openssl.rb in bitcoin-ruby-0.0.2

- old
+ new

@@ -1,56 +1,79 @@
+# encoding: ascii-8bit
+
 # autoload when you need to re-generate a public_key from only its private_key.
 # ported from: https://github.com/sipa/bitcoin/blob/2d40fe4da9ea82af4b652b691a4185431d6e47a8/key.h
 
-Bitcoin.require_dependency :ffi, exit: false, message:
-  "Skipping FFI needed for OpenSSL_EC.regenerate_key."
+Bitcoin.require_dependency :ffi, exit: false, message: "Skipping FFI needed for OpenSSL_EC methods."
 
 module Bitcoin
 module OpenSSL_EC
   extend FFI::Library
   ffi_lib 'ssl'
 
   NID_secp256k1 = 714
+  POINT_CONVERSION_COMPRESSED = 2
+  POINT_CONVERSION_UNCOMPRESSED = 4
 
   attach_function :SSL_library_init, [], :int
   attach_function :ERR_load_crypto_strings, [], :void
   attach_function :SSL_load_error_strings, [], :void
   attach_function :RAND_poll, [], :int
 
-  #attach_function :BN_bin2bn, [:string, :int, :pointer], :pointer
+  attach_function :BN_CTX_free, [:pointer], :int
+  attach_function :BN_CTX_new, [], :pointer
+  attach_function :BN_add, [:pointer, :pointer, :pointer], :int
   attach_function :BN_bin2bn, [:pointer, :int, :pointer], :pointer
-  attach_function :EC_KEY_new_by_curve_name, [:int], :pointer
-  attach_function :EC_KEY_get0_group, [:pointer], :pointer
+  attach_function :BN_bn2bin, [:pointer, :pointer], :void
+  attach_function :BN_cmp, [:pointer, :pointer], :int
+  attach_function :BN_copy, [:pointer, :pointer], :pointer
+  attach_function :BN_dup, [:pointer], :pointer
+  attach_function :BN_free, [:pointer], :int
+  attach_function :BN_mod_inverse, [:pointer, :pointer, :pointer, :pointer], :pointer
+  attach_function :BN_mod_mul, [:pointer, :pointer, :pointer, :pointer, :pointer], :int
+  attach_function :BN_mod_sub, [:pointer, :pointer, :pointer, :pointer, :pointer], :int
+  attach_function :BN_mul_word, [:pointer, :int], :int
   attach_function :BN_new, [], :pointer
-  attach_function :BN_CTX_new, [], :pointer
+  attach_function :BN_rshift, [:pointer, :pointer, :int], :int
+  attach_function :BN_set_word, [:pointer, :int], :int
+  attach_function :EC_GROUP_get_curve_GFp, [:pointer, :pointer, :pointer, :pointer, :pointer], :int
+  attach_function :EC_GROUP_get_degree, [:pointer], :int
   attach_function :EC_GROUP_get_order, [:pointer, :pointer, :pointer], :int
-  attach_function :EC_POINT_new, [:pointer], :pointer
-  attach_function :EC_POINT_mul, [:pointer, :pointer, :pointer, :pointer, :pointer, :pointer], :int
+  attach_function :EC_KEY_free, [:pointer], :int
+  attach_function :EC_KEY_get0_group, [:pointer], :pointer
+  attach_function :EC_KEY_get0_private_key, [:pointer], :pointer
+  attach_function :EC_KEY_new_by_curve_name, [:int], :pointer
+  attach_function :EC_KEY_set_conv_form, [:pointer, :int], :void
   attach_function :EC_KEY_set_private_key, [:pointer, :pointer], :int
   attach_function :EC_KEY_set_public_key,  [:pointer, :pointer], :int
-  attach_function :BN_free, [:pointer], :int
   attach_function :EC_POINT_free, [:pointer], :int
-  attach_function :BN_CTX_free, [:pointer], :int
-  attach_function :EC_KEY_free, [:pointer], :int
-  attach_function :i2o_ECPublicKey, [:pointer, :pointer], :uint
-  attach_function :i2d_ECPrivateKey, [:pointer, :pointer], :int
+  attach_function :EC_POINT_is_at_infinity, [:pointer, :pointer], :int
+  attach_function :EC_POINT_mul, [:pointer, :pointer, :pointer, :pointer, :pointer, :pointer], :int
+  attach_function :EC_POINT_new, [:pointer], :pointer
+  attach_function :EC_POINT_set_compressed_coordinates_GFp, [:pointer, :pointer, :pointer, :int, :pointer], :int
   attach_function :d2i_ECPrivateKey, [:pointer, :pointer, :long], :pointer
-  attach_function :EC_KEY_get0_private_key, [:pointer], :pointer
-  attach_function :BN_bn2bin, [:pointer, :pointer], :void
+  attach_function :i2d_ECPrivateKey, [:pointer, :pointer], :int
+  attach_function :i2o_ECPublicKey, [:pointer, :pointer], :uint
+  attach_function :EC_KEY_check_key, [:pointer], :uint
+  attach_function :ECDSA_do_sign, [:pointer, :uint, :pointer], :pointer
+  attach_function :BN_num_bits, [:pointer], :int
+  attach_function :ECDSA_SIG_free, [:pointer], :void
 
