crypto++ rsa key into buffer - c++

Question

i started to make an encrypt decrypt file with rsa but i want to save the keys into a buffer like string and etc so i can work with it
i know i can save the key into file like this
AutoSeededRandomPool rng;
RSA::PrivateKey privateKey;
privateKey.GenerateRandomWithKeySize(rng, 2048);
RSA::PublicKey publicKey(privateKey);
Base64Encoder privkeysink(new FileSink("C:\\1\\privkey.txt"));
privateKey.DEREncode(privkeysink);
privkeysink.MessageEnd();
Base64Encoder pubkeysink(new FileSink("C:\\1\\pubkey.txt"));
publicKey.DEREncode(pubkeysink);
pubkeysink.MessageEnd();
but i don't think it a good idea to save to file and then read the file,
is there any way to do it directly?

Answer 1

AutoSeededRandomPool rng;
RSA::PrivateKey privateKey;
privateKey.GenerateRandomWithKeySize(rng, 2048);
Base64Encoder privkeysink(new FileSink("C:\\1\\privkey.txt"));
privateKey.DEREncode(privkeysink);
privkeysink.MessageEnd();
...
You kinda have two things going on. First, how to create and use an RSA key. Second, how do you save the key. In between, you seemed to have added an extra step of reloading a key.
The creation of the key looks fine (which you are doing):
privateKey.GenerateRandomWithKeySize(rng, 2048);
When you want to save it, simply save it (which you are doing):
privateKey.DEREncode(FileSink("privkey.der", true).Ref());
There's no need to reload it. Its still good after you save it. In this case, simply use it (you are adding extra steps here):
RSAES_OAEP_SHA_Decryptor dec(privateKey);
If the key is persisted to disk and you need to reload it, then:
privateKey.BERDecode(FileSource("privkey.der").Ref());
Or even:
RSAES_OAEP_SHA_Decryptor dec;
dec.AccessKey().BERDecode(FileSource("privkey.der").Ref());
I want to save the keys into a buffer like string
This kind of confuses me because I'm not sure what you goal is based on round tripping the key from a file. Recall you can use the key directly:
RSAES_OAEP_SHA_Decryptor dec(privateKey);
But if you want to save it to an in-memory buffer, then:
string buff;
privateKey.DEREncode(StringSink(buff).Ref());
Or:
ByteQueue queue;
privateKey.DEREncode(queue);
And you can still use the pipeline if you like:
privateKey.DEREncode(Base64Encoder(new FileSink("privkey.der")).Ref());
A related wiki page is Keys and Formats.