1.\" $OpenBSD: BIO_f_base64.3,v 1.15 2023/09/11 04:00:40 jsg Exp $ 2.\" OpenSSL fc1d88f0 Wed Jul 2 22:42:40 2014 -0400 3.\" 4.\" This file was written by Dr. Stephen Henson <steve@openssl.org>. 5.\" Copyright (c) 2000, 2003, 2005, 2014 The OpenSSL Project. 6.\" All rights reserved. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in 17.\" the documentation and/or other materials provided with the 18.\" distribution. 19.\" 20.\" 3. All advertising materials mentioning features or use of this 21.\" software must display the following acknowledgment: 22.\" "This product includes software developed by the OpenSSL Project 23.\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 24.\" 25.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 26.\" endorse or promote products derived from this software without 27.\" prior written permission. For written permission, please contact 28.\" openssl-core@openssl.org. 29.\" 30.\" 5. Products derived from this software may not be called "OpenSSL" 31.\" nor may "OpenSSL" appear in their names without prior written 32.\" permission of the OpenSSL Project. 33.\" 34.\" 6. Redistributions of any form whatsoever must retain the following 35.\" acknowledgment: 36.\" "This product includes software developed by the OpenSSL Project 37.\" for use in the OpenSSL Toolkit (http://www.openssl.org/)" 38.\" 39.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 40.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 41.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 42.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 43.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 44.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 45.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 46.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 47.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 48.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 49.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 50.\" OF THE POSSIBILITY OF SUCH DAMAGE. 51.\" 52.Dd $Mdocdate: September 11 2023 $ 53.Dt BIO_F_BASE64 3 54.Os 55.Sh NAME 56.Nm BIO_f_base64 57.\" .Nm EVP_ENCODE_LENGTH and 58.\" .Nm EVP_DECODE_LENGTH are intentionally undocumented 59.\" because they are internal implementation details of BIO_f_base64(3) 60.\" and practically unused outside evp/bio_b64.c. 61.Nd base64 BIO filter 62.Sh SYNOPSIS 63.In openssl/bio.h 64.In openssl/evp.h 65.Ft const BIO_METHOD * 66.Fo BIO_f_base64 67.Fa void 68.Fc 69.Sh DESCRIPTION 70.Fn BIO_f_base64 71returns the base64 BIO method. 72This is a filter BIO that base64 encodes any data written through it 73and decodes any data read through it. 74.Pp 75Base64 BIOs do not support 76.Xr BIO_gets 3 77or 78.Xr BIO_puts 3 . 79.Pp 80.Xr BIO_flush 3 81on a base64 BIO that is being written through 82is used to signal that no more data is to be encoded: 83this is used to flush the final block through the BIO. 84.Pp 85To encode the data all on one line and to expect the data to be all 86on one line, initialize the base64 BIO as follows: 87.Bd -literal -offset indent 88BIO *b64 = BIO_new(BIO_f_base64()); 89BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL); 90.Ed 91.Sh RETURN VALUES 92.Fn BIO_f_base64 93returns the base64 BIO method. 94.Pp 95When called on a base64 BIO object, 96.Xr BIO_method_type 3 97returns the constant 98.Dv BIO_TYPE_BASE64 99and 100.Xr BIO_method_name 3 101returns a pointer to the static string 102.Qq base64 encoding . 103.Sh EXAMPLES 104Base64 encode the string "hello, world\en" 105and write the result to standard output: 106.Bd -literal -offset indent 107BIO *bio, *b64; 108char message[] = "hello, world\en"; 109 110b64 = BIO_new(BIO_f_base64()); 111bio = BIO_new_fp(stdout, BIO_NOCLOSE); 112BIO_push(b64, bio); 113BIO_write(b64, message, strlen(message)); 114BIO_flush(b64); 115 116BIO_free_all(b64); 117.Ed 118.Pp 119Read Base64-encoded data from standard input 120and write the decoded data to standard output: 121.Bd -literal -offset indent 122BIO *bio, *b64, *bio_out; 123char inbuf[512]; 124int inlen; 125 126b64 = BIO_new(BIO_f_base64()); 127bio = BIO_new_fp(stdin, BIO_NOCLOSE); 128bio_out = BIO_new_fp(stdout, BIO_NOCLOSE); 129BIO_push(b64, bio); 130while((inlen = BIO_read(b64, inbuf, 512)) > 0) 131 BIO_write(bio_out, inbuf, inlen); 132 133BIO_flush(bio_out); 134BIO_free_all(b64); 135.Ed 136.Sh SEE ALSO 137.Xr BIO_new 3 , 138.Xr EVP_EncodeInit 3 139.Sh HISTORY 140.Fn BIO_f_base64 141first appeared in SSLeay 0.6.5 and has been available since 142.Ox 2.4 . 143.Sh BUGS 144The ambiguity of EOF in base64-encoded data can cause additional 145data following the base64-encoded block to be misinterpreted. 146.Pp 147There should be some way of specifying a test that the BIO can perform 148to reliably determine EOF (for example a MIME boundary). 149