diff --git a/crypto_sign/sphincs-shake256-128f-simple/META.yml b/crypto_sign/sphincs-shake256-128f-simple/META.yml
new file mode 100644
index 00000000..d130eaed
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/META.yml
@@ -0,0 +1,27 @@
+name: SPHINCS+
+type: signature
+claimed-nist-level: 1
+length-public-key: 32
+length-signature: 16976
+testvectors-sha256: a14cb8e4f149493fc5979e465e09ce943e8d669186ff5c7c3d11239fa869def6
+principal-submitter: Andreas Hülsing
+auxiliary-submitters:
+  - Jean-Philippe Aumasson
+  - Daniel J. Bernstein,
+  - Christoph Dobraunig
+  - Maria Eichlseder
+  - Scott Fluhrer
+  - Stefan-Lukas Gazdag
+  - Panos Kampanakis
+  - Stefan Kölbl
+  - Tanja Lange
+  - Martin M. Lauridsen
+  - Florian Mendel
+  - Ruben Niederhagen
+  - Christian Rechberger
+  - Joost Rijneveld
+  - Peter Schwabe
+implementations:
+    - name: clean
+      version: https://github.com/sphincs/sphincsplus/commit/492ec4f1f6d3b3dc4b435783bbaaf4e41cdb6f32
+      length-secret-key: 64
diff --git a/crypto_sign/sphincs-shake256-128f-simple/clean/LICENSE b/crypto_sign/sphincs-shake256-128f-simple/clean/LICENSE
new file mode 100644
index 00000000..670154e3
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/clean/LICENSE
@@ -0,0 +1,116 @@
+CC0 1.0 Universal
+
+Statement of Purpose
+
+The laws of most jurisdictions throughout the world automatically confer
+exclusive Copyright and Related Rights (defined below) upon the creator and
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+  vii. other similar, equivalent or corresponding rights throughout the world
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+2. Waiver. To the greatest extent permitted by, but not in contravention of,
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+any other legal or equitable action to disrupt the quiet enjoyment of the Work
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+
+3. Public License Fallback. Should any part of the Waiver for any reason be
+judged legally invalid or ineffective under applicable law, then the Waiver
+shall be preserved to the maximum extent permitted taking into account
+Affirmer's express Statement of Purpose. In addition, to the extent the Waiver
+is so judged Affirmer hereby grants to each affected person a royalty-free,
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+unconditional license to exercise Affirmer's Copyright and Related Rights in
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+invalidate the remainder of the License, and in such case Affirmer hereby
+affirms that he or she will not (i) exercise any of his or her remaining
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+4. Limitations and Disclaimers.
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+  a. No trademark or patent rights held by Affirmer are waived, abandoned,
+  surrendered, licensed or otherwise affected by this document.
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+<http://creativecommons.org/publicdomain/zero/1.0/>
diff --git a/crypto_sign/sphincs-shake256-128f-simple/clean/Makefile b/crypto_sign/sphincs-shake256-128f-simple/clean/Makefile
new file mode 100644
index 00000000..cdb3195d
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/clean/Makefile
@@ -0,0 +1,22 @@
+# This Makefile can be used with GNU Make or BSD Make
+
+LIB=libsphincs-shake256-128f-simple_clean.a
+HASH = shake256
+THASH = simple
+
+HEADERS = params.h address.h wots.h utils.h fors.h api.h  hash.h thash.h
+OBJECTS =          address.o wots.o utils.o fors.o sign.o hash_shake256.o thash_shake256_simple.o
+
+CFLAGS=-Wall -Wextra -Wpedantic -Werror -std=c99 -I../../../common $(EXTRAFLAGS)
+
+all: $(LIB)
+
+%.o: %.c $(HEADERS)
+	$(CC) $(CFLAGS) -c -o $@ $<
+
+$(LIB): $(OBJECTS)
+	$(AR) -r $@ $(OBJECTS)
+
+clean:
+	$(RM) $(OBJECTS)
+	$(RM) $(LIB)
diff --git a/crypto_sign/sphincs-shake256-128f-simple/clean/Makefile.Microsoft_nmake b/crypto_sign/sphincs-shake256-128f-simple/clean/Makefile.Microsoft_nmake
new file mode 100644
index 00000000..12936213
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/clean/Makefile.Microsoft_nmake
@@ -0,0 +1,19 @@
+# This Makefile can be used with Microsoft Visual Studio's nmake using the command:
+#    nmake /f Makefile.Microsoft_nmake
+
+LIBRARY=libsphincs-shake256-128f-simple_clean.lib
+OBJECTS=address.obj wots.obj utils.obj fors.obj sign.obj hash_shake256.obj thash_shake256_simple.obj
+
+CFLAGS=/nologo /I ..\..\..\common /W4 /WX
+
+all: $(LIBRARY)
+
+# Make sure objects are recompiled if headers change.
+$(OBJECTS): *.h
+
+$(LIBRARY): $(OBJECTS)
+	LIB.EXE /NOLOGO /WX /OUT:$@ $**
+
+clean:
+    -DEL $(OBJECTS)
+    -DEL $(LIBRARY)
diff --git a/crypto_sign/sphincs-shake256-128f-simple/clean/address.c b/crypto_sign/sphincs-shake256-128f-simple/clean/address.c
new file mode 100644
index 00000000..0cf69534
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/clean/address.c
@@ -0,0 +1,77 @@
+#include <stdint.h>
+
+#include "params.h"
+#include "utils.h"
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_addr_to_bytes(
+    unsigned char *bytes, const uint32_t addr[8]) {
+    int i;
+
+    for (i = 0; i < 8; i++) {
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_ull_to_bytes(
+            bytes + i * 4, 4, addr[i]);
+    }
+}
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_layer_addr(
+    uint32_t addr[8], uint32_t layer) {
+    addr[0] = layer;
+}
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_addr(
+    uint32_t addr[8], uint64_t tree) {
+    addr[1] = 0;
+    addr[2] = (uint32_t) (tree >> 32);
+    addr[3] = (uint32_t) tree;
+}
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_type(
+    uint32_t addr[8], uint32_t type) {
+    addr[4] = type;
+}
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_copy_subtree_addr(
+    uint32_t out[8], const uint32_t in[8]) {
+    out[0] = in[0];
+    out[1] = in[1];
+    out[2] = in[2];
+    out[3] = in[3];
+}
+
+/* These functions are used for OTS addresses. */
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_keypair_addr(
+    uint32_t addr[8], uint32_t keypair) {
+    addr[5] = keypair;
+}
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_copy_keypair_addr(
+    uint32_t out[8], const uint32_t in[8]) {
+    out[0] = in[0];
+    out[1] = in[1];
+    out[2] = in[2];
+    out[3] = in[3];
+    out[5] = in[5];
+}
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_chain_addr(
+    uint32_t addr[8], uint32_t chain) {
+    addr[6] = chain;
+}
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_hash_addr(
+    uint32_t addr[8], uint32_t hash) {
+    addr[7] = hash;
+}
+
+/* These functions are used for all hash tree addresses (including FORS). */
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_height(
+    uint32_t addr[8], uint32_t tree_height) {
+    addr[6] = tree_height;
+}
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_index(
+    uint32_t addr[8], uint32_t tree_index) {
+    addr[7] = tree_index;
+}
diff --git a/crypto_sign/sphincs-shake256-128f-simple/clean/address.h b/crypto_sign/sphincs-shake256-128f-simple/clean/address.h
new file mode 100644
index 00000000..16666c00
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/clean/address.h
@@ -0,0 +1,50 @@
+#ifndef SPX_ADDRESS_H
+#define SPX_ADDRESS_H
+
+#include <stdint.h>
+
+#define SPX_ADDR_TYPE_WOTS 0
+#define SPX_ADDR_TYPE_WOTSPK 1
+#define SPX_ADDR_TYPE_HASHTREE 2
+#define SPX_ADDR_TYPE_FORSTREE 3
+#define SPX_ADDR_TYPE_FORSPK 4
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_addr_to_bytes(
+    unsigned char *bytes, const uint32_t addr[8]);
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_layer_addr(
+    uint32_t addr[8], uint32_t layer);
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_addr(
+    uint32_t addr[8], uint64_t tree);
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_type(
+    uint32_t addr[8], uint32_t type);
+
+/* Copies the layer and tree part of one address into the other */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_copy_subtree_addr(
+    uint32_t out[8], const uint32_t in[8]);
+
