=pod

=head1 NAME

ASN1_generate_nconf, ASN1_generate_v3 - ASN1 generation functions

=head1 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);

=head1 DESCRIPTION

These functions generate the ASN1 encoding of a string

in an B<ASN1_TYPE> structure.

B<str> contains the string to encode B<nconf> or B<cnf> contains

the optional configuration information where additional strings

will be read from. B<nconf> will typically come from a config

file whereas B<cnf> is obtained from an B<X509V3_CTX> structure

which will typically be used by X509 v3 certificate extension

functions. B<cnf> or B<nconf> can be set to B<NULL> if no additional

configuration will be used.

=head1 GENERATION STRING FORMAT

The actual data encoded is determined by the string B<str> and

the configuration information. The general format of the string

is:

=over 4

=item B<[modifier,]type[:value]>

=back

That is zero or more comma separated modifiers followed by a type

followed by an optional colon and a value. The formats of B<type>,

B<value> and B<modifier> are explained below.

=head2 Supported Types

The supported types are listed below. Unless otherwise specified

only the B<ASCII> format is permissible.

=over 4

=item B<BOOLEAN>, B<BOOL>

This encodes a boolean type. The B<value> string is mandatory and

should be B<TRUE> or B<FALSE>. Additionally B<TRUE>, B<true>, B<Y>,

B<y>, B<YES>, B<yes>, B<FALSE>, B<false>, B<N>, B<n>, B<NO> and B<no>

are acceptable.

=item B<NULL>

Encode the B<NULL> type, the B<value> string must not be present.

=item B<INTEGER>, B<INT>

Encodes an ASN1 B<INTEGER> type. The B<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 B<0x>

is included.

=item B<ENUMERATED>, B<ENUM>

Encodes the ASN1 B<ENUMERATED> type, it is otherwise identical to

B<INTEGER>.

=item B<OBJECT>, B<OID>

Encodes an ASN1 B<OBJECT IDENTIFIER>, the B<value> string can be

a short name, a long name or numerical format.

=item B<UTCTIME>, B<UTC>

Encodes an ASN1 B<UTCTime> structure, the value should be in

the format B<YYMMDDHHMMSSZ>.

=item B<GENERALIZEDTIME>, B<GENTIME>

Encodes an ASN1 B<GeneralizedTime> structure, the value should be in

the format B<YYYYMMDDHHMMSSZ>.

=item B<OCTETSTRING>, B<OCT>

Encodes an ASN1 B<OCTET STRING>. B<value> represents the contents

of this structure, the format strings B<ASCII> and B<HEX> can be

used to specify the format of B<value>.

=item B<BITSTRING>, B<BITSTR>

Encodes an ASN1 B<BIT STRING>. B<value> represents the contents

of this structure, the format strings B<ASCII>, B<HEX> and B<BITLIST>

can be used to specify the format of B<value>.

If the format is anything other than B<BITLIST> the number of unused

bits is set to zero.

=item B<UNIVERSALSTRING>, B<UNIV>, B<IA5>, B<IA5STRING>, B<UTF8>,

B<UTF8String>, B<BMP>, B<BMPSTRING>, B<VISIBLESTRING>,

B<VISIBLE>, B<PRINTABLESTRING>, B<PRINTABLE>, B<T61>,

B<T61STRING>, B<TELETEXSTRING>, B<GeneralString>, B<NUMERICSTRING>,

B<NUMERIC>

These encode the corresponding string types. B<value> represents the

contents of this structure. The format can be B<ASCII> or B<UTF8>.

=item B<SEQUENCE>, B<SEQ>, B<SET>

Formats the result as an ASN1 B<SEQUENCE> or B<SET> type. B<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 B<value> is absent then an empty SEQUENCE

will be encoded.

=back

=head2 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.

=over 4

=item B<EXPLICIT>, B<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 B<U>, B, B
 or B<C> UNIVERSAL,

APPLICATION, PRIVATE or CONTEXT SPECIFIC tagging can be used,

the default is CONTEXT SPECIFIC.

=item B<IMPLICIT>, B<IMP>

This is the same as B<EXPLICIT> except IMPLICIT tagging is used

instead.

=item B<OCTWRAP>, B<SEQWRAP>, B<SETWRAP>, B<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.

=item B<FORMAT>

This specifies the format of the ultimate value. It should be followed

by a colon and one of the strings B<ASCII>, B<UTF8>, B<HEX> or B<BITLIST>.

If no format specifier is included then B<ASCII> is used. If B<UTF8> is

specified then the value string must be a valid B<UTF8> string. For B<HEX> the

output must be a set of hex digits. B<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.

=back

=head1 RETURN VALUES

ASN1_generate_nconf() and ASN1_generate_v3() return the encoded

data as an B<ASN1_TYPE> structure or B<NULL> if an error occurred.

The error codes that can be obtained by L<ERR_get_error(3)>.

=head1 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

=head1 SEE ALSO

L<ERR_get_error(3)>

=head1 COPYRIGHT

Copyright 2002-2019 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (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

L<https://www.openssl.org/source/license.html>.

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