Add import/export functions for the RC4 state

2 files changed, 56 insertions, 0 deletions

diff --git a/src/crypto.c b/src/crypto.c
index 3ed6070..aca22f0 100644
--- a/src/crypto.c
+++ b/src/crypto.c
@@ -176,6 +176,42 @@ void RC4_FREE(struct ntlm_rc4_handle **handle)
     safefree(*handle);
 }
 
+int RC4_EXPORT(struct ntlm_rc4_handle *handle, struct ntlm_buffer *out)
+{
+    int i;
+
+    if (out->length < 258) return EAGAIN;
+
+    out->data[0] = (uint8_t)(handle->key.x & 0xff);
+    out->data[1] = (uint8_t)(handle->key.y & 0xff);
+    for (i = 0; i < 256; i++) {
+        out->data[i + 2] = (uint8_t)(handle->key.data[i] & 0xff);
+    }
+
+    out->length = 258;
+    return 0;
+}
+
+int RC4_IMPORT(struct ntlm_rc4_handle **_handle, struct ntlm_buffer *in)
+{
+    struct ntlm_rc4_handle *handle;
+    int i;
+
+    if (in->length != 258) return EINVAL;
+
+    handle = malloc(sizeof(struct ntlm_rc4_handle));
+    if (!handle) return ENOMEM;
+
+    handle->key.x = in->data[0];
+    handle->key.y = in->data[1];
+    for (i = 0; i < 256; i++) {
+        handle->key.data[i] = in->data[i + 2];
+    }
+
+    *_handle = handle;
+    return 0;
+}
+
 int RC4K(struct ntlm_buffer *key,
          enum ntlm_cipher_mode mode,
          struct ntlm_buffer *payload,
diff --git a/src/crypto.h b/src/crypto.h
index 87ff830..e40852e 100644
--- a/src/crypto.h
+++ b/src/crypto.h
@@ -113,6 +113,26 @@ int RC4_UPDATE(struct ntlm_rc4_handle *handle,
 void RC4_FREE(struct ntlm_rc4_handle **handle);
 
 /**
+ * @brief Exports the RC4 state
+ *
+ * @param handle    The RC4 handle to export from
+ * @param out       A buffer at least 258 bytes long
+ *
+ * @return  0 on success or EAGAIN if the buffer is too small
+ */
+int RC4_EXPORT(struct ntlm_rc4_handle *handle, struct ntlm_buffer *out);
+
+/**
+ * @brief Import an RC4 state
+ *
+ * @param handle    A new ntlm_rc4_handle on success
+ * @param in        A buffer containing an exported state
+ *
+ * @return 0 on success or EINVAL if the buffer is not an exported state
+ */
+int RC4_IMPORT(struct ntlm_rc4_handle **handle, struct ntlm_buffer *in);
+
+/**
  * @brief RC4 encryption/decryption all in one
  *
  * @param key       The encryption/decryption key