diff --git a/include/polarssl/aes.h b/include/polarssl/aes.h
index 58b348e7c..2e9092f95 100644
--- a/include/polarssl/aes.h
+++ b/include/polarssl/aes.h
@@ -73,6 +73,20 @@ typedef struct
 }
 aes_context;
 
+/**
+ * \brief          Initialize AES context
+ *
+ * \param ctx      AES context to be initialized
+ */
+void aes_init( aes_context *ctx );
+
+/**
+ * \brief          Clear AES context
+ *
+ * \param ctx      AES context to be cleared
+ */
+void aes_free( aes_context *ctx );
+
 /**
  * \brief          AES key schedule (encryption)
  *
diff --git a/include/polarssl/arc4.h b/include/polarssl/arc4.h
index c6c676b3c..555f54fab 100644
--- a/include/polarssl/arc4.h
+++ b/include/polarssl/arc4.h
@@ -55,9 +55,23 @@ typedef struct
 arc4_context;
 
 /**
- * \brief          ARC4 key schedule
+ * \brief          Initialize ARC4 context
  *
  * \param ctx      ARC4 context to be initialized
+ */
+void arc4_init( arc4_context *ctx );
+
+/**
+ * \brief          Clear ARC4 context
+ *
+ * \param ctx      ARC4 context to be cleared
+ */
+void arc4_free( arc4_context *ctx );
+
+/**
+ * \brief          ARC4 key schedule
+ *
+ * \param ctx      ARC4 context to be setup
  * \param key      the secret key
  * \param keylen   length of the key, in bytes
  */
diff --git a/include/polarssl/blowfish.h b/include/polarssl/blowfish.h
index c9c867289..c652b463d 100644
--- a/include/polarssl/blowfish.h
+++ b/include/polarssl/blowfish.h
@@ -70,6 +70,20 @@ typedef struct
 }
 blowfish_context;
 
+/**
+ * \brief          Initialize Blowfish context
+ *
+ * \param ctx      Blowfish context to be initialized
+ */
+void blowfish_init( blowfish_context *ctx );
+
+/**
+ * \brief          Clear Blowfish context
+ *
+ * \param ctx      Blowfish context to be cleared
+ */
+void blowfish_free( blowfish_context *ctx );
+
 /**
  * \brief          Blowfish key schedule
  *
diff --git a/include/polarssl/camellia.h b/include/polarssl/camellia.h
index 34c199068..8488d1df8 100644
--- a/include/polarssl/camellia.h
+++ b/include/polarssl/camellia.h
@@ -66,6 +66,20 @@ typedef struct
 }
 camellia_context;
 
+/**
+ * \brief          Initialize CAMELLIA context
+ *
+ * \param ctx      CAMELLIA context to be initialized
+ */
+void camellia_init( camellia_context *ctx );
+
+/**
+ * \brief          Clear CAMELLIA context
+ *
+ * \param ctx      CAMELLIA context to be cleared
+ */
+void camellia_free( camellia_context *ctx );
+
 /**
  * \brief          CAMELLIA key schedule (encryption)
  *
diff --git a/include/polarssl/des.h b/include/polarssl/des.h
index 78729750f..89bb394e0 100644
--- a/include/polarssl/des.h
+++ b/include/polarssl/des.h
@@ -77,6 +77,34 @@ typedef struct
 }
 des3_context;
 
+/**
+ * \brief          Initialize DES context
+ *
+ * \param ctx      DES context to be initialized
+ */
+void des_init( des_context *ctx );
+
+/**
+ * \brief          Clear DES context
+ *
+ * \param ctx      DES context to be cleared
+ */
+void des_free( des_context *ctx );
+
+/**
+ * \brief          Initialize Triple-DES context
+ *
+ * \param ctx      DES3 context to be initialized
+ */
+void des3_init( des3_context *ctx );
+
+/**
+ * \brief          Clear Triple-DES context
+ *
+ * \param ctx      DES3 context to be cleared
+ */
+void des3_free( des3_context *ctx );
+
 /**
  * \brief          Set key parity on the given key to odd.
  *
diff --git a/include/polarssl/xtea.h b/include/polarssl/xtea.h
index 07118d977..794c5efa3 100644
--- a/include/polarssl/xtea.h
+++ b/include/polarssl/xtea.h
@@ -64,6 +64,20 @@ typedef struct
 }
 xtea_context;
 
