asn1.h File Reference

Generic ASN.1 parsing. More...

#include "config.h"
#include <stddef.h>
#include "bignum.h"

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Classes
struct	mbedtls_asn1_buf
struct	mbedtls_asn1_bitstring
struct	mbedtls_asn1_sequence
struct	mbedtls_asn1_named_data

Macros
#define	MBEDTLS_OID_SIZE(x)   (sizeof(x) - 1)
#define	MBEDTLS_OID_CMP(oid_str, oid_buf)
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
#define	MBEDTLS_ERR_ASN1_UNEXPECTED_TAG   -0x0062
#define	MBEDTLS_ERR_ASN1_INVALID_LENGTH   -0x0064
#define	MBEDTLS_ERR_ASN1_LENGTH_MISMATCH   -0x0066
#define	MBEDTLS_ERR_ASN1_INVALID_DATA   -0x0068
#define	MBEDTLS_ERR_ASN1_ALLOC_FAILED   -0x006A
#define	MBEDTLS_ERR_ASN1_BUF_TOO_SMALL   -0x006C
DER constants
These constants comply with DER encoded the ANS1 type tags. DER encoding uses hexadecimal representation. An example DER sequence is: 0x02 – tag indicating INTEGER 0x01 – length in octets 0x05 – value Such sequences are typically read into 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

Functions to parse ASN.1 data structures
typedef struct mbedtls_asn1_buf	mbedtls_asn1_buf
typedef struct mbedtls_asn1_bitstring	mbedtls_asn1_bitstring
typedef struct mbedtls_asn1_sequence	mbedtls_asn1_sequence
typedef struct mbedtls_asn1_named_data	mbedtls_asn1_named_data
int	mbedtls_asn1_get_len (unsigned char **p, const unsigned char *end, size_t *len)
	Get the length of an ASN.1 element. Updates the pointer to immediately behind the length. More...
int	mbedtls_asn1_get_tag (unsigned char **p, const unsigned char *end, size_t *len, int tag)
	Get the tag and length of the tag. Check for the requested tag. Updates the pointer to immediately behind the tag and length. More...
int	mbedtls_asn1_get_bool (unsigned char **p, const unsigned char *end, int *val)
	Retrieve a boolean ASN.1 tag and its value. Updates the pointer to immediately behind the full tag. More...
int	mbedtls_asn1_get_int (unsigned char **p, const unsigned char *end, int *val)
	Retrieve an integer ASN.1 tag and its value. Updates the pointer to immediately behind the full tag. More...
int	mbedtls_asn1_get_bitstring (unsigned char **p, const unsigned char *end, mbedtls_asn1_bitstring *bs)
	Retrieve a bitstring ASN.1 tag and its value. Updates the pointer to immediately behind the full tag. More...
int	mbedtls_asn1_get_bitstring_null (unsigned char **p, const unsigned char *end, size_t *len)
	Retrieve a bitstring ASN.1 tag without unused bits and its value. Updates the pointer to the beginning of the bit/octet string. More...
int	mbedtls_asn1_get_sequence_of (unsigned char **p, const unsigned char *end, mbedtls_asn1_sequence *cur, int tag)
	Parses and splits an ASN.1 "SEQUENCE OF <tag>" Updated the pointer to immediately behind the full sequence tag. More...
int	mbedtls_asn1_get_mpi (unsigned char **p, const unsigned char *end, mbedtls_mpi *X)
	Retrieve a MPI value from an integer ASN.1 tag. Updates the pointer to immediately behind the full tag. More...
int	mbedtls_asn1_get_alg (unsigned char **p, const unsigned char *end, mbedtls_asn1_buf *alg, mbedtls_asn1_buf *params)
	Retrieve an AlgorithmIdentifier ASN.1 sequence. Updates the pointer to immediately behind the full AlgorithmIdentifier. More...
int	mbedtls_asn1_get_alg_null (unsigned char **p, const unsigned char *end, mbedtls_asn1_buf *alg)
	Retrieve an AlgorithmIdentifier ASN.1 sequence with NULL or no params. Updates the pointer to immediately behind the full AlgorithmIdentifier. More...
mbedtls_asn1_named_data *	mbedtls_asn1_find_named_data (mbedtls_asn1_named_data *list, const char *oid, size_t len)
	Find a specific named_data entry in a sequence or list based on the OID. More...
void	mbedtls_asn1_free_named_data (mbedtls_asn1_named_data *entry)
	Free a mbedtls_asn1_named_data entry. More...
void	mbedtls_asn1_free_named_data_list (mbedtls_asn1_named_data **head)
	Free all entries in a mbedtls_asn1_named_data list Head will be set to NULL. More...

Detailed Description

Generic ASN.1 parsing.

Copyright (C) 2006-2015, ARM Limited, All Rights Reserved SPDX-License-Identifier: Apache-2.0

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

This file is part of mbed TLS (https://tls.mbed.org)

Macro Definition Documentation

MBEDTLS_OID_CMP

#define MBEDTLS_OID_CMP	(		oid_str,
			oid_buf
	)

Value:

( ( MBEDTLS_OID_SIZE(oid_str) != (oid_buf)->len ) ||                \
          memcmp( (oid_str), (oid_buf)->p, (oid_buf)->len) != 0 )

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!

MBEDTLS_OID_SIZE

#define MBEDTLS_OID_SIZE

(

x

)

(sizeof(x) - 1)

Returns the size of the binary string, without the trailing \0

Typedef Documentation

mbedtls_asn1_bitstring

typedef struct mbedtls_asn1_bitstring mbedtls_asn1_bitstring

Container for ASN1 bit strings.

mbedtls_asn1_buf

typedef struct mbedtls_asn1_buf mbedtls_asn1_buf

Type-length-value structure that allows for ASN1 using DER.

mbedtls_asn1_named_data

typedef struct mbedtls_asn1_named_data mbedtls_asn1_named_data

Container for a sequence or list of 'named' ASN.1 data items

mbedtls_asn1_sequence

typedef struct mbedtls_asn1_sequence mbedtls_asn1_sequence

Container for a sequence of ASN.1 items

Function Documentation

mbedtls_asn1_find_named_data()

mbedtls_asn1_named_data* mbedtls_asn1_find_named_data	(	mbedtls_asn1_named_data *	list,
		const char *	oid,
		size_t	len
	)

Find a specific named_data entry in a sequence or list based on the OID.

Parameters

list	The list to seek through
oid	The OID to look for
len	Size of the OID

Returns

NULL if not found, or a pointer to the existing entry.

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mbedtls_asn1_free_named_data()

void mbedtls_asn1_free_named_data

(

mbedtls_asn1_named_data *

entry

)

Free a mbedtls_asn1_named_data entry.

Parameters

entry

The named data entry to free

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mbedtls_asn1_free_named_data_list()

void mbedtls_asn1_free_named_data_list

(

mbedtls_asn1_named_data **

head

)

Free all entries in a mbedtls_asn1_named_data list Head will be set to NULL.

Parameters

head	Pointer to the head of the list of named data entries to free

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mbedtls_asn1_get_alg()

int mbedtls_asn1_get_alg	(	unsigned char **	p,
		const unsigned char *	end,
		mbedtls_asn1_buf *	alg,
		mbedtls_asn1_buf *	params
	)

Retrieve an AlgorithmIdentifier ASN.1 sequence. Updates the pointer to immediately behind the full AlgorithmIdentifier.

Parameters

p	The position in the ASN.1 data
end	End of data
alg	The buffer to receive the OID
params	The buffer to receive the params (if any)

Returns

0 if successful or a specific ASN.1 or MPI error code.

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mbedtls_asn1_get_alg_null()

int mbedtls_asn1_get_alg_null	(	unsigned char **	p,
		const unsigned char *	end,
		mbedtls_asn1_buf *	alg
	)

Retrieve an AlgorithmIdentifier ASN.1 sequence with NULL or no params. Updates the pointer to immediately behind the full AlgorithmIdentifier.

Parameters

p	The position in the ASN.1 data
end	End of data
alg	The buffer to receive the OID

Returns

0 if successful or a specific ASN.1 or MPI error code.

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mbedtls_asn1_get_bitstring()

int mbedtls_asn1_get_bitstring	(	unsigned char **	p,
		const unsigned char *	end,
		mbedtls_asn1_bitstring *	bs
	)

Retrieve a bitstring ASN.1 tag and its value. Updates the pointer to immediately behind the full tag.

Parameters

p	The position in the ASN.1 data
end	End of data
bs	The variable that will receive the value

Returns

0 if successful or a specific ASN.1 error code.

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mbedtls_asn1_get_bitstring_null()

int mbedtls_asn1_get_bitstring_null	(	unsigned char **	p,
		const unsigned char *	end,
		size_t *	len
	)

Retrieve a bitstring ASN.1 tag without unused bits and its value. Updates the pointer to the beginning of the bit/octet string.

Parameters

p	The position in the ASN.1 data
end	End of data
len	Length of the actual bit/octect string in bytes

Returns

0 if successful or a specific ASN.1 error code.

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mbedtls_asn1_get_bool()

int mbedtls_asn1_get_bool	(	unsigned char **	p,
		const unsigned char *	end,
		int *	val
	)

Retrieve a boolean ASN.1 tag and its value. Updates the pointer to immediately behind the full tag.

Parameters

p	The position in the ASN.1 data
end	End of data
val	The variable that will receive the value

Returns

0 if successful or a specific ASN.1 error code.

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mbedtls_asn1_get_int()

int mbedtls_asn1_get_int	(	unsigned char **	p,
		const unsigned char *	end,
		int *	val
	)

Retrieve an integer ASN.1 tag and its value. Updates the pointer to immediately behind the full tag.

Parameters

p	The position in the ASN.1 data
end	End of data
val	The variable that will receive the value

Returns

0 if successful or a specific ASN.1 error code.

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mbedtls_asn1_get_len()

int mbedtls_asn1_get_len	(	unsigned char **	p,
		const unsigned char *	end,
		size_t *	len
	)

Get the length of an ASN.1 element. Updates the pointer to immediately behind the length.

Parameters

p	The position in the ASN.1 data
end	End of data
len	The variable that will receive the value

Returns

0 if successful, MBEDTLS_ERR_ASN1_OUT_OF_DATA on reaching end of data, MBEDTLS_ERR_ASN1_INVALID_LENGTH if length is unparseable.

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mbedtls_asn1_get_mpi()

int mbedtls_asn1_get_mpi	(	unsigned char **	p,
		const unsigned char *	end,
		mbedtls_mpi *	X
	)

Retrieve a MPI value from an integer ASN.1 tag. Updates the pointer to immediately behind the full tag.

Parameters

p	The position in the ASN.1 data
end	End of data
X	The MPI that will receive the value

Returns

0 if successful or a specific ASN.1 or MPI error code.

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mbedtls_asn1_get_sequence_of()

int mbedtls_asn1_get_sequence_of	(	unsigned char **	p,
		const unsigned char *	end,
		mbedtls_asn1_sequence *	cur,
		int	tag
	)

Parses and splits an ASN.1 "SEQUENCE OF <tag>" Updated the pointer to immediately behind the full sequence tag.

Parameters

p	The position in the ASN.1 data
end	End of data
cur	First variable in the chain to fill
tag	Type of sequence

Returns

0 if successful or a specific ASN.1 error code.

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mbedtls_asn1_get_tag()

int mbedtls_asn1_get_tag	(	unsigned char **	p,
		const unsigned char *	end,
		size_t *	len,
		int	tag
	)

Get the tag and length of the tag. Check for the requested tag. Updates the pointer to immediately behind the tag and length.

Parameters

p	The position in the ASN.1 data
end	End of data
len	The variable that will receive the length
tag	The expected tag

Returns

0 if successful, MBEDTLS_ERR_ASN1_UNEXPECTED_TAG if tag did not match requested tag, or another specific ASN.1 error code.

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