X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=libtomcrypt%2Fsrc%2Fmodes%2Fctr%2Fctr_encrypt.c;fp=libtomcrypt%2Fsrc%2Fmodes%2Fctr%2Fctr_encrypt.c;h=eb7328c2dcbc7d2563901e98a8ce87fad0956577;hb=66bc25938679f1d6a1d1200f329093d82a5e99b4;hp=0000000000000000000000000000000000000000;hpb=a52ee0733f420ca20224049260d6fc5cf7d8f621;p=zpackage

diff --git a/libtomcrypt/src/modes/ctr/ctr_encrypt.c b/libtomcrypt/src/modes/ctr/ctr_encrypt.c
new file mode 100644
index 0000000..eb7328c
--- /dev/null
+++ b/libtomcrypt/src/modes/ctr/ctr_encrypt.c
@@ -0,0 +1,139 @@
+/* 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.
+ */
+#include "tomcrypt.h"
+
+/**
+  @file ctr_encrypt.c
+  CTR implementation, encrypt data, Tom St Denis
+*/
+
+
+#ifdef LTC_CTR_MODE
+
+/**
+  CTR encrypt software implementation
+  @param pt     Plaintext
+  @param ct     [out] Ciphertext
+  @param len    Length of plaintext (octets)
+  @param ctr    CTR state
+  @return CRYPT_OK if successful
+*/
+static int _ctr_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_CTR *ctr)
+{
+   int x, err;
+
+   while (len) {
+      /* is the pad empty? */
+      if (ctr->padlen == ctr->blocklen) {
+         /* increment counter */
+         if (ctr->mode == CTR_COUNTER_LITTLE_ENDIAN) {
+            /* little-endian */
+            for (x = 0; x < ctr->ctrlen; x++) {
+               ctr->ctr[x] = (ctr->ctr[x] + (unsigned char)1) & (unsigned char)255;
+               if (ctr->ctr[x] != (unsigned char)0) {
+                  break;
+               }
+            }
+         } else {
+            /* big-endian */
+            for (x = ctr->blocklen-1; x >= ctr->ctrlen; x--) {
+               ctr->ctr[x] = (ctr->ctr[x] + (unsigned char)1) & (unsigned char)255;
+               if (ctr->ctr[x] != (unsigned char)0) {
+                  break;
+               }
+            }
+         }
+
+         /* encrypt it */
+         if ((err = cipher_descriptor[ctr->cipher].ecb_encrypt(ctr->ctr, ctr->pad, &ctr->key)) != CRYPT_OK) {
+            return err;
+         }
+         ctr->padlen = 0;
+      }
+#ifdef LTC_FAST
+      if ((ctr->padlen == 0) && (len >= (unsigned long)ctr->blocklen)) {
+         for (x = 0; x < ctr->blocklen; x += sizeof(LTC_FAST_TYPE)) {
+            *(LTC_FAST_TYPE_PTR_CAST((unsigned char *)ct + x)) = *(LTC_FAST_TYPE_PTR_CAST((unsigned char *)pt + x)) ^
+                                                           *(LTC_FAST_TYPE_PTR_CAST((unsigned char *)ctr->pad + x));
+         }
+       pt         += ctr->blocklen;
+       ct         += ctr->blocklen;
+       len        -= ctr->blocklen;
+       ctr->padlen = ctr->blocklen;
+       continue;
+      }
+#endif
+      *ct++ = *pt++ ^ ctr->pad[ctr->padlen++];
+      --len;
+   }
+   return CRYPT_OK;
+}
+
+/**
+  CTR encrypt
+  @param pt     Plaintext
+  @param ct     [out] Ciphertext
+  @param len    Length of plaintext (octets)
+  @param ctr    CTR state
+  @return CRYPT_OK if successful
+*/
+int ctr_encrypt(const unsigned char *pt, unsigned char *ct, unsigned long len, symmetric_CTR *ctr)
+{
+   int err, fr;
+
+   LTC_ARGCHK(pt != NULL);
+   LTC_ARGCHK(ct != NULL);
+   LTC_ARGCHK(ctr != NULL);
+
+   if ((err = cipher_is_valid(ctr->cipher)) != CRYPT_OK) {
+       return err;
+   }
+
+   /* is blocklen/padlen valid? */
+   if ((ctr->blocklen < 1) || (ctr->blocklen > (int)sizeof(ctr->ctr)) ||
+       (ctr->padlen   < 0) || (ctr->padlen   > (int)sizeof(ctr->pad))) {
+      return CRYPT_INVALID_ARG;
+   }
+
+#ifdef LTC_FAST
+   if (ctr->blocklen % sizeof(LTC_FAST_TYPE)) {
+      return CRYPT_INVALID_ARG;
+   }
+#endif
+
+   /* handle acceleration only if pad is empty, accelerator is present and length is >= a block size */
+   if ((cipher_descriptor[ctr->cipher].accel_ctr_encrypt != NULL) && (len >= (unsigned long)ctr->blocklen)) {
+     if (ctr->padlen < ctr->blocklen) {
+       fr = ctr->blocklen - ctr->padlen;
+       if ((err = _ctr_encrypt(pt, ct, fr, ctr)) != CRYPT_OK) {
+          return err;
+       }
+       pt += fr;
+       ct += fr;
+       len -= fr;
+     }
+
+     if (len >= (unsigned long)ctr->blocklen) {
+       if ((err = cipher_descriptor[ctr->cipher].accel_ctr_encrypt(pt, ct, len/ctr->blocklen, ctr->ctr, ctr->mode, &ctr->key)) != CRYPT_OK) {
+          return err;
+       }
+       pt += (len / ctr->blocklen) * ctr->blocklen;
+       ct += (len / ctr->blocklen) * ctr->blocklen;
+       len %= ctr->blocklen;
+     }
+   }
+
+   return _ctr_encrypt(pt, ct, len, ctr);
+}
+
+#endif
+
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */