+static int find_privkey_bignum_offset(const unsigned char *data, int len)
+{
+ const unsigned char *p = data, *end = data + len;
+
+ /* like the public key, the whole thing is contained in a sequence */
+ if (*p != ASN1_TYPE_SEQUENCE)
+ return -E_ASN1_PARSE;
+ p++;
+ if (p >= end)
+ return -E_ASN1_PARSE;
+ if (is_short_form(*p))
+ p++;
+ else
+ p += 1 + get_long_form_num_length_bytes(*p);
+ if (p >= end)
+ return -E_ASN1_PARSE;
+
+ /* Skip next integer */
+ if (*p != ASN1_TYPE_INTEGER)
+ return -E_ASN1_PARSE;
+ p++;
+ if (p >= end)
+ return -E_ASN1_PARSE;
+ if (is_short_form(*p))
+ p += 1 + get_short_form_length(*p);
+ else
+ p += 1 + get_long_form_num_length_bytes(*p);
+ if (p >= end)
+ return -E_ASN1_PARSE;
+ return p - data;
+}
+
+/** Private keys start with this header. */
+#define PRIVATE_KEY_HEADER "-----BEGIN RSA PRIVATE KEY-----"
+/** Private keys end with this footer. */
+#define PRIVATE_KEY_FOOTER "-----END RSA PRIVATE KEY-----"
+
+static int get_private_key(const char *key_file, struct asymmetric_key **result)
+{
+ gcry_mpi_t n = NULL, e = NULL, d = NULL, p = NULL, q = NULL,
+ u = NULL;
+ unsigned char *blob, *cp, *end;
+ int blob_size, ret, n_size;
+ gcry_error_t gret;
+ size_t erroff;
+ gcry_sexp_t sexp;
+ struct asymmetric_key *key;
+
+ ret = decode_key(key_file, PRIVATE_KEY_HEADER, PRIVATE_KEY_FOOTER,
+ &blob);
+ if (ret < 0)
+ return ret;
+ blob_size = ret;
+ end = blob + blob_size;
+ ret = find_privkey_bignum_offset(blob, blob_size);
+ if (ret < 0)
+ goto free_blob;
+ PARA_INFO_LOG("reading RSA params at offset %d\n", ret);
+ cp = blob + ret;
+
+ ret = read_bignum(cp, end, &n, &n_size);
+ if (ret < 0)
+ goto free_blob;
+ cp += ret;
+
+ ret = read_bignum(cp, end, &e, NULL);
+ if (ret < 0)
+ goto release_n;
+ cp += ret;
+
+ ret = read_bignum(cp, end, &d, NULL);
+ if (ret < 0)
+ goto release_e;
+ cp += ret;
+
+ ret = read_bignum(cp, end, &p, NULL);
+ if (ret < 0)
+ goto release_d;
+ cp += ret;
+
+ ret = read_bignum(cp, end, &q, NULL);
+ if (ret < 0)
+ goto release_p;
+ cp += ret;
+ ret = read_bignum(cp, end, &u, NULL);
+ if (ret < 0)
+ goto release_q;
+ /*
+ * OpenSSL uses slightly different parameters than gcrypt. To use these
+ * parameters we need to swap the values of p and q and recompute u.
+ */
+ if (gcry_mpi_cmp(p, q) > 0) {
+ gcry_mpi_swap(p, q);
+ gcry_mpi_invm(u, p, q);
+ }
+ gret = gcry_sexp_build(&sexp, &erroff, RSA_PRIVKEY_SEXP,
+ n, e, d, p, q, u);
+
+ if (gret) {
+ PARA_ERROR_LOG("offset %zu: %s\n", erroff,
+ gcry_strerror(gcry_err_code(gret)));
+ ret = -E_SEXP_BUILD;
+ goto release_u;
+ }
+ key = para_malloc(sizeof(*key));
+ key->sexp = sexp;
+ *result = key;
+ ret = n_size * 8;
+ PARA_INFO_LOG("succesfully read %d bit private key\n", ret);
+release_u:
+ gcry_mpi_release(u);
+release_q:
+ gcry_mpi_release(q);
+release_p:
+ gcry_mpi_release(p);
+release_d:
+ gcry_mpi_release(d);
+release_e:
+ gcry_mpi_release(e);
+release_n:
+ gcry_mpi_release(n);
+free_blob:
+ free(blob);
+ return ret;
+}
+
+/** Public keys start with this header. */
+#define PUBLIC_KEY_HEADER "-----BEGIN PUBLIC KEY-----"
+/** Public keys end with this footer. */
+#define PUBLIC_KEY_FOOTER "-----END PUBLIC KEY-----"
+
+static int get_asn_public_key(const char *key_file, struct asymmetric_key **result)
+{
+ gcry_mpi_t n = NULL, e = NULL;
+ unsigned char *blob, *cp, *end;
+ int blob_size, ret, n_size;
+ gcry_error_t gret;
+ size_t erroff;
+ gcry_sexp_t sexp;
+ struct asymmetric_key *key;
+
+ ret = decode_key(key_file, PUBLIC_KEY_HEADER, PUBLIC_KEY_FOOTER,
+ &blob);
+ if (ret < 0)
+ return ret;
+ blob_size = ret;
+ end = blob + blob_size;
+ ret = find_pubkey_bignum_offset(blob, blob_size);
+ if (ret < 0)
+ goto free_blob;
+ PARA_DEBUG_LOG("decoding public RSA params at offset %d\n", ret);