+/**
+ * \brief          Initialize XTEA context
+ *
+ * \param ctx      XTEA context to be initialized
+ */
+void xtea_init( xtea_context *ctx );
+
+/**
+ * \brief          Clear XTEA context
+ *
+ * \param ctx      XTEA context to be cleared
+ */
+void xtea_free( xtea_context *ctx );
+
 /**
  * \brief          XTEA key schedule
  *
diff --git a/library/aes.c b/library/aes.c
index a90cefff5..f295747c5 100644
--- a/library/aes.c
+++ b/library/aes.c
@@ -463,6 +463,19 @@ static void aes_gen_tables( void )
 
 #endif /* POLARSSL_AES_ROM_TABLES */
 
+void aes_init( aes_context *ctx )
+{
+    memset( ctx, 0, sizeof( aes_context ) );
+}
+
+void aes_free( aes_context *ctx )
+{
+    if( ctx == NULL )
+        return;
+
+    polarssl_zeroize( ctx, sizeof( aes_context ) );
+}
+
 /*
  * AES key schedule (encryption)
  */
@@ -581,11 +594,12 @@ int aes_setkey_enc( aes_context *ctx, const unsigned char *key,
 int aes_setkey_dec( aes_context *ctx, const unsigned char *key,
                     unsigned int keysize )
 {
-    int i, j;
+    int i, j, ret;
     aes_context cty;
     uint32_t *RK;
     uint32_t *SK;
-    int ret;
+
+    aes_init( &cty );
 
 #if defined(POLARSSL_PADLOCK_C) && defined(PADLOCK_ALIGN16)
     if( aes_padlock_ace == -1 )
@@ -599,7 +613,7 @@ int aes_setkey_dec( aes_context *ctx, const unsigned char *key,
 
     /* Also checks keysize */
     if( ( ret = aes_setkey_enc( &cty, key, keysize ) ) != 0 )
-        return( ret );
+        goto exit;
 
     ctx->nr = cty.nr;
 
@@ -608,7 +622,7 @@ int aes_setkey_dec( aes_context *ctx, const unsigned char *key,
     {
         aesni_inverse_key( (unsigned char *) ctx->rk,
                            (const unsigned char *) cty.rk, ctx->nr );
-        goto done;
+        goto exit;
     }
 #endif
 
@@ -635,12 +649,10 @@ int aes_setkey_dec( aes_context *ctx, const unsigned char *key,
     *RK++ = *SK++;
     *RK++ = *SK++;
 
-#if defined(POLARSSL_AESNI_C) && defined(POLARSSL_HAVE_X86_64)
-done:
-#endif
-    polarssl_zeroize( &cty, sizeof( aes_context ) );
+exit:
+    aes_free( &cty );
 
-    return( 0 );
+    return( ret );
 }
 
 #define AES_FROUND(X0,X1,X2,X3,Y0,Y1,Y2,Y3)     \
@@ -1171,7 +1183,7 @@ static const int aes_test_ctr_len[3] =
  */
 int aes_self_test( int verbose )
 {
-    int i, j, u, v;
+    int ret = 0, i, j, u, v;
     unsigned char key[32];
     unsigned char buf[64];
     unsigned char iv[16];
@@ -1189,6 +1201,7 @@ int aes_self_test( int verbose )
     aes_context ctx;
 
     memset( key, 0, 32 );
+    aes_init( &ctx );
 
     /*
      * ECB mode
@@ -1216,7 +1229,8 @@ int aes_self_test( int verbose )
                 if( verbose != 0 )
                     polarssl_printf( "failed\n" );
 
-                return( 1 );
+                ret = 1;
+                goto exit;
             }
         }
         else
@@ -1231,7 +1245,8 @@ int aes_self_test( int verbose )
                 if( verbose != 0 )
                     polarssl_printf( "failed\n" );
 
-                return( 1 );
+                ret = 1;
+                goto exit;
             }
         }
 
@@ -1271,7 +1286,8 @@ int aes_self_test( int verbose )
                 if( verbose != 0 )
                     polarssl_printf( "failed\n" );
 
-                return( 1 );
+                ret = 1;
+                goto exit;
             }
         }
         else
@@ -1294,7 +1310,8 @@ int aes_self_test( int verbose )
                 if( verbose != 0 )
                     polarssl_printf( "failed\n" );
 
-                return( 1 );
+                ret = 1;
+                goto exit;
             }
         }
 
@@ -1335,7 +1352,8 @@ int aes_self_test( int verbose )
                 if( verbose != 0 )
                     polarssl_printf( "failed\n" );
 
-                return( 1 );
+                ret = 1;
+                goto exit;
             }
         }
         else
@@ -1348,7 +1366,8 @@ int aes_self_test( int verbose )
                 if( verbose != 0 )
                     polarssl_printf( "failed\n" );
 
-                return( 1 );
+                ret = 1;
+                goto exit;
             }
         }
 
@@ -1392,7 +1411,8 @@ int aes_self_test( int verbose )
                 if( verbose != 0 )
                     polarssl_printf( "failed\n" );
 
-                return( 1 );
+                ret = 1;
+                goto exit;
             }
         }
         else
@@ -1408,7 +1428,8 @@ int aes_self_test( int verbose )
                 if( verbose != 0 )
                     polarssl_printf( "failed\n" );
 
-                return( 1 );
+                ret = 1;
+                goto exit;
             }
         }
 
@@ -1420,7 +1441,12 @@ int aes_self_test( int verbose )
         polarssl_printf( "\n" );
 #endif /* POLARSSL_CIPHER_MODE_CTR */
 
-    return( 0 );
+    ret = 0;
+
+exit:
+    aes_free( &ctx );
+
+    return( ret );
 }
 
 #endif /* POLARSSL_SELF_TEST */
diff --git a/library/arc4.c b/library/arc4.c
index d722c56ea..54e89ea88 100644
--- a/library/arc4.c
+++ b/library/arc4.c
@@ -46,6 +46,24 @@
 
 #if !defined(POLARSSL_ARC4_ALT)
 
+/* Implementation that should never be optimized out by the compiler */
+static void polarssl_zeroize( void *v, size_t n ) {
+    volatile unsigned char *p = v; while( n-- ) *p++ = 0;
+}
+
+void arc4_init( arc4_context *ctx )
+{
+    memset( ctx, 0, sizeof( arc4_context ) );
+}
+
+void arc4_free( arc4_context *ctx )
+{
+    if( ctx == NULL )
+        return;
+
+    polarssl_zeroize( ctx, sizeof( arc4_context ) );
+}
+
 /*
  * ARC4 key schedule
  */
@@ -146,11 +164,13 @@ static const unsigned char arc4_test_ct[3][8] =
  */
 int arc4_self_test( int verbose )
 {
-    int i;
+    int i, ret = 0;
     unsigned char ibuf[8];
     unsigned char obuf[8];
     arc4_context ctx;
 
+    arc4_init( &ctx );
+
     for( i = 0; i < 3; i++ )
     {
         if( verbose != 0 )
@@ -166,7 +186,8 @@ int arc4_self_test( int verbose )
             if( verbose != 0 )
                 polarssl_printf( "failed\n" );
 
-            return( 1 );
+            ret = 1;
+            goto exit;
         }
 
         if( verbose != 0 )
@@ -176,7 +197,10 @@ int arc4_self_test( int verbose )
     if( verbose != 0 )
         polarssl_printf( "\n" );
 
