BIO_f_base64(3) - NetBSD Manual Pages

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BIO_f_base64(3)                     OpenSSL                    BIO_f_base64(3)




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, by default output is divided to lines of length 64
       characters and there is a newline at the end of output.  This behavior
       can be changed with BIO_FLAGS_BASE64_NO_NL flag.

       For reading, first line should be at most 1024 bytes long including
       newline unless the flag BIO_FLAGS_BASE64_NO_NL is set.  Further input
       lines can be of any length (i.e., newlines may appear anywhere in the
       input) and a newline at the end of input is not needed.

       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 removes all expectations on newlines in
       the input data.


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

       On decoding, if the flag BIO_FLAGS_BASE64_NO_NL is not set and the
       first 1024 bytes of input do not include a newline character the first
       two lines of input are ignored.

       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 2000-2024 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>.



3.0.15                            2024-09-03                   BIO_f_base64(3)