X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=libtomcrypt%2Fsrc%2Fpk%2Fasn1%2Fder%2Fshort_integer%2Fder_length_short_integer.c;fp=libtomcrypt%2Fsrc%2Fpk%2Fasn1%2Fder%2Fshort_integer%2Fder_length_short_integer.c;h=52d0e1aef346fb2cd5278ee0d2443aa4137dcdee;hb=66bc25938679f1d6a1d1200f329093d82a5e99b4;hp=0000000000000000000000000000000000000000;hpb=a52ee0733f420ca20224049260d6fc5cf7d8f621;p=zpackage

diff --git a/libtomcrypt/src/pk/asn1/der/short_integer/der_length_short_integer.c b/libtomcrypt/src/pk/asn1/der/short_integer/der_length_short_integer.c
new file mode 100644
index 0000000..52d0e1a
--- /dev/null
+++ b/libtomcrypt/src/pk/asn1/der/short_integer/der_length_short_integer.c
@@ -0,0 +1,68 @@
+/* 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 der_length_short_integer.c
+  ASN.1 DER, get length of encoding, Tom St Denis
+*/
+
+
+#ifdef LTC_DER
+/**
+  Gets length of DER encoding of num
+  @param num    The integer to get the size of
+  @param outlen [out] The length of the DER encoding for the given integer
+  @return CRYPT_OK if successful
+*/
+int der_length_short_integer(unsigned long num, unsigned long *outlen)
+{
+   unsigned long z, y, len;
+
+   LTC_ARGCHK(outlen  != NULL);
+
+   /* force to 32 bits */
+   num &= 0xFFFFFFFFUL;
+
+   /* get the number of bytes */
+   z = 0;
+   y = num;
+   while (y) {
+     ++z;
+     y >>= 8;
+   }
+
+   /* handle zero */
+   if (z == 0) {
+      z = 1;
+   }
+
+   /* we need a 0x02 to indicate it's INTEGER */
+   len = 1;
+
+   /* length byte */
+   ++len;
+
+   /* bytes in value */
+   len += z;
+
+   /* see if msb is set */
+   len += (num&(1UL<<((z<<3) - 1))) ? 1 : 0;
+
+   /* return length */
+   *outlen = len;
+
+   return CRYPT_OK;
+}
+
+#endif
+
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */