--- /dev/null
+/*
+ * Copyright (c) 2018 Thomas Pornin <pornin@bolet.org>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "inner.h"
+
+/*
+ * CCM initialisation. This does everything except setting the vtable,
+ * which depends on whether this is a context for encrypting or for
+ * decrypting.
+ */
+static void
+gen_ccm_init(br_sslrec_ccm_context *cc,
+ const br_block_ctrcbc_class *bc_impl,
+ const void *key, size_t key_len,
+ const void *iv, size_t tag_len)
+{
+ cc->seq = 0;
+ bc_impl->init(&cc->bc.vtable, key, key_len);
+ memcpy(cc->iv, iv, sizeof cc->iv);
+ cc->tag_len = tag_len;
+}
+
+static void
+in_ccm_init(br_sslrec_ccm_context *cc,
+ const br_block_ctrcbc_class *bc_impl,
+ const void *key, size_t key_len,
+ const void *iv, size_t tag_len)
+{
+ cc->vtable.in = &br_sslrec_in_ccm_vtable;
+ gen_ccm_init(cc, bc_impl, key, key_len, iv, tag_len);
+}
+
+static int
+ccm_check_length(const br_sslrec_ccm_context *cc, size_t rlen)
+{
+ /*
+ * CCM overhead is 8 bytes for nonce_explicit, and the tag
+ * (normally 8 or 16 bytes, depending on cipher suite).
+ */
+ size_t over;
+
+ over = 8 + cc->tag_len;
+ return rlen >= over && rlen <= (16384 + over);
+}
+
+static unsigned char *
+ccm_decrypt(br_sslrec_ccm_context *cc,
+ int record_type, unsigned version, void *data, size_t *data_len)
+{
+ br_ccm_context zc;
+ unsigned char *buf;
+ unsigned char nonce[12], header[13];
+ size_t len;
+
+ buf = (unsigned char *)data + 8;
+ len = *data_len - (8 + cc->tag_len);
+
+ /*
+ * Make nonce (implicit + explicit parts).
+ */
+ memcpy(nonce, cc->iv, sizeof cc->iv);
+ memcpy(nonce + 4, data, 8);
+
+ /*
+ * Assemble synthetic header for the AAD.
+ */
+ br_enc64be(header, cc->seq ++);
+ header[8] = (unsigned char)record_type;
+ br_enc16be(header + 9, version);
+ br_enc16be(header + 11, len);
+
+ /*
+ * Perform CCM decryption.
+ */
+ br_ccm_init(&zc, &cc->bc.vtable);
+ br_ccm_reset(&zc, nonce, sizeof nonce, sizeof header, len, cc->tag_len);
+ br_ccm_aad_inject(&zc, header, sizeof header);
+ br_ccm_flip(&zc);
+ br_ccm_run(&zc, 0, buf, len);
+ if (!br_ccm_check_tag(&zc, buf + len)) {
+ return NULL;
+ }
+ *data_len = len;
+ return buf;
+}
+
+/* see bearssl_ssl.h */
+const br_sslrec_in_ccm_class br_sslrec_in_ccm_vtable = {
+ {
+ sizeof(br_sslrec_ccm_context),
+ (int (*)(const br_sslrec_in_class *const *, size_t))
+ &ccm_check_length,
+ (unsigned char *(*)(const br_sslrec_in_class **,
+ int, unsigned, void *, size_t *))
+ &ccm_decrypt
+ },
+ (void (*)(const br_sslrec_in_ccm_class **,
+ const br_block_ctrcbc_class *, const void *, size_t,
+ const void *, size_t))
+ &in_ccm_init
+};
+
+static void
+out_ccm_init(br_sslrec_ccm_context *cc,
+ const br_block_ctrcbc_class *bc_impl,
+ const void *key, size_t key_len,
+ const void *iv, size_t tag_len)
+{
+ cc->vtable.out = &br_sslrec_out_ccm_vtable;
+ gen_ccm_init(cc, bc_impl, key, key_len, iv, tag_len);
+}
+
+static void
+ccm_max_plaintext(const br_sslrec_ccm_context *cc,
+ size_t *start, size_t *end)
+{
+ size_t len;
+
+ *start += 8;
+ len = *end - *start - cc->tag_len;
+ if (len > 16384) {
+ len = 16384;
+ }
+ *end = *start + len;
+}
+
+static unsigned char *
+ccm_encrypt(br_sslrec_ccm_context *cc,
+ int record_type, unsigned version, void *data, size_t *data_len)
+{
+ br_ccm_context zc;
+ unsigned char *buf;
+ unsigned char nonce[12], header[13];
+ size_t len;
+
+ buf = (unsigned char *)data;
+ len = *data_len;
+
+ /*
+ * Make nonce; the explicit part is an encoding of the sequence
+ * number.
+ */
+ memcpy(nonce, cc->iv, sizeof cc->iv);
+ br_enc64be(nonce + 4, cc->seq);
+
+ /*
+ * Assemble synthetic header for the AAD.
+ */
+ br_enc64be(header, cc->seq ++);
+ header[8] = (unsigned char)record_type;
+ br_enc16be(header + 9, version);
+ br_enc16be(header + 11, len);
+
+ /*
+ * Perform CCM encryption.
+ */
+ br_ccm_init(&zc, &cc->bc.vtable);
+ br_ccm_reset(&zc, nonce, sizeof nonce, sizeof header, len, cc->tag_len);
+ br_ccm_aad_inject(&zc, header, sizeof header);
+ br_ccm_flip(&zc);
+ br_ccm_run(&zc, 1, buf, len);
+ br_ccm_get_tag(&zc, buf + len);
+
+ /*
+ * Assemble header and adjust pointer/length.
+ */
+ len += 8 + cc->tag_len;
+ buf -= 13;
+ memcpy(buf + 5, nonce + 4, 8);
+ buf[0] = (unsigned char)record_type;
+ br_enc16be(buf + 1, version);
+ br_enc16be(buf + 3, len);
+ *data_len = len + 5;
+ return buf;
+}
+
+/* see bearssl_ssl.h */
+const br_sslrec_out_ccm_class br_sslrec_out_ccm_vtable = {
+ {
+ sizeof(br_sslrec_ccm_context),
+ (void (*)(const br_sslrec_out_class *const *,
+ size_t *, size_t *))
+ &ccm_max_plaintext,
+ (unsigned char *(*)(const br_sslrec_out_class **,
+ int, unsigned, void *, size_t *))
+ &ccm_encrypt
+ },
+ (void (*)(const br_sslrec_out_ccm_class **,
+ const br_block_ctrcbc_class *, const void *, size_t,
+ const void *, size_t))
+ &out_ccm_init
+};
projects / BearSSL / blobdiff