pubkey), ecdhSharedSecretHash, nil)
# This function only fail if the hash function return zero.
# Because our hash function always success, we can turn the error into defect
doAssert res.isOk, $res.error
SharedSecret(data: res.get)
proc ecdhSharedSecretFullHash(output: ptr byte, x32, y32: ptr byte, data: pointer): cint
{.cdecl, raises: [].} =
## Hash function used by `ecdhSharedSecretFull` below
# `x32` and `y32` are result of scalar multiplication of publicKey * privateKey.
# Leading byte is 0x02 if `y32` is even and 0x03 if odd. Then concat with `x32`.
# output length is derived from `x32` length + 1 and taken from ecdh
# generic parameter `FullKeyLength`
# output[0] = 0x02 | (y32[31] & 1)
output[] = 0x02 or (y32.offset(31)[] and 0x01)
copyMem(output.offset(1), x32, KeyLength)
return 1
func ecdhSharedSecretFull*(seckey: PrivateKey, pubkey: PublicKey): SharedSecretFull =
## Compute ecdh agreed shared secret with leading byte.
let res = ecdh[FullKeyLength](SkSecretKey(seckey), SkPublicKey(pubkey), ecdhSharedSecretFullHash, nil)
# This function only fail if the hash function return zero.
# Because our hash function always success, we can turn the error into defect
doAssert res.isOk, $res.error
SharedSecretFull(data: res.get)
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