+/* These functions are used for WOTS and FORS addresses. */
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_keypair_addr(
+    uint32_t addr[8], uint32_t keypair);
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_chain_addr(
+    uint32_t addr[8], uint32_t chain);
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_hash_addr(
+    uint32_t addr[8], uint32_t hash);
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_copy_keypair_addr(
+    uint32_t out[8], const uint32_t in[8]);
+
+/* These functions are used for all hash tree addresses (including FORS). */
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_height(
+    uint32_t addr[8], uint32_t tree_height);
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_index(
+    uint32_t addr[8], uint32_t tree_index);
+
+#endif
diff --git a/crypto_sign/sphincs-shake256-128f-simple/clean/api.h b/crypto_sign/sphincs-shake256-128f-simple/clean/api.h
new file mode 100644
index 00000000..59c6b75f
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/clean/api.h
@@ -0,0 +1,78 @@
+#ifndef PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_API_H
+#define PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_API_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#define PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_ALGNAME "SPHINCS+"
+
+#define PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_SECRETKEYBYTES 64
+#define PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_PUBLICKEYBYTES 32
+#define PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_BYTES 16976
+#define PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_SEEDBYTES 48
+
+/*
+ * Returns the length of a secret key, in bytes
+ */
+size_t PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_secretkeybytes(void);
+
+/*
+ * Returns the length of a public key, in bytes
+ */
+size_t PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_publickeybytes(void);
+
+/*
+ * Returns the length of a signature, in bytes
+ */
+size_t PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_bytes(void);
+
+/*
+ * Returns the length of the seed required to generate a key pair, in bytes
+ */
+size_t PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_seedbytes(void);
+
+/*
+ * Generates a SPHINCS+ key pair given a seed.
+ * Format sk: [SK_SEED || SK_PRF || PUB_SEED || root]
+ * Format pk: [root || PUB_SEED]
+ */
+int PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_seed_keypair(
+    uint8_t *pk, uint8_t *sk, const uint8_t *seed);
+
+/*
+ * Generates a SPHINCS+ key pair.
+ * Format sk: [SK_SEED || SK_PRF || PUB_SEED || root]
+ * Format pk: [root || PUB_SEED]
+ */
+int PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_keypair(
+    uint8_t *pk, uint8_t *sk);
+
+/**
+ * Returns an array containing a detached signature.
+ */
+int PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_signature(
+    uint8_t *sig, size_t *siglen,
+    const uint8_t *m, size_t mlen, const uint8_t *sk);
+
+/**
+ * Verifies a detached signature and message under a given public key.
+ */
+int PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_verify(
+    const uint8_t *sig, size_t siglen,
+    const uint8_t *m, size_t mlen, const uint8_t *pk);
+
+/**
+ * Returns an array containing the signature followed by the message.
+ */
+int PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign(
+    uint8_t *sm, size_t *smlen,
+    const uint8_t *m, size_t mlen, const uint8_t *sk);
+
+/**
+ * Verifies a given signature-message pair under a given public key.
+ */
+int PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_open(
+    uint8_t *m, size_t *mlen,
+    const uint8_t *sm, size_t smlen, const uint8_t *pk);
+
+#endif
diff --git a/crypto_sign/sphincs-shake256-128f-simple/clean/fors.c b/crypto_sign/sphincs-shake256-128f-simple/clean/fors.c
new file mode 100644
index 00000000..74090621
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/clean/fors.c
@@ -0,0 +1,164 @@
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "address.h"
+#include "fors.h"
+#include "hash.h"
+#include "thash.h"
+#include "utils.h"
+
+static void fors_gen_sk(unsigned char *sk, const unsigned char *sk_seed,
+                        uint32_t fors_leaf_addr[8]) {
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_prf_addr(
+        sk, sk_seed, fors_leaf_addr);
+}
+
+static void fors_sk_to_leaf(unsigned char *leaf, const unsigned char *sk,
+                            const unsigned char *pub_seed,
+                            uint32_t fors_leaf_addr[8]) {
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash_1(
+        leaf, sk, pub_seed, fors_leaf_addr);
+}
+
+static void fors_gen_leaf(unsigned char *leaf, const unsigned char *sk_seed,
+                          const unsigned char *pub_seed,
+                          uint32_t addr_idx, const uint32_t fors_tree_addr[8]) {
+    uint32_t fors_leaf_addr[8] = {0};
+
+    /* Only copy the parts that must be kept in fors_leaf_addr. */
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_copy_keypair_addr(
+        fors_leaf_addr, fors_tree_addr);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_type(
+        fors_leaf_addr, SPX_ADDR_TYPE_FORSTREE);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_index(
+        fors_leaf_addr, addr_idx);
+
+    fors_gen_sk(leaf, sk_seed, fors_leaf_addr);
+    fors_sk_to_leaf(leaf, leaf, pub_seed, fors_leaf_addr);
+}
+
+/**
+ * Interprets m as SPX_FORS_HEIGHT-bit unsigned integers.
+ * Assumes m contains at least SPX_FORS_HEIGHT * SPX_FORS_TREES bits.
+ * Assumes indices has space for SPX_FORS_TREES integers.
+ */
+static void message_to_indices(uint32_t *indices, const unsigned char *m) {
+    unsigned int i, j;
+    unsigned int offset = 0;
+
+    for (i = 0; i < SPX_FORS_TREES; i++) {
+        indices[i] = 0;
+        for (j = 0; j < SPX_FORS_HEIGHT; j++) {
+            indices[i] ^= ((m[offset >> 3] >> (offset & 0x7)) & 0x1) << j;
+            offset++;
+        }
+    }
+}
+
+/**
+ * Signs a message m, deriving the secret key from sk_seed and the FTS address.
+ * Assumes m contains at least SPX_FORS_HEIGHT * SPX_FORS_TREES bits.
+ */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_fors_sign(
+    unsigned char *sig, unsigned char *pk,
+    const unsigned char *m,
+    const unsigned char *sk_seed, const unsigned char *pub_seed,
+    const uint32_t fors_addr[8]) {
+    uint32_t indices[SPX_FORS_TREES];
+    unsigned char roots[SPX_FORS_TREES * SPX_N];
+    uint32_t fors_tree_addr[8] = {0};
+    uint32_t fors_pk_addr[8] = {0};
+    uint32_t idx_offset;
+    unsigned int i;
+
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_copy_keypair_addr(
+        fors_tree_addr, fors_addr);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_copy_keypair_addr(
+        fors_pk_addr, fors_addr);
+
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_type(
+        fors_tree_addr, SPX_ADDR_TYPE_FORSTREE);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_type(
+        fors_pk_addr, SPX_ADDR_TYPE_FORSPK);
+
+    message_to_indices(indices, m);
+
+    for (i = 0; i < SPX_FORS_TREES; i++) {
+        idx_offset = i * (1 << SPX_FORS_HEIGHT);
+
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_height(
+            fors_tree_addr, 0);
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_index(
+            fors_tree_addr, indices[i] + idx_offset);
+
+        /* Include the secret key part that produces the selected leaf node. */
+        fors_gen_sk(sig, sk_seed, fors_tree_addr);
+        sig += SPX_N;
+
+        /* Compute the authentication path for this leaf node. */
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_treehash_FORS_HEIGHT(
+            roots + i * SPX_N, sig, sk_seed, pub_seed,
+            indices[i], idx_offset, fors_gen_leaf, fors_tree_addr);
+        sig += SPX_N * SPX_FORS_HEIGHT;
+    }
+
+    /* Hash horizontally across all tree roots to derive the public key. */
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash_FORS_TREES(
+        pk, roots, pub_seed, fors_pk_addr);
+}
+
+/**
+ * Derives the FORS public key from a signature.