-    return( 0 );
+exit:
+    arc4_free( &ctx );
+
+    return( ret );
 }
 
 #endif /* POLARSSL_SELF_TEST */
diff --git a/library/blowfish.c b/library/blowfish.c
index d8b0c36ce..87396dc22 100644
--- a/library/blowfish.c
+++ b/library/blowfish.c
@@ -41,6 +41,11 @@
 
 #if !defined(POLARSSL_BLOWFISH_ALT)
 
+/* Implementation that should never be optimized out by the compiler */
+static void polarssl_zeroize( void *v, size_t n ) {
+    volatile unsigned char *p = v; while( n-- ) *p++ = 0;
+}
+
 /*
  * 32-bit integer manipulation macros (big endian)
  */
@@ -152,6 +157,19 @@ static void blowfish_dec( blowfish_context *ctx, uint32_t *xl, uint32_t *xr )
     *xr = Xr;
 }
 
+void blowfish_init( blowfish_context *ctx )
+{
+    memset( ctx, 0, sizeof( blowfish_context ) );
+}
+
+void blowfish_free( blowfish_context *ctx )
+{
+    if( ctx == NULL )
+        return;
+
+    polarssl_zeroize( ctx, sizeof( blowfish_context ) );
+}
+
 /*
  * Blowfish key schedule
  */
diff --git a/library/camellia.c b/library/camellia.c
index f1d4d6b24..a4968f411 100644
--- a/library/camellia.c
+++ b/library/camellia.c
@@ -322,6 +322,19 @@ static void camellia_feistel( const uint32_t x[2], const uint32_t k[2],
     z[1] ^= I0;
 }
 
+void camellia_init( camellia_context *ctx )
+{
+    memset( ctx, 0, sizeof( camellia_context ) );
+}
+
+void camellia_free( camellia_context *ctx )
+{
+    if( ctx == NULL )
+        return;
+
+    polarssl_zeroize( ctx, sizeof( camellia_context ) );
+}
+
 /*
  * Camellia key schedule (encryption)
  */
@@ -433,16 +446,17 @@ int camellia_setkey_enc( camellia_context *ctx, const unsigned char *key,
 int camellia_setkey_dec( camellia_context *ctx, const unsigned char *key,
                          unsigned int keysize )
 {
-    int idx;
+    int idx, ret;
     size_t i;
     camellia_context cty;
     uint32_t *RK;
     uint32_t *SK;
-    int ret;
+
+    camellia_init( &cty );
 
     /* Also checks keysize */
     if( ( ret = camellia_setkey_enc( &cty, key, keysize ) ) )
-        return( ret );
+        goto exit;
 
     ctx->nr = cty.nr;
     idx = ( ctx->nr == 4 );
@@ -468,9 +482,10 @@ int camellia_setkey_dec( camellia_context *ctx, const unsigned char *key,
     *RK++ = *SK++;
     *RK++ = *SK++;
 
-    polarssl_zeroize( &cty, sizeof( camellia_context ) );
+exit:
+    camellia_free( &cty );
 
-    return( 0 );
+    return( ret );
 }
 
 /*
diff --git a/library/cipher_wrap.c b/library/cipher_wrap.c
index 070963a36..47a69a97b 100644
--- a/library/cipher_wrap.c
+++ b/library/cipher_wrap.c
@@ -74,11 +74,6 @@
 
 #include <stdlib.h>
 
-/* Implementation that should never be optimized out by the compiler */
-static void polarssl_zeroize( void *v, size_t n ) {
-    volatile unsigned char *p = v; while( n-- ) *p++ = 0;
-}
-
 #if defined(POLARSSL_GCM_C)
 /* shared by all GCM ciphers */
 static void *gcm_ctx_alloc( void )
@@ -187,12 +182,19 @@ static int aes_setkey_enc_wrap( void *ctx, const unsigned char *key,
 
 static void * aes_ctx_alloc( void )
 {
-    return polarssl_malloc( sizeof( aes_context ) );
+    aes_context *aes = (aes_context *) polarssl_malloc( sizeof( aes_context ) );
+
+    if( aes == NULL )
+        return( NULL );
+
+    aes_init( aes );
+
+    return( aes );
 }
 
 static void aes_ctx_free( void *ctx )
 {
-    polarssl_zeroize( ctx, sizeof( aes_context ) );
+    aes_free( (aes_context *) ctx );
     polarssl_free( ctx );
 }
 
@@ -541,12 +543,20 @@ static int camellia_setkey_enc_wrap( void *ctx, const unsigned char *key,
 
 static void * camellia_ctx_alloc( void )
 {
-    return polarssl_malloc( sizeof( camellia_context ) );
+    camellia_context *ctx;
+    ctx = (camellia_context *) polarssl_malloc( sizeof( camellia_context ) );
+
+    if( ctx == NULL )
+        return( NULL );
+
+    camellia_init( ctx );
+
+    return( ctx );
 }
 
 static void camellia_ctx_free( void *ctx )
 {
-    polarssl_zeroize( ctx, sizeof( camellia_context ) );
+    camellia_free( (camellia_context *) ctx );
     polarssl_free( ctx );
 }
 
@@ -915,23 +925,38 @@ static int des3_set3key_enc_wrap( void *ctx, const unsigned char *key,
 
 static void * des_ctx_alloc( void )
 {
-    return polarssl_malloc( sizeof( des_context ) );
-}
+    des_context *des = (des_context *) polarssl_malloc( sizeof( des_context ) );
 
-static void * des3_ctx_alloc( void )
-{
-    return polarssl_malloc( sizeof( des3_context ) );
+    if( des == NULL )
+        return( NULL );
+
+    des_init( des );
+
+    return( des );
 }
 
 static void des_ctx_free( void *ctx )
 {
-    polarssl_zeroize( ctx, sizeof( des_context ) );
+    des_free( (des_context *) ctx );
     polarssl_free( ctx );
 }
 
+static void * des3_ctx_alloc( void )
+{
+    des3_context *des3;
+    des3 = (des3_context *) polarssl_malloc( sizeof( des3_context ) );
+
+    if( des3 == NULL )
+        return( NULL );
+
+    des3_init( des3 );
+
+    return( des3 );
+}
+
 static void des3_ctx_free( void *ctx )
 {
-    polarssl_zeroize( ctx, sizeof( des3_context ) );
+    des3_free( (des3_context *) ctx );
     polarssl_free( ctx );
 }
 
@@ -1122,12 +1147,20 @@ static int blowfish_setkey_wrap( void *ctx, const unsigned char *key,
 
 static void * blowfish_ctx_alloc( void )
 {
-    return polarssl_malloc( sizeof( blowfish_context ) );
+    blowfish_context *ctx;
+    ctx = (blowfish_context *) polarssl_malloc( sizeof( blowfish_context ) );
+
+    if( ctx == NULL )
+        return( NULL );
+
+    blowfish_init( ctx );
+
+    return( ctx );
 }
 
 static void blowfish_ctx_free( void *ctx )
 {
-    polarssl_zeroize( ctx, sizeof( blowfish_context ) );
+    blowfish_free( (blowfish_context *) ctx );
     polarssl_free( ctx );
 }
 
@@ -1216,12 +1249,20 @@ static int arc4_setkey_wrap( void *ctx, const unsigned char *key,
 
 static void * arc4_ctx_alloc( void )
 {
-    return polarssl_malloc( sizeof( arc4_context ) );
+    arc4_context *ctx;
+    ctx = (arc4_context *) polarssl_malloc( sizeof( arc4_context ) );
+
+    if( ctx == NULL )
+        return( NULL );
+
+    arc4_init( ctx );
+
+    return( ctx );
 }
 
 static void arc4_ctx_free( void *ctx )
 {
-    polarssl_zeroize( ctx, sizeof( arc4_context ) );
+    arc4_free( (arc4_context *) ctx );
     polarssl_free( ctx );
 }
 
diff --git a/library/ctr_drbg.c b/library/ctr_drbg.c
index 3db517d55..249b84069 100644
--- a/library/ctr_drbg.c
+++ b/library/ctr_drbg.c
@@ -66,6 +66,8 @@ int ctr_drbg_init_entropy_len(
     memset( ctx, 0, sizeof(ctr_drbg_context) );
     memset( key, 0, CTR_DRBG_KEYSIZE );
 
