Docs for cipher and base64 BIOs.

=pod

=head1 NAME

	BIO_f_base64 - base64 BIO

=head1 SYNOPSIS

 #include <openssl/bio.h>

 #include <openssl/evp.h>

 BIO_METHOD *	BIO_f_base64(void);

=head1 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.

=head1 NOTES

Because of the format of base64 encoding the end of the encoded

block cannot always be reliably determined.

=head1 RETURN VALUES

BIO_f_base64() returns the base64 BIO method.

=head1 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 = BIO_push(b64, bio);

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

 BIO_flush(bio);

 BIO_free_all(bio);

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;

 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);

=head1 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).

=head1 SEE ALSO

TBA

=pod

=head1 NAME

	BIO_f_cipher - cipher BIO

=head1 SYNOPSIS

 #include <openssl/bio.h>

 #include <openssl/evp.h>

 BIO_METHOD *	BIO_f_cipher(void);

 void BIO_set_cipher(BIO *b,const EVP_CIPHER *cipher,

		unsigned char *key, unsigned char *iv, int enc);

 int BIO_get_cipher_status(BIO *b)

 int BIO_get_cipher_ctx(BIO *b, EVP_CIPHER_CTX **pctx)

=head1 DESCRIPTION

BIO_f_cipher() returns the cipher BIO method. This is a filter

BIO that encrypts any data written through it, and decrypts any data

read from it. It is a BIO wrapper for the cipher routines

EVP_CipherInit(), EVP_CipherUpdate() and EVP_CipherFinal().

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

BIO_flush() on an encryption BIO that is being written through is

used to signal that no more data is to be encrypted: this is used

to flush and possibly pad the final block through the BIO.

BIO_set_cipher() sets the cipher of BIO <b> to B<cipher> using key B<key>

and IV B<iv>. B<enc> should be set to 1 for encryption and zero for

decryption.

When reading from an encryption BIO the final block is automatically

decrypted and checked when EOF is detected. BIO_get_cipher_status()

is a BIO_ctrl() macro which can be called to determine whether the

decryption operation was successful.

BIO_get_cipher_ctx() is a BIO_ctrl() macro which retrieves the internal

BIO cipher context. The retrieved context can be used in conjustion

with the standard cipher routines to set it up. This is useful when

BIO_set_cipher() is not flexible enough for the applications needs.

=head1 NOTES

When encrypting BIO_flush() B<must> be called to flush the final block

through the BIO. If it is not then the final block will fail a subsequent

decrypt.

When decrypting an error on the final block is signalled by a zero

return value from the read operation. A successful decrypt followed

by EOF will also return zero for the final read. BIO_get_cipher_status()

should be called to determine if the decrypt was successful.

As always, if BIO_gets() or BIO_puts() support is needed then it can

be achieved by preceding the cipher BIO with a buffering BIO.

=head1 RETURN VALUES

BIO_f_cipher() returns the cipher BIO method.

BIO_set_cipher() does not return a value.

BIO_get_cipher_status() returns 1 for a successful decrypt and 0

for failure.

BIO_get_cipher_ctx() currently always returns 1.

=head1 EXAMPLES

TBA

=head1 SEE ALSO

TBA

BIO_get_md_ctx() returns the digest BIOs context into B<mdcp>.

=head1 NOTES

The context returned by BIO_get_md_ctx() can be used in calls

=head1 DESCRIPTION

BIO_s_null() returns the null sink BIO method. Data written to

the null sink is discraded, reads return EOF.

the null sink is discarded, reads return EOF.

=head1 NOTES

passed through it.

A null sink is useful if, for example, an application wishes to digest some

data but not write the result anywhere. Since a BIO chain must normally

include a source/sink BIO this can be achieved by adding a null sink BIO

to the end of the chain

data by writing through a digest bio but not send the digested data anywhere.

Since a BIO chain must normally include a source/sink BIO this can be achieved

by adding a null sink BIO to the end of the chain

=head1 RETURN VALUES