+ * This can be used for verification by comparing to a known public key, or to
+ * subsequently verify a signature on the derived public key. The latter is the
+ * typical use-case when used as an FTS below an OTS in a hypertree.
+ * Assumes m contains at least SPX_FORS_HEIGHT * SPX_FORS_TREES bits.
+ */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_fors_pk_from_sig(
+    unsigned char *pk,
+    const unsigned char *sig, const unsigned char *m,
+    const unsigned char *pub_seed, const uint32_t fors_addr[8]) {
+    uint32_t indices[SPX_FORS_TREES];
+    unsigned char roots[SPX_FORS_TREES * SPX_N];
+    unsigned char leaf[SPX_N];
+    uint32_t fors_tree_addr[8] = {0};
+    uint32_t fors_pk_addr[8] = {0};
+    uint32_t idx_offset;
+    unsigned int i;
+
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_copy_keypair_addr(
+        fors_tree_addr, fors_addr);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_copy_keypair_addr(
+        fors_pk_addr, fors_addr);
+
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_type(
+        fors_tree_addr, SPX_ADDR_TYPE_FORSTREE);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_type(
+        fors_pk_addr, SPX_ADDR_TYPE_FORSPK);
+
+    message_to_indices(indices, m);
+
+    for (i = 0; i < SPX_FORS_TREES; i++) {
+        idx_offset = i * (1 << SPX_FORS_HEIGHT);
+
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_height(
+            fors_tree_addr, 0);
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_index(
+            fors_tree_addr, indices[i] + idx_offset);
+
+        /* Derive the leaf from the included secret key part. */
+        fors_sk_to_leaf(leaf, sig, pub_seed, fors_tree_addr);
+        sig += SPX_N;
+
+        /* Derive the corresponding root node of this tree. */
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_compute_root(
+            roots + i * SPX_N, leaf, indices[i], idx_offset, sig,
+            SPX_FORS_HEIGHT, pub_seed, fors_tree_addr);
+        sig += SPX_N * SPX_FORS_HEIGHT;
+    }
+
+    /* Hash horizontally across all tree roots to derive the public key. */
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash_FORS_TREES(
+        pk, roots, pub_seed, fors_pk_addr);
+}
diff --git a/crypto_sign/sphincs-shake256-128f-simple/clean/fors.h b/crypto_sign/sphincs-shake256-128f-simple/clean/fors.h
new file mode 100644
index 00000000..089f09c0
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/clean/fors.h
@@ -0,0 +1,30 @@
+#ifndef SPX_FORS_H
+#define SPX_FORS_H
+
+#include <stdint.h>
+
+#include "params.h"
+
+/**
+ * Signs a message m, deriving the secret key from sk_seed and the FTS address.
+ * Assumes m contains at least SPX_FORS_HEIGHT * SPX_FORS_TREES bits.
+ */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_fors_sign(
+    unsigned char *sig, unsigned char *pk,
+    const unsigned char *m,
+    const unsigned char *sk_seed, const unsigned char *pub_seed,
+    const uint32_t fors_addr[8]);
+
+/**
+ * Derives the FORS public key from a signature.
+ * This can be used for verification by comparing to a known public key, or to
+ * subsequently verify a signature on the derived public key. The latter is the
+ * typical use-case when used as an FTS below an OTS in a hypertree.
+ * Assumes m contains at least SPX_FORS_HEIGHT * SPX_FORS_TREES bits.
+ */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_fors_pk_from_sig(
+    unsigned char *pk,
+    const unsigned char *sig, const unsigned char *m,
+    const unsigned char *pub_seed, const uint32_t fors_addr[8]);
+
+#endif
diff --git a/crypto_sign/sphincs-shake256-128f-simple/clean/hash.h b/crypto_sign/sphincs-shake256-128f-simple/clean/hash.h
new file mode 100644
index 00000000..e6675ac1
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/clean/hash.h
@@ -0,0 +1,22 @@
+#ifndef SPX_HASH_H
+#define SPX_HASH_H
+
+#include <stdint.h>
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_initialize_hash_function(
+    const unsigned char *pub_seed, const unsigned char *sk_seed);
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_prf_addr(
+    unsigned char *out, const unsigned char *key, const uint32_t addr[8]);
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_gen_message_random(
+    unsigned char *R,
+    const unsigned char *sk_prf, const unsigned char *optrand,
+    const unsigned char *m, size_t mlen);
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_hash_message(
+    unsigned char *digest, uint64_t *tree, uint32_t *leaf_idx,
+    const unsigned char *R, const unsigned char *pk,
+    const unsigned char *m, size_t mlen);
+
+#endif
diff --git a/crypto_sign/sphincs-shake256-128f-simple/clean/hash_shake256.c b/crypto_sign/sphincs-shake256-128f-simple/clean/hash_shake256.c
new file mode 100644
index 00000000..a7ab8e15
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/clean/hash_shake256.c
@@ -0,0 +1,86 @@
+#include <stdint.h>
+#include <string.h>
+
+#include "address.h"
+#include "fips202.h"
+#include "hash.h"
+#include "params.h"
+#include "utils.h"
+
+/* For SHAKE256, there is no immediate reason to initialize at the start,
+   so this function is an empty operation. */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_initialize_hash_function(
+    const unsigned char *pub_seed, const unsigned char *sk_seed) {
+    (void)pub_seed; /* Suppress an 'unused parameter' warning. */
+    (void)sk_seed; /* Suppress an 'unused parameter' warning. */
+}
+
+/*
+ * Computes PRF(key, addr), given a secret key of SPX_N bytes and an address
+ */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_prf_addr(
+    unsigned char *out, const unsigned char *key, const uint32_t addr[8]) {
+    unsigned char buf[SPX_N + SPX_ADDR_BYTES];
+
+    memcpy(buf, key, SPX_N);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_addr_to_bytes(buf + SPX_N, addr);
+
+    shake256(out, SPX_N, buf, SPX_N + SPX_ADDR_BYTES);
+}
+
+/**
+ * Computes the message-dependent randomness R, using a secret seed and an
+ * optional randomization value as well as the message.
+ */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_gen_message_random(
+    unsigned char *R,
+    const unsigned char *sk_prf, const unsigned char *optrand,
+    const unsigned char *m, size_t mlen) {
+    uint64_t s_inc[26];
+
+    shake256_inc_init(s_inc);
+    shake256_inc_absorb(s_inc, sk_prf, SPX_N);
+    shake256_inc_absorb(s_inc, optrand, SPX_N);
+    shake256_inc_absorb(s_inc, m, mlen);
+    shake256_inc_finalize(s_inc);
+    shake256_inc_squeeze(R, SPX_N, s_inc);
+}
+
+/**
+ * Computes the message hash using R, the public key, and the message.
+ * Outputs the message digest and the index of the leaf. The index is split in
+ * the tree index and the leaf index, for convenient copying to an address.