+    aes_init( &ctx->aes_ctx );
+
     ctx->f_entropy = f_entropy;
     ctx->p_entropy = p_entropy;
 
@@ -122,6 +124,7 @@ static int block_cipher_df( unsigned char *output,
     size_t buf_len, use_len;
 
     memset( buf, 0, CTR_DRBG_MAX_SEED_INPUT + CTR_DRBG_BLOCKSIZE + 16 );
+    aes_init( &aes_ctx );
 
     /*
      * Construct IV (16 bytes) and S in buffer
@@ -189,6 +192,8 @@ static int block_cipher_df( unsigned char *output,
         p += CTR_DRBG_BLOCKSIZE;
     }
 
+    aes_free( &aes_ctx );
+
     return( 0 );
 }
 
diff --git a/library/des.c b/library/des.c
index 8c156aef6..12fe4f46a 100644
--- a/library/des.c
+++ b/library/des.c
@@ -305,6 +305,32 @@ static const uint32_t RHs[16] =
 
 #define SWAP(a,b) { uint32_t t = a; a = b; b = t; t = 0; }
 
+void des_init( des_context *ctx )
+{
+    memset( ctx, 0, sizeof( des_context ) );
+}
+
+void des_free( des_context *ctx )
+{
+    if( ctx == NULL )
+        return;
+
+    polarssl_zeroize( ctx, sizeof( des_context ) );
+}
+
+void des3_init( des3_context *ctx )
+{
+    memset( ctx, 0, sizeof( des3_context ) );
+}
+
+void des3_free( des3_context *ctx )
+{
+    if( ctx == NULL )
+        return;
+
+    polarssl_zeroize( ctx, sizeof( des3_context ) );
+}
+
 static const unsigned char odd_parity_table[128] = { 1,  2,  4,  7,  8,
         11, 13, 14, 16, 19, 21, 22, 25, 26, 28, 31, 32, 35, 37, 38, 41, 42, 44,
         47, 49, 50, 52, 55, 56, 59, 61, 62, 64, 67, 69, 70, 73, 74, 76, 79, 81,
@@ -839,7 +865,7 @@ static const unsigned char des3_test_cbc_enc[3][8] =
  */
 int des_self_test( int verbose )
 {
-    int i, j, u, v;
+    int i, j, u, v, ret = 0;
     des_context ctx;
     des3_context ctx3;
     unsigned char buf[8];
@@ -848,6 +874,8 @@ int des_self_test( int verbose )
     unsigned char iv[8];
 #endif
 
+    des_init( &ctx );
+    des3_init( &ctx3 );
     /*
      * ECB mode
      */
@@ -909,7 +937,8 @@ int des_self_test( int verbose )
             if( verbose != 0 )
                 polarssl_printf( "failed\n" );
 
-            return( 1 );
+            ret = 1;
+            goto exit;
         }
 
         if( verbose != 0 )
@@ -1004,7 +1033,8 @@ int des_self_test( int verbose )
             if( verbose != 0 )
                 polarssl_printf( "failed\n" );
 
-            return( 1 );
+            ret = 1;
+            goto exit;
         }
 
         if( verbose != 0 )
@@ -1015,7 +1045,11 @@ int des_self_test( int verbose )
     if( verbose != 0 )
         polarssl_printf( "\n" );
 
-    return( 0 );
+exit:
+    des_free( &ctx );
+    des3_free( &ctx3 );
+
+    return( ret );
 }
 