+  def self.BN_num_bytes(ptr); (BN_num_bits(ptr) + 7) / 8; end
 
+
   # resolve public from private key, using ffi and libssl.so
   # example:
   #   keypair = Bitcoin.generate_key; Bitcoin::OpenSSL_EC.regenerate_key(keypair.first) == keypair
   def self.regenerate_key(private_key)
     private_key = [private_key].pack("H*") if private_key.bytesize >= (32*2)
     private_key_hex = private_key.unpack("H*")[0]
 
     #private_key = FFI::MemoryPointer.new(:uint8, private_key.bytesize)
     #                .put_bytes(0, private_key, 0, private_key.bytesize)
     private_key = FFI::MemoryPointer.from_string(private_key)
- 
+
     init_ffi_ssl
     eckey = EC_KEY_new_by_curve_name(NID_secp256k1)
     #priv_key = BN_bin2bn(private_key, private_key.size, BN_new())
     priv_key = BN_bin2bn(private_key, private_key.size-1, BN_new())
 
@@ -67,26 +90,28 @@
     EC_POINT_free(pub_key)
     BN_free(priv_key)
 
 
     length = i2d_ECPrivateKey(eckey, nil)
-    ptr = FFI::MemoryPointer.new(:pointer)
+    buf = FFI::MemoryPointer.new(:uint8, length)
+    ptr = FFI::MemoryPointer.new(:pointer).put_pointer(0, buf)
     priv_hex = if i2d_ECPrivateKey(eckey, ptr) == length
-      size = ptr.read_pointer.get_array_of_uint8(8, 1)[0]
-      ptr.read_pointer.get_array_of_uint8(9, size).pack("C*").rjust(32, "\x00").unpack("H*")[0]
+      size = buf.get_array_of_uint8(8, 1)[0]
+      buf.get_array_of_uint8(9, size).pack("C*").rjust(32, "\x00").unpack("H*")[0]
       #der_to_private_key( ptr.read_pointer.read_string(length).unpack("H*")[0] )
     end
 
     if priv_hex != private_key_hex
       raise "regenerated wrong private_key, raise here before generating a faulty public_key too!"
     end
 
 
     length = i2o_ECPublicKey(eckey, nil)
-    ptr = FFI::MemoryPointer.new(:pointer)
+    buf = FFI::MemoryPointer.new(:uint8, length)
+    ptr = FFI::MemoryPointer.new(:pointer).put_pointer(0, buf)
     pub_hex = if i2o_ECPublicKey(eckey, ptr) == length
-      ptr.read_pointer.read_string(length).unpack("H*")[0]
+      buf.read_string(length).unpack("H*")[0]
     end
 
     EC_KEY_free(eckey)
 
