diff --git a/src/fr/anssi/smartpgp/Common.java b/src/fr/anssi/smartpgp/Common.java
index d174613..317a99a 100644
--- a/src/fr/anssi/smartpgp/Common.java
+++ b/src/fr/anssi/smartpgp/Common.java
@@ -21,8 +21,21 @@
 package fr.anssi.smartpgp;
 
 import javacard.framework.*;
+import javacard.security.*;
+import javacardx.crypto.*;
 
 public final class Common {
+    protected final Cipher cipher_aes_cbc_nopad;
+    protected final Cipher cipher_rsa_pkcs1;
+
+    protected final RandomData random;
+
+    protected Common() {
+        cipher_aes_cbc_nopad = Cipher.getInstance(Cipher.ALG_AES_BLOCK_128_CBC_NOPAD, false);
+        cipher_rsa_pkcs1 = Cipher.getInstance(Cipher.ALG_RSA_PKCS1, false);
+
+        random = RandomData.getInstance(RandomData.ALG_SECURE_RANDOM);
+    }
 
     protected static final void beginTransaction(final boolean isRegistering) {
         if(!isRegistering) {
diff --git a/src/fr/anssi/smartpgp/PGPKey.java b/src/fr/anssi/smartpgp/PGPKey.java
index c4fc843..88e779c 100644
--- a/src/fr/anssi/smartpgp/PGPKey.java
+++ b/src/fr/anssi/smartpgp/PGPKey.java
@@ -40,12 +40,7 @@ public final class PGPKey {
 
     private KeyPair keys;
 
-    private final Cipher cipher_rsa_pkcs1;
-
     protected PGPKey() {
-
-        cipher_rsa_pkcs1 = Cipher.getInstance(Cipher.ALG_RSA_PKCS1, false);
-
         fingerprint = new Fingerprint();
         generation_date = new byte[Constants.GENERATION_DATE_SIZE];
 
@@ -447,7 +442,8 @@ public final class PGPKey {
 
 
 
-    protected final short sign(final byte[] buf, final short lc,
+    protected final short sign(final Common common,
+                               final byte[] buf, final short lc,
                                final boolean forAuth) {
 
         if(!isInitialized()) {
@@ -486,10 +482,10 @@ public final class PGPKey {
                 return 0;
             }
 
-            cipher_rsa_pkcs1.init(priv, Cipher.MODE_ENCRYPT);
+            common.cipher_rsa_pkcs1.init(priv, Cipher.MODE_ENCRYPT);
 
-            off = cipher_rsa_pkcs1.doFinal(buf, (short)0, lc,
-                                           buf, lc);
+            off = common.cipher_rsa_pkcs1.doFinal(buf, (short)0, lc,
+                                                  buf, lc);
 
             return Util.arrayCopyNonAtomic(buf, lc,
                                            buf, (short)0,
@@ -502,7 +498,8 @@ public final class PGPKey {
     }
 
 
-    protected final short decipher(final byte[] buf, final short lc) {
+    protected final short decipher(final Common common,
+                                   final byte[] buf, final short lc) {
 
         if(!isInitialized()) {
             ISOException.throwIt(Constants.SW_REFERENCE_DATA_NOT_FOUND);
@@ -526,10 +523,10 @@ public final class PGPKey {
                 return 0;
             }
 
-            cipher_rsa_pkcs1.init(priv, Cipher.MODE_DECRYPT);
+            common.cipher_rsa_pkcs1.init(priv, Cipher.MODE_DECRYPT);
 
-            final short len = cipher_rsa_pkcs1.doFinal(buf, (short)1, (short)(lc - 1),
-                                                       buf, lc);
+            final short len = common.cipher_rsa_pkcs1.doFinal(buf, (short)1, (short)(lc - 1),
+                                                              buf, lc);
 
             off = Util.arrayCopyNonAtomic(buf, lc,
                                           buf, (short)0,
diff --git a/src/fr/anssi/smartpgp/SmartPGPApplet.java b/src/fr/anssi/smartpgp/SmartPGPApplet.java
index d86317a..e1da35a 100644
--- a/src/fr/anssi/smartpgp/SmartPGPApplet.java
+++ b/src/fr/anssi/smartpgp/SmartPGPApplet.java
@@ -26,16 +26,13 @@ import javacardx.crypto.*;
 
 public final class SmartPGPApplet extends Applet {
 
+    private final Common common;
     private final Persistent data;
 
     private final Transients transients;
 