 #endif /* POLARSSL_SELF_TEST */
diff --git a/library/pem.c b/library/pem.c
index 4e00b63f6..a0ad46ee0 100644
--- a/library/pem.c
+++ b/library/pem.c
@@ -141,13 +141,15 @@ static void pem_des_decrypt( unsigned char des_iv[8],
     des_context des_ctx;
     unsigned char des_key[8];
 
+    des_init( &des_ctx );
+
     pem_pbkdf1( des_key, 8, des_iv, pwd, pwdlen );
 
     des_setkey_dec( &des_ctx, des_key );
     des_crypt_cbc( &des_ctx, DES_DECRYPT, buflen,
                      des_iv, buf, buf );
 
-    polarssl_zeroize( &des_ctx, sizeof( des_ctx ) );
+    des_free( &des_ctx );
     polarssl_zeroize( des_key, 8 );
 }
 
@@ -161,13 +163,15 @@ static void pem_des3_decrypt( unsigned char des3_iv[8],
     des3_context des3_ctx;
     unsigned char des3_key[24];
 
+    des3_init( &des3_ctx );
+
     pem_pbkdf1( des3_key, 24, des3_iv, pwd, pwdlen );
 
     des3_set3key_dec( &des3_ctx, des3_key );
     des3_crypt_cbc( &des3_ctx, DES_DECRYPT, buflen,
                      des3_iv, buf, buf );
 
-    polarssl_zeroize( &des3_ctx, sizeof( des3_ctx ) );
+    des3_free( &des3_ctx );
     polarssl_zeroize( des3_key, 24 );
 }
 #endif /* POLARSSL_DES_C */
@@ -183,13 +187,15 @@ static void pem_aes_decrypt( unsigned char aes_iv[16], unsigned int keylen,
     aes_context aes_ctx;
     unsigned char aes_key[32];
 
+    aes_init( &aes_ctx );
+
     pem_pbkdf1( aes_key, keylen, aes_iv, pwd, pwdlen );
 
     aes_setkey_dec( &aes_ctx, aes_key, keylen * 8 );
     aes_crypt_cbc( &aes_ctx, AES_DECRYPT, buflen,
                      aes_iv, buf, buf );
 
-    polarssl_zeroize( &aes_ctx, sizeof( aes_ctx ) );
+    aes_free( &aes_ctx );
     polarssl_zeroize( aes_key, keylen );
 }
 #endif /* POLARSSL_AES_C */
diff --git a/library/pkcs12.c b/library/pkcs12.c
index b0254508d..027f84a82 100644
--- a/library/pkcs12.c
+++ b/library/pkcs12.c
@@ -147,6 +147,8 @@ int pkcs12_pbe_sha1_rc4_128( asn1_buf *pbe_params, int mode,
     arc4_context ctx;
     ((void) mode);
 
+    arc4_init( &ctx );
+
     if( ( ret = pkcs12_pbe_derive_key_iv( pbe_params, POLARSSL_MD_SHA1,
                                           pwd, pwdlen,
                                           key, 16, NULL, 0 ) ) != 0 )
@@ -156,9 +158,13 @@ int pkcs12_pbe_sha1_rc4_128( asn1_buf *pbe_params, int mode,
 
     arc4_setup( &ctx, key, 16 );
     if( ( ret = arc4_crypt( &ctx, len, data, output ) ) != 0 )
-        return( ret );
+        goto exit;
 
-    return( 0 );
+exit:
+    polarssl_zeroize( key, sizeof( key ) );
+    arc4_free( &ctx );
+
+    return( ret );
 #endif /* POLARSSL_ARC4_C */
 }
 
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 8040f9092..28ca14aa2 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -3482,6 +3482,14 @@ int ssl_session_reset( ssl_context *ssl )
 }
 
