Merge pull request #539 from rhenium/ky/pkey-dsa-generate-fix-q

pkey/dsa: let PKey::DSA.generate choose appropriate q size

lib/openssl/pkey.rb

@@ -167,8 +167,16 @@ class << self
  # +size+::
  # The desired key size in bits.
  def generate(size, &blk)
+ # FIPS 186-4 specifies four (L,N) pairs: (1024,160), (2048,224),
+ # (2048,256), and (3072,256).
+ #
+ # q size is derived here with compatibility with
+ # DSA_generator_parameters_ex() which previous versions of ruby/openssl
+ # used to call.
+ qsize = size >= 2048 ? 256 : 160
  dsaparams = OpenSSL::PKey.generate_parameters("DSA", {
  "dsa_paramgen_bits" => size,
+ "dsa_paramgen_q_bits" => qsize,
  }, &blk)
  OpenSSL::PKey.generate_key(dsaparams)
  end

test/openssl/test_pkey_dsa.rb

@@ -28,6 +28,25 @@ def test_new_break
  end
  end
 
+ def test_generate
+ # DSA.generate used to call DSA_generate_parameters_ex(), which adjusts the
+ # size of q according to the size of p
+ key1024 = OpenSSL::PKey::DSA.generate(1024)
+ assert_predicate key1024, :private?
+ assert_equal 1024, key1024.p.num_bits
+ assert_equal 160, key1024.q.num_bits
+
+ key2048 = OpenSSL::PKey::DSA.generate(2048)
+ assert_equal 2048, key2048.p.num_bits
+ assert_equal 256, key2048.q.num_bits
+
+ if ENV["OSSL_TEST_ALL"] == "1" # slow
+ key3072 = OpenSSL::PKey::DSA.generate(3072)
+ assert_equal 3072, key3072.p.num_bits
+ assert_equal 256, key3072.q.num_bits
+ end
+ end
+
  def test_sign_verify
  dsa512 = Fixtures.pkey("dsa512")
  data = "Sign me!"