From 52926494f12d2952775ee4dc0f2f22eb9a3661cd Mon Sep 17 00:00:00 2001
From: Donald Stufft <donald@stufft.io>
Date: Sun, 17 Mar 2013 17:35:09 -0400
Subject: [PATCH] Enable deriving PublicKey from a PrivateKey
* Uses lower level functions to generate a public_key from a private
key.
* Reworks the generate method to just generate a random value.
---
nacl/nacl.py | 7 +++++++
nacl/public.py | 47 +++++++++++++++++++++--------------------------
2 files changed, 28 insertions(+), 26 deletions(-)
diff --git a/nacl/nacl.py b/nacl/nacl.py
index aa78d852..20cc74d3 100644
--- a/nacl/nacl.py
+++ b/nacl/nacl.py
@@ -66,6 +66,11 @@ ffi.cdef(
"""
void randombytes(unsigned char * const buf, const unsigned long long buf_len);
"""
+
+ # Low Level - Scalar Multiplication
+ """
+ int crypto_scalarmult_curve25519_base(unsigned char *q, const unsigned char *n);
+ """
)
@@ -98,3 +103,5 @@ lib.crypto_box_beforenm = wrap_nacl_function(lib.crypto_box_beforenm)
lib.crypto_hash = wrap_nacl_function(lib.crypto_hash)
lib.crypto_hash_sha256 = wrap_nacl_function(lib.crypto_hash_sha256)
lib.crypto_hash_sha512 = wrap_nacl_function(lib.crypto_hash_sha512)
+
+lib.crypto_scalarmult_curve25519_base = wrap_nacl_function(lib.crypto_scalarmult_curve25519_base)
diff --git a/nacl/public.py b/nacl/public.py
index c62b6edd..0f84a7b8 100644
--- a/nacl/public.py
+++ b/nacl/public.py
@@ -5,6 +5,7 @@ from . import six
from . import nacl, encoding
from .exceptions import CryptoError
+from .utils import random
class PublicKey(encoding.Encodable, six.StringFixer, object):
@@ -47,12 +48,24 @@ class PrivateKey(encoding.Encodable, six.StringFixer, object):
PRIVATEKEY_SIZE = nacl.lib.crypto_box_SECRETKEYBYTES
def __init__(self, private_key, encoder=encoding.RawEncoder):
- self._private_key = encoder.decode(private_key)
- self._public_key = None
+ # Decode the secret_key
+ private_key = encoder.decode(private_key)
- if len(self._private_key) != self.PRIVATEKEY_SIZE:
- raise ValueError('The private key must be exactly %s bytes long' %
- self.PRIVATEKEY_SIZE)
+ # Verify that our seed is the proper size
+ skey_size = nacl.lib.crypto_box_SECRETKEYBYTES
+ if len(private_key) != skey_size:
+ raise ValueError(
+ 'The secret key must be exactly %d bytes long' % (skey_size,))
+
+ pk = nacl.ffi.new("unsigned char[]", nacl.lib.crypto_box_PUBLICKEYBYTES)
+
+ if not nacl.lib.crypto_scalarmult_curve25519_base(pk, private_key):
+ raise CryptoError("Failed to generate a key pair")
+
+ _pkey = nacl.ffi.buffer(pk, nacl.lib.crypto_box_PUBLICKEYBYTES)[:]
+
+ self._private_key = private_key
+ self.public_key = PublicKey(_pkey)
def __bytes__(self):
return self._private_key
@@ -64,27 +77,9 @@ class PrivateKey(encoding.Encodable, six.StringFixer, object):
:rtype: :class:`~nacl.public.PrivateKey`
"""
- pk = nacl.ffi.new("unsigned char[]", PublicKey.PUBLICKEY_SIZE)
- sk = nacl.ffi.new("unsigned char[]", cls.PRIVATEKEY_SIZE)
-
- public_key = nacl.ffi.buffer(pk, PublicKey.PUBLICKEY_SIZE)[:]
- private_key = nacl.ffi.buffer(sk, cls.PRIVATEKEY_SIZE)[:]
-
- if not nacl.lib.crypto_box_keypair(public_key, private_key):
- raise CryptoError("Failed to generate key pair")
-
- sk = cls(private_key)
- sk.public_key = public_key
-
- return sk
-
- @property
- def public_key(self):
- return self._public_key
-
- @public_key.setter
- def public_key(self, value):
- self._public_key = value
+ return cls(random(nacl.lib.nacl.lib.crypto_box_SECRETKEYBYTES),
+ encoder=encoding.RawEncoder,
+ )
class Box(encoding.Encodable, six.StringFixer, object):
--
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