--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtomcrypt/src/pk/rsa/rsa_import_x509.c	Fri Feb 09 21:44:05 2018 +0800
@@ -0,0 +1,118 @@
+/* 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 rsa_import.c
+  Import an RSA key from a X.509 certificate, Steffen Jaeckel
+*/
+
+#ifdef LTC_MRSA
+
+/**
+  Import an RSA key from a X.509 certificate
+  @param in      The packet to import from
+  @param inlen   It's length (octets)
+  @param key     [out] Destination for newly imported key
+  @return CRYPT_OK if successful, upon error allocated memory is freed
+*/
+int rsa_import_x509(const unsigned char *in, unsigned long inlen, rsa_key *key)
+{
+   int           err;
+   unsigned char *tmpbuf;
+   unsigned long tmpbuf_len, tmp_inlen;
+   ltc_asn1_list *decoded_list = NULL, *l;
+
+   LTC_ARGCHK(in          != NULL);
+   LTC_ARGCHK(key         != NULL);
+   LTC_ARGCHK(ltc_mp.name != NULL);
+
+   /* init key */
+   if ((err = mp_init_multi(&key->e, &key->d, &key->N, &key->dQ,
+                            &key->dP, &key->qP, &key->p, &key->q, NULL)) != CRYPT_OK) {
+      return err;
+   }
+
+   tmpbuf_len = inlen;
+   tmpbuf = XCALLOC(1, tmpbuf_len);
+   if (tmpbuf == NULL) {
+       err = CRYPT_MEM;
+       goto LBL_ERR;
+   }
+
+   tmp_inlen = inlen;
+   if ((err = der_decode_sequence_flexi(in, &tmp_inlen, &decoded_list)) == CRYPT_OK) {
+      l = decoded_list;
+      /* Move 2 levels up in the tree
+         SEQUENCE
+             SEQUENCE
+                 ...
+       */
+      if (l->type == LTC_ASN1_SEQUENCE && l->child) {
+         l = l->child;
+         if (l->type == LTC_ASN1_SEQUENCE && l->child) {
+            l = l->child;
+
+            err = CRYPT_ERROR;
+
+            /* Move forward in the tree until we find this combination
+                 ...
+                 SEQUENCE
+                     SEQUENCE
+                         OBJECT IDENTIFIER 1.2.840.113549.1.1.1
+                         NULL
+                     BIT STRING
+             */
+            do {
+               /* The additional check for l->data is there to make sure
+                * we won't try to decode a list that has been 'shrunk'
+                */
+               if (l->type == LTC_ASN1_SEQUENCE && l->data && l->child &&
+                     l->child->type == LTC_ASN1_SEQUENCE && l->child->child &&
+                     l->child->child->type == LTC_ASN1_OBJECT_IDENTIFIER && l->child->next &&
+                     l->child->next->type == LTC_ASN1_BIT_STRING) {
+                  err = der_decode_subject_public_key_info(l->data, l->size,
+                       PKA_RSA, tmpbuf, &tmpbuf_len,
+                       LTC_ASN1_NULL, NULL, 0);
+                  if (err == CRYPT_OK) {
+                     /* now it should be SEQUENCE { INTEGER, INTEGER } */
+                     if ((err = der_decode_sequence_multi(tmpbuf, tmpbuf_len,
+                                                          LTC_ASN1_INTEGER, 1UL, key->N,
+                                                          LTC_ASN1_INTEGER, 1UL, key->e,
+                                                          LTC_ASN1_EOL,     0UL, NULL)) != CRYPT_OK) {
+                        goto LBL_ERR;
+                     }
+                     key->type = PK_PUBLIC;
+                     err = CRYPT_OK;
+                     goto LBL_FREE;
+                  }
+               }
+               l = l->next;
+            } while(l);
+         }
+      }
+   }
+
+
+LBL_ERR:
+   rsa_free(key);
+
+LBL_FREE:
+   if (decoded_list) der_free_sequence_flexi(decoded_list);
+   if (tmpbuf != NULL) XFREE(tmpbuf);
+
+   return err;
+}
+
+#endif /* LTC_MRSA */
+
+
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */