Add function for generating validation signatures.

src/trusted/validator/caching/validation_signature.cc

Index: src/trusted/validator/caching/validation_signature.cc
diff --git a/src/trusted/validator/caching/validation_signature.cc b/src/trusted/validator/caching/validation_signature.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5124c10999c126b8c3f50e33d13ff395be788185
--- /dev/null
+++ b/src/trusted/validator/caching/validation_signature.cc
@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2012 The Native Client Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include <string.h>
+
+#include "native_client/src/trusted/validator/caching/validation_signature.h"
+#include "native_client/src/trusted/validator/caching/hashing_interface.h"
+
+void GetValidationSignature(const HashingInterface *hashing,
+                            const ValidationInfo *info,
+                            const unsigned char *code,
+                            unsigned int code_length,
+                            ValidationSignature *sig) {
+  void *ctx = hashing->create(info->key, info->key_length);
+  /* Generic validation info */
+  hashing->update(ctx, (const unsigned char*) info->isa,
+                  strlen(info->isa));
+  hashing->update(ctx, (const unsigned char*) info->version,
+                  strlen(info->version));
+  hashing->update(ctx, (const unsigned char *) info->cpu_features,
+                  sizeof(NaClCPUFeatures));
+  /* Code identity */
+  hashing->update(ctx, code, code_length);
+  /* Generate hash and cleanup */
+  hashing->end(ctx, sig->data, &sig->length, VALIDATION_SIGNATURE_MAX_LENGTH);
+}