[proxmark3-svn] / common / mbedtls / asn1.h

/**
 * \file asn1.h
 *
 * \brief Generic ASN.1 parsing
 */
/*
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: GPL-2.0
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */
#ifndef MBEDTLS_ASN1_H
#define MBEDTLS_ASN1_H

#if !defined(MBEDTLS_CONFIG_FILE)
#include "config.h"
#else
#include MBEDTLS_CONFIG_FILE
#endif

#include <stddef.h>

#if defined(MBEDTLS_BIGNUM_C)
#include "bignum.h"
#endif

/**
 * \addtogroup asn1_module
 * \{
 */

/**
 * \name ASN1 Error codes
 * These error codes are OR'ed to X509 error codes for
 * higher error granularity.
 * ASN1 is a standard to specify data structures.
 * \{
 */
#define MBEDTLS_ERR_ASN1_OUT_OF_DATA                      -0x0060  /**< Out of data when parsing an ASN1 data structure. */
#define MBEDTLS_ERR_ASN1_UNEXPECTED_TAG                   -0x0062  /**< ASN1 tag was of an unexpected value. */
#define MBEDTLS_ERR_ASN1_INVALID_LENGTH                   -0x0064  /**< Error when trying to determine the length or invalid length. */
#define MBEDTLS_ERR_ASN1_LENGTH_MISMATCH                  -0x0066  /**< Actual length differs from expected length. */
#define MBEDTLS_ERR_ASN1_INVALID_DATA                     -0x0068  /**< Data is invalid. (not used) */
#define MBEDTLS_ERR_ASN1_ALLOC_FAILED                     -0x006A  /**< Memory allocation failed */
#define MBEDTLS_ERR_ASN1_BUF_TOO_SMALL                    -0x006C  /**< Buffer too small when writing ASN.1 data structure. */

/* \} name */

/**
 * \name DER constants
 * These constants comply with the DER encoded ASN.1 type tags.
 * DER encoding uses hexadecimal representation.
 * An example DER sequence is:\n
 * - 0x02 -- tag indicating INTEGER
 * - 0x01 -- length in octets
 * - 0x05 -- value
 * Such sequences are typically read into \c ::mbedtls_x509_buf.
 * \{
 */
#define MBEDTLS_ASN1_BOOLEAN                 0x01
#define MBEDTLS_ASN1_INTEGER                 0x02
#define MBEDTLS_ASN1_BIT_STRING              0x03
#define MBEDTLS_ASN1_OCTET_STRING            0x04
#define MBEDTLS_ASN1_NULL                    0x05
#define MBEDTLS_ASN1_OID                     0x06
#define MBEDTLS_ASN1_UTF8_STRING             0x0C
#define MBEDTLS_ASN1_SEQUENCE                0x10
#define MBEDTLS_ASN1_SET                     0x11
#define MBEDTLS_ASN1_PRINTABLE_STRING        0x13
#define MBEDTLS_ASN1_T61_STRING              0x14
#define MBEDTLS_ASN1_IA5_STRING              0x16
#define MBEDTLS_ASN1_UTC_TIME                0x17
#define MBEDTLS_ASN1_GENERALIZED_TIME        0x18
#define MBEDTLS_ASN1_UNIVERSAL_STRING        0x1C
#define MBEDTLS_ASN1_BMP_STRING              0x1E
#define MBEDTLS_ASN1_PRIMITIVE               0x00
#define MBEDTLS_ASN1_CONSTRUCTED             0x20
#define MBEDTLS_ASN1_CONTEXT_SPECIFIC        0x80

/*
 * Bit masks for each of the components of an ASN.1 tag as specified in
 * ITU X.690 (08/2015), section 8.1 "General rules for encoding",
 * paragraph 8.1.2.2:
 *
 * Bit  8     7   6   5          1
 *     +-------+-----+------------+
 *     | Class | P/C | Tag number |
 *     +-------+-----+------------+
 */
#define MBEDTLS_ASN1_TAG_CLASS_MASK          0xC0
#define MBEDTLS_ASN1_TAG_PC_MASK             0x20
#define MBEDTLS_ASN1_TAG_VALUE_MASK          0x1F

