asn1\_length\_der(3) libtasn1 asn1\_length\_der(3)

# [NAME](#NAME)

asn1\_length\_der - API function

# [SYNOPSIS](#SYNOPSIS)

**#include <libtasn1.h>**

**void asn1\_length\_der(unsigned long int len, unsigned char * der, int * der\_len);**

# [ARGUMENTS](#ARGUMENTS)

[unsigned long int len](#unsigned)

value to convert.

[unsigned char * der](#unsigned~2)

buffer to hold the returned encoding (may be **NULL**).

[int * der\_len](#int)

number of meaningful bytes of ANS (der\[0]..der\[der\_len-1]).

# [DESCRIPTION](#DESCRIPTION)

Creates the DER encoding of the provided length value. The *der* buffer must have enough room for the output. The maximum length this function will encode is **ASN1\_MAX\_LENGTH\_SIZE**.

To know the size of the DER encoding use a **NULL** value for *der* .

# [COPYRIGHT](#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.

# [SEE ALSO](#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/**

4.21.0 libtasn1

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Document: asn1_length_der(3) from libtasn1 4.21.0-r9 (Chainguard OS)
Source: https://gitlab.com/gnutls/libtasn1