nim-libp2p-experimental/libp2p/crypto/secp.nim

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## Nim-Libp2p
## Copyright (c) 2018 Status Research & Development GmbH
## Licensed under either of
## * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
## * MIT license ([LICENSE-MIT](LICENSE-MIT))
## at your option.
## This file may not be copied, modified, or distributed except according to
## those terms.
import strutils
import secp256k1, nimcrypto/sysrand, nimcrypto/utils, nimcrypto/hash,
nimcrypto/sha2
export sha2
const
SkRawPrivateKeySize* = 256 div 8
## Size of private key in octets (bytes)
SkRawSignatureSize* = SkRawPrivateKeySize * 2 + 1
## Size of signature in octets (bytes)
SkRawPublicKeySize* = SkRawPrivateKeySize + 1
## Size of public key in octets (bytes)
type
SkPublicKey* = secp256k1_pubkey
## Representation of public key.
SkPrivateKey* = object
## Representation of secret key.
data*: array[SkRawPrivateKeySize, byte]
SkKeyPair* = object
## Representation of private/public keys pair.
seckey*: SkPrivateKey
pubkey*: SkPublicKey
SkSignature* = secp256k1_ecdsa_recoverable_signature
## Representation of signature.
SkContext* = ref object
## Representation of Secp256k1 context object.
context: ptr secp256k1_context
error: string
Secp256k1Error* = object of CatchableError
## Exceptions generated by `libsecp256k1`
##
## Private procedures interface
##
var secpContext {.threadvar.}: SkContext
## Thread local variable which holds current context
proc illegalCallback(message: cstring, data: pointer) {.cdecl.} =
let ctx = cast[SkContext](data)
ctx.error = $message
proc errorCallback(message: cstring, data: pointer) {.cdecl.} =
let ctx = cast[SkContext](data)
ctx.error = $message
proc shutdownLibsecp256k1(ctx: SkContext) =
# TODO: use destructor when finalizer are deprecated for destructors
if not(isNil(ctx.context)):
secp256k1_context_destroy(ctx.context)
proc newSkContext(): SkContext =
## Create new Secp256k1 context object.
new(result, shutdownLibsecp256k1)
let flags = cuint(SECP256K1_CONTEXT_VERIFY or SECP256K1_CONTEXT_SIGN)
result.context = secp256k1_context_create(flags)
secp256k1_context_set_illegal_callback(result.context, illegalCallback,
cast[pointer](result))
secp256k1_context_set_error_callback(result.context, errorCallback,
cast[pointer](result))
result.error = ""
proc getContext(): SkContext =
## Get current `EccContext`
if isNil(secpContext):
secpContext = newSkContext()
result = secpContext
template raiseSecp256k1Error() =
## Raises `libsecp256k1` error as exception
let mctx = getContext()
if len(mctx.error) > 0:
let msg = mctx.error
mctx.error.setLen(0)
raise newException(Secp256k1Error, msg)
else:
raise newException(Secp256k1Error, "")
proc init*(key: var SkPrivateKey, data: openarray[byte]): bool =
## Initialize Secp256k1 `private key` ``key`` from raw binary
## representation ``data``.
##
## Procedure returns ``true`` on success.
let ctx = getContext()
if len(data) >= SkRawPrivateKeySize:
let res = secp256k1_ec_seckey_verify(ctx.context,
cast[ptr cuchar](unsafeAddr data[0]))
result = (res == 1) and (len(ctx.error) == 0)
if result:
copyMem(addr key.data[0], unsafeAddr data[0], SkRawPrivateKeySize)
proc init*(key: var SkPrivateKey, data: string): bool {.inline.} =
## Initialize Secp256k1 `private key` ``key`` from hexadecimal string
## representation ``data``.
##
## Procedure returns ``true`` on success.
var buffer: seq[byte]
try:
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buffer = utils.fromHex(stripSpaces(data))
except:
return false
result = init(key, buffer)
proc init*(key: var SkPublicKey, data: openarray[byte]): bool =
## Initialize Secp256k1 `public key` ``key`` from raw binary
## representation ``data``.
##
## Procedure returns ``true`` on success.
let ctx = getContext()
var length = 0
if len(data) > 0:
if data[0] == 0x02'u8 or data[0] == 0x03'u8:
length = min(len(data), 33)
elif data[0] == 0x04'u8 or data[0] == 0x06'u8 or data[0] == 0x07'u8:
length = min(len(data), 65)
else:
return false
let res = secp256k1_ec_pubkey_parse(ctx.context, addr key,
cast[ptr cuchar](unsafeAddr data[0]),
length)
result = (res == 1) and (len(ctx.error) == 0)
