+ if (!key)
+ return;
+ gcry_sexp_release(key->sexp);
+ free(key);
+}
+
+static int decode_rsa(gcry_sexp_t sexp, int key_size, unsigned char *outbuf,
+ size_t *nbytes)
+{
+ int ret;
+ gcry_error_t gret;
+ unsigned char oaep_buf[512];
+ gcry_mpi_t out_mpi;
+
+ if (libgcrypt_has_oaep) {
+ const char *p = gcry_sexp_nth_data(sexp, 1, nbytes);
+
+ if (!p) {
+ PARA_ERROR_LOG("could not get data from list\n");
+ return -E_OEAP;
+ }
+ memcpy(outbuf, p, *nbytes);
+ return 1;
+ }
+ out_mpi = gcry_sexp_nth_mpi(sexp, 0, GCRYMPI_FMT_USG);
+ if (!out_mpi)
+ return -E_SEXP_FIND;
+ gret = gcry_mpi_print(GCRYMPI_FMT_USG, oaep_buf, sizeof(oaep_buf),
+ nbytes, out_mpi);
+ if (gret) {
+ PARA_ERROR_LOG("mpi_print: %s\n", gcrypt_strerror(gret));
+ ret = -E_MPI_PRINT;
+ goto out_mpi_release;
+ }
+ /*
+ * An oaep-encoded buffer always starts with at least one zero byte.
+ * However, leading zeroes in an mpi are omitted in the output of
+ * gcry_mpi_print() when using the GCRYMPI_FMT_USG format. The
+ * alternative, GCRYMPI_FMT_STD, does not work either because here the
+ * leading zero(es) might also be omitted, depending on the value of
+ * the second byte.
+ *
+ * To circumvent this, we shift the oaep buffer to the right. But first
+ * we check that the buffer actually started with a zero byte, i.e. that
+ * nbytes < key_size. Otherwise a decoding error occurred.
+ */
+ ret = -E_SEXP_DECRYPT;
+ if (*nbytes >= key_size)
+ goto out_mpi_release;
+ memmove(oaep_buf + key_size - *nbytes, oaep_buf, *nbytes);
+ memset(oaep_buf, 0, key_size - *nbytes);
+
+ PARA_DEBUG_LOG("decrypted buffer before unpad (%d bytes):\n",
+ key_size);
+ dump_buffer("non-unpadded decrypted buffer", oaep_buf, key_size);
+ ret = unpad_oaep(oaep_buf, key_size, outbuf, nbytes);
+ if (ret < 0)
+ goto out_mpi_release;
+ PARA_DEBUG_LOG("decrypted buffer after unpad (%zu bytes):\n",
+ *nbytes);
+ dump_buffer("unpadded decrypted buffer", outbuf, *nbytes);
+ ret = 1;
+out_mpi_release:
+ gcry_mpi_release(out_mpi);
+ return ret;
+}
+
+int priv_decrypt(const char *key_file, unsigned char *outbuf,
+ unsigned char *inbuf, int inlen)
+{
+ gcry_error_t gret;
+ int ret, key_size;
+ struct asymmetric_key *priv;
+ gcry_mpi_t in_mpi = NULL;
+ gcry_sexp_t in, out, priv_key;
+ size_t nbytes;
+
+ ret = check_key_file(key_file, true);
+ if (ret < 0)
+ return ret;
+ PARA_INFO_LOG("decrypting %d byte input\n", inlen);
+ /* key_file -> asymmetric key priv */
+ ret = get_private_key(key_file, &priv);
+ if (ret < 0)
+ return ret;
+ key_size = ret / 8;
+
+ /* asymmetric key priv -> sexp priv_key */
+ ret = -E_SEXP_FIND;
+ priv_key = gcry_sexp_find_token(priv->sexp, "private-key", 0);
+ if (!priv_key)
+ goto free_key;
+
+ /* inbuf -> in_mpi */
+ gret = gcry_mpi_scan(&in_mpi, GCRYMPI_FMT_USG, inbuf,
+ inlen, NULL);
+ if (gret) {
+ PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
+ ret = -E_MPI_SCAN;
+ goto key_release;
+ }
+ /* in_mpi -> in sexp */
+ gret = gcry_sexp_build(&in, NULL, rsa_decrypt_sexp, in_mpi);
+ if (gret) {
+ PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
+ ret = -E_SEXP_BUILD;
+ goto in_mpi_release;
+ }
+
+ /* rsa decryption: in sexp -> out sexp */
+ gret = gcry_pk_decrypt(&out, in, priv_key);
+ if (gret) {
+ PARA_ERROR_LOG("decrypt: %s\n", gcrypt_strerror(gret));
+ ret = -E_SEXP_DECRYPT;
+ goto in_release;
+ }
+ ret = decode_rsa(out, key_size, outbuf, &nbytes);
+ if (ret < 0)
+ goto out_release;
+ PARA_INFO_LOG("successfully decrypted %zu byte message\n", nbytes);
+ ret = nbytes;
+out_release:
+ gcry_sexp_release(out);