+ */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_hash_message(
+    unsigned char *digest, uint64_t *tree, uint32_t *leaf_idx,
+    const unsigned char *R, const unsigned char *pk,
+    const unsigned char *m, size_t mlen) {
+#define SPX_TREE_BITS (SPX_TREE_HEIGHT * (SPX_D - 1))
+#define SPX_TREE_BYTES ((SPX_TREE_BITS + 7) / 8)
+#define SPX_LEAF_BITS SPX_TREE_HEIGHT
+#define SPX_LEAF_BYTES ((SPX_LEAF_BITS + 7) / 8)
+#define SPX_DGST_BYTES (SPX_FORS_MSG_BYTES + SPX_TREE_BYTES + SPX_LEAF_BYTES)
+
+    unsigned char buf[SPX_DGST_BYTES];
+    unsigned char *bufp = buf;
+    uint64_t s_inc[26];
+
+    shake256_inc_init(s_inc);
+    shake256_inc_absorb(s_inc, R, SPX_N);
+    shake256_inc_absorb(s_inc, pk, SPX_PK_BYTES);
+    shake256_inc_absorb(s_inc, m, mlen);
+    shake256_inc_finalize(s_inc);
+    shake256_inc_squeeze(buf, SPX_DGST_BYTES, s_inc);
+
+    memcpy(digest, bufp, SPX_FORS_MSG_BYTES);
+    bufp += SPX_FORS_MSG_BYTES;
+
+    *tree = PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_bytes_to_ull(
+                bufp, SPX_TREE_BYTES);
+    *tree &= (~(uint64_t)0) >> (64 - SPX_TREE_BITS);
+    bufp += SPX_TREE_BYTES;
+
+    *leaf_idx = (uint32_t)PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_bytes_to_ull(
+                    bufp, SPX_LEAF_BYTES);
+    *leaf_idx &= (~(uint32_t)0) >> (32 - SPX_LEAF_BITS);
+}
diff --git a/crypto_sign/sphincs-shake256-128f-simple/clean/params.h b/crypto_sign/sphincs-shake256-128f-simple/clean/params.h
new file mode 100644
index 00000000..367ef88d
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/clean/params.h
@@ -0,0 +1,53 @@
+#ifndef SPX_PARAMS_H
+#define SPX_PARAMS_H
+
+/* Hash output length in bytes. */
+#define SPX_N 16
+/* Height of the hypertree. */
+#define SPX_FULL_HEIGHT 60
+/* Number of subtree layer. */
+#define SPX_D 20
+/* FORS tree dimensions. */
+#define SPX_FORS_HEIGHT 9
+#define SPX_FORS_TREES 30
+/* Winternitz parameter, */
+#define SPX_WOTS_W 16
+
+/* The hash function is defined by linking a different hash.c file, as opposed
+   to setting a #define constant. */
+
+/* For clarity */
+#define SPX_ADDR_BYTES 32
+
+/* WOTS parameters. */
+#define SPX_WOTS_LOGW 4
+
+#define SPX_WOTS_LEN1 (8 * SPX_N / SPX_WOTS_LOGW)
+
+/* SPX_WOTS_LEN2 is floor(log(len_1 * (w - 1)) / log(w)) + 1; we precompute */
+#define SPX_WOTS_LEN2 3
+
+#define SPX_WOTS_LEN (SPX_WOTS_LEN1 + SPX_WOTS_LEN2)
+#define SPX_WOTS_BYTES (SPX_WOTS_LEN * SPX_N)
+#define SPX_WOTS_PK_BYTES SPX_WOTS_BYTES
+
+/* Subtree size. */
+#define SPX_TREE_HEIGHT (SPX_FULL_HEIGHT / SPX_D)
+
+/* FORS parameters. */
+#define SPX_FORS_MSG_BYTES ((SPX_FORS_HEIGHT * SPX_FORS_TREES + 7) / 8)
+#define SPX_FORS_BYTES ((SPX_FORS_HEIGHT + 1) * SPX_FORS_TREES * SPX_N)
+#define SPX_FORS_PK_BYTES SPX_N
+
+/* Resulting SPX sizes. */
+#define SPX_BYTES (SPX_N + SPX_FORS_BYTES + SPX_D * SPX_WOTS_BYTES +\
+                   SPX_FULL_HEIGHT * SPX_N)
+#define SPX_PK_BYTES (2 * SPX_N)
+#define SPX_SK_BYTES (2 * SPX_N + SPX_PK_BYTES)
+
+/* Optionally, signing can be made non-deterministic using optrand.
+   This can help counter side-channel attacks that would benefit from
+   getting a large number of traces when the signer uses the same nodes. */
+#define SPX_OPTRAND_BYTES 32
+
+#endif
diff --git a/crypto_sign/sphincs-shake256-128f-simple/clean/sign.c b/crypto_sign/sphincs-shake256-128f-simple/clean/sign.c
new file mode 100644
index 00000000..16523460
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/clean/sign.c
@@ -0,0 +1,344 @@
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+#include "address.h"
+#include "api.h"
+#include "fors.h"
+#include "hash.h"
+#include "params.h"
+#include "randombytes.h"
+#include "thash.h"
+#include "utils.h"
+#include "wots.h"
+
+/**
+ * Computes the leaf at a given address. First generates the WOTS key pair,
+ * then computes leaf by hashing horizontally.
+ */
+static void wots_gen_leaf(unsigned char *leaf, const unsigned char *sk_seed,
+                          const unsigned char *pub_seed,
+                          uint32_t addr_idx, const uint32_t tree_addr[8]) {
+    unsigned char pk[SPX_WOTS_BYTES];
+    uint32_t wots_addr[8] = {0};
+    uint32_t wots_pk_addr[8] = {0};
+
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_type(
+        wots_addr, SPX_ADDR_TYPE_WOTS);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_type(
+        wots_pk_addr, SPX_ADDR_TYPE_WOTSPK);
+
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_copy_subtree_addr(
+        wots_addr, tree_addr);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_keypair_addr(
+        wots_addr, addr_idx);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_wots_gen_pk(
+        pk, sk_seed, pub_seed, wots_addr);
+
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_copy_keypair_addr(
+        wots_pk_addr, wots_addr);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash_WOTS_LEN(
+        leaf, pk, pub_seed, wots_pk_addr);
+}
+
+/*
+ * Returns the length of a secret key, in bytes
+ */
+size_t PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_secretkeybytes(void) {
+    return PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_SECRETKEYBYTES;
+}
+
+/*
+ * Returns the length of a public key, in bytes
+ */
+size_t PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_publickeybytes(void) {
+    return PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_PUBLICKEYBYTES;
+}
+
+/*
+ * Returns the length of a signature, in bytes
+ */
+size_t PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_bytes(void) {
+    return PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_BYTES;
+}
+
+/*
+ * Returns the length of the seed required to generate a key pair, in bytes
+ */
+size_t PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_seedbytes(void) {
+    return PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_SEEDBYTES;
+}
+
+/*
+ * Generates an SPX key pair given a seed of length
+ * Format sk: [SK_SEED || SK_PRF || PUB_SEED || root]
+ * Format pk: [PUB_SEED || root]
+ */
+int PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_seed_keypair(
+    uint8_t *pk, uint8_t *sk, const uint8_t *seed) {
+    /* We do not need the auth path in key generation, but it simplifies the
+       code to have just one treehash routine that computes both root and path
+       in one function. */
+    unsigned char auth_path[SPX_TREE_HEIGHT * SPX_N];
+    uint32_t top_tree_addr[8] = {0};
+
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_layer_addr(
+        top_tree_addr, SPX_D - 1);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_type(
+        top_tree_addr, SPX_ADDR_TYPE_HASHTREE);
+
+    /* Initialize SK_SEED, SK_PRF and PUB_SEED from seed. */
+    memcpy(sk, seed, PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_SEEDBYTES);
+
+    memcpy(pk, sk + 2 * SPX_N, SPX_N);
+
+    /* This hook allows the hash function instantiation to do whatever
+       preparation or computation it needs, based on the public seed. */
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_initialize_hash_function(pk, sk);
+
+    /* Compute root node of the top-most subtree. */
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_treehash_TREE_HEIGHT(
+        sk + 3 * SPX_N, auth_path, sk, sk + 2 * SPX_N, 0, 0,
+        wots_gen_leaf, top_tree_addr);
+
+    memcpy(pk + SPX_N, sk + 3 * SPX_N, SPX_N);
+
+    return 0;
+}
+
+/*
+ * Generates an SPX key pair.
