NAME

       BIO_f_base64 - base64 BIO filter

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().

       For writing, output is by default divided to lines of length 64 characters and there is
       always a newline at the end of output.

       For reading, first line should be at most 1024 characters long. If it is longer then it is
       ignored completely.  Other input lines can be of any length. There must be a newline at
       the end of input.

       This behavior can be changed with BIO_FLAGS_BASE64_NO_NL flag.

       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().  For writing, it causes
       all data to be written on one line without newline at the end.  For reading, it expects
       the data to be all on one line (with or without a trailing newline).

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 2000-2022 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (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>.