ASN1_generate_nconf(3SSL) OpenSSL ASN1_generate_nconf(3SSL)
NAME
ASN1_generate_nconf, ASN1_generate_v3 - ASN1 generation functions
SYNOPSIS
#include <openssl/asn1.h>
ASN1_TYPE *ASN1_generate_nconf(char *str, CONF *nconf);
ASN1_TYPE *ASN1_generate_v3(char *str, X509V3_CTX *cnf);
DESCRIPTION
These functions generate the ASN1 encoding of a string in an ASN1_TYPE structure.
str contains the string to encode nconf or cnf contains the optional configuration information where additional strings will be read from.
nconf will typically come from a config file wherease cnf is obtained from an X509V3_CTX structure which will typically be used by X509 v3
certificate extension functions. cnf or nconf can be set to NULL if no additional configuration will be used.
GENERATION STRING FORMAT
The actual data encoded is determined by the string str and the configuration information. The general format of the string is:
[modifier,]type[:value]
That is zero or more comma separated modifiers followed by a type followed by an optional colon and a value. The formats of type, value and
modifier are explained below.
SUPPORTED TYPES
The supported types are listed below. Unless otherwise specified only the ASCII format is permissible.
BOOLEAN, BOOL
This encodes a boolean type. The value string is mandatory and should be TRUE or FALSE. Additionally TRUE, true, Y, y, YES, yes, FALSE,
false, N, n, NO and no are acceptable.
NULL
Encode the NULL type, the value string must not be present.
INTEGER, INT
Encodes an ASN1 INTEGER type. The value string represents the value of the integer, it can be preceded by a minus sign and is normally
interpreted as a decimal value unless the prefix 0x is included.
ENUMERATED, ENUM
Encodes the ASN1 ENUMERATED type, it is otherwise identical to INTEGER.
OBJECT, OID
Encodes an ASN1 OBJECT IDENTIFIER, the value string can be a short name, a long name or numerical format.
UTCTIME, UTC
Encodes an ASN1 UTCTime structure, the value should be in the format YYMMDDHHMMSSZ.
GENERALIZEDTIME, GENTIME
Encodes an ASN1 GeneralizedTime structure, the value should be in the format YYYYMMDDHHMMSSZ.
OCTETSTRING, OCT
Encodes an ASN1 OCTET STRING. value represents the contents of this structure, the format strings ASCII and HEX can be used to specify
the format of value.
BITSTRING, BITSTR
Encodes an ASN1 BIT STRING. value represents the contents of this structure, the format strings ASCII, HEX and BITLIST can be used to
specify the format of value.
If the format is anything other than BITLIST the number of unused bits is set to zero.
UNIVERSALSTRING, UNIV, IA5, IA5STRING, UTF8, UTF8String, BMP, BMPSTRING, VISIBLESTRING, VISIBLE, PRINTABLESTRING, PRINTABLE, T61,
T61STRING, TELETEXSTRING, GeneralString, NUMERICSTRING, NUMERIC
These encode the corresponding string types. value represents the contents of this structure. The format can be ASCII or UTF8.
SEQUENCE, SEQ, SET
Formats the result as an ASN1 SEQUENCE or SET type. value should be a section name which will contain the contents. The field names in
the section are ignored and the values are in the generated string format. If value is absent then an empty SEQUENCE will be encoded.
MODIFIERS
Modifiers affect the following structure, they can be used to add EXPLICIT or IMPLICIT tagging, add wrappers or to change the string format
of the final type and value. The supported formats are documented below.
EXPLICIT, EXP
Add an explicit tag to the following structure. This string should be followed by a colon and the tag value to use as a decimal value.
By following the number with U, A, P or C UNIVERSAL, APPLICATION, PRIVATE or CONTEXT SPECIFIC tagging can be used, the default is CONTEXT
SPECIFIC.
IMPLICIT, IMP
This is the same as EXPLICIT except IMPLICIT tagging is used instead.
OCTWRAP, SEQWRAP, SETWRAP, BITWRAP
The following structure is surrounded by an OCTET STRING, a SEQUENCE, a SET or a BIT STRING respectively. For a BIT STRING the number of
unused bits is set to zero.
FORMAT
This specifies the format of the ultimate value. It should be followed by a colon and one of the strings ASCII, UTF8, HEX or BITLIST.
If no format specifier is included then ASCII is used. If UTF8 is specified then the value string must be a valid UTF8 string. For HEX
the output must be a set of hex digits. BITLIST (which is only valid for a BIT STRING) is a comma separated list of the indices of the
set bits, all other bits are zero.
EXAMPLES
A simple IA5String:
IA5STRING:Hello World
An IA5String explicitly tagged:
EXPLICIT:0,IA5STRING:Hello World
An IA5String explicitly tagged using APPLICATION tagging:
EXPLICIT:0A,IA5STRING:Hello World
A BITSTRING with bits 1 and 5 set and all others zero:
FORMAT:BITLIST,BITSTRING:1,5
A more complex example using a config file to produce a SEQUENCE consiting of a BOOL an OID and a UTF8String:
asn1 = SEQUENCE:seq_section
[seq_section]
field1 = BOOLEAN:TRUE
field2 = OID:commonName
field3 = UTF8:Third field
This example produces an RSAPrivateKey structure, this is the key contained in the file client.pem in all OpenSSL distributions (note: the
field names such as 'coeff' are ignored and are present just for clarity):
asn1=SEQUENCE:private_key
[private_key]
version=INTEGER:0
n=INTEGER:0xBB6FE79432CC6EA2D8F970675A5A87BFBE1AFF0BE63E879F2AFFB93644
D4D2C6D000430DEC66ABF47829E74B8C5108623A1C0EE8BE217B3AD8D36D5EB4FCA1D9
e=INTEGER:0x010001
d=INTEGER:0x6F05EAD2F27FFAEC84BEC360C4B928FD5F3A9865D0FCAAD291E2A52F4A
F810DC6373278C006A0ABBA27DC8C63BF97F7E666E27C5284D7D3B1FFFE16B7A87B51D
p=INTEGER:0xF3929B9435608F8A22C208D86795271D54EBDFB09DDEF539AB083DA912
D4BD57
q=INTEGER:0xC50016F89DFF2561347ED1186A46E150E28BF2D0F539A1594BBD7FE467
46EC4F
exp1=INTEGER:0x9E7D4326C924AFC1DEA40B45650134966D6F9DFA3A7F9D698CD4ABEA
9C0A39B9
exp2=INTEGER:0xBA84003BB95355AFB7C50DF140C60513D0BA51D637272E355E397779
E7B2458F
coeff=INTEGER:0x30B9E4F2AFA5AC679F920FC83F1F2DF1BAF1779CF989447FABC2F5
628657053A
This example is the corresponding public key in a SubjectPublicKeyInfo structure:
# Start with a SEQUENCE
asn1=SEQUENCE:pubkeyinfo
# pubkeyinfo contains an algorithm identifier and the public key wrapped
# in a BIT STRING
[pubkeyinfo]
algorithm=SEQUENCE:rsa_alg
pubkey=BITWRAP,SEQUENCE:rsapubkey
# algorithm ID for RSA is just an OID and a NULL
[rsa_alg]
algorithm=OID:rsaEncryption
parameter=NULL
# Actual public key: modulus and exponent
[rsapubkey]
n=INTEGER:0xBB6FE79432CC6EA2D8F970675A5A87BFBE1AFF0BE63E879F2AFFB93644
D4D2C6D000430DEC66ABF47829E74B8C5108623A1C0EE8BE217B3AD8D36D5EB4FCA1D9
e=INTEGER:0x010001
RETURN VALUES
ASN1_generate_nconf() and ASN1_generate_v3() return the encoded data as an ASN1_TYPE structure or NULL if an error occurred.
The error codes that can be obtained by ERR_get_error(3).
SEE ALSO
ERR_get_error(3)
HISTORY
ASN1_generate_nconf() and ASN1_generate_v3() were added to OpenSSL 0.9.8
1.0.1e 2014-08-06 ASN1_generate_nconf(3SSL)