void LoadKey(const char* file, RSA::PrivateKey& key)
{
ByteQueue q;
FileSource KeyFile(file, true, new Base64Decoder());
KeyFile.TransferTo(q);
key.BERDecodePrivateKey(q,false,0); // last 2 params unused
}
static bool DecodeFromFile(const char* filename, RSA::PrivateKey& key)
{
try {
ByteQueue queue;
FileSource file(filename, true);
file.TransferTo(queue);
queue.MessageEnd();
key.BERDecodePrivateKey(queue, false, queue.MaxRetrievable());
return key.Validate(rng, 3);
} catch (...) {
return false;
}
}
extern "C" int rsa_pss_sign(const char *key_file, const unsigned char *msg,
int len, unsigned char *sig_buf, unsigned char *modulus_buf)
{
try {
AutoSeededRandomPool rng;
FileSource file(key_file, true);
RSA::PrivateKey key;
ByteQueue bq;
// Load the key
file.TransferTo(bq);
bq.MessageEnd();
key.BERDecodePrivateKey(bq, false, bq.MaxRetrievable());
// Write the modulus
Integer mod = key.GetModulus();
// error check
if (mod.ByteCount() != RCM_RSA_MODULUS_SIZE)
throw std::length_error("incorrect rsa key modulus length");
for (int i = 0; i < mod.ByteCount(); i++)
modulus_buf[i] = mod.GetByte(i);
// Sign the message
RSASS<PSS, SHA256>::Signer signer(key);
size_t length = signer.MaxSignatureLength();
SecByteBlock signature(length);
length = signer.SignMessage(rng, msg, len, signature);
// Copy in reverse order
for (int i = 0; i < length; i++)
sig_buf[length - i - 1] = signature[i];
}
catch(const CryptoPP::Exception& e) {
cerr << e.what() << endl;
return 1;
}
catch(std::length_error& le) {
cerr << "Error: " << le.what() << endl;
return 1;
}
return 0;
}
extern "C" int rsa_pss_sign_file(const char *key_file, const char *msg_file,
unsigned char *sig_buf)
{
try {
AutoSeededRandomPool rng;
FileSource file(key_file, true);
RSA::PrivateKey key;
ByteQueue bq;
// Load the key
file.TransferTo(bq);
bq.MessageEnd();
key.BERDecodePrivateKey(bq, false, bq.MaxRetrievable());
// Sign the message
RSASS<PSS, SHA256>::Signer signer(key);
string signature;
FileSource src(msg_file, true,
new SignerFilter(rng, signer,
new StringSink(signature)));
int length = signature.length();
// error check
if (length != RCM_RSA_SIG_SIZE)
throw std::length_error("incorrect rsa key length");
// Copy in reverse order
for (int i = 0; i < length; i++)
sig_buf[length - i - 1] = signature[i];
}
catch(const CryptoPP::Exception& e) {
cerr << e.what() << endl;
return 1;
}
catch(std::length_error& le) {
cerr << "Error: " << le.what() << endl;
return 1;
}
return 0;
}