+in_release:
+ gcry_sexp_release(in);
+in_mpi_release:
+ gcry_mpi_release(in_mpi);
+key_release:
+ gcry_sexp_release(priv_key);
+free_key:
+ free_asymmetric_key(priv);
+ return ret;
+}
+
+int pub_encrypt(struct asymmetric_key *pub, unsigned char *inbuf,
+ unsigned len, unsigned char *outbuf)
+{
+ gcry_error_t gret;
+ gcry_sexp_t pub_key, in, out, out_a;
+ gcry_mpi_t out_mpi = NULL;
+ size_t nbytes;
+ int ret;
+
+ PARA_INFO_LOG("encrypting %u byte input with %d-byte key\n", len, pub->num_bytes);
+
+ /* get pub key */
+ pub_key = gcry_sexp_find_token(pub->sexp, "public-key", 0);
+ if (!pub_key)
+ return -E_SEXP_FIND;
+ if (libgcrypt_has_oaep) {
+ gret = gcry_sexp_build(&in, NULL,
+ "(data(flags oaep)(value %b))", len, inbuf);
+ } else {
+ unsigned char padded_input[256];
+ const size_t pad_size = 256;
+ /* inbuf -> padded inbuf */
+ pad_oaep(inbuf, len, padded_input, pad_size);
+ /* padded inbuf -> in sexp */
+ gret = gcry_sexp_build(&in, NULL,
+ "(data(flags raw)(value %b))", pad_size, padded_input);
+ }
+ if (gret) {
+ PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
+ ret = -E_SEXP_BUILD;
+ goto key_release;
+ }
+ /* rsa sexp encryption: in -> out */
+ gret = gcry_pk_encrypt(&out, in, pub_key);
+ if (gret) {
+ PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
+ ret = -E_SEXP_ENCRYPT;
+ goto in_release;
+ }
+ /* extract a, an MPI with the result of the RSA operation */
+ ret = -E_SEXP_FIND;
+ out_a = gcry_sexp_find_token(out, "a", 0);
+ if (!out_a)
+ goto out_release;
+ /* convert sexp out_a -> out_mpi */
+ out_mpi = gcry_sexp_nth_mpi(out_a, 1, GCRYMPI_FMT_USG);
+ if (!out_mpi) {
+ ret = -E_SEXP_FIND;
+ goto out_a_release;
+ }
+ gret = gcry_mpi_print(GCRYMPI_FMT_USG, outbuf, 512 /* FIXME */, &nbytes, out_mpi);
+ if (gret) {
+ PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
+ ret = -E_SEXP_ENCRYPT;
+ goto out_mpi_release;
+ }
+ PARA_INFO_LOG("encrypted buffer is %zu bytes\n", nbytes);
+ dump_buffer("enc buf", outbuf, nbytes);
+ ret = nbytes;
+
+out_mpi_release:
+ gcry_mpi_release(out_mpi);
+out_a_release:
+ gcry_sexp_release(out_a);
+out_release:
+ gcry_sexp_release(out);
+in_release:
+ gcry_sexp_release(in);
+key_release:
+ gcry_sexp_release(pub_key);
+ return ret;
+}
+
+struct stream_cipher {
+ gcry_cipher_hd_t handle;
+};
+
+struct stream_cipher *sc_new(const unsigned char *data, int len,
+ bool use_aes)
+{
+ gcry_error_t gret;
+ struct stream_cipher *sc = para_malloc(sizeof(*sc));
+
+ if (use_aes) {
+ assert(len >= 2 * AES_CRT128_BLOCK_SIZE);
+ gret = gcry_cipher_open(&sc->handle, GCRY_CIPHER_AES128,
+ GCRY_CIPHER_MODE_CTR, 0);
+ assert(gret == 0);
+ gret = gcry_cipher_setkey(sc->handle, data,
+ AES_CRT128_BLOCK_SIZE);
+ assert(gret == 0);
+ gret = gcry_cipher_setctr(sc->handle,
+ data + AES_CRT128_BLOCK_SIZE, AES_CRT128_BLOCK_SIZE);
+ assert(gret == 0);
+ return sc;
+ }
+ gret = gcry_cipher_open(&sc->handle, GCRY_CIPHER_ARCFOUR,
+ GCRY_CIPHER_MODE_STREAM, 0);
+ if (gret) {
+ PARA_ERROR_LOG("%s\n", gcrypt_strerror(gret));
+ free(sc);
+ return NULL;
+ }
+ gret = gcry_cipher_setkey(sc->handle, data, (size_t)len);
+ assert(gret == 0);
+ return sc;
+}
+
+void sc_free(struct stream_cipher *sc)
+{
+ if (!sc)
+ return;
+ gcry_cipher_close(sc->handle);
+ free(sc);
+}
+
+void sc_crypt(struct stream_cipher *sc, struct iovec *src, struct iovec *dst)
+{
+ gcry_cipher_hd_t handle = sc->handle;
+ gcry_error_t gret;
+
+ /* perform in-place encryption */
+ *dst = *src;
+ gret = gcry_cipher_encrypt(handle, src->iov_base, src->iov_len,
+ NULL, 0);
+ assert(gret == 0);