diff --git a/Cargo.lock b/Cargo.lock
index ca5e1d309..e03f3c250 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -8,6 +8,7 @@ version = "0.10.6"
 dependencies = [
  "digest",
  "hex-literal",
+ "zeroize",
 ]
 
 [[package]]
@@ -205,6 +206,7 @@ dependencies = [
  "digest",
  "hex-literal",
  "sha1-asm",
+ "zeroize",
 ]
 
 [[package]]
@@ -225,6 +227,7 @@ dependencies = [
  "digest",
  "hex-literal",
  "sha2-asm",
+ "zeroize",
 ]
 
 [[package]]
diff --git a/blake2/Cargo.toml b/blake2/Cargo.toml
index adb06e061..0141cad0b 100644
--- a/blake2/Cargo.toml
+++ b/blake2/Cargo.toml
@@ -13,6 +13,7 @@ categories = ["cryptography", "no-std"]
 
 [dependencies]
 digest = { version = "0.10.7", features = ["mac"] }
+zeroize = { version = "1", default-features = false, optional = true }
 
 [dev-dependencies]
 digest = { version = "0.10.7", features = ["dev"] }
diff --git a/blake2/src/macros.rs b/blake2/src/macros.rs
index 917a212c8..44e0c3a9a 100644
--- a/blake2/src/macros.rs
+++ b/blake2/src/macros.rs
@@ -243,6 +243,17 @@ macro_rules! blake2_impl {
             }
         }
 
+        #[cfg(feature = "zeroize")]
+        impl Drop for $name {
+            fn drop(&mut self) {
+                use zeroize::Zeroize;
+                self.h.zeroize();
+                self.t.zeroize();
+            }
+        }
+        #[cfg(feature = "zeroize")]
+        impl zeroize::ZeroizeOnDrop for $name {}
+
         impl fmt::Debug for $name {
             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                 f.write_str(concat!(stringify!($name), " { ... }"))
diff --git a/blake2/src/simd/simdty.rs b/blake2/src/simd/simdty.rs
index 008b8b48c..a2b313c63 100644
--- a/blake2/src/simd/simdty.rs
+++ b/blake2/src/simd/simdty.rs
@@ -50,6 +50,16 @@ decl_simd! {
                          pub T, pub T, pub T, pub T);
 }
 
+#[cfg(feature = "zeroize")]
+impl<T: zeroize::Zeroize> zeroize::Zeroize for Simd4<T> {
+    fn zeroize(&mut self) {
+        self.0.zeroize();
+        self.1.zeroize();
+        self.2.zeroize();
+        self.3.zeroize();
+    }
+}
+
 pub type u64x2 = Simd2<u64>;
 
 pub type u32x4 = Simd4<u32>;
diff --git a/sha1/Cargo.toml b/sha1/Cargo.toml
index 3f4b8d3ff..5cafe8bf7 100644
--- a/sha1/Cargo.toml
+++ b/sha1/Cargo.toml
@@ -14,6 +14,7 @@ categories = ["cryptography", "no-std"]
 [dependencies]
 digest = "0.10.7"
 cfg-if = "1.0"
+zeroize = { version = "1", default-features = false, optional = true }
 
 [target.'cfg(any(target_arch = "aarch64", target_arch = "x86", target_arch = "x86_64"))'.dependencies]
 cpufeatures = "0.2"
diff --git a/sha1/src/lib.rs b/sha1/src/lib.rs
index 25e867e0f..9987311f9 100644
--- a/sha1/src/lib.rs
+++ b/sha1/src/lib.rs
@@ -150,6 +150,17 @@ impl AlgorithmName for Sha1Core {
     }
 }
 
+#[cfg(feature = "zeroize")]
+impl Drop for Sha1Core {
+    fn drop(&mut self) {
+        use zeroize::Zeroize;
+        self.h.zeroize();
+        self.block_len.zeroize();
+    }
+}
+#[cfg(feature = "zeroize")]
+impl zeroize::ZeroizeOnDrop for Sha1Core {}
+
 impl fmt::Debug for Sha1Core {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.write_str("Sha1Core { ... }")
diff --git a/sha2/Cargo.toml b/sha2/Cargo.toml
index a3dafeaa2..4645cff23 100644
--- a/sha2/Cargo.toml
+++ b/sha2/Cargo.toml
@@ -17,6 +17,7 @@ categories = ["cryptography", "no-std"]
 [dependencies]
 digest = "0.10.7"
 cfg-if = "1.0"
+zeroize = { version = "1", default-features = false, optional = true }
 
 [target.'cfg(any(target_arch = "aarch64", target_arch = "x86_64", target_arch = "x86"))'.dependencies]
 cpufeatures = "0.2"
diff --git a/sha2/src/core_api.rs b/sha2/src/core_api.rs
index cfec02a64..d286e9fd5 100644
--- a/sha2/src/core_api.rs
+++ b/sha2/src/core_api.rs
@@ -75,6 +75,17 @@ impl AlgorithmName for Sha256VarCore {
     }
 }
 
+#[cfg(feature = "zeroize")]
+impl Drop for Sha256VarCore {
+    fn drop(&mut self) {
+        use zeroize::Zeroize;
+        self.state.zeroize();
+        self.block_len.zeroize();
+    }
+}
+#[cfg(feature = "zeroize")]
+impl zeroize::ZeroizeOnDrop for Sha256VarCore {}
+
 impl fmt::Debug for Sha256VarCore {
     #[inline]
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
@@ -149,6 +160,17 @@ impl AlgorithmName for Sha512VarCore {
     }
 }
 
+#[cfg(feature = "zeroize")]
+impl Drop for Sha512VarCore {
+    fn drop(&mut self) {
+        use zeroize::Zeroize;
+        self.state.zeroize();
+        self.block_len.zeroize();
+    }
+}
+#[cfg(feature = "zeroize")]
+impl zeroize::ZeroizeOnDrop for Sha512VarCore {}
+
 impl fmt::Debug for Sha512VarCore {
     #[inline]
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {