diff --git a/tools/deps.bzl b/tools/deps.bzl
index d056483891...c7b88e94b8 100644
--- a/tools/deps.bzl
+++ b/tools/deps.bzl
@@ -21,7 +21,7 @@
 GITILES_REPO = GERRIT
 
 # When updating Bouncy Castle, also update it in bazlets.
-BC_VERS = "1.72"
+BC_VERS = "1.78.1"
 HTTPCOMP_VERS = "4.5.14"
 JETTY_VERS = "9.4.53.v20231009"
 BYTE_BUDDY_VERSION = "1.14.9"
@@ -423,25 +423,25 @@
     maven_jar(
         name = "bcprov",
         artifact = "org.bouncycastle:bcprov-jdk18on:" + BC_VERS,
-        sha1 = "d8dc62c28a3497d29c93fee3e71c00b27dff41b4",
+        sha1 = "39e9e45359e20998eb79c1828751f94a818d25f8",
     )
 
     maven_jar(
         name = "bcpg",
         artifact = "org.bouncycastle:bcpg-jdk18on:" + BC_VERS,
-        sha1 = "1a36a1740d07869161f6f0d01fae8d72dd1d8320",
+        sha1 = "6c8dbcec20355278ec54840e735f63db2479150e",
     )
 
     maven_jar(
         name = "bcpkix",
         artifact = "org.bouncycastle:bcpkix-jdk18on:" + BC_VERS,
-        sha1 = "bb3fdb5162ccd5085e8d7e57fada4d8eaa571f5a",
+        sha1 = "17b3541f736df97465f87d9f5b5dfa4991b37bb3",
     )
 
     maven_jar(
         name = "bcutil",
         artifact = "org.bouncycastle:bcutil-jdk18on:" + BC_VERS,
-        sha1 = "41f19a69ada3b06fa48781120d8bebe1ba955c77",
+        sha1 = "5353ca39fe2f148dab9ca1d637a43d0750456254",
     )
 
     maven_jar(