-    private final Cipher cipher_aes_cbc_nopad;
-    private final RandomData random_data;
-
     public SmartPGPApplet() {
-        cipher_aes_cbc_nopad = Cipher.getInstance(Cipher.ALG_AES_BLOCK_128_CBC_NOPAD, false);
-        random_data = RandomData.getInstance(RandomData.ALG_SECURE_RANDOM);
+        common = new Common();
         data = new Persistent();
         transients = new Transients();
     }
@@ -1287,7 +1284,7 @@ public final class SmartPGPApplet extends Applet {
             }
             JCSystem.commitTransaction();
 
-            return data.pgp_keys[Persistent.PGP_KEYS_OFFSET_SIG].sign(transients.buffer, lc, false);
+            return data.pgp_keys[Persistent.PGP_KEYS_OFFSET_SIG].sign(common, transients.buffer, lc, false);
         }
 
         /* PSO : DECIPHER */
@@ -1312,10 +1309,10 @@ public final class SmartPGPApplet extends Applet {
                     return 0;
                 }
 
-                cipher_aes_cbc_nopad.init(data.aes_key, Cipher.MODE_DECRYPT);
+                common.cipher_aes_cbc_nopad.init(data.aes_key, Cipher.MODE_DECRYPT);
 
-                final short res = cipher_aes_cbc_nopad.doFinal(transients.buffer, (short)1, (short)(lc - 1),
-                                                               transients.buffer, lc);
+                final short res = common.cipher_aes_cbc_nopad.doFinal(transients.buffer, (short)1, (short)(lc - 1),
+                                                                      transients.buffer, lc);
 
                 Util.arrayCopyNonAtomic(transients.buffer, lc,
                                         transients.buffer, (short)0, res);
@@ -1325,7 +1322,7 @@ public final class SmartPGPApplet extends Applet {
                 return res;
             }
 
-            return data.pgp_keys[Persistent.PGP_KEYS_OFFSET_DEC].decipher(transients.buffer, lc);
+            return data.pgp_keys[Persistent.PGP_KEYS_OFFSET_DEC].decipher(common, transients.buffer, lc);
         }
 
         /* PSO : ENCIPHER */
@@ -1343,10 +1340,10 @@ public final class SmartPGPApplet extends Applet {
                 return 0;
             }
 
-            cipher_aes_cbc_nopad.init(data.aes_key, Cipher.MODE_ENCRYPT);
+            common.cipher_aes_cbc_nopad.init(data.aes_key, Cipher.MODE_ENCRYPT);
 
-            final short res = cipher_aes_cbc_nopad.doFinal(transients.buffer, (short)0, lc,
-                                                           transients.buffer, (short)(lc + 1));
+            final short res = common.cipher_aes_cbc_nopad.doFinal(transients.buffer, (short)0, lc,
+                                                                  transients.buffer, (short)(lc + 1));
 
             transients.buffer[lc] = (byte)0x02;
             Util.arrayCopyNonAtomic(transients.buffer, lc,
@@ -1369,7 +1366,7 @@ public final class SmartPGPApplet extends Applet {
             case (byte)0x00:
                 sensitiveData();
                 assertUserMode82();
-                return data.pgp_keys[Persistent.PGP_KEYS_OFFSET_AUT].sign(transients.buffer, lc, true);
+                return data.pgp_keys[Persistent.PGP_KEYS_OFFSET_AUT].sign(common, transients.buffer, lc, true);
 
             default:
                 break;
@@ -1397,7 +1394,7 @@ public final class SmartPGPApplet extends Applet {
         }
 
         if(le != 0) {
-            random_data.generateData(transients.buffer, (short)0, le);
+            common.random.generateData(transients.buffer, (short)0, le);
         }
 
         return le;