version 0.3.33

[fms.git] / libs / libtomcrypt / pk / asn1 / der / short_integer / der_decode_short_integer.c

diff --git a/libs/libtomcrypt/pk/asn1/der/short_integer/der_decode_short_integer.c b/libs/libtomcrypt/pk/asn1/der/short_integer/der_decode_short_integer.c
new file mode 100644 (file)
index 0000000..1407e9a
--- /dev/null
+++ b/libs/libtomcrypt/pk/asn1/der/short_integer/der_decode_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.
+ *
+ * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com
+ */
+#include "tomcrypt.h"
+
+/**
+  @file der_decode_short_integer.c
+  ASN.1 DER, decode an integer, Tom St Denis
+*/
+
+
+#ifdef LTC_DER
+
+/**
+  Read a short integer
+  @param in       The DER encoded data
+  @param inlen    Size of data
+  @param num      [out] The integer to decode
+  @return CRYPT_OK if successful
+*/
+int der_decode_short_integer(const unsigned char *in, unsigned long inlen, unsigned long *num)
+{
+   unsigned long len, x, y;
+
+   LTC_ARGCHK(num    != NULL);
+   LTC_ARGCHK(in     != NULL);
+
+   /* check length */
+   if (inlen < 2) {
+      return CRYPT_INVALID_PACKET;
+   }
+
+   /* check header */
+   x = 0;
+   if ((in[x++] & 0x1F) != 0x02) {
+      return CRYPT_INVALID_PACKET;
+   }
+
+   /* get the packet len */
+   len = in[x++];
+
+   if (x + len > inlen) {
+      return CRYPT_INVALID_PACKET;
+   }
+
+   /* read number */
+   y = 0;
+   while (len--) {
+      y = (y<<8) | (unsigned long)in[x++];
+   }
+   *num = y;
+
+   return CRYPT_OK;
+
+}
+
+#endif
+
+/* $Source: /cvs/libtom/libtomcrypt/src/pk/asn1/der/short_integer/der_decode_short_integer.c,v $ */
+/* $Revision: 1.6 $ */
+/* $Date: 2006/03/31 14:15:35 $ */