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-rw-r--r--source3/libsmb/smbencrypt.c114
1 files changed, 114 insertions, 0 deletions
diff --git a/source3/libsmb/smbencrypt.c b/source3/libsmb/smbencrypt.c
index a8a88a8a7e..0742976635 100644
--- a/source3/libsmb/smbencrypt.c
+++ b/source3/libsmb/smbencrypt.c
@@ -782,3 +782,117 @@ WERROR decode_wkssvc_join_password_buffer(TALLOC_CTX *mem_ctx,
return WERR_OK;
}
+
+DATA_BLOB decrypt_drsuapi_blob(TALLOC_CTX *mem_ctx,
+ const DATA_BLOB *session_key,
+ bool rcrypt,
+ uint32_t rid,
+ const DATA_BLOB *buffer)
+{
+ DATA_BLOB confounder;
+ DATA_BLOB enc_buffer;
+
+ struct MD5Context md5;
+ uint8_t _enc_key[16];
+ DATA_BLOB enc_key;
+
+ DATA_BLOB dec_buffer;
+
+ uint32_t crc32_given;
+ uint32_t crc32_calc;
+ DATA_BLOB checked_buffer;
+
+ DATA_BLOB plain_buffer;
+
+ /*
+ * the combination "c[3] s[1] e[1] d[0]..."
+ * was successful!!!!!!!!!!!!!!!!!!!!!!!!!!
+ */
+
+ /*
+ * the first 16 bytes at the beginning are the confounder
+ * followed by the 4 byte crc32 checksum
+ */
+ if (buffer->length < 20) {
+ return data_blob_const(NULL, 0);
+ }
+ confounder = data_blob_const(buffer->data, 16);
+ enc_buffer = data_blob_const(buffer->data + 16, buffer->length - 16);
+
+ /*
+ * build the encryption key md5 over the session key followed
+ * by the confounder
+ *
+ * here the gensec session key is used and
+ * not the dcerpc ncacn_ip_tcp "SystemLibraryDTC" key!
+ */
+ enc_key = data_blob_const(_enc_key, sizeof(_enc_key));
+ MD5Init(&md5);
+ MD5Update(&md5, session_key->data, session_key->length);
+ MD5Update(&md5, confounder.data, confounder.length);
+ MD5Final(enc_key.data, &md5);
+
+ /*
+ * copy the encrypted buffer part and
+ * decrypt it using the created encryption key using arcfour
+ */
+ dec_buffer = data_blob_talloc(mem_ctx, enc_buffer.data, enc_buffer.length);
+ if (!dec_buffer.data) {
+ return data_blob_const(NULL, 0);
+ }
+ SamOEMhashBlob(dec_buffer.data, dec_buffer.length, &enc_key);
+
+ /*
+ * the first 4 byte are the crc32 checksum
+ * of the remaining bytes
+ */
+ crc32_given = IVAL(dec_buffer.data, 0);
+ crc32_calc = crc32_calc_buffer((const char *)dec_buffer.data + 4 , dec_buffer.length - 4);
+ if (crc32_given != crc32_calc) {
+ DEBUG(1,("CRC32: given[0x%08X] calc[0x%08X]\n",
+ crc32_given, crc32_calc));
+ return data_blob_const(NULL, 0);
+ }
+ checked_buffer = data_blob_talloc(mem_ctx, dec_buffer.data + 4, dec_buffer.length - 4);
+ if (!checked_buffer.data) {
+ return data_blob_const(NULL, 0);
+ }
+
+ /*
+ * some attributes seem to be in a usable form after this decryption
+ * (supplementalCredentials, priorValue, currentValue, trustAuthOutgoing,
+ * trustAuthIncoming, initialAuthOutgoing, initialAuthIncoming)
+ * At least supplementalCredentials contains plaintext
+ * like "Primary:Kerberos" (in unicode form)
+ *
+ * some attributes seem to have some additional encryption
+ * dBCSPwd, unicodePwd, ntPwdHistory, lmPwdHistory
+ *
+ * it's the sam_rid_crypt() function, as the value is constant,
+ * so it doesn't depend on sessionkeys.
+ */
+ if (rcrypt) {
+ uint32_t i, num_hashes;
+
+ if ((checked_buffer.length % 16) != 0) {
+ return data_blob_const(NULL, 0);
+ }
+
+ plain_buffer = data_blob_talloc(mem_ctx, checked_buffer.data, checked_buffer.length);
+ if (!plain_buffer.data) {
+ return data_blob_const(NULL, 0);
+ }
+
+ num_hashes = plain_buffer.length / 16;
+ for (i = 0; i < num_hashes; i++) {
+ uint32_t offset = i * 16;
+ sam_pwd_hash(rid, checked_buffer.data + offset, plain_buffer.data + offset, 0);
+ }
+ } else {
+ plain_buffer = checked_buffer;
+ }
+
+ return plain_buffer;
+}
+
+