proc init*(key: var SkPublicKey, data: string): bool =
## Initialize Secp256k1 `public key` ``key`` from hexadecimal string
## representation ``data``.
##
## Procedure returns ``true`` on success.
var buffer: seq[byte]
try:
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buffer = utils.fromHex(stripSpaces(data))
except:
return false
result = init(key, buffer)
proc init*(sig: var SkSignature, data: openarray[byte]): bool =
## Initialize Secp256k1 `signature` ``sig`` from raw binary
## representation ``data``.
##
## Procedure returns ``true`` on success.
let ctx = getContext()
let length = len(data)
if length >= SkRawSignatureSize:
var recid = cint(data[SkRawPrivateKeySize * 2])
let res = secp256k1_ecdsa_recoverable_signature_parse_compact(ctx.context,
addr sig, cast[ptr cuchar](unsafeAddr data[0]), recid)
result = (res == 1) and (len(ctx.error) == 0)
proc init*(sig: var SkSignature, data: string): bool =
## Initialize Secp256k1 `signature` ``sig`` from hexadecimal string
## representation ``data``.
##
## Procedure returns ``true`` on success.
var buffer: seq[byte]
try:
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buffer = utils.fromHex(stripSpaces(data))
except:
return false
result = init(sig, buffer)
proc init*(t: typedesc[SkPrivateKey],
data: openarray[byte]): SkPrivateKey {.inline.} =
## Initialize Secp256k1 `private key` from raw binary
## representation ``data``.
##
## Procedure returns `private key` on success.
if not init(result, data):
raise newException(Secp256k1Error, "Incorrect binary form")
proc init*(t: typedesc[SkPrivateKey],
data: string): SkPrivateKey {.inline.} =
## Initialize Secp256k1 `private key` from hexadecimal string
## representation ``data``.
##
## Procedure returns `private key` on success.
if not init(result, data):
raise newException(Secp256k1Error, "Incorrect binary form")
proc init*(t: typedesc[SkPublicKey],
data: openarray[byte]): SkPublicKey {.inline.} =
## Initialize Secp256k1 `public key` from raw binary
## representation ``data``.
##
## Procedure returns `public key` on success.
if not init(result, data):
raise newException(Secp256k1Error, "Incorrect binary form")
proc init*(t: typedesc[SkPublicKey],
data: string): SkPublicKey {.inline.} =
## Initialize Secp256k1 `public key` from hexadecimal string
## representation ``data``.
##
## Procedure returns `public key` on success.
if not init(result, data):
raise newException(Secp256k1Error, "Incorrect binary form")
proc init*(t: typedesc[SkSignature],
data: openarray[byte]): SkSignature {.inline.} =
## Initialize Secp256k1 `signature` from raw binary
## representation ``data``.
##
## Procedure returns `signature` on success.
if not init(result, data):
raise newException(Secp256k1Error, "Incorrect binary form")
proc init*(t: typedesc[SkSignature],
data: string): SkSignature {.inline.} =
## Initialize Secp256k1 `signature` from hexadecimal string
## representation ``data``.
##
## Procedure returns `signature` on success.
if not init(result, data):
raise newException(Secp256k1Error, "Incorrect binary form")
proc getKey*(key: SkPrivateKey): SkPublicKey =
## Calculate and return Secp256k1 `public key` from `private key` ``key``.
let ctx = getContext()
let res = secp256k1_ec_pubkey_create(ctx.context, addr result,
cast[ptr cuchar](unsafeAddr key))
if (res != 1) or (len(ctx.error) != 0):
raiseSecp256k1Error()
proc random*(t: typedesc[SkPrivateKey]): SkPrivateKey =
## Generates new random private key.
let ctx = getContext()
while true:
if randomBytes(result.data) == SkRawPrivateKeySize:
let res = secp256k1_ec_seckey_verify(ctx.context,
cast[ptr cuchar](addr result.data[0]))
if (res == 1) and (len(ctx.error) == 0):
break
proc random*(t: typedesc[SkKeyPair]): SkKeyPair {.inline.} =
## Generates new random key pair.
result.seckey = SkPrivateKey.random()
result.pubkey = result.seckey.getKey()
proc toBytes*(key: SkPrivateKey, data: var openarray[byte]): int =
## Serialize Secp256k1 `private key` ``key`` to raw binary form and store it
## to ``data``.
##
## Procedure returns number of bytes (octets) needed to store
## Secp256k1 private key.
result = SkRawPrivateKeySize
if len(data) >= SkRawPrivateKeySize:
copyMem(addr data[0], unsafeAddr key.data[0], SkRawPrivateKeySize)