/* \} name */
/* \} addtogroup asn1_module */

/** Returns the size of the binary string, without the trailing \\0 */
#define MBEDTLS_OID_SIZE(x) (sizeof(x) - 1)

/**
 * Compares an mbedtls_asn1_buf structure to a reference OID.
 *
 * Only works for 'defined' oid_str values (MBEDTLS_OID_HMAC_SHA1), you cannot use a
 * 'unsigned char *oid' here!
 */
#define MBEDTLS_OID_CMP(oid_str, oid_buf)                                   \
        ( ( MBEDTLS_OID_SIZE(oid_str) != (oid_buf)->len ) ||                \
          memcmp( (oid_str), (oid_buf)->p, (oid_buf)->len) != 0 )

#ifdef __cplusplus
extern "C" {
#endif

/**
 * \name Functions to parse ASN.1 data structures
 * \{
 */

/**
 * Type-length-value structure that allows for ASN1 using DER.
 */
typedef struct mbedtls_asn1_buf
{
    int tag;                /**< ASN1 type, e.g. MBEDTLS_ASN1_UTF8_STRING. */
    size_t len;             /**< ASN1 length, in octets. */
    unsigned char *p;       /**< ASN1 data, e.g. in ASCII. */
}
mbedtls_asn1_buf;

/**
 * Container for ASN1 bit strings.
 */
typedef struct mbedtls_asn1_bitstring
{
    size_t len;                 /**< ASN1 length, in octets. */
    unsigned char unused_bits;  /**< Number of unused bits at the end of the string */
    unsigned char *p;           /**< Raw ASN1 data for the bit string */
}
mbedtls_asn1_bitstring;

/**
 * Container for a sequence of ASN.1 items
 */
typedef struct mbedtls_asn1_sequence
{
    mbedtls_asn1_buf buf;                   /**< Buffer containing the given ASN.1 item. */
    struct mbedtls_asn1_sequence *next;    /**< The next entry in the sequence. */
}
mbedtls_asn1_sequence;

/**
 * Container for a sequence or list of 'named' ASN.1 data items
 */
typedef struct mbedtls_asn1_named_data
{
    mbedtls_asn1_buf oid;                   /**< The object identifier. */
    mbedtls_asn1_buf val;                   /**< The named value. */
    struct mbedtls_asn1_named_data *next;  /**< The next entry in the sequence. */
    unsigned char next_merged;      /**< Merge next item into the current one? */
}
mbedtls_asn1_named_data;

/**
 * \brief       Get the length of an ASN.1 element.
 *              Updates the pointer to immediately behind the length.
 *
 * \param p     The position in the ASN.1 data
 * \param end   End of data
 * \param len   The variable that will receive the value
 *
 * \return      0 if successful, MBEDTLS_ERR_ASN1_OUT_OF_DATA on reaching
 *              end of data, MBEDTLS_ERR_ASN1_INVALID_LENGTH if length is
 *              unparseable.
 */
int mbedtls_asn1_get_len( unsigned char **p,
                  const unsigned char *end,
                  size_t *len );

/**
 * \brief       Get the tag and length of the tag. Check for the requested tag.
 *              Updates the pointer to immediately behind the tag and length.
 *
 * \param p     The position in the ASN.1 data
 * \param end   End of data
 * \param len   The variable that will receive the length
 * \param tag   The expected tag
 *
 * \return      0 if successful, MBEDTLS_ERR_ASN1_UNEXPECTED_TAG if tag did
 *              not match requested tag, or another specific ASN.1 error code.
 */
int mbedtls_asn1_get_tag( unsigned char **p,
                  const unsigned char *end,
                  size_t *len, int tag );

