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
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:
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
orFALSE
. Additionallytrue
,Y
,y
,YES
,yes
,false
,N
,n
,NO
andno
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
andHEX
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
, andBITLIST
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. BMPSTRING
,BMP
,GeneralString
,IA5STRING
,IA5
,NUMERICSTRING
,NUMERIC
,PRINTABLESTRING
,PRINTABLE
,T61STRING
,T61
,TELETEXSTRING
,UNIVERSALSTRING
,UNIV
,UTF8String
,UTF8
,VISIBLESTRING
,VISIBLE
- These encode the corresponding string types. value
represents the contents of this structure. The format can be
ASCII
orUTF8
. 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:
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
orC
, 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
, orBITLIST
.If no format specifier is included, then
ASCII
is used. IfUTF8
is specified, then the value string must be a valid UTF8 string. ForHEX
, 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 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 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 that 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
SEE ALSO
HISTORY
ASN1_generate_nconf
() and
ASN1_generate_v3
() were added to OpenSSL 0.9.8.