+ cp = blob + ret;
+
+ ret = read_bignum(cp, end, &n, &n_size);
+ if (ret < 0)
+ goto free_blob;
+ cp += ret;
+
+ ret = read_bignum(cp, end, &e, NULL);
+ if (ret < 0)
+ goto release_n;
+
+ gret = gcry_sexp_build(&sexp, &erroff, RSA_PUBKEY_SEXP, n, e);
+ if (gret) {
+ PARA_ERROR_LOG("offset %zu: %s\n", erroff,
+ gcry_strerror(gcry_err_code(gret)));
+ ret = -E_SEXP_BUILD;
+ goto release_e;
+ }
+ key = para_malloc(sizeof(*key));
+ key->sexp = sexp;
+ *result = key;
+ ret = n_size;
+ PARA_INFO_LOG("successfully read %u bit asn public key\n", n_size * 8);
+
+release_e:
+ gcry_mpi_release(e);
+release_n:
+ gcry_mpi_release(n);
+free_blob:
+ free(blob);
+ return ret;
+}
+
+static int get_ssh_public_key(unsigned char *data, int size, gcry_sexp_t *result)
+{
+ int ret;
+ gcry_error_t gret;
+ unsigned char *blob = NULL, *p, *end;
+ size_t nr_scanned, erroff, decoded_size;
+ gcry_mpi_t e = NULL, n = NULL;
+
+ PARA_DEBUG_LOG("decoding %d byte public rsa-ssh key\n", size);
+ if (size > INT_MAX / 4)
+ return -ERRNO_TO_PARA_ERROR(EOVERFLOW);
+ blob = para_malloc(2 * size);
+ ret = uudecode((char *)data, blob, 2 * size);
+ if (ret < 0)
+ goto free_blob;
+ decoded_size = ret;
+ end = blob + decoded_size;
+ dump_buffer("decoded key", blob, decoded_size);
+ ret = check_ssh_key_header(blob, decoded_size);
+ if (ret < 0)
+ goto free_blob;
+ p = blob + ret;
+ ret = -E_SSH_PARSE;
+ if (p >= end)
+ goto free_blob;
+ PARA_DEBUG_LOG("scanning modulus and public exponent\n");
+ gret = gcry_mpi_scan(&e, GCRYMPI_FMT_SSH, p, end - p, &nr_scanned);
+ if (gret) {
+ ret = -E_MPI_SCAN;
+ PARA_CRIT_LOG("%s\n", gcry_strerror(gcry_err_code(gret)));
+ goto free_blob;
+ }
+ PARA_DEBUG_LOG("scanned e (%zu bytes)\n", nr_scanned);
+// gcry_mpi_aprint(GCRYMPI_FMT_HEX, &buf, NULL, rsa_e);
+// PARA_CRIT_LOG("e: %s\n", buf);
+ p += nr_scanned;
+ if (p >= end)
+ goto release_e;
+ gret = gcry_mpi_scan(&n, GCRYMPI_FMT_SSH, p, end - p, &nr_scanned);
+ if (gret) {
+ ret = -E_MPI_SCAN;
+ PARA_ERROR_LOG("%s\n", gcry_strerror(gcry_err_code(gret)));
+ goto release_e;
+ }
+ PARA_DEBUG_LOG("scanned n (%zu bytes)\n", nr_scanned);
+// gcry_mpi_aprint(GCRYMPI_FMT_HEX, &buf, NULL, rsa_n);
+// PARA_CRIT_LOG("n: %s\n", buf);
+ gret = gcry_sexp_build(result, &erroff, RSA_PUBKEY_SEXP, n, e);
+ if (gret) {
+ PARA_ERROR_LOG("offset %zu: %s\n", erroff,
+ gcry_strerror(gcry_err_code(gret)));
+ ret = -E_SEXP_BUILD;
+ goto release_n;
+ }
+ ret = nr_scanned / 32 * 32;
+ PARA_INFO_LOG("successfully read %u bit ssh public key\n", ret * 8);
+release_n:
+ gcry_mpi_release(n);
+release_e:
+ gcry_mpi_release(e);
+free_blob:
+ free(blob);
+ return ret;
+}
+
+int get_asymmetric_key(const char *key_file, int private,
+ struct asymmetric_key **result)
+{
+ int ret, ret2;
+ void *map;
+ size_t map_size;
+ unsigned char *start, *end;
+ gcry_sexp_t sexp;
+ struct asymmetric_key *key;
+
+ if (private)
+ return get_private_key(key_file, result);
+ ret = mmap_full_file(key_file, O_RDONLY, &map, &map_size, NULL);
+ if (ret < 0)
+ return ret;
+ ret = is_ssh_rsa_key(map, map_size);
+ if (!ret) {
+ ret = para_munmap(map, map_size);
+ if (ret < 0)
+ return ret;
+ return get_asn_public_key(key_file, result);
+ }
+ start = map + ret;
+ end = map + map_size;
+ ret = -E_SSH_PARSE;
+ if (start >= end)
+ goto unmap;
+ ret = get_ssh_public_key(start, end - start, &sexp);
+ if (ret < 0)
+ goto unmap;
+ key = para_malloc(sizeof(*key));
+ key->num_bytes = ret;
+ key->sexp = sexp;
+ *result = key;
+unmap:
+ ret2 = para_munmap(map, map_size);
+ if (ret >= 0 && ret2 < 0)
+ ret = ret2;
+ return ret;
+}
+
+void free_asymmetric_key(struct asymmetric_key *key)
+{
+ 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;
+
+ 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)