llblowfishcipher.cpp

Go to the documentation of this file.

#include "linden_common.h"
#include "llblowfishcipher.h"
#include <openssl/evp.h>


LLBlowfishCipher::LLBlowfishCipher(const U8* secret, size_t secret_size)
:       LLCipher()
{
        llassert(secret);

        mSecretSize = secret_size;
        mSecret = new U8[mSecretSize];
        memcpy(mSecret, secret, mSecretSize);
}

LLBlowfishCipher::~LLBlowfishCipher()
{
        delete [] mSecret;
        mSecret = NULL;
}

// virtual
U32 LLBlowfishCipher::encrypt(const U8* src, U32 src_len, U8* dst, U32 dst_len)
{
        if (!src || !src_len || !dst || !dst_len) return 0;
        if (src_len > dst_len) return 0;

        // OpenSSL uses "cipher contexts" to hold encryption parameters.
    EVP_CIPHER_CTX context;
    EVP_CIPHER_CTX_init(&context);

        // We want a blowfish cyclic block chain cipher, but need to set 
        // the key length before we pass in a key, so call EncryptInit 
        // first with NULLs.
        EVP_EncryptInit_ex(&context, EVP_bf_cbc(), NULL, NULL, NULL);
        EVP_CIPHER_CTX_set_key_length(&context, (int)mSecretSize);
        
        // Complete initialization.  Per EVP_EncryptInit man page, the
        // cipher pointer must be NULL.  Apparently initial_vector must
        // be 8 bytes for blowfish, as this is the block size.
    unsigned char initial_vector[] = { 0, 0, 0, 0, 0, 0, 0, 0 };
        EVP_EncryptInit_ex(&context, NULL, NULL, mSecret, initial_vector);

    int blocksize = EVP_CIPHER_CTX_block_size(&context);
    int keylen = EVP_CIPHER_CTX_key_length(&context);
    int iv_length = EVP_CIPHER_CTX_iv_length(&context);
    lldebugs << "LLBlowfishCipher blocksize " << blocksize
                << " keylen " << keylen
                << " iv_len " << iv_length
                << llendl;

        int output_len = 0;
        int temp_len = 0;
        if (!EVP_EncryptUpdate(&context,
                        dst,
                        &output_len,
                        src,
                        src_len))
        {
                llwarns << "LLBlowfishCipher::encrypt EVP_EncryptUpdate failure" << llendl;
                goto ERROR;
        }

        // There may be some final data left to encrypt if the input is
        // not an exact multiple of the block size.
        if (!EVP_EncryptFinal_ex(&context, (unsigned char*)(dst + output_len), &temp_len))
        {
                llwarns << "LLBlowfishCipher::encrypt EVP_EncryptFinal failure" << llendl;
                goto ERROR;
        }
        output_len += temp_len;

        EVP_CIPHER_CTX_cleanup(&context);
        return output_len;

ERROR:
        EVP_CIPHER_CTX_cleanup(&context);
        return 0;
}

// virtual
U32 LLBlowfishCipher::decrypt(const U8* src, U32 src_len, U8* dst, U32 dst_len)
{
        llerrs << "LLBlowfishCipher decrypt unsupported" << llendl;
        return 0;
}

// virtual
U32 LLBlowfishCipher::requiredEncryptionSpace(U32 len) const
{
        // *HACK: We know blowfish uses an 8 byte block size.
        // Oddly, sometimes EVP_Encrypt produces an extra block
        // if the input is an exact multiple of the block size.
        // So round up.
        const U32 BLOCK_SIZE = 8;
        len += BLOCK_SIZE;
        len -= (len % BLOCK_SIZE);
        return len;
}

---