SymmetricCipher: Add keySize(), don't rely on state for sizes

This additionally makes keySize() and blockSize() work before
setting the key and IV. Required for SSH agent decryption.

src/crypto/SymmetricCipher.cpp

@@ -74,6 +74,11 @@ bool SymmetricCipher::reset()
     return m_backend->reset();
 }
 
+int SymmetricCipher::keySize() const
+{
+    return m_backend->keySize();
+}
+
 int SymmetricCipher::blockSize() const
 {
     return m_backend->blockSize();

src/crypto/SymmetricCipher.h

@@ -70,6 +70,7 @@ public:
     }
 
     bool reset();
+    int keySize() const;
     int blockSize() const;
     QString errorString() const;
 

src/crypto/SymmetricCipherBackend.h

@@ -33,6 +33,7 @@ public:
     Q_REQUIRED_RESULT virtual bool processInPlace(QByteArray& data, quint64 rounds) = 0;
 
     virtual bool reset() = 0;
+    virtual int keySize() const = 0;
     virtual int blockSize() const = 0;
 
     virtual QString errorString() const = 0;

src/crypto/SymmetricCipherGcrypt.cpp

@@ -26,7 +26,6 @@ SymmetricCipherGcrypt::SymmetricCipherGcrypt(SymmetricCipher::Algorithm algo, Sy
     , m_algo(gcryptAlgo(algo))
     , m_mode(gcryptMode(mode))
     , m_direction(direction)
-    , m_blockSize(-1)
 {
 }
 
@@ -95,14 +94,6 @@ bool SymmetricCipherGcrypt::init()
         return false;
     }
 
-    size_t blockSizeT;
-    error = gcry_cipher_algo_info(m_algo, GCRYCTL_GET_BLKLEN, nullptr, &blockSizeT);
-    if (error != 0) {
-        setErrorString(error);
-        return false;
-    }
-
-    m_blockSize = blockSizeT;
     return true;
 }
 
@@ -237,9 +228,28 @@ bool SymmetricCipherGcrypt::reset()
     return true;
 }
 
+int SymmetricCipherGcrypt::keySize() const
+{
+    gcry_error_t error;
+    size_t keySizeT;
+
+    error = gcry_cipher_algo_info(m_algo, GCRYCTL_GET_KEYLEN, nullptr, &keySizeT);
+    if (error != 0)
+        return -1;
+
+    return keySizeT;
+}
+
 int SymmetricCipherGcrypt::blockSize() const
 {
-    return m_blockSize;
+    gcry_error_t error;
+    size_t blockSizeT;
+
+    error = gcry_cipher_algo_info(m_algo, GCRYCTL_GET_BLKLEN, nullptr, &blockSizeT);
+    if (error != 0)
+        return -1;
+
+    return blockSizeT;
 }
 
 QString SymmetricCipherGcrypt::errorString() const

src/crypto/SymmetricCipherGcrypt.h

@@ -39,6 +39,7 @@ public:
     Q_REQUIRED_RESULT bool processInPlace(QByteArray& data, quint64 rounds);
 
     bool reset();
+    int keySize() const;
     int blockSize() const;
 
     QString errorString() const;
@@ -54,7 +55,6 @@ private:
     const SymmetricCipher::Direction m_direction;
     QByteArray m_key;
     QByteArray m_iv;
-    int m_blockSize;
     QString m_errorString;
 };