Add Mac implementations of new SymmetricKey and Encryptor classes.

base/crypto/encryptor_mac.cc

Index: base/crypto/encryptor_mac.cc
diff --git a/base/crypto/encryptor_mac.cc b/base/crypto/encryptor_mac.cc
index 2b04537a2d1bd32364dc76a5dfc7cb3916a845a1..4e8984aff459fc440e71144190cc1c7f2c71c09b 100644
--- a/base/crypto/encryptor_mac.cc
+++ b/base/crypto/encryptor_mac.cc
@@ -4,10 +4,12 @@
 
 #include "base/crypto/encryptor.h"
 
-namespace base {
+#include <CommonCrypto/CommonCryptor.h>
+
+#include "base/logging.h"
+#include "base/string_util.h"
 
-// TODO(albertb): Implement on Mac using the Common Crypto Library:
-// http://developer.apple.com/mac/library/documentation/Darwin/Reference/ManPages/man3/CCCryptor.3cc.html#//apple_ref/doc/man/10.5/3cc/CCCryptor?useVersion=10.5
+namespace base {
 
 Encryptor::Encryptor() {
 }
@@ -16,15 +18,56 @@ Encryptor::~Encryptor() {
 }
 
 bool Encryptor::Init(SymmetricKey* key, Mode mode, const std::string& iv) {
-  return false;
+  DCHECK(key);
+  DCHECK_EQ(CBC, mode) << "Unsupported mode of operation";
+  CSSM_DATA raw_key = key->cssm_data();
+  if (raw_key.Length != kCCKeySizeAES128 &&
+      raw_key.Length != kCCKeySizeAES192 &&
+      raw_key.Length != kCCKeySizeAES256)
+    return false;
+  if (iv.size() != kCCBlockSizeAES128)
+    return false;
+
+  key_.reset(key);
+  mode_ = mode;
+  iv_ = iv;
+  return true;
+}
+
+bool Encryptor::Crypt(int /*CCOperation*/ op,
+                      const std::string& input,
+                      std::string* output) {
+  DCHECK(key_.get());
+  CSSM_DATA raw_key = key_->cssm_data();
+  // CommonCryptor.h: "A general rule for the size of the output buffer which
+  // must be provided by the caller is that for block ciphers, the output 
+  // length is never larger than the input length plus the block size."
+  
+  size_t output_size = input.size() + iv_.size();
+  CCCryptorStatus err = CCCrypt(op,
+                                kCCAlgorithmAES128,
+                                kCCOptionPKCS7Padding,
+                                raw_key.Data, raw_key.Length,
+                                iv_.data(),
+                                input.data(), input.size(),
+                                WriteInto(output, output_size),
+                                output_size,
+                                &output_size);
+  if (err) {
+    output->resize(0);
+    LOG(ERROR) << "CCCrypt returned " << err;
+    return false;
+  }
+  output->resize(output_size);
+  return true;
 }
 
 bool Encryptor::Encrypt(const std::string& plaintext, std::string* ciphertext) {
-  return false;
+  return Crypt(kCCEncrypt, plaintext, ciphertext);
 }
 
 bool Encryptor::Decrypt(const std::string& ciphertext, std::string* plaintext) {
-  return false;
+  return Crypt(kCCDecrypt, ciphertext, plaintext);
 }
 
 }  // namespace base