.\" $OpenBSD: s2i_ASN1_INTEGER.3,v 1.6 2023/10/01 10:51:19 tb Exp $ .\" .\" Copyright (c) 2023 Theo Buehler .\" .\" Permission to use, copy, modify, and distribute this software for any .\" purpose with or without fee is hereby granted, provided that the above .\" copyright notice and this permission notice appear in all copies. .\" .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF .\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR .\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES .\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. .\" .Dd $Mdocdate: October 1 2023 $ .Dt I2S_ASN1_INTEGER 3 .Os .Sh NAME .Nm i2s_ASN1_ENUMERATED , .Nm i2s_ASN1_ENUMERATED_TABLE , .Nm i2s_ASN1_INTEGER , .Nm s2i_ASN1_INTEGER , .Nm i2s_ASN1_OCTET_STRING , .Nm s2i_ASN1_OCTET_STRING .Nd ASN.1 data type conversion utilities for certificate extensions .Sh SYNOPSIS .In openssl/asn1.h .In openssl/x509v3.h .Ft "char *" .Fo i2s_ASN1_ENUMERATED .Fa "X509V3_EXT_METHOD *method" .Fa "const ASN1_ENUMERATED *a" .Fc .Ft "char *" .Fo i2s_ASN1_INTEGER .Fa "X509V3_EXT_METHOD *method" .Fa "const ASN1_INTEGER *a" .Fc .Ft "ASN1_INTEGER *" .Fo s2i_ASN1_INTEGER .Fa "X509V3_EXT_METHOD *method" .Fa "const char *value" .Fc .Ft "char *" .Fo i2s_ASN1_OCTET_STRING .Fa "X509V3_EXT_METHOD *method" .Fa "const ASN1_OCTET_STRING *aos" .Fc .Ft "ASN1_OCTET_STRING *" .Fo s2i_ASN1_OCTET_STRING .Fa "X509V3_EXT_METHOD *method" .Fa "X509V3_CTX *ctx" .Fa "const char *value" .Fc .Ft "char *" .Fo i2s_ASN1_ENUMERATED_TABLE .Fa "X509V3_EXT_METHOD *method" .Fa "const ASN1_ENUMERATED *aenum" .Fc .Sh DESCRIPTION These functions convert to and from .Vt ASN1_ENUMERATED , .Vt ASN1_INTEGER , and .Vt ASN1_OCTET_STRING objects. They are primarily used internally for parsing configuration files and displaying X.509v3 certificate extensions. With the exception of .Fn i2s_ASN1_ENUMERATED_TABLE , these functions ignore the .Fa method argument. Any object or string returned by these functions must be freed by the caller. .Pp .Fn i2s_ASN1_ENUMERATED and .Fn i2s_ASN1_INTEGER first convert .Fa a into a .Vt BIGNUM object with .Xr ASN1_ENUMERATED_to_BN 3 or .Xr ASN1_INTEGER_to_BN 3 and then derive a string representation using .Xr BN_bn2dec 3 or .Xr BN_bn2hex 3 . Decimal representation is used if the number has less than 128 bits, otherwise hexadecimal representation is used to avoid excessive conversion cost. .Pp .Fn s2i_ASN1_INTEGER converts the NUL-terminated decimal or hexadecimal string representation of an integer in .Fa value into an .Vt ASN1_INTEGER object. A sign prefix of .Sq - indicates a negative number and the base prefixes .Sq 0x and .Sq 0X indicate hexadecimal representation, otherwise decimal representation is assumed. After skipping the sign and base prefixes, an intermediate conversion into a .Vt BIGNUM is performed using .Xr BN_dec2bn 3 or .Xr BN_hex2bn 3 and the .Vt ASN1_INTEGER is then obtained with .Xr BN_to_ASN1_INTEGER 3 . .Pp .Fn i2s_ASN1_OCTET_STRING converts the octets in .Fa aos into a string where the octets are colon-separated and represented as pairs of uppercase hexadecimal digits. .Pp .Fn s2i_ASN1_OCTET_STRING converts the NUL-terminated string .Fa str into an .Vt ASN1_OCTET_STRING . The .Fa method and .Fa ctx arguments are ignored. Every pair of hexadecimal digits is converted into an octet. Colons are ignored if they are at the start, the end or if they separate two pairs of digits. .Pp .Fn i2s_ASN1_ENUMERATED_TABLE uses strings provided in the usr_data field of the non-NULL .Fa method to convert the value of .Fa a into a string. If no such string is available, .Fa a is passed to .Fn i2s_ASN1_ENUMERATED . The .Fa method argument can be provided by application programs or it can be a default method obtained from .Xr X509V3_EXT_get_nid 3 . The default .Fa methods corresponding to the following .Fa nid arguments have strings configured in their usr_data field: .Pp .Bl -column NID_netscape_cert_type "Netscape certificate type (obsolete)" -compact .It Dv NID_crl_reason Ta reason codes, RFC 5280, 5.3.1 .It Dv NID_key_usage Ta key usage, RFC 5280, 4.2.1.3 .It Dv NID_netscape_cert_type Ta Netscape certificate type (obsolete) .El .Sh RETURN VALUES .Fn i2s_ASN1_ENUMERATED , .Fn i2s_ASN1_ENUMERATED_TABLE , .Fn i2s_ASN1_INTEGER , and .Fn i2s_ASN1_OCTET_STRING return a NUL-terminated string, or NULL on memory allocation failure. .Pp .Fn s2i_ASN1_INTEGER returns an .Vt ASN1_INTEGER , or NULL on error. Error conditions are memory allocation failure or if .Fa value is not a valid decimal or hexadecimal encoding of an integer. .Pp .Fn s2i_ASN1_OCTET_STRING returns an .Vt ASN1_OCTET_STRING , or NULL on error. Error conditions are memory allocation failure or if .Fa value contains an odd number of hexadecimal digits or anything except colons at the start, the end or between pairs of hexadecimal digits. .Pp Error codes can sometimes be obtained by .Xr ERR_get_error 3 . .Sh SEE ALSO .Xr ASN1_INTEGER_new 3 , .Xr ASN1_INTEGER_to_BN 3 , .Xr ASN1_OCTET_STRING_new 3 , .Xr crypto 3 , .Xr X509V3_get_d2i 3 .Sh HISTORY These functions first appeared in OpenSSL 0.9.4 and have been available since .Ox 2.6 . .Sh BUGS Of these functions at least .Fn i2s_ASN1_ENUMERATED_TABLE can succeed while setting an error and fail without setting an error on the error stack.