+ * Format sk: [SK_SEED || SK_PRF || PUB_SEED || root]
+ * Format pk: [PUB_SEED || root]
+ */
+int PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_keypair(
+    uint8_t *pk, uint8_t *sk) {
+    unsigned char seed[PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_SEEDBYTES];
+    randombytes(seed, PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_CRYPTO_SEEDBYTES);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_seed_keypair(
+        pk, sk, seed);
+
+    return 0;
+}
+
+/**
+ * Returns an array containing a detached signature.
+ */
+int PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_signature(
+    uint8_t *sig, size_t *siglen,
+    const uint8_t *m, size_t mlen, const uint8_t *sk) {
+    const unsigned char *sk_seed = sk;
+    const unsigned char *sk_prf = sk + SPX_N;
+    const unsigned char *pk = sk + 2 * SPX_N;
+    const unsigned char *pub_seed = pk;
+
+    unsigned char optrand[SPX_N];
+    unsigned char mhash[SPX_FORS_MSG_BYTES];
+    unsigned char root[SPX_N];
+    uint32_t i;
+    uint64_t tree;
+    uint32_t idx_leaf;
+    uint32_t wots_addr[8] = {0};
+    uint32_t tree_addr[8] = {0};
+
+    /* This hook allows the hash function instantiation to do whatever
+       preparation or computation it needs, based on the public seed. */
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_initialize_hash_function(
+        pub_seed, sk_seed);
+
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_type(
+        wots_addr, SPX_ADDR_TYPE_WOTS);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_type(
+        tree_addr, SPX_ADDR_TYPE_HASHTREE);
+
+    /* Optionally, signing can be made non-deterministic using optrand.
+       This can help counter side-channel attacks that would benefit from
+       getting a large number of traces when the signer uses the same nodes. */
+    randombytes(optrand, SPX_N);
+    /* Compute the digest randomization value. */
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_gen_message_random(
+        sig, sk_prf, optrand, m, mlen);
+
+    /* Derive the message digest and leaf index from R, PK and M. */
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_hash_message(
+        mhash, &tree, &idx_leaf, sig, pk, m, mlen);
+    sig += SPX_N;
+
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_addr(wots_addr, tree);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_keypair_addr(
+        wots_addr, idx_leaf);
+
+    /* Sign the message hash using FORS. */
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_fors_sign(
+        sig, root, mhash, sk_seed, pub_seed, wots_addr);
+    sig += SPX_FORS_BYTES;
+
+    for (i = 0; i < SPX_D; i++) {
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_layer_addr(tree_addr, i);
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_addr(tree_addr, tree);
+
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_copy_subtree_addr(
+            wots_addr, tree_addr);
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_keypair_addr(
+            wots_addr, idx_leaf);
+
+        /* Compute a WOTS signature. */
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_wots_sign(
+            sig, root, sk_seed, pub_seed, wots_addr);
+        sig += SPX_WOTS_BYTES;
+
+        /* Compute the authentication path for the used WOTS leaf. */
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_treehash_TREE_HEIGHT(
+            root, sig, sk_seed, pub_seed, idx_leaf, 0,
+            wots_gen_leaf, tree_addr);
+        sig += SPX_TREE_HEIGHT * SPX_N;
+
+        /* Update the indices for the next layer. */
+        idx_leaf = (tree & ((1 << SPX_TREE_HEIGHT) - 1));
+        tree = tree >> SPX_TREE_HEIGHT;
+    }
+
+    *siglen = SPX_BYTES;
+
+    return 0;
+}
+
+/**
+ * Verifies a detached signature and message under a given public key.
+ */
+int PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_verify(
+    const uint8_t *sig, size_t siglen,
+    const uint8_t *m, size_t mlen, const uint8_t *pk) {
+    const unsigned char *pub_seed = pk;
+    const unsigned char *pub_root = pk + SPX_N;
+    unsigned char mhash[SPX_FORS_MSG_BYTES];
+    unsigned char wots_pk[SPX_WOTS_BYTES];
+    unsigned char root[SPX_N];
+    unsigned char leaf[SPX_N];
+    unsigned int i;
+    uint64_t tree;
+    uint32_t idx_leaf;
+    uint32_t wots_addr[8] = {0};
+    uint32_t tree_addr[8] = {0};
+    uint32_t wots_pk_addr[8] = {0};
+
+    if (siglen != SPX_BYTES) {
+        return -1;
+    }
+
+    /* This hook allows the hash function instantiation to do whatever
+       preparation or computation it needs, based on the public seed. */
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_initialize_hash_function(
+        pub_seed, NULL);
+
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_type(
+        wots_addr, SPX_ADDR_TYPE_WOTS);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_type(
+        tree_addr, SPX_ADDR_TYPE_HASHTREE);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_type(
+        wots_pk_addr, SPX_ADDR_TYPE_WOTSPK);
+
+    /* Derive the message digest and leaf index from R || PK || M. */
+    /* The additional SPX_N is a result of the hash domain separator. */
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_hash_message(
+        mhash, &tree, &idx_leaf, sig, pk, m, mlen);
+    sig += SPX_N;
+
+    /* Layer correctly defaults to 0, so no need to set_layer_addr */
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_addr(wots_addr, tree);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_keypair_addr(
+        wots_addr, idx_leaf);
+
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_fors_pk_from_sig(
+        root, sig, mhash, pub_seed, wots_addr);
+    sig += SPX_FORS_BYTES;
+
+    /* For each subtree.. */
+    for (i = 0; i < SPX_D; i++) {
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_layer_addr(tree_addr, i);
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_addr(tree_addr, tree);
+
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_copy_subtree_addr(
+            wots_addr, tree_addr);
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_keypair_addr(
+            wots_addr, idx_leaf);
+
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_copy_keypair_addr(
+            wots_pk_addr, wots_addr);
+
+        /* The WOTS public key is only correct if the signature was correct. */
+        /* Initially, root is the FORS pk, but on subsequent iterations it is
+           the root of the subtree below the currently processed subtree. */
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_wots_pk_from_sig(
+            wots_pk, sig, root, pub_seed, wots_addr);
+        sig += SPX_WOTS_BYTES;
+
+        /* Compute the leaf node using the WOTS public key. */
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash_WOTS_LEN(
+            leaf, wots_pk, pub_seed, wots_pk_addr);
+
+        /* Compute the root node of this subtree. */
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_compute_root(
+            root, leaf, idx_leaf, 0, sig, SPX_TREE_HEIGHT,
+            pub_seed, tree_addr);
+        sig += SPX_TREE_HEIGHT * SPX_N;
+
+        /* Update the indices for the next layer. */
+        idx_leaf = (tree & ((1 << SPX_TREE_HEIGHT) - 1));
+        tree = tree >> SPX_TREE_HEIGHT;
+    }
+
+    /* Check if the root node equals the root node in the public key. */
+    if (memcmp(root, pub_root, SPX_N) != 0) {
+        return -1;
+    }
+
+    return 0;
+}
+
+
+/**
+ * Returns an array containing the signature followed by the message.
