Extract "raw" encrypted data from ECIES/ECP encryption?

[Lars Magnusson]

Hi,   I'm using ECIES/ECP for encryption/decryption. As I understand it, a message with size n encrypted with 224 bit ECIES should be n bytes long + two 224 bit numbers, which is n+56 bytes. When I encrypt a 16 byte message, the result is 93 bytes rather than 72. What are the other bytes and how can I extract the "raw" encrypted message from the data I get from crypto++?     Source code: ----------   #include <string> #include <stdio.h>   // Lot's of warnings from the lib without these on MSVC 2003 #pragma warning(disable:4267) #pragma warning(disable:4661)   #include <oids.h> #include <osrng.h> #include <eccrypto.h>   using namespace CryptoPP;     void test() {            // Generate keys and initialize encryptor            AutoSeededRandomPool rng;              typedef ECIES<ECP>::PrivateKey ECPrivateKey;            ECPrivateKey privkey;            Integer integer("11111111111111111111111111111111111111111111111111111111h");            privkey.Initialize(ASN1::secp224r1(), integer);              typedef ECIES<ECP>::PublicKey ECPublicKey;            ECPublicKey pubkey;               privkey.MakePublicKey(pubkey);              typedef ECIES<ECP>::Encryptor ECEncryptor;            ECEncryptor encryptor(pubkey);                // Encrypt            string sContents("0123456789012345"); // 16 bytes            SecByteBlock sbbCipherText(encryptor.CiphertextLength(sContents.size()));              encryptor.Encrypt(                       rng,                       (byte const*) sContents.data(),                       sContents.size(),                       sbbCipherText.begin());              // This prints 93, expected 72 (72 is 2*224/8+16)            printf("Size: %d\n", sbbCipherText.size()); }   int main() {            test();            return 0; }   ---------     //Lars