--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libtomcrypt/src/pk/asn1/der/sequence/der_decode_subject_public_key_info.c	Fri Feb 09 21:44:05 2018 +0800
@@ -0,0 +1,112 @@
+/* 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_subject_public_key_info.c
+  ASN.1 DER, encode a Subject Public Key structure --nmav
+*/
+
+#ifdef LTC_DER
+
+/* AlgorithmIdentifier := SEQUENCE {
+ *    algorithm OBJECT IDENTIFIER,
+ *    parameters ANY DEFINED BY algorithm
+ * }
+ *
+ * SubjectPublicKeyInfo := SEQUENCE {
+ *    algorithm AlgorithmIdentifier,
+ *    subjectPublicKey BIT STRING
+ * }
+ */
+/**
+  Decode a subject public key info
+   @param in      The input buffer
+   @param inlen   The length of the input buffer
+   @param algorithm             One out of the enum #public_key_algorithms
+   @param public_key            The buffer for the public key
+   @param public_key_len        [in/out] The length of the public key buffer and the written length
+   @param parameters_type       The parameters' type out of the enum ltc_asn1_type
+   @param parameters            The parameters to include
+   @param parameters_len        The number of parameters to include
+   @return CRYPT_OK on success
+*/
+int der_decode_subject_public_key_info(const unsigned char *in, unsigned long inlen,
+        unsigned int algorithm, void* public_key, unsigned long* public_key_len,
+        unsigned long parameters_type, ltc_asn1_list* parameters, unsigned long parameters_len)
+{
+   int err;
+   unsigned long len;
+   oid_st oid;
+   unsigned char *tmpbuf;
+   unsigned long  tmpoid[16];
+   ltc_asn1_list alg_id[2];
+   ltc_asn1_list subject_pubkey[2];
+
+   LTC_ARGCHK(in    != NULL);
+   LTC_ARGCHK(inlen != 0);
+   LTC_ARGCHK(public_key_len != NULL);
+
+   err = pk_get_oid(algorithm, &oid);
+   if (err != CRYPT_OK) {
+        return err;
+   }
+
+   /* see if the OpenSSL DER format RSA public key will work */
+   tmpbuf = XCALLOC(1, inlen);
+   if (tmpbuf == NULL) {
+       err = CRYPT_MEM;
+       goto LBL_ERR;
+   }
+
+   /* this includes the internal hash ID and optional params (NULL in this case) */
+   LTC_SET_ASN1(alg_id, 0, LTC_ASN1_OBJECT_IDENTIFIER, tmpoid, sizeof(tmpoid)/sizeof(tmpoid[0]));
+   LTC_SET_ASN1(alg_id, 1, (ltc_asn1_type)parameters_type, parameters, parameters_len);
+
+   /* the actual format of the SSL DER key is odd, it stores a RSAPublicKey
+    * in a **BIT** string ... so we have to extract it then proceed to convert bit to octet
+    */
+   LTC_SET_ASN1(subject_pubkey, 0, LTC_ASN1_SEQUENCE, alg_id, 2);
+   LTC_SET_ASN1(subject_pubkey, 1, LTC_ASN1_RAW_BIT_STRING, tmpbuf, inlen*8U);
+
+   err=der_decode_sequence(in, inlen, subject_pubkey, 2UL);
+   if (err != CRYPT_OK) {
+           goto LBL_ERR;
+   }
+
+   if ((alg_id[0].size != oid.OIDlen) ||
+        XMEMCMP(oid.OID, alg_id[0].data, oid.OIDlen * sizeof(oid.OID[0]))) {
+        /* OID mismatch */
+        err = CRYPT_PK_INVALID_TYPE;
+        goto LBL_ERR;
+   }
+
+   len = subject_pubkey[1].size/8;
+   if (*public_key_len > len) {
+       XMEMCPY(public_key, subject_pubkey[1].data, len);
+       *public_key_len = len;
+    } else {
+        *public_key_len = len;
+        err = CRYPT_BUFFER_OVERFLOW;
+        goto LBL_ERR;
+    }
+
+    err = CRYPT_OK;
+
+LBL_ERR:
+
+    XFREE(tmpbuf);
+
+    return err;
+}
+
+#endif
+
+/* ref:         $Format:%D$ */
+/* git commit:  $Format:%H$ */
+/* commit time: $Format:%ai$ */