/**
 * \brief       Retrieve a boolean ASN.1 tag and its value.
 *              Updates the pointer to immediately behind the full tag.
 *
 * \param p     The position in the ASN.1 data
 * \param end   End of data
 * \param val   The variable that will receive the value
 *
 * \return      0 if successful or a specific ASN.1 error code.
 */
int mbedtls_asn1_get_bool( unsigned char **p,
                   const unsigned char *end,
                   int *val );

/**
 * \brief       Retrieve an integer ASN.1 tag and its value.
 *              Updates the pointer to immediately behind the full tag.
 *
 * \param p     The position in the ASN.1 data
 * \param end   End of data
 * \param val   The variable that will receive the value
 *
 * \return      0 if successful or a specific ASN.1 error code.
 */
int mbedtls_asn1_get_int( unsigned char **p,
                  const unsigned char *end,
                  int *val );

/**
 * \brief       Retrieve a bitstring ASN.1 tag and its value.
 *              Updates the pointer to immediately behind the full tag.
 *
 * \param p     The position in the ASN.1 data
 * \param end   End of data
 * \param bs    The variable that will receive the value
 *
 * \return      0 if successful or a specific ASN.1 error code.
 */
int mbedtls_asn1_get_bitstring( unsigned char **p, const unsigned char *end,
                        mbedtls_asn1_bitstring *bs);

/**
 * \brief       Retrieve a bitstring ASN.1 tag without unused bits and its
 *              value.
 *              Updates the pointer to the beginning of the bit/octet string.
 *
 * \param p     The position in the ASN.1 data
 * \param end   End of data
 * \param len   Length of the actual bit/octect string in bytes
 *
 * \return      0 if successful or a specific ASN.1 error code.
 */
int mbedtls_asn1_get_bitstring_null( unsigned char **p, const unsigned char *end,
                             size_t *len );

/**
 * \brief       Parses and splits an ASN.1 "SEQUENCE OF <tag>"
 *              Updated the pointer to immediately behind the full sequence tag.
 *
 * \param p     The position in the ASN.1 data
 * \param end   End of data
 * \param cur   First variable in the chain to fill
 * \param tag   Type of sequence
 *
 * \return      0 if successful or a specific ASN.1 error code.
 */
int mbedtls_asn1_get_sequence_of( unsigned char **p,
                          const unsigned char *end,
                          mbedtls_asn1_sequence *cur,
                          int tag);

#if defined(MBEDTLS_BIGNUM_C)
/**
 * \brief       Retrieve a MPI value from an integer ASN.1 tag.
 *              Updates the pointer to immediately behind the full tag.
 *
 * \param p     The position in the ASN.1 data
 * \param end   End of data
 * \param X     The MPI that will receive the value
 *
 * \return      0 if successful or a specific ASN.1 or MPI error code.
 */
int mbedtls_asn1_get_mpi( unsigned char **p,
                  const unsigned char *end,
                  mbedtls_mpi *X );
#endif /* MBEDTLS_BIGNUM_C */

/**
 * \brief       Retrieve an AlgorithmIdentifier ASN.1 sequence.
 *              Updates the pointer to immediately behind the full
 *              AlgorithmIdentifier.
 *
 * \param p     The position in the ASN.1 data
 * \param end   End of data
 * \param alg   The buffer to receive the OID
 * \param params The buffer to receive the params (if any)
 *
 * \return      0 if successful or a specific ASN.1 or MPI error code.
 */
int mbedtls_asn1_get_alg( unsigned char **p,
                  const unsigned char *end,
                  mbedtls_asn1_buf *alg, mbedtls_asn1_buf *params );

/**
 * \brief       Retrieve an AlgorithmIdentifier ASN.1 sequence with NULL or no
 *              params.
 *              Updates the pointer to immediately behind the full
 *              AlgorithmIdentifier.
 *
 * \param p     The position in the ASN.1 data
 * \param end   End of data
 * \param alg   The buffer to receive the OID
 *
 * \return      0 if successful or a specific ASN.1 or MPI error code.
 */
int mbedtls_asn1_get_alg_null( unsigned char **p,
                       const unsigned char *end,
                       mbedtls_asn1_buf *alg );

/**
 * \brief       Find a specific named_data entry in a sequence or list based on
 *              the OID.
 *
 * \param list  The list to seek through
 * \param oid   The OID to look for
 * \param len   Size of the OID
 *
 * \return      NULL if not found, or a pointer to the existing entry.
 */
mbedtls_asn1_named_data *mbedtls_asn1_find_named_data( mbedtls_asn1_named_data *list,
                                       const char *oid, size_t len );

/**
 * \brief       Free a mbedtls_asn1_named_data entry
 *
 * \param entry The named data entry to free
 */
void mbedtls_asn1_free_named_data( mbedtls_asn1_named_data *entry );

/**
 * \brief       Free all entries in a mbedtls_asn1_named_data list
 *              Head will be set to NULL
 *
 * \param head  Pointer to the head of the list of named data entries to free
 */
void mbedtls_asn1_free_named_data_list( mbedtls_asn1_named_data **head );

#ifdef __cplusplus
}
#endif

#endif /* asn1.h */
Commit	Line	Data
700d8687 OM	1	/**
	2	* \file asn1.h
	3	*
	4	* \brief Generic ASN.1 parsing
	5	*/
	6	/*
	7	* Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
	8	* SPDX-License-Identifier: GPL-2.0
	9	*
	10	* This program is free software; you can redistribute it and/or modify
	11	* it under the terms of the GNU General Public License as published by
	12	* the Free Software Foundation; either version 2 of the License, or
	13	* (at your option) any later version.
	14	*
	15	* This program is distributed in the hope that it will be useful,
	16	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	17	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	18	* GNU General Public License for more details.
	19	*
	20	* You should have received a copy of the GNU General Public License along
	21	* with this program; if not, write to the Free Software Foundation, Inc.,
	22	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
	23	*
	24	* This file is part of mbed TLS (https://tls.mbed.org)
	25	*/
	26	#ifndef MBEDTLS_ASN1_H
	27	#define MBEDTLS_ASN1_H
	28
	29	#if !defined(MBEDTLS_CONFIG_FILE)
	30	#include "config.h"
	31	#else
	32	#include MBEDTLS_CONFIG_FILE
	33	#endif
	34
	35	#include <stddef.h>
	36
	37	#if defined(MBEDTLS_BIGNUM_C)
	38	#include "bignum.h"
	39	#endif
	40
	41	/**
	42	* \addtogroup asn1_module
	43	* \{
	44	*/
	45
	46	/**
	47	* \name ASN1 Error codes
	48	* These error codes are OR'ed to X509 error codes for
	49	* higher error granularity.
	50	* ASN1 is a standard to specify data structures.
	51	* \{
	52	*/
	53	#define MBEDTLS_ERR_ASN1_OUT_OF_DATA -0x0060 /*< Out of data when parsing an ASN1 data structure. /
	54	#define MBEDTLS_ERR_ASN1_UNEXPECTED_TAG -0x0062 /*< ASN1 tag was of an unexpected value. /
	55	#define MBEDTLS_ERR_ASN1_INVALID_LENGTH -0x0064 /*< Error when trying to determine the length or invalid length. /
	56	#define MBEDTLS_ERR_ASN1_LENGTH_MISMATCH -0x0066 /*< Actual length differs from expected length. /
	57	#define MBEDTLS_ERR_ASN1_INVALID_DATA -0x0068 /*< Data is invalid. (not used) /
	58	#define MBEDTLS_ERR_ASN1_ALLOC_FAILED -0x006A /*< Memory allocation failed /
	59	#define MBEDTLS_ERR_ASN1_BUF_TOO_SMALL -0x006C /*< Buffer too small when writing ASN.1 data structure. /
	60
	61	/* \} name */
	62
	63	/**
	64	* \name DER constants
65	* These constants comply with the DER encoded ASN.1 type tags.
66	* DER encoding uses hexadecimal representation.
67	* An example DER sequence is:\n
68	* - 0x02 -- tag indicating INTEGER
69	* - 0x01 -- length in octets
70	* - 0x05 -- value
71	* Such sequences are typically read into \c ::mbedtls_x509_buf.
72	* \{
73	*/
74	#define MBEDTLS_ASN1_BOOLEAN 0x01
75	#define MBEDTLS_ASN1_INTEGER 0x02
76	#define MBEDTLS_ASN1_BIT_STRING 0x03
77	#define MBEDTLS_ASN1_OCTET_STRING 0x04
78	#define MBEDTLS_ASN1_NULL 0x05
79	#define MBEDTLS_ASN1_OID 0x06
80	#define MBEDTLS_ASN1_UTF8_STRING 0x0C
81	#define MBEDTLS_ASN1_SEQUENCE 0x10
82	#define MBEDTLS_ASN1_SET 0x11
83	#define MBEDTLS_ASN1_PRINTABLE_STRING 0x13
84	#define MBEDTLS_ASN1_T61_STRING 0x14
85	#define MBEDTLS_ASN1_IA5_STRING 0x16
86	#define MBEDTLS_ASN1_UTC_TIME 0x17
87	#define MBEDTLS_ASN1_GENERALIZED_TIME 0x18
88	#define MBEDTLS_ASN1_UNIVERSAL_STRING 0x1C
89	#define MBEDTLS_ASN1_BMP_STRING 0x1E
90	#define MBEDTLS_ASN1_PRIMITIVE 0x00
91	#define MBEDTLS_ASN1_CONSTRUCTED 0x20
92	#define MBEDTLS_ASN1_CONTEXT_SPECIFIC 0x80
93
94	/*
95	* Bit masks for each of the components of an ASN.1 tag as specified in
96	* ITU X.690 (08/2015), section 8.1 "General rules for encoding",
97	* paragraph 8.1.2.2:
98	*
99	* Bit 8 7 6 5 1
100	* +-------+-----+------------+
101	* \| Class \| P/C \| Tag number \|
102	* +-------+-----+------------+
103	*/
104	#define MBEDTLS_ASN1_TAG_CLASS_MASK 0xC0
105	#define MBEDTLS_ASN1_TAG_PC_MASK 0x20
106	#define MBEDTLS_ASN1_TAG_VALUE_MASK 0x1F
107
108	/* \} name */
109	/* \} addtogroup asn1_module */
110
111	/** Returns the size of the binary string, without the trailing \\0 */
112	#define MBEDTLS_OID_SIZE(x) (sizeof(x) - 1)
113
114	/**
115	* Compares an mbedtls_asn1_buf structure to a reference OID.
116	*
117	* Only works for 'defined' oid_str values (MBEDTLS_OID_HMAC_SHA1), you cannot use a
118	* 'unsigned char *oid' here!
119	*/
120	#define MBEDTLS_OID_CMP(oid_str, oid_buf) \
121	( ( MBEDTLS_OID_SIZE(oid_str) != (oid_buf)->len ) \|\| \
122	memcmp( (oid_str), (oid_buf)->p, (oid_buf)->len) != 0 )
123
124	#ifdef __cplusplus
125	extern "C" {
126	#endif
127
128	/**
129	* \name Functions to parse ASN.1 data structures
130	* \{
131	*/
132
133	/**
134	* Type-length-value structure that allows for ASN1 using DER.
135	*/
136	typedef struct mbedtls_asn1_buf
137	{
138	int tag; /*< ASN1 type, e.g. MBEDTLS_ASN1_UTF8_STRING. /
139	size_t len; /*< ASN1 length, in octets. /
140	unsigned char p; /< ASN1 data, e.g. in ASCII. /
141	}
142	mbedtls_asn1_buf;
143
144	/**
145	* Container for ASN1 bit strings.
146	*/
147	typedef struct mbedtls_asn1_bitstring
148	{
149	size_t len; /*< ASN1 length, in octets. /
150	unsigned char unused_bits; /*< Number of unused bits at the end of the string /
151	unsigned char p; /< Raw ASN1 data for the bit string /
152	}
153	mbedtls_asn1_bitstring;
154
155	/**
156	* Container for a sequence of ASN.1 items
157	*/
158	typedef struct mbedtls_asn1_sequence
159	{
160	mbedtls_asn1_buf buf; /*< Buffer containing the given ASN.1 item. /
161	struct mbedtls_asn1_sequence next; /< The next entry in the sequence. /
162	}
163	mbedtls_asn1_sequence;
164
165	/**
166	* Container for a sequence or list of 'named' ASN.1 data items
167	*/
168	typedef struct mbedtls_asn1_named_data
169	{
170	mbedtls_asn1_buf oid; /*< The object identifier. /
171	mbedtls_asn1_buf val; /*< The named value. /
172	struct mbedtls_asn1_named_data next; /< The next entry in the sequence. /
173	unsigned char next_merged; /*< Merge next item into the current one? /
174	}
175	mbedtls_asn1_named_data;
176
177	/**
178	* \brief Get the length of an ASN.1 element.
179	* Updates the pointer to immediately behind the length.
180	*
181	* \param p The position in the ASN.1 data
182	* \param end End of data
183	* \param len The variable that will receive the value
184	*
185	* \return 0 if successful, MBEDTLS_ERR_ASN1_OUT_OF_DATA on reaching
186	* end of data, MBEDTLS_ERR_ASN1_INVALID_LENGTH if length is
187	* unparseable.
188	*/
189	int mbedtls_asn1_get_len( unsigned char **p,
190	const unsigned char *end,
191	size_t *len );
192
193	/**
194	* \brief Get the tag and length of the tag. Check for the requested tag.
195	* Updates the pointer to immediately behind the tag and length.
196	*
197	* \param p The position in the ASN.1 data
198	* \param end End of data
199	* \param len The variable that will receive the length
200	* \param tag The expected tag
201	*
202	* \return 0 if successful, MBEDTLS_ERR_ASN1_UNEXPECTED_TAG if tag did
203	* not match requested tag, or another specific ASN.1 error code.
204	*/
205	int mbedtls_asn1_get_tag( unsigned char **p,
206	const unsigned char *end,
207	size_t *len, int tag );
208
209	/**
210	* \brief Retrieve a boolean ASN.1 tag and its value.
211	* Updates the pointer to immediately behind the full tag.
212	*
213	* \param p The position in the ASN.1 data
214	* \param end End of data
215	* \param val The variable that will receive the value
216	*
217	* \return 0 if successful or a specific ASN.1 error code.
218	*/
219	int mbedtls_asn1_get_bool( unsigned char **p,
220	const unsigned char *end,
221	int *val );
222
223	/**
224	* \brief Retrieve an integer ASN.1 tag and its value.
225	* Updates the pointer to immediately behind the full tag.
226	*
227	* \param p The position in the ASN.1 data
228	* \param end End of data
229	* \param val The variable that will receive the value
230	*
231	* \return 0 if successful or a specific ASN.1 error code.
232	*/
233	int mbedtls_asn1_get_int( unsigned char **p,
234	const unsigned char *end,
235	int *val );
236
237	/**
238	* \brief Retrieve a bitstring ASN.1 tag and its value.
239	* Updates the pointer to immediately behind the full tag.
240	*
241	* \param p The position in the ASN.1 data
242	* \param end End of data
243	* \param bs The variable that will receive the value
244	*
245	* \return 0 if successful or a specific ASN.1 error code.
246	*/
247	int mbedtls_asn1_get_bitstring( unsigned char *p, const unsigned char end,
248	mbedtls_asn1_bitstring *bs);
249
250	/**
251	* \brief Retrieve a bitstring ASN.1 tag without unused bits and its
252	* value.
253	* Updates the pointer to the beginning of the bit/octet string.
254	*
255	* \param p The position in the ASN.1 data
256	* \param end End of data
257	* \param len Length of the actual bit/octect string in bytes
258	*
259	* \return 0 if successful or a specific ASN.1 error code.
260	*/
261	int mbedtls_asn1_get_bitstring_null( unsigned char *p, const unsigned char end,
262	size_t *len );
263
264	/**
265	* \brief Parses and splits an ASN.1 "SEQUENCE OF <tag>"
266	* Updated the pointer to immediately behind the full sequence tag.
267	*
268	* \param p The position in the ASN.1 data
269	* \param end End of data
270	* \param cur First variable in the chain to fill
271	* \param tag Type of sequence
272	*
273	* \return 0 if successful or a specific ASN.1 error code.
274	*/
275	int mbedtls_asn1_get_sequence_of( unsigned char **p,
276	const unsigned char *end,
277	mbedtls_asn1_sequence *cur,
278	int tag);
279
280	#if defined(MBEDTLS_BIGNUM_C)
281	/**
282	* \brief Retrieve a MPI value from an integer ASN.1 tag.
283	* Updates the pointer to immediately behind the full tag.
284	*
285	* \param p The position in the ASN.1 data
286	* \param end End of data
287	* \param X The MPI that will receive the value
288	*
289	* \return 0 if successful or a specific ASN.1 or MPI error code.
290	*/
291	int mbedtls_asn1_get_mpi( unsigned char **p,
292	const unsigned char *end,
293	mbedtls_mpi *X );
294	#endif /* MBEDTLS_BIGNUM_C */
295
296	/**
297	* \brief Retrieve an AlgorithmIdentifier ASN.1 sequence.
298	* Updates the pointer to immediately behind the full
299	* AlgorithmIdentifier.
300	*
301	* \param p The position in the ASN.1 data
302	* \param end End of data
303	* \param alg The buffer to receive the OID
304	* \param params The buffer to receive the params (if any)
305	*
306	* \return 0 if successful or a specific ASN.1 or MPI error code.
307	*/
308	int mbedtls_asn1_get_alg( unsigned char **p,
309	const unsigned char *end,
310	mbedtls_asn1_buf alg, mbedtls_asn1_buf params );
311
312	/**
313	* \brief Retrieve an AlgorithmIdentifier ASN.1 sequence with NULL or no
314	* params.
315	* Updates the pointer to immediately behind the full
316	* AlgorithmIdentifier.
317	*
318	* \param p The position in the ASN.1 data
319	* \param end End of data
320	* \param alg The buffer to receive the OID
321	*
322	* \return 0 if successful or a specific ASN.1 or MPI error code.
323	*/
324	int mbedtls_asn1_get_alg_null( unsigned char **p,
325	const unsigned char *end,
326	mbedtls_asn1_buf *alg );
327
328	/**
329	* \brief Find a specific named_data entry in a sequence or list based on
330	* the OID.
331	*
332	* \param list The list to seek through
333	* \param oid The OID to look for
334	* \param len Size of the OID
335	*
336	* \return NULL if not found, or a pointer to the existing entry.
337	*/
338	mbedtls_asn1_named_data mbedtls_asn1_find_named_data( mbedtls_asn1_named_data list,
339	const char *oid, size_t len );
340
341	/**
342	* \brief Free a mbedtls_asn1_named_data entry
343	*
344	* \param entry The named data entry to free
345	*/
346	void mbedtls_asn1_free_named_data( mbedtls_asn1_named_data *entry );
347
348	/**
349	* \brief Free all entries in a mbedtls_asn1_named_data list
350	* Head will be set to NULL
351	*
352	* \param head Pointer to the head of the list of named data entries to free
353	*/
354	void mbedtls_asn1_free_named_data_list( mbedtls_asn1_named_data **head );
355
356	#ifdef __cplusplus
357	}
358	#endif
359
360	#endif /* asn1.h */