asn1_write_value(3)

🦋 NAME 🦋

okay so bestie, this is the manual page for asn1_write_value — an API function — and it lives in the libtasn1 manual, section 3. 💖

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✨ SYNOPSIS ✨

#include <libtasn1.h>

int asn1_write_value(asn1_node node_root, const char * name, const void * ivalue, int len);

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🎀 ARGUMENTS 🎀

• asn1_node node_root — pointer to a structure. that's the whole vibe. 🫶
• const char * name — the name of the element inside the structure that you want to set.
• const void * ivalue — the vector used to specify the value to set. If len is >0, VALUE must be a two's complement form integer. If len=0, *VALUE must be a null terminated string with an integer value.
• int len — number of bytes of *value to use to set the value: value[0]..value[len-1], or 0 if value is a null terminated string.

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💖 DESCRIPTION 💖

Set the value of one element inside a structure. that's literally the entire job description, no notes. 👑

If an element is OPTIONAL and you want to delete it, you must use the value=NULL and len=0. Using "pkix.asn":

result=asn1_write_value(cert, "tbsCertificate.issuerUniqueID", NULL, 0);

Now, description for each type. grab a snack, this is a long one. 🍓

🔢 INTEGER

VALUE must contain a two's complement form integer.

value[0]=0xFF ,               len=1 -> integer=-1.
value[0]=0xFF value[1]=0xFF , len=2 -> integer=-1.
value[0]=0x01 ,               len=1 -> integer= 1.
value[0]=0x00 value[1]=0x01 , len=2 -> integer= 1.
value="123"                 , len=0 -> integer= 123.

🌈 ENUMERATED

As INTEGER (but only with not negative numbers). ✨

✅ BOOLEAN

VALUE must be the null terminated string "TRUE" or "FALSE" and LEN != 0.

value="TRUE" , len=1 -> boolean=TRUE.
value="FALSE" , len=1 -> boolean=FALSE.

🏷️ OBJECT IDENTIFIER

VALUE must be a null terminated string with each number separated by a dot (e.g. "1.2.3.543.1"). LEN != 0.

value="1 2 840 10040 4 3" , len=1 -> OID=dsa-with-sha.

⏰ UTCTIME

VALUE must be a null terminated string in one of these formats: "YYMMDDhhmmssZ", "YYMMDDhhmmssZ", "YYMMDDhhmmss+hh'mm'", "YYMMDDhhmmss-hh'mm'", "YYMMDDhhmm+hh'mm'", or "YYMMDDhhmm-hh'mm'". LEN != 0.

value="9801011200Z" , len=1 -> time=Jannuary 1st, 1998 at 12h 00m Greenwich Mean Time

🗓️ GENERALIZEDTIME

VALUE must be in one of this format: "YYYYMMDDhhmmss.sZ", "YYYYMMDDhhmmss.sZ", "YYYYMMDDhhmmss.s+hh'mm'", "YYYYMMDDhhmmss.s-hh'mm'", "YYYYMMDDhhmm+hh'mm'", or "YYYYMMDDhhmm-hh'mm'" where ss.s indicates the seconds with any precision like "10.1" or "01.02". LEN != 0

value="2001010112001.12-0700" , len=1 -> time=Jannuary 1st, 2001 at 12h 00m 01.12s Pacific Daylight Time

🧵 OCTET STRING

VALUE contains the octet string and LEN is the number of octets.

value="$ssh$x01$ssh$x02$ssh$x03" , len=3 -> three bytes octet string

🌸 GENERALSTRING

VALUE contains the generalstring and LEN is the number of octets.

value="$ssh$x01$ssh$x02$ssh$x03" , len=3 -> three bytes generalstring

🎚️ BIT STRING

VALUE contains the bit string organized by bytes and LEN is the number of bits.

value="$ssh$xCF" , len=6 -> bit string="110011" (six bits)

🍴 CHOICE

if NAME indicates a choice type, VALUE must specify one of the alternatives with a null terminated string. LEN != 0. Using "pkix.asn"

result=asn1_write_value(cert, "certificate1.tbsCertificate.subject", "rdnSequence", 1);

🎁 ANY

VALUE indicates the der encoding of a structure. LEN != 0.

🧬 SEQUENCE OF

VALUE must be the null terminated string "NEW" and LEN != 0. With this instruction another element is appended in the sequence. The name of this element will be "?1" if it's the first one, "?2" for the second and so on.

Using "pkix.asn"

result=asn1_write_value(cert, "certificate1.tbsCertificate.subject.rdnSequence", "NEW", 1);

🧺 SET OF

the same as SEQUENCE OF. Using "pkix.asn":

result=asn1_write_value(cert, "tbsCertificate.subject.rdnSequence.?LAST", "NEW", 1);

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🔥 RETURNS 🔥

ASN1_SUCCESS if the value was set, ASN1_ELEMENT_NOT_FOUND if name is not a valid element, and ASN1_VALUE_NOT_VALID if ivalue has a wrong format.

bestie pls actually check that return value, it is TELLING you something. 👀

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©️ COPYRIGHT ©️

Copyright © 2006-2025 Free Software Foundation, Inc..

Copying and distribution of this file, with or without modification, are permitted in any medium without royalty provided the copyright notice and this notice are preserved.

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👀 SEE ALSO 👀

The full documentation for libtasn1 is maintained as a Texinfo manual. If the info and libtasn1 programs are properly installed at your site, the command

info libtasn1

should give you access to the complete manual. As an alternative you may obtain the manual from:

https://www.gnu.org/software/libtasn1/manual/

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and that's the whole page, bestie 💅 this one ships as part of libtasn1 version 4.21.0, in the asn1_write_value(3) section, with the copyright sitting at 2006-2025. go set some values, you're gonna slay. 🌟🎀