c++ - Use of Pipelines to encrypt a file -

i have startet working crypto++ , have question piplenes , how use them encrypt file.

i want use aes encrypt file.

1.)would enough do:

eax<aes>::encryption encryptor; encryptor.setkeywithiv(derived.data(), 16, ivb, ivb.size()); filesource f("source", new authenticatedencryptionfilter(encryptor,new filesink("deststination"))); 

2.) if have huge input file, approach automaticly encrypt files in blocks?

3.) automaticly create output file if not there?

edit:

ok, got wok approch.

the 2.) question remains , have new one:

can tell skip first 24 bytes of file?

eax<aes>::encryption encryptor; encryptor.setkeywithiv(derived.data(), 16, ivb, ivb.size()); filesource f("source", new authenticatedencryptionfilter(encryptor,new filesink("deststination"))); 

close. authenticatedencryptionfilter coerced bool pumpall parameter of filesink. need:

filesource f("source", true, new authenticatedencryptionfilter(encryptor,new filesink("deststination"))); 

also see filesource on crypto++ wiki. , filesource class reference manual might of interest, too.

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if have huge input file, approach automatically encrypt files in blocks?

yes. internally, crypto++ "block" or "chunk" processing in 4096-bytes, iirc. recent discussion occurred on mailing list @ ios locking during encryption.

a program allows blocking provided in post. can use throttle processing, place update progress bar or yield processor, if needed. reproduced below.

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would automatically create output file if not there?

yes. filesource std::ifstream wrapper, while filesink std::ofstream wrapper.

again, here wiki pages:

• filesource
• filesink

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can tell skip first 24 bytes of file?

yes. in case, use bool pumpall , set false. like:

filesource fs("source", false, new authenticatedencryptionfilter(...)); fs.skip(24);  size_t remaining = <size of file>; size_t block_size = 512; while(remaining && !fs.sourceexhausted()) {         const unsigned int req = stdmin(remaining, block_size);     fs.pump(req);     fs.flush(false);      remaining -= req; } 

or, can:

filesource fs("source", false, new authenticatedencryptionfilter(...)); fs.skip(24); fs.pumpall(); 

also see filesource class reference in manual. skip part of bufferedtransformation; , pumpall part of source.

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there wiki pages covering eax mode , authenticated {en|de}cryption filters. see:

• eax mode
• authenticatedencryptionfilter
• authenticateddecryptionfilter

there's page on using java-like init/update/final at:

• init-update-final

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the program below uses cfb_mode<aes>, easy enough swap in cipher , mode. demonstrates how place objects on stack , use them in pipeline rather creating them on heap new.

int main(int argc, char* argv[]) {   static const unsigned int big_size = 2u * 1024u * 1024u;       static const unsigned int block_size = 4096u;    try     {       secbyteblock key(32);       os_generaterandomblock(false, key.data(), key.size());        // cout << "key: ";       // arraysource as(key.data(), key.size(), true, new hexencoder(new filesink(cout)));       // cout << endl;        cfb_mode<aes>::encryption enc;       enc.setkeywithiv(key.data(), key.size(), key.data());        meterfilter meter;       streamtransformationfilter stf(enc);        filesource source("/dev/zero", false);       filesink sink("zero.enc");        source.attach(new redirector(stf));       stf.attach(new redirector(meter));       meter.attach(new redirector(sink));            unsigned int remaining = big_size;       while(remaining && !source.sourceexhausted())       {         if(remaining % (1024) == 0)         {           cout << "processed: " << meter.gettotalbytes() << endl;             }          const unsigned int req = stdmin(remaining, block_size);         source.pump(req);         source.flush(false);          remaining -= req;     }   }   catch(const exception& ex)   {     cerr << ex.what() << endl;   }    return 0; }