proc toBytes*(key: SkPublicKey, data: var openarray[byte]): int =
## Serialize Secp256k1 `public key` ``key`` to raw binary form and store it
## to ``data``.
##
## Procedure returns number of bytes (octets) needed to store
## Secp256k1 public key.
let ctx = getContext()
var length = csize(len(data))
result = SkRawPublicKeySize
if len(data) >= SkRawPublicKeySize:
let res = secp256k1_ec_pubkey_serialize(ctx.context,
cast[ptr cuchar](addr data[0]),
addr length, unsafeAddr key,
SECP256K1_EC_COMPRESSED)
proc toBytes*(sig: SkSignature, data: var openarray[byte]): int =
## Serialize Secp256k1 `signature` ``sig`` to raw binary form and store it
## to ``data``.
##
## Procedure returns number of bytes (octets) needed to store
## Secp256k1 signature.
let ctx = getContext()
var recid = cint(0)
result = SkRawSignatureSize
if len(data) >= SkRawSignatureSize:
let res = secp256k1_ecdsa_recoverable_signature_serialize_compact(
ctx.context, cast[ptr cuchar](unsafeAddr data[0]),
addr recid, unsafeAddr sig)
if (res == 1) and (len(ctx.error) == 0):
data[64] = uint8(recid)
proc getBytes*(key: SkPrivateKey): seq[byte] {.inline.} =
## Serialize Secp256k1 `private key` and return it.
result = @(key.data)
proc getBytes*(key: SkPublicKey): seq[byte] {.inline.} =
## Serialize Secp256k1 `public key` and return it.
result = newSeq[byte](SkRawPublicKeySize)
discard toBytes(key, result)
proc getBytes*(sig: SkSignature): seq[byte] {.inline.} =
## Serialize Secp256k1 `signature` and return it.
result = newSeq[byte](SkRawSignatureSize)
discard toBytes(sig, result)
proc `==`*(ska, skb: SkPrivateKey): bool =
## Compare Secp256k1 `private key` objects for equality.
result = (ska.data == skb.data)
proc `==`*(pka, pkb: SkPublicKey): bool =
## Compare Secp256k1 `public key` objects for equality.
var
akey: array[SkRawPublicKeySize, byte]
bkey: array[SkRawPublicKeySize, byte]
discard pka.toBytes(akey)
discard pkb.toBytes(bkey)
result = (akey == bkey)
proc `==`*(sia, sib: SkSignature): bool =
## Compare Secp256k1 `signature` objects for equality.
var
asig: array[SkRawSignatureSize, byte]
bsig: array[SkRawSignatureSize, byte]
discard sia.toBytes(asig)
discard sib.toBytes(bsig)
result = (asig == bsig)
proc `$`*(key: SkPrivateKey): string = toHex(key.data)
## Return string representation of Secp256k1 `private key`.
proc `$`*(key: SkPublicKey): string =
## Return string representation of Secp256k1 `private key`.s
var spub: array[SkRawPublicKeySize, byte]
discard key.toBytes(spub)
result = toHex(spub)
proc `$`*(sig: SkSignature): string =
## Return string representation of Secp256k1 `signature`.s
var ssig: array[SkRawSignatureSize, byte]
discard sig.toBytes(ssig)
result = toHex(ssig)
proc sign*[T: byte|char](key: SkPrivateKey, msg: openarray[T]): SkSignature =
## Sign message `msg` using private key `key` and return signature object.
let ctx = getContext()
var hash = sha256.digest(msg)
let res = secp256k1_ecdsa_sign_recoverable(ctx.context, addr result,
cast[ptr cuchar](addr hash.data[0]),
cast[ptr cuchar](unsafeAddr key),
nil, nil)
if (res != 1) or (len(ctx.error) != 0):
raiseSecp256k1Error()
proc verify*[T: byte|char](sig: SkSignature, msg: openarray[T],
key: SkPublicKey): bool =
var pubkey: SkPublicKey
let ctx = getContext()
var hash = sha256.digest(msg)
let res = secp256k1_ecdsa_recover(ctx.context, addr pubkey, unsafeAddr sig,
cast[ptr cuchar](addr hash.data[0]))
if (res == 1) and (len(ctx.error) == 0):
if key == pubkey:
result = true
proc clear*(key: var SkPrivateKey) {.inline.} =
## Wipe and clear memory of Secp256k1 `private key`.
burnMem(key.data)
proc clear*(key: var SkPublicKey) {.inline.} =
## Wipe and clear memory of Secp256k1 `public key`.
burnMem(addr key, SkRawPrivateKeySize * 2)
proc clear*(sig: var SkSignature) {.inline.} =
## Wipe and clear memory of Secp256k1 `signature`.
# Internal memory representation size of signature object is 64 bytes.
burnMem(addr sig, SkRawPrivateKeySize * 2)
proc clear*(pair: var SkKeyPair) {.inline.} =
## Wipe and clear memory of Secp256k1 `key pair`.
pair.seckey.clear()
pair.pubkey.clear()