diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 4040b6f..9267091 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -98,6 +98,10 @@ To publish new versions, run the following:
 yarn release
 ```
 
+### Upgrade Libsodium c library
+
+Download a the new minisig file e.g. `libsodium-1.0.19-stable.tar.gz.minisig` to `./libsodium`. Update the version in `./libsodium/build.sh` and run `cd libsodium && ./build.sh` to build the new library.
+
 ### Scripts
 
 The `package.json` file contains various scripts for common tasks:
diff --git a/libsodium/build.sh b/libsodium/build.sh
index 2432f9e..867a31a 100755
--- a/libsodium/build.sh
+++ b/libsodium/build.sh
@@ -4,7 +4,7 @@
 script_dir=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
 cd $script_dir
 
-source_file='libsodium-1.0.18-stable.tar.gz'
+source_file='libsodium-1.0.19-stable.tar.gz'
 source_dir='libsodium-stable'
 build_dir='build'
 
diff --git a/libsodium/build.tgz b/libsodium/build.tgz
index 7894eb7..7d451e2 100644
Binary files a/libsodium/build.tgz and b/libsodium/build.tgz differ
diff --git a/libsodium/libsodium-1.0.18-stable.tar.gz b/libsodium/libsodium-1.0.18-stable.tar.gz
deleted file mode 100644
index 15baf1d..0000000
Binary files a/libsodium/libsodium-1.0.18-stable.tar.gz and /dev/null differ
diff --git a/libsodium/libsodium-1.0.18-stable.tar.gz.minisig b/libsodium/libsodium-1.0.18-stable.tar.gz.minisig
deleted file mode 100644
index fe78220..0000000
--- a/libsodium/libsodium-1.0.18-stable.tar.gz.minisig
+++ /dev/null
@@ -1,4 +0,0 @@
-untrusted comment: signature from minisign secret key
-RUQf6LRCGA9i53qndLq7+XKYIhmu/RStn4XfzDzAU1zczcs3zWte+jfqj5iHKG48zUiv9W3fwSjh/sIOYnNgsMFTucErITTOYQA=
-trusted comment: timestamp:1670027914	file:libsodium-stable.tar.gz	hashed
-2znBAfvZamDxTQt/fhrQaqDsBPHIIYOc4hNkKjbGpJTzwV5qCGnDLb9h13jeBBVT1iW15fPxse7UEh1w6C4QCA==
diff --git a/libsodium/libsodium-1.0.19-stable.tar.gz.minisig b/libsodium/libsodium-1.0.19-stable.tar.gz.minisig
new file mode 100644
index 0000000..ac50889
--- /dev/null
+++ b/libsodium/libsodium-1.0.19-stable.tar.gz.minisig
@@ -0,0 +1,4 @@
+untrusted comment: signature from minisign secret key
+RUQf6LRCGA9i540gXY9hLA5lPk5UCMZ37cmOVCEkNGMqjk/Kys9EBX06Rj2jLilbRnao4wUjXf/SYQ2OH6wkD54lt9Xr/0V1JAc=
+trusted comment: timestamp:1701131736	file:libsodium-stable.tar.gz	hashed
+LCktgn5SS5UPc/AJdSuyQAHBa98ENEa1WFdHlbMXrbEqh8uPj+xfd1Gro7xzZvzqU0LlbZPtzpIekC1o0lrwBw==