+ */
+int PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign(
+    uint8_t *sm, size_t *smlen,
+    const uint8_t *m, size_t mlen, const uint8_t *sk) {
+    size_t siglen;
+
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_signature(
+        sm, &siglen, m, mlen, sk);
+
+    memmove(sm + SPX_BYTES, m, mlen);
+    *smlen = siglen + mlen;
+
+    return 0;
+}
+
+/**
+ * Verifies a given signature-message pair under a given public key.
+ */
+int PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_open(
+    uint8_t *m, size_t *mlen,
+    const uint8_t *sm, size_t smlen, const uint8_t *pk) {
+    /* The API caller does not necessarily know what size a signature should be
+       but SPHINCS+ signatures are always exactly SPX_BYTES. */
+    if (smlen < SPX_BYTES) {
+        memset(m, 0, smlen);
+        *mlen = 0;
+        return -1;
+    }
+
+    *mlen = smlen - SPX_BYTES;
+
+    if (PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_crypto_sign_verify(
+                sm, SPX_BYTES, sm + SPX_BYTES, *mlen, pk)) {
+        memset(m, 0, smlen);
+        *mlen = 0;
+        return -1;
+    }
+
+    /* If verification was successful, move the message to the right place. */
+    memmove(m, sm + SPX_BYTES, *mlen);
+
+    return 0;
+}
diff --git a/crypto_sign/sphincs-shake256-128f-simple/clean/thash.h b/crypto_sign/sphincs-shake256-128f-simple/clean/thash.h
new file mode 100644
index 00000000..605de340
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/clean/thash.h
@@ -0,0 +1,22 @@
+#ifndef SPX_THASH_H
+#define SPX_THASH_H
+
+#include <stdint.h>
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash_1(
+    unsigned char *out, const unsigned char *in,
+    const unsigned char *pub_seed, uint32_t addr[8]);
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash_2(
+    unsigned char *out, const unsigned char *in,
+    const unsigned char *pub_seed, uint32_t addr[8]);
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash_WOTS_LEN(
+    unsigned char *out, const unsigned char *in,
+    const unsigned char *pub_seed, uint32_t addr[8]);
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash_FORS_TREES(
+    unsigned char *out, const unsigned char *in,
+    const unsigned char *pub_seed, uint32_t addr[8]);
+
+#endif
diff --git a/crypto_sign/sphincs-shake256-128f-simple/clean/thash_shake256_simple.c b/crypto_sign/sphincs-shake256-128f-simple/clean/thash_shake256_simple.c
new file mode 100644
index 00000000..7c2cdb63
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/clean/thash_shake256_simple.c
@@ -0,0 +1,61 @@
+#include <stdint.h>
+#include <string.h>
+
+#include "thash.h"
+#include "address.h"
+#include "params.h"
+
+#include "fips202.h"
+
+/**
+ * Takes an array of inblocks concatenated arrays of SPX_N bytes.
+ */
+static void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash(
+    unsigned char *out, unsigned char *buf,
+    const unsigned char *in, unsigned int inblocks,
+    const unsigned char *pub_seed, uint32_t addr[8]) {
+
+    memcpy(buf, pub_seed, SPX_N);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_addr_to_bytes(buf + SPX_N, addr);
+    memcpy(buf + SPX_N + SPX_ADDR_BYTES, in, inblocks * SPX_N);
+
+    shake256(out, SPX_N, buf, SPX_N + SPX_ADDR_BYTES + inblocks * SPX_N);
+}
+
+/* The wrappers below ensure that we use fixed-size buffers on the stack */
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash_1(
+    unsigned char *out, const unsigned char *in,
+    const unsigned char *pub_seed, uint32_t addr[8]) {
+
+    unsigned char buf[SPX_N + SPX_ADDR_BYTES + 1 * SPX_N];
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash(
+        out, buf, in, 1, pub_seed, addr);
+}
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash_2(
+    unsigned char *out, const unsigned char *in,
+    const unsigned char *pub_seed, uint32_t addr[8]) {
+
+    unsigned char buf[SPX_N + SPX_ADDR_BYTES + 2 * SPX_N];
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash(
+        out, buf, in, 2, pub_seed, addr);
+}
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash_WOTS_LEN(
+    unsigned char *out, const unsigned char *in,
+    const unsigned char *pub_seed, uint32_t addr[8]) {
+
+    unsigned char buf[SPX_N + SPX_ADDR_BYTES + SPX_WOTS_LEN * SPX_N];
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash(
+        out, buf, in, SPX_WOTS_LEN, pub_seed, addr);
+}
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash_FORS_TREES(
+    unsigned char *out, const unsigned char *in,
+    const unsigned char *pub_seed, uint32_t addr[8]) {
+
+    unsigned char buf[SPX_N + SPX_ADDR_BYTES + SPX_FORS_TREES * SPX_N];
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash(
+        out, buf, in, SPX_FORS_TREES, pub_seed, addr);
+}
diff --git a/crypto_sign/sphincs-shake256-128f-simple/clean/utils.c b/crypto_sign/sphincs-shake256-128f-simple/clean/utils.c
new file mode 100644
index 00000000..2a367645
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/clean/utils.c
@@ -0,0 +1,192 @@
+#include <stddef.h>
+#include <string.h>
+
+#include "address.h"
+#include "hash.h"
+#include "params.h"
+#include "thash.h"
+#include "utils.h"
+
+/**
+ * Converts the value of 'in' to 'outlen' bytes in big-endian byte order.
+ */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_ull_to_bytes(
+    unsigned char *out, size_t outlen, unsigned long long in) {
+
+    /* Iterate over out in decreasing order, for big-endianness. */
+    for (size_t i = outlen; i > 0; i--) {
+        out[i - 1] = in & 0xff;
+        in = in >> 8;
+    }
+}
+
+/**
+ * Converts the inlen bytes in 'in' from big-endian byte order to an integer.
+ */
+unsigned long long PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_bytes_to_ull(
+    const unsigned char *in, size_t inlen) {
+    unsigned long long retval = 0;
+
+    for (size_t i = 0; i < inlen; i++) {
+        retval |= ((unsigned long long)in[i]) << (8 * (inlen - 1 - i));
+    }
+    return retval;
+}
+
+/**
+ * Computes a root node given a leaf and an auth path.
+ * Expects address to be complete other than the tree_height and tree_index.
+ */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_compute_root(
+    unsigned char *root, const unsigned char *leaf,
+    uint32_t leaf_idx, uint32_t idx_offset,
+    const unsigned char *auth_path, uint32_t tree_height,
+    const unsigned char *pub_seed, uint32_t addr[8]) {
+    uint32_t i;
+    unsigned char buffer[2 * SPX_N];
+
+    /* If leaf_idx is odd (last bit = 1), current path element is a right child
+       and auth_path has to go left. Otherwise it is the other way around. */
+    if (leaf_idx & 1) {
+        memcpy(buffer + SPX_N, leaf, SPX_N);
+        memcpy(buffer, auth_path, SPX_N);
+    } else {
+        memcpy(buffer, leaf, SPX_N);
+        memcpy(buffer + SPX_N, auth_path, SPX_N);
+    }
+    auth_path += SPX_N;
+
+    for (i = 0; i < tree_height - 1; i++) {
+        leaf_idx >>= 1;
+        idx_offset >>= 1;
+        /* Set the address of the node we're creating. */
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_height(addr, i + 1);
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_index(
+            addr, leaf_idx + idx_offset);
+
+        /* Pick the right or left neighbor, depending on parity of the node. */
+        if (leaf_idx & 1) {
+            PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash_2(
+                buffer + SPX_N, buffer, pub_seed, addr);
+            memcpy(buffer, auth_path, SPX_N);
+        } else {
+            PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash_2(
+                buffer, buffer, pub_seed, addr);
+            memcpy(buffer + SPX_N, auth_path, SPX_N);
+        }
+        auth_path += SPX_N;
+    }
+
+    /* The last iteration is exceptional; we do not copy an auth_path node. */
+    leaf_idx >>= 1;
+    idx_offset >>= 1;
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_height(addr, tree_height);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_index(
+        addr, leaf_idx + idx_offset);
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash_2(
+        root, buffer, pub_seed, addr);
+}
+
+/**
+ * For a given leaf index, computes the authentication path and the resulting
+ * root node using Merkle's TreeHash algorithm.
