diff --git a/src/sha1.d.ts b/src/sha1.d.ts
new file mode 100644
index 0000000..1d05d0b
--- /dev/null
+++ b/src/sha1.d.ts
@@ -0,0 +1,11 @@
+declare function sha1<T>(dest: string | Array<T> | ArrayBuffer | Uint8Array): string;
+
+declare namespace sha1 {
+    export function hex(arg: string): string;
+    export function update<T>(arg: string | Array<T> | Uint8Array | ArrayBuffer): string;
+    export function array(): Uint8Array;
+    export function digest(): Uint8Array;
+    export function arrayBuffer(): ArrayBuffer;
+}
+
+export default sha1;
\ No newline at end of file