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ASN1_STRING_print_ex(3) OpenSSL ASN1_STRING_print_ex(3)
ASN1_STRING_print_ex, ASN1_STRING_print_ex_fp, ASN1_STRING_print -
ASN1_STRING output routines.
int ASN1_STRING_print_ex(BIO *out, ASN1_STRING *str, unsigned long flags);
int ASN1_STRING_print_ex_fp(FILE *fp, ASN1_STRING *str, unsigned long flags);
int ASN1_STRING_print(BIO *out, ASN1_STRING *str);
These functions output an ASN1_STRING structure. ASN1_STRING is used to
represent all the ASN1 string types.
ASN1_STRING_print_ex() outputs str to out, the format is determined by
the options flags. ASN1_STRING_print_ex_fp() is identical except it
outputs to fp instead.
ASN1_STRING_print() prints str to out but using a different format to
ASN1_STRING_print_ex(). It replaces unprintable characters (other than
CR, LF) with '.'.
ASN1_STRING_print() is a legacy function which should be avoided in new
Although there are a large number of options frequently
ASN1_STRFLGS_RFC2253 is suitable, or on UTF8 terminals
ASN1_STRFLGS_RFC2253 & ~ASN1_STRFLGS_ESC_MSB.
The complete set of supported options for flags is listed below.
Various characters can be escaped. If ASN1_STRFLGS_ESC_2253 is set the
characters determined by RFC2253 are escaped. If ASN1_STRFLGS_ESC_CTRL
is set control characters are escaped. If ASN1_STRFLGS_ESC_MSB is set
characters with the MSB set are escaped: this option should not be used
if the terminal correctly interprets UTF8 sequences.
Escaping takes several forms.
If the character being escaped is a 16 bit character then the form
"\UXXXX" is used using exactly four characters for the hex
representation. If it is 32 bits then "\WXXXXXXXX" is used using eight
characters of its hex representation. These forms will only be used if
UTF8 conversion is not set (see below).
Printable characters are normally escaped using the backslash '\'
character. If ASN1_STRFLGS_ESC_QUOTE is set then the whole string is
instead surrounded by double quote characters: this is arguably more
readable than the backslash notation. Other characters use the "\XX"
using exactly two characters of the hex representation.
If ASN1_STRFLGS_UTF8_CONVERT is set then characters are converted to
UTF8 format first. If the terminal supports the display of UTF8
sequences then this option will correctly display multi byte
If ASN1_STRFLGS_IGNORE_TYPE is set then the string type is not
interpreted at all: everything is assumed to be one byte per character.
This is primarily for debugging purposes and can result in confusing
output in multi character strings.
If ASN1_STRFLGS_SHOW_TYPE is set then the string type itself is printed
out before its value (for example "BMPSTRING"), this actually uses
The content of a string instead of being interpreted can be "dumped":
this just outputs the value of the string using the form #XXXX using
hex format for each octet.
If ASN1_STRFLGS_DUMP_ALL is set then any type is dumped.
Normally non character string types (such as OCTET STRING) are assumed
to be one byte per character, if ASN1_STRFLGS_DUMP_UNKNOWN is set then
they will be dumped instead.
When a type is dumped normally just the content octets are printed, if
ASN1_STRFLGS_DUMP_DER is set then the complete encoding is dumped
instead (including tag and length octets).
ASN1_STRFLGS_RFC2253 includes all the flags required by RFC2253. It is
ASN1_STRFLGS_ESC_2253 | ASN1_STRFLGS_ESC_CTRL | ASN1_STRFLGS_ESC_MSB |
ASN1_STRFLGS_UTF8_CONVERT | ASN1_STRFLGS_DUMP_UNKNOWN
1.0.2h 2016-05-03 ASN1_STRING_print_ex(3)