+ * Expects the layer and tree parts of the tree_addr to be set, as well as the
+ * tree type (i.e. SPX_ADDR_TYPE_HASHTREE or SPX_ADDR_TYPE_FORSTREE).
+ * Applies the offset idx_offset to indices before building addresses, so that
+ * it is possible to continue counting indices across trees.
+ */
+static void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_treehash(
+    unsigned char *root, unsigned char *auth_path,
+    unsigned char *stack, unsigned int *heights,
+    const unsigned char *sk_seed, const unsigned char *pub_seed,
+    uint32_t leaf_idx, uint32_t idx_offset, uint32_t tree_height,
+    void (*gen_leaf)(
+        unsigned char * /* leaf */,
+        const unsigned char * /* sk_seed */,
+        const unsigned char * /* pub_seed */,
+        uint32_t /* addr_idx */, const uint32_t[8] /* tree_addr */),
+    uint32_t tree_addr[8]) {
+
+    unsigned int offset = 0;
+    uint32_t idx;
+    uint32_t tree_idx;
+
+    for (idx = 0; idx < (uint32_t)(1 << tree_height); idx++) {
+        /* Add the next leaf node to the stack. */
+        gen_leaf(stack + offset * SPX_N,
+                 sk_seed, pub_seed, idx + idx_offset, tree_addr);
+        offset++;
+        heights[offset - 1] = 0;
+
+        /* If this is a node we need for the auth path.. */
+        if ((leaf_idx ^ 0x1) == idx) {
+            memcpy(auth_path, stack + (offset - 1)*SPX_N, SPX_N);
+        }
+
+        /* While the top-most nodes are of equal height.. */
+        while (offset >= 2 && heights[offset - 1] == heights[offset - 2]) {
+            /* Compute index of the new node, in the next layer. */
+            tree_idx = (idx >> (heights[offset - 1] + 1));
+
+            /* Set the address of the node we're creating. */
+            PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_height(
+                tree_addr, heights[offset - 1] + 1);
+            PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_tree_index(
+                tree_addr, tree_idx + (idx_offset >> (heights[offset - 1] + 1)));
+            /* Hash the top-most nodes from the stack together. */
+            PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash_2(
+                stack + (offset - 2)*SPX_N, stack + (offset - 2)*SPX_N,
+                pub_seed, tree_addr);
+            offset--;
+            /* Note that the top-most node is now one layer higher. */
+            heights[offset - 1]++;
+
+            /* If this is a node we need for the auth path.. */
+            if (((leaf_idx >> heights[offset - 1]) ^ 0x1) == tree_idx) {
+                memcpy(auth_path + heights[offset - 1]*SPX_N,
+                       stack + (offset - 1)*SPX_N, SPX_N);
+            }
+        }
+    }
+    memcpy(root, stack, SPX_N);
+}
+
+/* The wrappers below ensure that we use fixed-size buffers on the stack */
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_treehash_FORS_HEIGHT(
+    unsigned char *root, unsigned char *auth_path,
+    const unsigned char *sk_seed, const unsigned char *pub_seed,
+    uint32_t leaf_idx, uint32_t idx_offset,
+    void (*gen_leaf)(
+        unsigned char * /* leaf */,
+        const unsigned char * /* sk_seed */,
+        const unsigned char * /* pub_seed */,
+        uint32_t /* addr_idx */, const uint32_t[8] /* tree_addr */),
+    uint32_t tree_addr[8]) {
+
+    unsigned char stack[(SPX_FORS_HEIGHT + 1)*SPX_N];
+    unsigned int heights[SPX_FORS_HEIGHT + 1];
+
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_treehash(
+        root, auth_path, stack, heights, sk_seed, pub_seed,
+        leaf_idx, idx_offset, SPX_FORS_HEIGHT, gen_leaf, tree_addr);
+}
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_treehash_TREE_HEIGHT(
+    unsigned char *root, unsigned char *auth_path,
+    const unsigned char *sk_seed, const unsigned char *pub_seed,
+    uint32_t leaf_idx, uint32_t idx_offset,
+    void (*gen_leaf)(
+        unsigned char * /* leaf */,
+        const unsigned char * /* sk_seed */,
+        const unsigned char * /* pub_seed */,
+        uint32_t /* addr_idx */, const uint32_t[8] /* tree_addr */),
+    uint32_t tree_addr[8]) {
+
+    unsigned char stack[(SPX_TREE_HEIGHT + 1)*SPX_N];
+    unsigned int heights[SPX_TREE_HEIGHT + 1];
+
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_treehash(
+        root, auth_path, stack, heights, sk_seed, pub_seed,
+        leaf_idx, idx_offset, SPX_TREE_HEIGHT, gen_leaf, tree_addr);
+}
diff --git a/crypto_sign/sphincs-shake256-128f-simple/clean/utils.h b/crypto_sign/sphincs-shake256-128f-simple/clean/utils.h
new file mode 100644
index 00000000..dd89b4fc
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/clean/utils.h
@@ -0,0 +1,60 @@
+#ifndef SPX_UTILS_H
+#define SPX_UTILS_H
+
+#include "params.h"
+#include <stddef.h>
+#include <stdint.h>
+
+/**
+ * Converts the value of 'in' to 'outlen' bytes in big-endian byte order.
+ */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_ull_to_bytes(
+    unsigned char *out, size_t outlen, unsigned long long in);
+
+/**
+ * Converts the inlen bytes in 'in' from big-endian byte order to an integer.
+ */
+unsigned long long PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_bytes_to_ull(
+    const unsigned char *in, size_t inlen);
+
+/**
+ * Computes a root node given a leaf and an auth path.
+ * Expects address to be complete other than the tree_height and tree_index.
+ */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_compute_root(
+    unsigned char *root, const unsigned char *leaf,
+    uint32_t leaf_idx, uint32_t idx_offset,
+    const unsigned char *auth_path, uint32_t tree_height,
+    const unsigned char *pub_seed, uint32_t addr[8]);
+
+/**
+ * For a given leaf index, computes the authentication path and the resulting
+ * root node using Merkle's TreeHash algorithm.
+ * Expects the layer and tree parts of the tree_addr to be set, as well as the
+ * tree type (i.e. SPX_ADDR_TYPE_HASHTREE or SPX_ADDR_TYPE_FORSTREE).
+ * Applies the offset idx_offset to indices before building addresses, so that
+ * it is possible to continue counting indices across trees.
