Updated README file.

README.md

@@ -132,6 +132,12 @@ The following environment variables may be used:
 - **`SLUNK_THREADS`**:  
   Specifies the number of worker threads to use. By default, SlunkCrypt detects the number of available processors and creates one thread for each processor.
 
+- **`SLUNK_LEGACY_COMPAT`**:  
+  If set to a *non-zero* value, enables "legacy" compatibility-mode, required to decrypt files encrypted with SlunkCrypt version 1.2.x or older.
+
+- **`SLUNK_DEBUG_LOGGING`**:  
+  If set to a *non-zero* value, enables additional logging output to the syslog (Unix-like) or to the debugger (Windows). This is intended for debugging purposes only!
+
 Examples
 --------
 
@@ -288,7 +294,9 @@ Create and initialize a new **``Encryptor``** instance. Also generated a new, ra
 
     Encryptor::Encryptor(
       const std::string &passwd,
-      const size_t thread_count = 0U
+      const size_t thread_count = 0U,
+      const bool legacy_compat = false,
+      const bool debug_logging = false
     );
 
 ***Parameters:***
@@ -301,6 +309,12 @@ Create and initialize a new **``Encryptor``** instance. Also generated a new, ra
   * `thread_count`  
     Specifies the number of worker threads to use (optional). By default, SlunkCrypt detects the number of available processors and creates one thread for each processor.
 
+  * `legacy_compat`  
+    Enables "legacy" compatibility-mode; required to encrypt messages in a way that allows decryption with SlunkCrypt version 1.2.x or earlier. Option is disabled by default.
+
+  * `debug_logging`  
+    Enables additional debug logging. Messages are written to the syslog (Unix-like) or to the debugger (Windows). Option is disabled by default.
+
 ***Exceptions:***
 
   * Throws `std::runtime_error`, if the nonce could not be generated, or if the SlunkCrypt context could not be allocated.
@@ -424,7 +438,9 @@ Create and initialize a new **``Decryptor``** instance.
     Decryptor::Decryptor(
       const std::string &passwd,
       const uint64_t nonce,
-      const size_t thread_count = 0U
+      const size_t thread_count = 0U,
+      const bool legacy_compat = false,
+      const bool debug_logging = false
     );
 
 ***Parameters:***
@@ -442,6 +458,12 @@ Create and initialize a new **``Decryptor``** instance.
   * `thread_count`  
     Specifies the number of worker threads to use (optional). By default, SlunkCrypt detects the number of available processors and creates one thread for each processor.
 
+  * `legacy_compat`  
+    Enables "legacy" compatibility-mode; required to decrypt messages that were encrypted with SlunkCrypt version 1.2.x or earlier. Option is disabled by default.
+
+  * `debug_logging`  
+    Enables additional debug logging. Messages are written to the syslog (Unix-like) or to the debugger (Windows). Option is disabled by default.
+
 ***Exceptions:***
 
   * Throws `std::runtime_error`, if the SlunkCrypt context could not be allocated.
@@ -801,7 +823,9 @@ Erase the contents of a byte array, by overwriting it with *zero* bytes. Compile
 The `slunkparam_t` struct is used to pass additional parameters that will be used for initializing the SlunkCrypt context. It contains the following fields:
 
 * `version` – The version of the parameter struct; **must** be set to *`SLUNKCRYPT_PARAM_VERSION`*.
-* `thread_count` – The number of worker threads to use. If this parameter is set to **0**, which is the *default* value, then SlunkCrypt automatically detects the number of available (logical) processors and creates one thread for each processor. Also, the number of threads is capped to a maximum of `MAX_THREADS` (currently defined as **16**).
+* `thread_count` – The number of worker threads to use. If this parameter is set to **0**, which is the *default* value, then SlunkCrypt automatically detects the number of available (logical) processors and creates one thread for each processor. Also, the number of threads is capped to a maximum of `MAX_THREADS` (currently defined as **32**).
+* `legacy_compat` – If set to *`SLUNKCRYPT_TRUE`*, enables "legacy" compatibility-mode; required to decrypt messages that were encrypted with SlunkCrypt version 1.2.x or earlier.
+* `debug_logging` – If set to *`SLUNKCRYPT_TRUE`*, enables additional debug logging; messages are written to the syslog (Unix-like) or to the debugger (Windows).
 
 ### Global variables