Provided by: libbobcat-dev_6.03.02-2_amd64 
NAME
FBB::OSymCryptStreambuf - std::streambuf performing symmetric en/decryption
SYNOPSIS
#include <bobcat/osymcryptstreambuf>
Linking option: -lbobcat -lcrypto
DESCRIPTION
FBB::OSymCryptStreambuf objects can be used as std::streambuf objects of std::ostream
objects, and encrypt or decrypt information, that is made available via separate
std::istream streams.
The class OSymCryptStreambuf is a class template, using a FBB::CryptType template non-type
parameter. Objects of the class FBB::OSymCryptStreambuf<FBB::ENCRYPT> encrypt the
information they receive, objects of the class FBB::OSymCryptStreambuf<FBB::DECRYPT>
decrypt the information they receive.
All symmetric encryption methods defined by the OpenSSL library that can be selected by
name may be used to en/decrypt information. To select a particular encryption method an
identifier is passed to the constructor. E.g., "aes-256-gcm". For an overview of the
currently supported cipher algorithms issue the command
openssl list -cipher-algorithms
OSymCryptStreambuf objects read the information to en/decrypt from an external source
(e.g., from std::istream objects). The characters that are encrypted or decrypted by
OSymCryptStreambuf objects are written to std::ostream objects which are at
construction-time specified as ostream references or by filename.
NAMESPACE
FBB
All constructors, members, operators and manipulators, mentioned in this man-page, are
defined in the namespace FBB.
INHERITS FROM
FBB::OSymCryptBase (public)
The class FBB::OSymCryptBase is an `internal use only’ class, derived from std::streambuf,
and therefore OSymCryptStreambuf is a std::streambuf class.
CONSTRUCTORS
o OSymCryptStreambuf<CryptType>(std::ostream &outStreambuf, std::string const
&cipherName, std::string const &key, std::string const &iv, size_t inBufSize =
100):
This constructor defines a std::streambuf encrypting or decrypting the characters
it receives.
- OSymCryptStreambuf<FBB::ENCRYPT> objects perform encryption;
OSymCryptStreambuf<FBB::DECRYPT> objects perform decryption;
- OSymCryptStreambuf<CryptType> objects write the encrypted or decrypted characters
to outStreambuf;
- The encryption method to use is specified by the cipherName parameter. E.g.,
"AES-256-GCM";
- The symmetric key to use is specified by the key parameter;
- The initialization vector is specified by the iv parameter;
- The FBB::OSymCryptStreambufbuf internally used buffer will hold inBufSize
characters. The default value is the smallest value that is used. When specifying a
smaller bufSize value the default value is used;
o OSymCryptStreambuf<CryptType>(std::string const &outStreambufName, std::string
const &cipherName, std::string const &key, std::string const &iv, size_t inBufSize
= 100):
Same constructor as the previous one, but this constructor’s first parameter
specifies the name of the file to receive the encrypted or decrypted characters.
If the construction fails an exception is thrown, mentioning the openssl function that
failed to complete (see also errorMsg below).
The move constructor is available, the copy constructor and assignment operators are not
available,
INHERITED MEMBERS
Since the class is publicly derived from std::ostream, all std::streambuf members can be
used.
MEMBER FUNCTIONS
o static std::string errorMsg():
If an openssl function fails an exception is thrown mentioning the name of the
failing function. In those cases the function errorMsg can be called returning a
std::string containing the openssl error code (returned by ERR_get_error) and its
textual representation (returned by ERR_error_string). If the reported error code
is zero, then in fact no error has occurred and the exception was spuriously
reported;
o static size_t keyLength(std::string const &cipherName):
returns the minimum key length required for cipher cipherName;
o static size_t ivLength(std::sting const &cipherName):
returns the minimum length of the initialization vector that is required for cipher
cipherName.
The latter two functions throw exceptions if cipherName does not contain the name of a
supported cipher algorithm.
MANIPULATOR
o std::ostream &FBB::eoi(std::ostream &out):
By inserting the eoi manipulator into an std::ostream object that uses a
OSymCryptStreambuf streambuf insertion is considered complete. It completes the
insertion of information into the std::ostream specified at construction time as
the OSymCryptStreambuf’s first argument. That way, you don’t have to wait until the
OSymCryptStreambuf object’s destructor flushes that stream. The example provided at
the osymcryptstream(3bobcat) man-page illustrates the use of the eoi manipulator.
EXAMPLE
See the example in the osymcryptstream(3bobcat) man-page. Instead of defining an
OSymCryptStream an OSymCryptStreamBuf can be defined, passing its address to a
std::ostream which can then be used as the OSymCryptStream used in the example.
FILES
bobcat/osymcryptstreambuf - defines the class interface
SEE ALSO
bobcat(7), isymcryptstream(3bobcat), isymcryptstreambuf(3bobcat), osymcryptstream(3bobcat)
BUGS
None Reported.
BOBCAT PROJECT FILES
o https://fbb-git.gitlab.io/bobcat/: gitlab project page;
o bobcat_6.03.02-x.dsc: detached signature;
o bobcat_6.03.02-x.tar.gz: source archive;
o bobcat_6.03.02-x_i386.changes: change log;
o libbobcat1_6.03.02-x_*.deb: debian package containing the libraries;
o libbobcat1-dev_6.03.02-x_*.deb: debian package containing the libraries, headers
and manual pages;
BOBCAT
Bobcat is an acronym of `Brokken’s Own Base Classes And Templates’.
COPYRIGHT
This is free software, distributed under the terms of the GNU General Public License
(GPL).
AUTHOR
Frank B. Brokken (f.b.brokken@rug.nl).