BIO_f_base64(3) | OpenSSL | BIO_f_base64(3)

# NAME

BIO_f_base64 - base64 BIO filter

# LIBRARY

libcrypto, -lcrypto

# SYNOPSIS

     #include <openssl/bio.h>
     #include <openssl/evp.h>

     const BIO_METHOD *BIO_f_base64(void);

# DESCRIPTION

BIO_f_base64() returns the base64 BIO method. This is a filter BIO that base64 encodes any data written through it and decodes any data read through it.

Base64 BIOs do not support BIO_gets() or BIO_puts().

BIO_flush() on a base64 BIO that is being written through is used to signal that no more data is to be encoded: this is used to flush the final block through the BIO.

The flag BIO_FLAGS_BASE64_NO_NL can be set with BIO_set_flags() to encode the data all on one line or expect the data to be all on one line.

# NOTES

Because of the format of base64 encoding the end of the encoded block cannot always be reliably determined.

# RETURN VALUES

BIO_f_base64() returns the base64 BIO method.

# EXAMPLES

Base64 encode the string "Hello World\n" and write the result to standard output:

     BIO *bio, *b64;
     char message[] = "Hello World \n";

     b64 = BIO_new(BIO_f_base64());
     bio = BIO_new_fp(stdout, BIO_NOCLOSE);
     BIO_push(b64, bio);
     BIO_write(b64, message, strlen(message));
     BIO_flush(b64);

     BIO_free_all(b64);

Read Base64 encoded data from standard input and write the decoded data to standard output:

     BIO *bio, *b64, *bio_out;
     char inbuf[512];
     int inlen;

     b64 = BIO_new(BIO_f_base64());
     bio = BIO_new_fp(stdin, BIO_NOCLOSE);
     bio_out = BIO_new_fp(stdout, BIO_NOCLOSE);
     BIO_push(b64, bio);
     while ((inlen = BIO_read(b64, inbuf, 512)) > 0)
         BIO_write(bio_out, inbuf, inlen);

     BIO_flush(bio_out);
     BIO_free_all(b64);

# BUGS

The ambiguity of EOF in base64 encoded data can cause additional data following the base64 encoded block to be misinterpreted.

There should be some way of specifying a test that the BIO can perform to reliably determine EOF (for example a MIME boundary).

# COPYRIGHT

Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.

2018-09-23 | 1.1.1i