--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtomcrypt/src/pk/asn1/der/generalizedtime/der_decode_generalizedtime.c	Fri Feb 09 21:44:05 2018 +0800
@@ -0,0 +1,144 @@
+/* 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_decode_generalizedtime.c
+  ASN.1 DER, decode a GeneralizedTime, Steffen Jaeckel
+  Based on der_decode_utctime.c
+*/
+
+#ifdef LTC_DER
+
+static int _char_to_int(unsigned char x)
+{
+   switch (x)  {
+      case '0': return 0;
+      case '1': return 1;
+      case '2': return 2;
+      case '3': return 3;
+      case '4': return 4;
+      case '5': return 5;
+      case '6': return 6;
+      case '7': return 7;
+      case '8': return 8;
+      case '9': return 9;
+      default:  return 100;
+   }
+}
+
+#define DECODE_V(y, max) do {\
+   y  = _char_to_int(buf[x])*10 + _char_to_int(buf[x+1]); \
+   if (y >= max) return CRYPT_INVALID_PACKET;           \
+   x += 2; \
+} while(0)
+
+#define DECODE_V4(y, max) do {\
+   y  = _char_to_int(buf[x])*1000 + _char_to_int(buf[x+1])*100 + _char_to_int(buf[x+2])*10 + _char_to_int(buf[x+3]); \
+   if (y >= max) return CRYPT_INVALID_PACKET; \
+   x += 4; \
+} while(0)
+
+/**
+  Decodes a Generalized time structure in DER format (reads all 6 valid encoding formats)
+  @param in     Input buffer
+  @param inlen  Length of input buffer in octets
+  @param out    [out] Destination of Generalized time structure
+  @return CRYPT_OK   if successful
+*/
+int der_decode_generalizedtime(const unsigned char *in, unsigned long *inlen,
+                               ltc_generalizedtime *out)
+{
+   unsigned char buf[32];
+   unsigned long x;
+   int           y;
+
+   LTC_ARGCHK(in    != NULL);
+   LTC_ARGCHK(inlen != NULL);
+   LTC_ARGCHK(out   != NULL);
+
+   /* check header */
+   if (*inlen < 2UL || (in[1] >= sizeof(buf)) || ((in[1] + 2UL) > *inlen)) {
+      return CRYPT_INVALID_PACKET;
+   }
+
+   /* decode the string */
+   for (x = 0; x < in[1]; x++) {
+       y = der_ia5_value_decode(in[x+2]);
+       if (y == -1) {
+          return CRYPT_INVALID_PACKET;
+       }
+       if (!((y >= '0' && y <= '9')
+            || y == 'Z' || y == '.'
+            || y == '+' || y == '-')) {
+          return CRYPT_INVALID_PACKET;
+       }
+       buf[x] = y;
+   }
+   *inlen = 2 + x;
+
+   if (x < 15) {
+      return CRYPT_INVALID_PACKET;
+   }
+
+   /* possible encodings are
+YYYYMMDDhhmmssZ
+YYYYMMDDhhmmss+hh'mm'
+YYYYMMDDhhmmss-hh'mm'
+YYYYMMDDhhmmss.fsZ
+YYYYMMDDhhmmss.fs+hh'mm'
+YYYYMMDDhhmmss.fs-hh'mm'
+
+    So let's do a trivial decode upto [including] ss
+   */
+
+    x = 0;
+    DECODE_V4(out->YYYY, 10000);
+    DECODE_V(out->MM, 13);
+    DECODE_V(out->DD, 32);
+    DECODE_V(out->hh, 24);
+    DECODE_V(out->mm, 60);
+    DECODE_V(out->ss, 60);
+
+    /* clear fractional seconds info */
+    out->fs = 0;
+
+    /* now is it Z or . */
+    if (buf[x] == 'Z') {
+       return CRYPT_OK;
+    } else if (buf[x] == '.') {
+       x++;
+       while (buf[x] >= '0' && buf[x] <= '9') {
+          unsigned fs = out->fs;
+          if (x >= sizeof(buf)) return CRYPT_INVALID_PACKET;
+          out->fs *= 10;
+          out->fs += _char_to_int(buf[x]);
+          if (fs > out->fs) return CRYPT_OVERFLOW;
+          x++;
+       }
+    }
+
+    /* now is it Z, +, - */
+    if (buf[x] == 'Z') {
+       return CRYPT_OK;
+    } else if (buf[x] == '+' || buf[x] == '-') {
+       out->off_dir = (buf[x++] == '+') ? 0 : 1;
+       DECODE_V(out->off_hh, 24);
+       DECODE_V(out->off_mm, 60);
+       return CRYPT_OK;
+    } else {
+       return CRYPT_INVALID_PACKET;
+    }
+}
+
+#endif
+
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */