diff --git a/Cargo.lock b/Cargo.lock
index 9d307d4c3..5903a67d0 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3606,6 +3606,7 @@ dependencies = [
  "getrandom 0.2.6",
  "hex",
  "hex-literal",
+ "openssl",
  "rand 0.8.5",
  "rand_core 0.5.1",
  "rand_core 0.6.3",
@@ -3619,6 +3620,7 @@ dependencies = [
  "simple_asn1",
  "subtle",
  "thiserror",
+ "typenum",
  "x25519-dalek",
  "zeroize",
 ]
diff --git a/crates/tor-llcrypto/Cargo.toml b/crates/tor-llcrypto/Cargo.toml
index faa0e42bc..97c14e631 100644
--- a/crates/tor-llcrypto/Cargo.toml
+++ b/crates/tor-llcrypto/Cargo.toml
@@ -13,6 +13,7 @@ repository = "https://gitlab.torproject.org/tpo/core/arti.git/"
 
 [features]
 default = []
+with-openssl = ["openssl", "typenum", "cipher"]
 
 # Enable support for cryptography needed to be a Tor relay.
 relay = []
@@ -24,12 +25,14 @@ hsv3-client = []
 aes = { version = "0.8" }
 arrayref = "0.3"
 base64 = "0.13.0"
+cipher = { version = "0.4.3", optional = true }
 ctr = "0.9"
 curve25519-dalek = "3.2"
 digest = "0.10.0"
 ed25519-dalek = { version = "1", features = ["batch"] }
 hex = "0.4"
 old_rand_core = { package = "rand_core", version = "0.5.1" }
+openssl = { version = "0.10.30", optional = true }
 rand_core = "0.6.2"
 rsa = "0.5.0"
 serde = "1.0.103"
@@ -40,6 +43,7 @@ signature = "1"
 simple_asn1 = "0.6"
 subtle = "2"
 thiserror = "1"
+typenum = { version = "1.15.0", optional = true }
 x25519-dalek = "1.2"
 zeroize = "1"
 
diff --git a/crates/tor-llcrypto/src/cipher.rs b/crates/tor-llcrypto/src/cipher.rs
index 663d44ace..bf631be53 100644
--- a/crates/tor-llcrypto/src/cipher.rs
+++ b/crates/tor-llcrypto/src/cipher.rs
@@ -7,6 +7,7 @@
 ///
 /// These ciphers implement the `cipher::StreamCipher` trait, so use
 /// the [`cipher`](https://docs.rs/cipher) crate to access them.
+#[cfg(not(feature = "with-openssl"))]
 pub mod aes {
     // These implement StreamCipher.
     /// AES128 in counter mode as used by Tor.
@@ -15,3 +16,106 @@ pub mod aes {
     /// AES256 in counter mode as used by Tor.  
     pub type Aes256Ctr = ctr::Ctr128BE<aes::Aes256>;
 }
+
+/// Compatiblity layer between OpenSSL and `cipher::StreamCipher`.
+///
+/// These ciphers implement the `cipher::StreamCipher` trait, so use
+/// the [`cipher`](https://docs.rs/cipher) crate to access them.
+#[cfg(feature = "with-openssl")]
+pub mod aes {
+    use cipher::generic_array::GenericArray;
+    use cipher::inout::InOutBuf;
+    use cipher::{InnerIvInit, IvSizeUser, StreamCipher, StreamCipherError};
+    use digest::crypto_common::{InnerUser, KeyInit, KeySizeUser};
+    use openssl::symm::{Cipher, Crypter, Mode};
+
+    /// AES 128 in counter mode as used by Tor.
+    pub struct Aes128Ctr(Crypter);
+
+    /// AES 128 key
+    pub struct Aes128Key([u8; 16]);
+
+    impl KeySizeUser for Aes128Key {
+        type KeySize = typenum::consts::U16;
+    }
+
+    impl KeyInit for Aes128Key {
+        fn new(key: &GenericArray<u8, Self::KeySize>) -> Self {
+            Aes128Key((*key).into())
+        }
+    }
+
+    impl InnerUser for Aes128Ctr {
+        type Inner = Aes128Key;
+    }
+
+    impl IvSizeUser for Aes128Ctr {
+        type IvSize = typenum::consts::U16;
+    }
+
+    impl StreamCipher for Aes128Ctr {
+        fn try_apply_keystream_inout(
+            &mut self,
+            mut buf: InOutBuf<'_, '_, u8>,
+        ) -> Result<(), StreamCipherError> {
+            let in_buf = buf.get_in().to_vec();
+            self.0
+                .update(&in_buf, buf.get_out())
+                .map_err(|_| StreamCipherError)?;
+            Ok(())
+        }
+    }
+
+    impl InnerIvInit for Aes128Ctr {
+        fn inner_iv_init(inner: Self::Inner, iv: &GenericArray<u8, Self::IvSize>) -> Self {
+            let crypter = Crypter::new(Cipher::aes_128_ctr(), Mode::Encrypt, &inner.0, Some(iv))
+                .expect("openssl error while initializeing Aes128Ctr");
+            Aes128Ctr(crypter)
+        }
+    }
+
+    /// AES 256 in counter mode as used by Tor.
+    pub struct Aes256Ctr(Crypter);
+
+    /// AES 256 key
+    pub struct Aes256Key([u8; 32]);
+
+    impl KeySizeUser for Aes256Key {
+        type KeySize = typenum::consts::U32;
+    }
+
+    impl KeyInit for Aes256Key {
+        fn new(key: &GenericArray<u8, Self::KeySize>) -> Self {
+            Aes256Key((*key).into())
+        }
+    }
+
+    impl InnerUser for Aes256Ctr {
+        type Inner = Aes256Key;
+    }
+
+    impl IvSizeUser for Aes256Ctr {
+        type IvSize = typenum::consts::U16;
+    }
+
+    impl StreamCipher for Aes256Ctr {
+        fn try_apply_keystream_inout(
+            &mut self,
+            mut buf: InOutBuf<'_, '_, u8>,
+        ) -> Result<(), StreamCipherError> {
+            let in_buf = buf.get_in().to_vec();
+            self.0
+                .update(&in_buf, buf.get_out())
+                .map_err(|_| StreamCipherError)?;
+            Ok(())
+        }
+    }
+
+    impl InnerIvInit for Aes256Ctr {
+        fn inner_iv_init(inner: Self::Inner, iv: &GenericArray<u8, Self::IvSize>) -> Self {
+            let crypter = Crypter::new(Cipher::aes_256_ctr(), Mode::Encrypt, &inner.0, Some(iv))
+                .expect("openssl error while initializeing Aes256Ctr");
+            Aes256Ctr(crypter)
+        }
+    }
+}
diff --git a/crates/tor-llcrypto/src/d.rs b/crates/tor-llcrypto/src/d.rs
index 0c6dda072..432b39bb2 100644
--- a/crates/tor-llcrypto/src/d.rs
+++ b/crates/tor-llcrypto/src/d.rs
@@ -7,6 +7,40 @@
 //! Other code should access these digests via the traits in the
 //! [`digest`] crate.
 
+#[cfg(feature = "with-openssl")]
+pub use openssl_compat::Sha1;
+#[cfg(not(feature = "with-openssl"))]
 pub use sha1::Sha1;
+
 pub use sha2::{Sha256, Sha512};
 pub use sha3::{Sha3_256, Shake128, Shake256};
+
+/// Compatibility layer between OpenSSL and `digest`
+#[cfg(feature = "with-openssl")]
+mod openssl_compat {
+    use openssl::sha::Sha1 as OpenSslSha1;
+
+    use digest::{FixedOutput, HashMarker, Output, OutputSizeUser, Update};
+
+    /// Wrapper arround OpenSSL Sha1 to make it compatible with `digest`
+    #[derive(Default, Clone)]
+    pub struct Sha1(OpenSslSha1);
+
+    impl Update for Sha1 {
+        fn update(&mut self, data: &[u8]) {
+            self.0.update(data);
+        }
+    }
+
+    impl OutputSizeUser for Sha1 {
+        type OutputSize = typenum::consts::U20;
+    }
+
+    impl FixedOutput for Sha1 {
+        fn finalize_into(self, out: &mut Output<Self>) {
+            *out = self.0.finish().into();
+        }
+    }
+
+    impl HashMarker for Sha1 {}
+}