BIO Series 21 of openssl --- Base64 BIO, openssl21 --- base64

BIO Series 21 of openssl --- Base64 BIO, openssl21 --- base64

Base64 Type BIO

--- Based on openssl doc \ crypto \ bio_f_base64.pod translation and your own understanding, write

(Author: DragonKing, Mail: wzhah@263.net, published on: http://gdwzh.126.com o

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This type is filter Type BIO, which is defined as follows (openssl \ bio. h, openssl \ evp. h)

:

BIO_METHOD * BIO_f_base64 (void );

[BIO_f_base64]

This function returns a Base64 BIO_METHOD structure, which is defined as follows (evp \ bio_b64.c)

:

Static BIO_METHOD methods_b64 =

{

BIO_TYPE_BASE64,

"Base64 encoding ",

B64_write,

B64_read,

NULL,/* b64_puts ,*/

NULL,/* b64_gets ,*/

B64_ctrl,

B64_new,

B64_free,

B64_callback_ctrl,

};

It should be noted that this type of BIO is not defined in the bio directory, but in the evp directory.

When writing data to this BIO, the data is base64-encoded. When reading data from this BIO, the data is base64-decoded.

. This BIO does not support BIO_gets and BIO_puts.

BIO_flush indicates that the data to be written has been written when BIO of this type is called.

A piece of data is written into BIO.

[BIO_set_flags]

This function can be used to set the flag BIO_FLAGS_BASE64_NO_NL. After this flag is set, all data

Encode the data into a row or expect all the data to be on a row. Note that the base64 encoding format

The end position of the encoded data block cannot be determined accurately and reliably.

Pay attention to the Data Length.

[Example]

The following program encodes the string "Hello World \ n" in base64 and writes it to the standard output device.

BIO * bio, * b64;

Char message [] = "Hello World \ n ";

B64 = BIO_new (BIO_f_base64 ());

Bio = BIO_new_fp (stdout, BIO_NOCLOSE );

Bio = BIO_push (b64, bio );

BIO_write (bio, message, strlen (message ));

BIO_flush (bio );

BIO_free_all (bio );

The following program reads base64 encoded data from the standard input device and outputs the decoded data to the standard output.

Device:

BIO * bio, * b64, bio_out;

Char inbuf [512];

Int inlen;

Char message [] = "Hello World \ n ";

B64 = BIO_new (BIO_f_base64 ());

Bio = BIO_new_fp (stdin, BIO_NOCLOSE );

Bio_out = BIO_new_fp (stdout, BIO_NOCLOSE );

Bio = BIO_push (b64, bio );

While (inlen = BIO_read (bio, inbuf, strlen (message)> 0)

BIO_write (bio_out, inbuf, inlen );

BIO_free_all (bio );