X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=libtomcrypt%2Fsrc%2Fencauth%2Fgcm%2Fgcm_done.c;fp=libtomcrypt%2Fsrc%2Fencauth%2Fgcm%2Fgcm_done.c;h=ffd551e8305801dffc4a981f572c85679a25bc98;hb=66bc25938679f1d6a1d1200f329093d82a5e99b4;hp=0000000000000000000000000000000000000000;hpb=a52ee0733f420ca20224049260d6fc5cf7d8f621;p=zpackage

diff --git a/libtomcrypt/src/encauth/gcm/gcm_done.c b/libtomcrypt/src/encauth/gcm/gcm_done.c
new file mode 100644
index 0000000..ffd551e
--- /dev/null
+++ b/libtomcrypt/src/encauth/gcm/gcm_done.c
@@ -0,0 +1,90 @@
+/* LibTomCrypt, modular cryptographic library -- Tom St Denis
+ *
+ * LibTomCrypt is a library that provides various cryptographic
+ * algorithms in a highly modular and flexible manner.
+ *
+ * The library is free for all purposes without any express
+ * guarantee it works.
+ */
+
+/**
+   @file gcm_done.c
+   GCM implementation, Terminate the stream, by Tom St Denis
+*/
+#include "tomcrypt.h"
+
+#ifdef LTC_GCM_MODE
+
+/**
+  Terminate a GCM stream
+  @param gcm     The GCM state
+  @param tag     [out] The destination for the MAC tag
+  @param taglen  [in/out]  The length of the MAC tag
+  @return CRYPT_OK on success
+ */
+int gcm_done(gcm_state *gcm,
+                     unsigned char *tag,    unsigned long *taglen)
+{
+   unsigned long x;
+   int err;
+
+   LTC_ARGCHK(gcm     != NULL);
+   LTC_ARGCHK(tag     != NULL);
+   LTC_ARGCHK(taglen  != NULL);
+
+   if (gcm->buflen > 16 || gcm->buflen < 0) {
+      return CRYPT_INVALID_ARG;
+   }
+
+   if ((err = cipher_is_valid(gcm->cipher)) != CRYPT_OK) {
+      return err;
+   }
+
+   if (gcm->mode == LTC_GCM_MODE_IV) {
+      /* let's process the IV */
+      if ((err = gcm_add_aad(gcm, NULL, 0)) != CRYPT_OK) return err;
+   }
+
+   if (gcm->mode == LTC_GCM_MODE_AAD) {
+      /* let's process the AAD */
+      if ((err = gcm_process(gcm, NULL, 0, NULL, 0)) != CRYPT_OK) return err;
+   }
+
+   if (gcm->mode != LTC_GCM_MODE_TEXT) {
+      return CRYPT_INVALID_ARG;
+   }
+
+   /* handle remaining ciphertext */
+   if (gcm->buflen) {
+      gcm->pttotlen += gcm->buflen * CONST64(8);
+      gcm_mult_h(gcm, gcm->X);
+   }
+
+   /* length */
+   STORE64H(gcm->totlen, gcm->buf);
+   STORE64H(gcm->pttotlen, gcm->buf+8);
+   for (x = 0; x < 16; x++) {
+       gcm->X[x] ^= gcm->buf[x];
+   }
+   gcm_mult_h(gcm, gcm->X);
+
+   /* encrypt original counter */
+   if ((err = cipher_descriptor[gcm->cipher].ecb_encrypt(gcm->Y_0, gcm->buf, &gcm->K)) != CRYPT_OK) {
+      return err;
+   }
+   for (x = 0; x < 16 && x < *taglen; x++) {
+       tag[x] = gcm->buf[x] ^ gcm->X[x];
+   }
+   *taglen = x;
+
+   cipher_descriptor[gcm->cipher].done(&gcm->K);
+
+   return CRYPT_OK;
+}
+
+#endif
+
+
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */