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project/fm_viewer/module/rm_crypt.h

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+#ifndef RM_CRYPT_H
+#define RM_CRYPT_H
+
+
+// 일단 Telebit 만 사용
+#if (RM_MODEL_TB4000 || RM_MODEL_TB5000)
+
+#include "rm_include.h"
+
+#include <QObject>
+#include <QString>
+#include <QVector>
+#include <QFlags>
+
+
+class RMCrypt
+{
+public:
+    /**
+      CompressionMode describes if compression will be applied to the data to be
+      encrypted.
+      */
+    enum CompressionMode {
+        CompressionAuto,    /*!< Only apply compression if that results in a shorter plaintext. */
+        CompressionAlways,  /*!< Always apply compression. Note that for short inputs, a compression may result in longer data */
+        CompressionNever    /*!< Never apply compression. */
+    };
+    /**
+      IntegrityProtectionMode describes measures taken to make it possible to detect problems with the data
+      or wrong decryption keys.
+
+      Measures involve adding a checksum or a cryptograhpic hash to the data to be encrypted. This
+      increases the length of the resulting cypertext, but makes it possible to check if the plaintext
+      appears to be valid after decryption.
+    */
+    enum IntegrityProtectionMode {
+        ProtectionNone,    /*!< The integerity of the encrypted data is not protected. It is not really possible to detect a wrong key, for instance. */
+        ProtectionChecksum,/*!< A simple checksum is used to verify that the data is in order. If not, an empty string is returned. */
+        ProtectionHash     /*!< A cryptographic hash is used to verify the integrity of the data. This method produces a much stronger, but longer check */
+    };
+    /**
+      Error describes the type of error that occured.
+      */
+    enum Error {
+        ErrorNoError,         /*!< No error occurred. */
+        ErrorNoKeySet,        /*!< No key was set. You can not encrypt or decrypt without a valid key. */
+        ErrorUnknownVersion,  /*!< The version of this data is unknown, or the data is otherwise not valid. */
+        ErrorIntegrityFailed, /*!< The integrity check of the data failed. Perhaps the wrong key was used. */
+    };
+
+    /**
+      Constructor.
+
+      Constructs a SimpleCrypt instance without a valid key set on it.
+     */
+    RMCrypt();
+    /**
+      Constructor.
+
+      Constructs a SimpleCrypt instance and initializes it with the given @arg key.
+     */
+    explicit RMCrypt(quint64 key);
+
+    /**
+      (Re-) initializes the key with the given @arg key.
+      */
+    void setKey(quint64 key);
+    /**
+      Returns true if SimpleCrypt has been initialized with a key.
+      */
+    bool hasKey() const {return !m_keyParts.isEmpty();}
+
+    /**
+      Sets the compression mode to use when encrypting data. The default mode is Auto.
+
+      Note that decryption is not influenced by this mode, as the decryption recognizes
+      what mode was used when encrypting.
+      */
+    void setCompressionMode(CompressionMode mode) {m_compressionMode = mode;}
+    /**
+      Returns the CompressionMode that is currently in use.
+      */
+    CompressionMode compressionMode() const {return m_compressionMode;}
+
+    /**
+      Sets the integrity mode to use when encrypting data. The default mode is Checksum.
+
+      Note that decryption is not influenced by this mode, as the decryption recognizes
+      what mode was used when encrypting.
+      */
+    void setIntegrityProtectionMode(IntegrityProtectionMode mode) {m_protectionMode = mode;}
+    /**
+      Returns the IntegrityProtectionMode that is currently in use.
+      */
+    IntegrityProtectionMode integrityProtectionMode() const {return m_protectionMode;}
+
+    /**
+      Returns the last error that occurred.
+      */
+    Error lastError() const {return m_lastError;}
+
+    /**
+      Encrypts the @arg plaintext string with the key the class was initialized with, and returns
+      a cyphertext the result. The result is a base64 encoded version of the binary array that is the
+      actual result of the string, so it can be stored easily in a text format.
+      */
+    QString encryptToString(const QString& plaintext) ;
+    /**
+      Encrypts the @arg plaintext QByteArray with the key the class was initialized with, and returns
+      a cyphertext the result. The result is a base64 encoded version of the binary array that is the
+      actual result of the encryption, so it can be stored easily in a text format.
+      */
+    QString encryptToString(QByteArray plaintext) ;
+    /**
+      Encrypts the @arg plaintext string with the key the class was initialized with, and returns
+      a binary cyphertext in a QByteArray the result.
+
+      This method returns a byte array, that is useable for storing a binary format. If you need
+      a string you can store in a text file, use encryptToString() instead.
+      */
+    QByteArray encryptToByteArray(const QString& plaintext) ;
+    /**
+      Encrypts the @arg plaintext QByteArray with the key the class was initialized with, and returns
+      a binary cyphertext in a QByteArray the result.
+
+      This method returns a byte array, that is useable for storing a binary format. If you need
+      a string you can store in a text file, use encryptToString() instead.
+      */
+    QByteArray encryptToByteArray(QByteArray plaintext) ;
+
+    /**
+      Decrypts a cyphertext string encrypted with this class with the set key back to the
+      plain text version.
+
+      If an error occured, such as non-matching keys between encryption and decryption,
+      an empty string or a string containing nonsense may be returned.
+      */
+    QString decryptToString(const QString& cyphertext) ;
+    /**
+      Decrypts a cyphertext string encrypted with this class with the set key back to the
+      plain text version.
+
+      If an error occured, such as non-matching keys between encryption and decryption,
+      an empty string or a string containing nonsense may be returned.
+      */
+    QByteArray decryptToByteArray(const QString& cyphertext) ;
+    /**
+      Decrypts a cyphertext binary encrypted with this class with the set key back to the
+      plain text version.
+
+      If an error occured, such as non-matching keys between encryption and decryption,
+      an empty string or a string containing nonsense may be returned.
+      */
+    QString decryptToString(QByteArray cypher) ;
+    /**
+      Decrypts a cyphertext binary encrypted with this class with the set key back to the
+      plain text version.
+
+      If an error occured, such as non-matching keys between encryption and decryption,
+      an empty string or a string containing nonsense may be returned.
+      */
+    QByteArray decryptToByteArray(QByteArray cypher) ;
+
+    //enum to describe options that have been used for the encryption. Currently only one, but
+    //that only leaves room for future extensions like adding a cryptographic hash...
+    enum CryptoFlag{CryptoFlagNone = 0,
+                    CryptoFlagCompression = 0x01,
+                    CryptoFlagChecksum = 0x02,
+                    CryptoFlagHash = 0x04
+                   };
+    Q_DECLARE_FLAGS(CryptoFlags, CryptoFlag);
+private:
+
+    void splitKey();
+
+    quint64 m_key;
+    QVector<char> m_keyParts;
+    CompressionMode m_compressionMode;
+    IntegrityProtectionMode m_protectionMode;
+    Error m_lastError;
+};
+Q_DECLARE_OPERATORS_FOR_FLAGS(RMCrypt::CryptoFlags)
+#endif // #if (RM_MODEL == RM_MODEL_TYPE_TELEBIT)
+#endif // RM_CRYPT_H