z/OS support: AES128 & AES256

Introducing cipher feedback mode so that AES128 and AES256 become
usable as ciphers.

src/symmetric_gskssl.c

@@ -190,12 +190,51 @@ cryptoki_block_decrypt(pgp_crypt_t *crypt, void *out, const void *in)
     cryptoki_finish_int( crypt );
 }
 
+/*
+ * The input and output encrypted as though 128bit cfb mode is being used.
+ * The extra state information to record how much of the 128bit block we have
+ * used is contained in *num;
+ */
+void cryptoki_cfb128_encrypt( pgp_crypt_t *crypt, void *out, const void *in, size_t count )
+{
+    uint8_t c;
+    register int i, n;
+    for ( i = 0, n = crypt->num; i < count; i++, n = (n + 1) % 16 ) {
+        if( n == 0 ) {
+            cfb64_encrypt_iv( crypt );
+        }
+        c = (((uint8_t *)in)[i]) ^ (crypt->iv[n]);
+        ((uint8_t *)out)[i] = c;
+        crypt->iv[n] = c;
+    }
+
+    crypt->num = n;
+}
+
+void cryptoki_cfb128_decrypt( pgp_crypt_t *crypt, void *out, const void *in, size_t count )
+{
+    uint8_t c, cc;
+    register int i, n;
+
+    for ( i = 0, n = crypt->num; i < count; i++, n = (n + 1) % 16 ) {
+        if( n == 0 ) {
+            cfb64_encrypt_iv( crypt );
+        }
+        c = crypt->iv[n];
+        cc = ((uint8_t *)in)[i];
+        crypt->iv[n] = cc;
+        ((uint8_t *)out)[i] = c ^ cc;
+    }
+
+    crypt->num = n;
+}
+
+
 /*
  * The input and output encrypted as though 64bit cfb mode is being used.
  * The extra state information to record how much of the 64bit block we have
  * used is contained in *num;
  */
-
 void cryptoki_cfb64_encrypt( pgp_crypt_t *crypt, void *out, const void *in, size_t count)
 {
     uint8_t c;
@@ -307,8 +346,8 @@ static const pgp_crypt_t aes128 =
     std_resync,
     cryptoki_block_encrypt,
     cryptoki_block_decrypt,
-    cryptoki_cfb64_encrypt,
-    cryptoki_cfb64_decrypt,
+    cryptoki_cfb128_encrypt,
+    cryptoki_cfb128_decrypt,
     cryptoki_finish,
     TRAILER
 };
@@ -336,8 +375,8 @@ static const pgp_crypt_t aes256 =
     std_resync,
     cryptoki_block_encrypt,
     cryptoki_block_decrypt,
-    cryptoki_cfb64_encrypt,
-    cryptoki_cfb64_decrypt,
+    cryptoki_cfb128_encrypt,
+    cryptoki_cfb128_decrypt,
     cryptoki_finish,
     TRAILER
 };