Define Cipher #ccm_data_len= for CCM mode ciphers

Allow specifying just length to #update

CCM mode ciphers need to specify the total plaintext or ciphertext
length to EVP_CipherUpdate.

Update the link to the tests file

Define Cipher#ccm_data_len= for CCM mode ciphers

Add a unit test for CCM mode

Also check CCM is authenticated when testing

CONTRIBUTING.md

@@ -80,7 +80,7 @@ $ docker-compose run debug
 ```
 
 All possible values for `RUBY_VERSION` and `OPENSSL_VERSION` can be found in
-[`.travis.yml`](https://github.com/ruby/openssl/tree/master/.travis.yml).
+[`test.yml`](https://github.com/ruby/openssl/tree/master/.github/workflows/test.yml).
 
 **NOTE**: these commands must be run from the openssl repository root, in order
 to use the

ext/openssl/ossl_cipher.c

@@ -813,6 +813,31 @@ ossl_cipher_block_size(VALUE self)
     return INT2NUM(EVP_CIPHER_CTX_block_size(ctx));
 }
 
+/*
+ *  call-seq:
+ *     cipher.ccm_data_len = integer -> integer
+ *
+ *  Sets the length of the plaintext / ciphertext message that will be
+ *  processed in CCM mode. Make sure to call this method after #key= and
+ *  #iv= have been set, and before #auth_data=.
+ *
+ *  Only call this method after calling Cipher#encrypt or Cipher#decrypt.
+ */
+static VALUE
+ossl_cipher_set_ccm_data_len(VALUE self, VALUE data_len)
+{
+    int in_len, out_len;
+    EVP_CIPHER_CTX *ctx;
+
+    in_len = NUM2INT(data_len);
+
+    GetCipher(self, ctx);
+    if (EVP_CipherUpdate(ctx, NULL, &out_len, NULL, in_len) != 1)
+        ossl_raise(eCipherError, NULL);
+
+    return data_len;
+}
+
 /*
  * INIT
  */
@@ -1059,6 +1084,7 @@ Init_ossl_cipher(void)
     rb_define_method(cCipher, "iv_len", ossl_cipher_iv_length, 0);
     rb_define_method(cCipher, "block_size", ossl_cipher_block_size, 0);
     rb_define_method(cCipher, "padding=", ossl_cipher_set_padding, 1);
+    rb_define_method(cCipher, "ccm_data_len=", ossl_cipher_set_ccm_data_len, 1);
 
     id_auth_tag_len = rb_intern_const("auth_tag_len");
     id_key_set = rb_intern_const("key_set");

test/openssl/test_cipher.rb

@@ -174,6 +174,48 @@ def test_authenticated
     assert_not_predicate(cipher, :authenticated?)
   end
 
+  def test_aes_ccm
+    # RFC 3610 Section 8, Test Case 1
+    key = ["c0c1c2c3c4c5c6c7c8c9cacbcccdcecf"].pack("H*")
+    iv =  ["00000003020100a0a1a2a3a4a5"].pack("H*")
+    aad = ["0001020304050607"].pack("H*")
+    pt =  ["08090a0b0c0d0e0f101112131415161718191a1b1c1d1e"].pack("H*")
+    ct =  ["588c979a61c663d2f066d0c2c0f989806d5f6b61dac384"].pack("H*")
+    tag = ["17e8d12cfdf926e0"].pack("H*")
+
+    kwargs = {auth_tag_len: 8, iv_len: 13, key: key, iv: iv}
+    cipher = new_encryptor("aes-128-ccm", **kwargs, ccm_data_len: pt.length, auth_data: aad)
+    assert_equal ct, cipher.update(pt) << cipher.final
+    assert_equal tag, cipher.auth_tag
+    cipher = new_decryptor("aes-128-ccm", **kwargs, ccm_data_len: ct.length, auth_tag: tag, auth_data: aad)
+    assert_equal pt, cipher.update(ct) << cipher.final
+
+    # truncated tag is accepted
+    cipher = new_encryptor("aes-128-ccm", **kwargs, ccm_data_len: pt.length, auth_data: aad)
+    assert_equal ct, cipher.update(pt) << cipher.final
+    assert_equal tag[0, 8], cipher.auth_tag(8)
+    cipher = new_decryptor("aes-128-ccm", **kwargs, ccm_data_len: ct.length, auth_tag: tag[0, 8], auth_data: aad)
+    assert_equal pt, cipher.update(ct) << cipher.final
+
+    # wrong tag is rejected
+    tag2 = tag.dup
+    tag2.setbyte(-1, (tag2.getbyte(-1) + 1) & 0xff)
+    cipher = new_decryptor("aes-128-ccm", **kwargs, ccm_data_len: ct.length, auth_tag: tag2, auth_data: aad)
+    assert_raise(OpenSSL::Cipher::CipherError) { cipher.update(ct) }
+
+    # wrong aad is rejected
+    aad2 = aad[0..-2] << aad[-1].succ
+    cipher = new_decryptor("aes-128-ccm", **kwargs, ccm_data_len: ct.length, auth_tag: tag, auth_data: aad2)
+    assert_raise(OpenSSL::Cipher::CipherError) { cipher.update(ct) }
+
+    # wrong ciphertext is rejected
+    ct2 = ct[0..-2] << ct[-1].succ
+    cipher = new_decryptor("aes-128-ccm", **kwargs, ccm_data_len: ct2.length, auth_tag: tag, auth_data: aad)
+    assert_raise(OpenSSL::Cipher::CipherError) { cipher.update(ct2) }
+  end if has_cipher?("aes-128-ccm") &&
+         OpenSSL::Cipher.new("aes-128-ccm").authenticated? &&
+         OpenSSL::OPENSSL_VERSION_NUMBER >= 0x10101000  # version >= v1.1.1
+
   def test_aes_gcm
     # GCM spec Appendix B Test Case 4
     key = ["feffe9928665731c6d6a8f9467308308"].pack("H*")