includefile(include/header)

COMMENT(manpage, section, releasedate, archive, short name)
manpage(FBB::ISymCryptStreambuf)(3bobcat)(_CurYrs_)
        (libbobcat-dev__CurVers_)
        (Symmetric Encryption Stream Buffer)

manpagename(FBB::ISymCryptStreambuf)
            (Input Filtering stream buffer doing symmetric encryption)

manpagesynopsis()
    bf(#include <bobcat/isymcryptstreambuf>)nl()
    Linking option: tt(-lbobcat -lcrypto) 

manpagedescription()
    The information made available by bf(ISymCryptStreambuf) objects has
been subject to symmetric encryption or decryption. The information to be
encrypted or decrypted is made available to bf(ISymCryptStreambuf) object
via tt(std::istream) objects.

    The tt(class ISymCryptStreambuf) is a class template, using a
tt(FBB::CryptType) template non-type parameter. Objects of the class
tt(FBB::ISymCryptStreambuf<FBB::ENCRYPT>) encrypt the information they
receive, objects of the class tt(FBB::ISymCryptStreambuf<FBB::DECRYPT>)
decrypt the information they receive. See also section bf(ENUMERATION) below.

    All symmetric encryption methods defined by the OpenSSL library that can
be selected by name may be used in combination with tt(EncryptBuf) objects. To
select a particular encryption method an identifier is passed to the
constructor. E.g., tt("aes-128-cbc") indicating the AES (Rijndael) method,
using 128 bit sized keys and blocks using `cbc' mode (see below for an
explanation).

    When providing shorter keys than expected by the method the provided key
is extended by adding the required number of 0-bytes. (zero valued bytes,
not tt('0') characters). 

Most modes use an em(initialization vector). The initialization vector must be
provided at construction time. The matching decrypting object needs to know
the initialization vector that was used when encrypting the data: the
application must ensure that the matching decryption object receives the same
initialization vector as the one that was provided to the encryption
object. Initialization vectors are not security sensitive in the sense that
they can be sent in the clear to the decryption object. What em(is)
important, though, is that they contain random data when used `for real'. When
an initialization vector is specified that is shorter than expected by the
method it will be extended with the required number of 0-bytes.

includefile(blockciphers)

includefile(symcryptciphers)


includefile(include/namespace)

manpagesection(INHERITS FROM)
    bf(FBB::IFilterBuf)

manpagesection(MEMBER FUNCTIONS)
     All members of bf(FBB::IFilterBuf) are available, as
bf(ISymCryptStreambuf) inherits from this class.

    Overloaded move and/or copy assignment operators are not available.

manpagesection(ENUMERATION)

    bf(ISymCryptStreambuf) objects either encrypt or decrypt
information. bf(ISymCryptStreambuf) objects of the class
bf(FBB::ISymCryptStreambuf<FBB::ENCRYPT>) encrypt the data they receive,
bf(ISymCryptStreambuf) objects of the class
bf(FBB::ISymCryptStreambuf<FBB::DECRYPT>) decrypt the data they receive. 

The values tt(ENCRYPT) and tt(DECRYPT) are defined in the tt(enum CryptType),
which is defined in the tt(FBB) namespace.

manpagesection(CONSTRUCTOR)
    itemization(
    itb(ISymCryptStreambuf<CryptType>(
                   std::istream &in,        char const *type,
                   std::string const &key,  std::string const &iv,
                   size_t bufSize = 100,    size_t filterBufSize = 1000, 
                   ENGINE *engine = 0))
        This constructor initializes the streambuf.
    itemization(
    - tt(ISymCryptStreambuf<ENCRYPT>) objects perform encryption;nl()
        tt(ISymCryptStreambuf<DECRYPT>) objects perform decryption;nl()
    - tt(ISymCryptStreambuf<CryptType>) objects obtain the bytes to encrypt
or decrypt from tt(std::istream &in);nl()
    - The encryption method to use is specified by the tt(type)
parameter. E.g., tt("bf-cbc") selects the Blowfish Cipher Block Chaining
method;nl()
    - The symmetric key to use is specified by the tt(key) parameter;nl()
    - The initialization vector is specified by the tt(iv) parameter;nl()
    - The tt(FBB::ISymCryptStreambuf) internally used buffer will contain
tt(bufSize) characters. The default value is the smallest value that is
used. When a smaller tt(bufSize) value is specified, the default value is
used;nl()
    - tt(FBB::ISymCryptStreambuf)'s tt(IFilterBuf) base class is
initialized with a buffer of size tt(filterBufSize), using a lower bound
of 100;nl()
    - The parameter tt(ENGINE) can be used to specify a hardware
acceleration engine, as supported by the used encryption/decryption
method. Its default argument value indicates that no hardware acceleration is
available.
        )
    )

    Copy and move constructors (and assignment operators) are not available.

manpagesection(EXAMPLE)

    The example shows the construction of an tt(ISymCryptStreambuf<ENCRYPT>)
object tt(ebuf) which is used to initialize a tt(std::istream) object. The
information read from this tt(istream) is encrypted using the Blowfish CBC
method. A tt(ISymCryptStreambuf<DECRYPT>) object (tt(dbuf) reads the
information from that stream and decrypts it again). The tt(std::istream din)
object is initialized with the tt(ISymCryptStreambuf<DECRYPT>) object, and its
content is sent to tt(std::cout). The information that is presented at
tt(std::cin) and that appears at tt(std::cout) should be identical.

    verbinclude(../../isymcryptstreambuf/driver/driver.cc)

manpagefiles()
    em(bobcat/isymcryptstreambuf) - defines the class interface

manpageseealso()
    bf(bobcat)(7), bf(encryptbuf)(3bobcat), bf(isymcryptstream)(3bobcat),
bf(ibase64buf)(3bobcat), bf(ifilterbuf)(3bobcat),
bf(ofilterbuf)(3bobcat), bf(std::streambuf).

manpagebugs()

    Sep/Oct 2013: due to a change in library handling by the linker
(cf. lurl(http://fedoraproject.org/wiki/UnderstandingDSOLinkChange) and
lurl(https://wiki.debian.org/ToolChain/DSOLinking)) libraries that are
indirectly required are no longer automatically linked to your program. With
bf(BigInt) this is tt(libcrypto), which requires programs to link to both
tt(bobcat) and tt(crypto).

includefile(include/trailer)