     [ priv_hex, pub_hex ]
@@ -105,9 +130,150 @@
     ec_key = d2i_ECPrivateKey(nil, ptr, buf.size-1)
     return nil if ec_key.null?
     bn = EC_KEY_get0_private_key(ec_key)
     BN_bn2bin(bn, buf)
     buf.read_string(32).unpack("H*")[0]
+  end
+
+  # Given the components of a signature and a selector value, recover and
+  # return the public key that generated the signature according to the
+  # algorithm in SEC1v2 section 4.1.6.
+  #
+  # rec_id is an index from 0 to 3 that indicates which of the 4 possible
+  # keys is the correct one. Because the key recovery operation yields
+  # multiple potential keys, the correct key must either be stored alongside
+  # the signature, or you must be willing to try each rec_id in turn until
+  # you find one that outputs the key you are expecting.
+  #
+  # If this method returns nil, it means recovery was not possible and rec_id
+  # should be iterated.
+  #
+  # Given the above two points, a correct usage of this method is inside a
+  # for loop from 0 to 3, and if the output is nil OR a key that is not the
+  # one you expect, you try again with the next rec_id.
+  #
+  #   message_hash = hash of the signed message.
+  #   signature = the R and S components of the signature, wrapped.
+  #   rec_id = which possible key to recover.
+  #   is_compressed = whether or not the original pubkey was compressed.
+  def self.recover_public_key_from_signature(message_hash, signature, rec_id, is_compressed)
+    return nil if rec_id < 0 or signature.bytesize != 65
+    init_ffi_ssl
+
+    signature = FFI::MemoryPointer.from_string(signature)
+    #signature_bn = BN_bin2bn(signature, 65, BN_new())
+    r = BN_bin2bn(signature[1], 32, BN_new())
+    s = BN_bin2bn(signature[33], 32, BN_new())
+
+    n, i = 0, rec_id / 2
+    eckey = EC_KEY_new_by_curve_name(NID_secp256k1)
+
+    EC_KEY_set_conv_form(eckey, POINT_CONVERSION_COMPRESSED) if is_compressed
+
+    group = EC_KEY_get0_group(eckey)
+    order = BN_new()
+    EC_GROUP_get_order(group, order, nil)
+    x = BN_dup(order)
+    BN_mul_word(x, i)
+    BN_add(x, x, r)
+
+    field = BN_new()
+    EC_GROUP_get_curve_GFp(group, field, nil, nil, nil)
+
+    if BN_cmp(x, field) >= 0
+      [r, s, order, x, field].each{|i| BN_free(i) }
+      EC_KEY_free(eckey)
+      return nil
+    end
+
+    big_r = EC_POINT_new(group)
+    EC_POINT_set_compressed_coordinates_GFp(group, big_r, x, rec_id % 2, nil)
+
+    big_q = EC_POINT_new(group)
+    n = EC_GROUP_get_degree(group)
+    e = BN_bin2bn(message_hash, message_hash.bytesize, BN_new())
+    BN_rshift(e, e, 8 - (n & 7)) if 8 * message_hash.bytesize > n
+
+    ctx = BN_CTX_new()
+    zero, rr, sor, eor = BN_new(), BN_new(), BN_new(), BN_new()
+    BN_set_word(zero, 0)
+    BN_mod_sub(e, zero, e, order, ctx)
+    BN_mod_inverse(rr, r, order, ctx)
+    BN_mod_mul(sor, s, rr, order, ctx)
+    BN_mod_mul(eor, e, rr, order, ctx)
+    EC_POINT_mul(group, big_q, eor, big_r, sor, ctx)
+    EC_KEY_set_public_key(eckey, big_q)
+    BN_CTX_free(ctx)
+
+    [r, s, order, x, field, e, zero, rr, sor, eor].each{|i| BN_free(i) }
+    [big_r, big_q].each{|i| EC_POINT_free(i) }
+
+    length = i2o_ECPublicKey(eckey, nil)
+    buf = FFI::MemoryPointer.new(:uint8, length)
+    ptr = FFI::MemoryPointer.new(:pointer).put_pointer(0, buf)
+    pub_hex = if i2o_ECPublicKey(eckey, ptr) == length
+      buf.read_string(length).unpack("H*")[0]
+    end
+
+    EC_KEY_free(eckey)
+
+    pub_hex
+  end
+
+  def self.sign_compact(hash, private_key, public_key_hex = nil, pubkey_compressed = nil)
+    private_key = [private_key].pack("H*") if private_key.bytesize >= 64
+    private_key_hex = private_key.unpack("H*")[0]
+
+    public_key_hex = regenerate_key(private_key_hex).last unless public_key_hex
+    pubkey_compressed = (public_key_hex[0..1] == "04" ? false : true) unless pubkey_compressed
+
+    init_ffi_ssl
+    eckey = EC_KEY_new_by_curve_name(NID_secp256k1)
+    priv_key = BN_bin2bn(private_key, private_key.bytesize, BN_new())
+
+    group, order, ctx = EC_KEY_get0_group(eckey), BN_new(), BN_CTX_new()
+    EC_GROUP_get_order(group, order, ctx)
+
+    pub_key = EC_POINT_new(group)
+    EC_POINT_mul(group, pub_key, priv_key, nil, nil, ctx)
+    EC_KEY_set_private_key(eckey, priv_key)
+    EC_KEY_set_public_key(eckey, pub_key)
+
+    signature = ECDSA_do_sign(hash, hash.bytesize, eckey)
+
+    BN_free(order)
+    BN_CTX_free(ctx)
+    EC_POINT_free(pub_key)
+    BN_free(priv_key)
+    EC_KEY_free(eckey)
+
+    buf, rec_id, head = FFI::MemoryPointer.new(:uint8, 32), nil, nil
+    r, s = signature.get_array_of_pointer(0, 2).map{|i| BN_bn2bin(i, buf); buf.read_string(BN_num_bytes(i)).rjust(32, "\x00") }
+
+    if signature.get_array_of_pointer(0, 2).all?{|i| BN_num_bits(i) <= 256 }
+      4.times{|i|
+        head = [ 27 + i + (pubkey_compressed ? 4 : 0) ].pack("C")
+        if public_key_hex == recover_public_key_from_signature(hash, [head, r, s].join, i, pubkey_compressed)
+          rec_id = i; break
+        end
+      }
+    end
+
+    ECDSA_SIG_free(signature)
+
+    [ head, [r,s] ].join if rec_id
+  end
+
+  def self.recover_compact(hash, signature)
+    return false if signature.bytesize != 65
+    #i = signature.unpack("C")[0] - 27
+    #pubkey = recover_public_key_from_signature(hash, signature, (i & ~4), i >= 4)
+
+    version = signature.unpack('C')[0]
+    return false if version < 27 or version > 34
+
+    compressed = (version >= 31) ? (version -= 4; true) : false
+    pubkey = recover_public_key_from_signature(hash, signature, version-27, compressed)
   end
 
   def self.init_ffi_ssl
     return if @ssl_loaded
     SSL_library_init()