commoncrypto_utils.cpp

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/*
* Cipher Modes via CommonCrypto
* (C) 2018 Jose Pereira
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
 
#include <botan/internal/commoncrypto.h>
 
#include <botan/cipher_mode.h>
#include <botan/mem_ops.h>
#include <botan/internal/commoncrypto_utils.h>
#include <botan/internal/fmt.h>
#include <botan/internal/parsing.h>
#include <botan/internal/scan_name.h>
 
namespace Botan {
 
CommonCrypto_Error::CommonCrypto_Error(std::string_view what) : Exception(what), m_rc(0) {}
 
CommonCrypto_Error::CommonCrypto_Error(std::string_view what, int32_t status) :
      Exception(fmt("CommonCrypto op {} failed with err {} ({})", what, status, ccryptorstatus_to_string(status))),
      m_rc(status) {}
 
std::string CommonCrypto_Error::ccryptorstatus_to_string(CCCryptorStatus status) {
   switch(status) {
      case kCCSuccess:
         return "Success";
      case kCCParamError:
         return "ParamError";
      case kCCBufferTooSmall:
         return "BufferTooSmall";
      case kCCMemoryFailure:
         return "MemoryFailure";
      case kCCAlignmentError:
         return "AlignmentError";
      case kCCDecodeError:
         return "DecodeError";
      case kCCUnimplemented:
         return "Unimplemented";
      case kCCOverflow:
         return "Overflow";
      case kCCRNGFailure:
         return "RNGFailure";
      case kCCUnspecifiedError:
         return "UnspecifiedError";
      case kCCCallSequenceError:
         return "CallSequenceError";
      case kCCKeySizeError:
         return "KeySizeError";
      default:
         return "Unknown";
   }
};
 
CommonCryptor_Opts commoncrypto_opts_from_algo_name(std::string_view algo_name) {
   CommonCryptor_Opts opts;
 
   if(algo_name.compare(0, 3, "AES") == 0) {
      opts.algo = kCCAlgorithmAES;
      opts.block_size = kCCBlockSizeAES128;
      if(algo_name == "AES-128") {
         opts.key_spec = Key_Length_Specification(kCCKeySizeAES128);
      } else if(algo_name == "AES-192") {
         opts.key_spec = Key_Length_Specification(kCCKeySizeAES192);
      } else if(algo_name == "AES-256") {
         opts.key_spec = Key_Length_Specification(kCCKeySizeAES256);
      } else {
         throw CommonCrypto_Error("Unknown AES algorithm");
      }
   } else if(algo_name == "DES") {
      opts.algo = kCCAlgorithmDES;
      opts.block_size = kCCBlockSizeDES;
      opts.key_spec = Key_Length_Specification(kCCKeySizeDES);
   } else if(algo_name == "TripleDES") {
      opts.algo = kCCAlgorithm3DES;
      opts.block_size = kCCBlockSize3DES;
      opts.key_spec = Key_Length_Specification(16, kCCKeySize3DES, 8);
   } else if(algo_name == "Blowfish") {
      opts.algo = kCCAlgorithmBlowfish;
      opts.block_size = kCCBlockSizeBlowfish;
      opts.key_spec = Key_Length_Specification(1, kCCKeySizeMaxBlowfish, 1);
   } else if(algo_name == "CAST-128") {
      opts.algo = kCCAlgorithmCAST;
      opts.block_size = kCCBlockSizeCAST;
      // Botan's base implementation of CAST does not support shorter keys
      // so we limit its minimum key size to 11 here.
      opts.key_spec = Key_Length_Specification(11, kCCKeySizeMaxCAST, 1);
   } else {
      throw CommonCrypto_Error("Unsupported cipher");
   }
 
   return opts;
}
 
CommonCryptor_Opts commoncrypto_opts_from_algo(std::string_view algo) {
   SCAN_Name spec(algo);
 
   std::string algo_name = spec.algo_name();
   std::string cipher_mode = spec.cipher_mode();
   std::string cipher_mode_padding = spec.cipher_mode_pad();
 
   CommonCryptor_Opts opts = commoncrypto_opts_from_algo_name(algo_name);
 
   //TODO add CFB and XTS support
   if(cipher_mode.empty() || cipher_mode == "ECB") {
      opts.mode = kCCModeECB;
   } else if(cipher_mode == "CBC") {
      opts.mode = kCCModeCBC;
   } else if(cipher_mode == "CTR") {
      opts.mode = kCCModeCTR;
   } else if(cipher_mode == "OFB") {
      opts.mode = kCCModeOFB;
   } else {
      throw CommonCrypto_Error("Unsupported cipher mode!");
   }
 
   if(cipher_mode_padding == "NoPadding") {
      opts.padding = ccNoPadding;
   }
   /*
   else if(cipher_mode_padding.empty() || cipher_mode_padding == "PKCS7")
      {
      opts.padding = ccPKCS7Padding;
      }
   */
   else {
      throw CommonCrypto_Error("Unsupported cipher mode padding!");
   }
 
   return opts;
}
 
void commoncrypto_adjust_key_size(const uint8_t key[],
                                  size_t length,
                                  const CommonCryptor_Opts& opts,
                                  secure_vector<uint8_t>& full_key) {
   if(opts.algo == kCCAlgorithmBlowfish && length < 8) {
      size_t repeat;
      switch(length) {
         case 1:
            repeat = 8;
            break;
         case 2:
            repeat = 4;
            break;
         case 3:
            repeat = 3;
            break;
         default:
            repeat = 2;
            break;
      }
 
      full_key.resize(length * repeat);
      for(size_t i = 0; i < repeat; i++) {
         copy_mem(full_key.data() + i * length, key, length);
      }
   } else if(opts.algo == kCCAlgorithm3DES && length == 16) {
      full_key += std::make_pair(key, 8);
   }
}
}  // namespace Botan