Ubuntu Manpage: ASN1_generate_nconf, ASN1_generate_v3

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NAME

       ASN1_generate_nconf, ASN1_generate_v3 - ASN1 string generation functions

SYNOPSIS

        #include <openssl/asn1.h>

        ASN1_TYPE *ASN1_generate_nconf(const char *str, CONF *nconf);
        ASN1_TYPE *ASN1_generate_v3(const 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 whereas 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. Case is not significant in the type names. 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 prefaced 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.

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).

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 consisting 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

COPYRIGHT

       Copyright 2002-2021 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (the "License").  You may not use this file except
       in compliance with the License.  You can obtain a copy in the file LICENSE in the source
       distribution or at <https://www.openssl.org/source/license.html>.