 #if defined(POLARSSL_SSL_SESSION_TICKETS)
+static void ssl_ticket_keys_free( ssl_ticket_keys *tkeys )
+{
+    aes_free( &tkeys->enc );
+    aes_free( &tkeys->dec );
+
+    polarssl_zeroize( tkeys, sizeof(ssl_ticket_keys) );
+}
+
 /*
  * Allocate and initialize ticket keys
  */
@@ -3498,8 +3506,12 @@ static int ssl_ticket_keys_init( ssl_context *ssl )
     if( tkeys == NULL )
         return( POLARSSL_ERR_SSL_MALLOC_FAILED );
 
+    aes_init( &tkeys->enc );
+    aes_init( &tkeys->dec );
+
     if( ( ret = ssl->f_rng( ssl->p_rng, tkeys->key_name, 16 ) ) != 0 )
     {
+        ssl_ticket_keys_free( tkeys );
         polarssl_free( tkeys );
         return( ret );
     }
@@ -3508,12 +3520,14 @@ static int ssl_ticket_keys_init( ssl_context *ssl )
         ( ret = aes_setkey_enc( &tkeys->enc, buf, 128 ) ) != 0 ||
         ( ret = aes_setkey_dec( &tkeys->dec, buf, 128 ) ) != 0 )
     {
+        ssl_ticket_keys_free( tkeys );
         polarssl_free( tkeys );
         return( ret );
     }
 
     if( ( ret = ssl->f_rng( ssl->p_rng, tkeys->mac_key, 16 ) ) != 0 )
     {
+        ssl_ticket_keys_free( tkeys );
         polarssl_free( tkeys );
         return( ret );
     }
@@ -4580,7 +4594,11 @@ void ssl_free( ssl_context *ssl )
     }
 
 #if defined(POLARSSL_SSL_SESSION_TICKETS)
-    polarssl_free( ssl->ticket_keys );
+    if( ssl->ticket_keys )
+    {
+        ssl_ticket_keys_free( ssl->ticket_keys );
+        polarssl_free( ssl->ticket_keys );
+    }
 #endif
 
 #if defined(POLARSSL_SSL_SERVER_NAME_INDICATION)
diff --git a/library/xtea.c b/library/xtea.c
index 5ff8a044f..75215c50a 100644
--- a/library/xtea.c
+++ b/library/xtea.c
@@ -41,6 +41,11 @@
 
 #if !defined(POLARSSL_XTEA_ALT)
 
+/* Implementation that should never be optimized out by the compiler */
+static void polarssl_zeroize( void *v, size_t n ) {
+    volatile unsigned char *p = v; while( n-- ) *p++ = 0;
+}
+
 /*
  * 32-bit integer manipulation macros (big endian)
  */
@@ -64,6 +69,19 @@
 }
 #endif
 
+void xtea_init( xtea_context *ctx )
+{
+    memset( ctx, 0, sizeof( xtea_context ) );
+}
+
+void xtea_free( xtea_context *ctx )
+{
+    if( ctx == NULL )
+        return;
+
+    polarssl_zeroize( ctx, sizeof( xtea_context ) );
+}
+
 /*
  * XTEA key schedule
  */
@@ -223,10 +241,11 @@ static const unsigned char xtea_test_ct[6][8] =
  */
 int xtea_self_test( int verbose )
 {
-    int i;
+    int i, ret = 0;
     unsigned char buf[8];
     xtea_context ctx;
 
+    xtea_init( &ctx );
     for( i = 0; i < 6; i++ )
     {
         if( verbose != 0 )
@@ -242,7 +261,8 @@ int xtea_self_test( int verbose )
             if( verbose != 0 )
                 polarssl_printf( "failed\n" );
 
-            return( 1 );
+            ret = 1;
+            goto exit;
         }
 
         if( verbose != 0 )
@@ -252,7 +272,10 @@ int xtea_self_test( int verbose )
     if( verbose != 0 )
         polarssl_printf( "\n" );
 
-    return( 0 );
+exit:
+    xtea_free( &ctx );
+
+    return( ret );
 }
 
 #endif /* POLARSSL_SELF_TEST */