+ */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_treehash_FORS_HEIGHT(
+    unsigned char *root, unsigned char *auth_path,
+    const unsigned char *sk_seed, const unsigned char *pub_seed,
+    uint32_t leaf_idx, uint32_t idx_offset,
+    void (*gen_leaf)(
+        unsigned char * /* leaf */,
+        const unsigned char * /* sk_seed */,
+        const unsigned char * /* pub_seed */,
+        uint32_t /* addr_idx */, const uint32_t[8] /* tree_addr */),
+    uint32_t tree_addr[8]);
+
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_treehash_TREE_HEIGHT(
+    unsigned char *root, unsigned char *auth_path,
+    const unsigned char *sk_seed, const unsigned char *pub_seed,
+    uint32_t leaf_idx, uint32_t idx_offset,
+    void (*gen_leaf)(
+        unsigned char * /* leaf */,
+        const unsigned char * /* sk_seed */,
+        const unsigned char * /* pub_seed */,
+        uint32_t /* addr_idx */, const uint32_t[8] /* tree_addr */),
+    uint32_t tree_addr[8]);
+
+#endif
diff --git a/crypto_sign/sphincs-shake256-128f-simple/clean/wots.c b/crypto_sign/sphincs-shake256-128f-simple/clean/wots.c
new file mode 100644
index 00000000..f88b3a69
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/clean/wots.c
@@ -0,0 +1,159 @@
+#include <stdint.h>
+#include <string.h>
+
+#include "utils.h"
+#include "address.h"
+#include "hash.h"
+#include "params.h"
+#include "thash.h"
+#include "wots.h"
+
+// TODO clarify address expectations, and make them more uniform.
+// TODO i.e. do we expect types to be set already?
+// TODO and do we expect modifications or copies?
+
+/**
+ * Computes the starting value for a chain, i.e. the secret key.
+ * Expects the address to be complete up to the chain address.
+ */
+static void wots_gen_sk(unsigned char *sk, const unsigned char *sk_seed,
+                        uint32_t wots_addr[8]) {
+    /* Make sure that the hash address is actually zeroed. */
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_hash_addr(wots_addr, 0);
+
+    /* Generate sk element. */
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_prf_addr(sk, sk_seed, wots_addr);
+}
+
+/**
+ * Computes the chaining function.
+ * out and in have to be n-byte arrays.
+ *
+ * Interprets in as start-th value of the chain.
+ * addr has to contain the address of the chain.
+ */
+static void gen_chain(unsigned char *out, const unsigned char *in,
+                      unsigned int start, unsigned int steps,
+                      const unsigned char *pub_seed, uint32_t addr[8]) {
+    uint32_t i;
+
+    /* Initialize out with the value at position 'start'. */
+    memcpy(out, in, SPX_N);
+
+    /* Iterate 'steps' calls to the hash function. */
+    for (i = start; i < (start + steps) && i < SPX_WOTS_W; i++) {
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_hash_addr(addr, i);
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_thash_1(
+            out, out, pub_seed, addr);
+    }
+}
+
+/**
+ * base_w algorithm as described in draft.
+ * Interprets an array of bytes as integers in base w.
+ * This only works when log_w is a divisor of 8.
+ */
+static void base_w(int *output, const int out_len, const unsigned char *input) {
+    int in = 0;
+    int out = 0;
+    unsigned char total = 0;
+    int bits = 0;
+    int consumed;
+
+    for (consumed = 0; consumed < out_len; consumed++) {
+        if (bits == 0) {
+            total = input[in];
+            in++;
+            bits += 8;
+        }
+        bits -= SPX_WOTS_LOGW;
+        output[out] = (total >> bits) & (SPX_WOTS_W - 1);
+        out++;
+    }
+}
+
+/* Computes the WOTS+ checksum over a message (in base_w). */
+static void wots_checksum(int *csum_base_w, const int *msg_base_w) {
+    int csum = 0;
+    unsigned char csum_bytes[(SPX_WOTS_LEN2 * SPX_WOTS_LOGW + 7) / 8];
+    unsigned int i;
+
+    /* Compute checksum. */
+    for (i = 0; i < SPX_WOTS_LEN1; i++) {
+        csum += SPX_WOTS_W - 1 - msg_base_w[i];
+    }
+
+    /* Convert checksum to base_w. */
+    /* Make sure expected empty zero bits are the least significant bits. */
+    csum = csum << (8 - ((SPX_WOTS_LEN2 * SPX_WOTS_LOGW) % 8));
+    PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_ull_to_bytes(
+        csum_bytes, sizeof(csum_bytes), csum);
+    base_w(csum_base_w, SPX_WOTS_LEN2, csum_bytes);
+}
+
+/* Takes a message and derives the matching chain lengths. */
+static void chain_lengths(int *lengths, const unsigned char *msg) {
+    base_w(lengths, SPX_WOTS_LEN1, msg);
+    wots_checksum(lengths + SPX_WOTS_LEN1, lengths);
+}
+
+/**
+ * WOTS key generation. Takes a 32 byte sk_seed, expands it to WOTS private key
+ * elements and computes the corresponding public key.
+ * It requires the seed pub_seed (used to generate bitmasks and hash keys)
+ * and the address of this WOTS key pair.
+ *
+ * Writes the computed public key to 'pk'.
+ */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_wots_gen_pk(
+    unsigned char *pk, const unsigned char *sk_seed,
+    const unsigned char *pub_seed, uint32_t addr[8]) {
+    uint32_t i;
+
+    for (i = 0; i < SPX_WOTS_LEN; i++) {
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_chain_addr(addr, i);
+        wots_gen_sk(pk + i * SPX_N, sk_seed, addr);
+        gen_chain(pk + i * SPX_N, pk + i * SPX_N,
+                  0, SPX_WOTS_W - 1, pub_seed, addr);
+    }
+}
+
+/**
+ * Takes a n-byte message and the 32-byte sk_see to compute a signature 'sig'.
+ */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_wots_sign(
+    unsigned char *sig, const unsigned char *msg,
+    const unsigned char *sk_seed, const unsigned char *pub_seed,
+    uint32_t addr[8]) {
+    int lengths[SPX_WOTS_LEN];
+    uint32_t i;
+
+    chain_lengths(lengths, msg);
+
+    for (i = 0; i < SPX_WOTS_LEN; i++) {
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_chain_addr(addr, i);
+        wots_gen_sk(sig + i * SPX_N, sk_seed, addr);
+        gen_chain(sig + i * SPX_N, sig + i * SPX_N, 0, lengths[i], pub_seed, addr);
+    }
+}
+
+/**
+ * Takes a WOTS signature and an n-byte message, computes a WOTS public key.
+ *
+ * Writes the computed public key to 'pk'.
+ */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_wots_pk_from_sig(
+    unsigned char *pk,
+    const unsigned char *sig, const unsigned char *msg,
+    const unsigned char *pub_seed, uint32_t addr[8]) {
+    int lengths[SPX_WOTS_LEN];
+    uint32_t i;
+
+    chain_lengths(lengths, msg);
+
+    for (i = 0; i < SPX_WOTS_LEN; i++) {
+        PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_set_chain_addr(addr, i);
+        gen_chain(pk + i * SPX_N, sig + i * SPX_N,
+                  lengths[i], SPX_WOTS_W - 1 - lengths[i], pub_seed, addr);
+    }
+}
diff --git a/crypto_sign/sphincs-shake256-128f-simple/clean/wots.h b/crypto_sign/sphincs-shake256-128f-simple/clean/wots.h
new file mode 100644
index 00000000..54b6781a
--- /dev/null
+++ b/crypto_sign/sphincs-shake256-128f-simple/clean/wots.h
@@ -0,0 +1,38 @@
+#ifndef SPX_WOTS_H
+#define SPX_WOTS_H
+
+#include "params.h"
+#include <stdint.h>
+
+/**
+ * WOTS key generation. Takes a 32 byte seed for the private key, expands it to
+ * a full WOTS private key and computes the corresponding public key.
+ * It requires the seed pub_seed (used to generate bitmasks and hash keys)
+ * and the address of this WOTS key pair.
+ *
+ * Writes the computed public key to 'pk'.
+ */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_wots_gen_pk(
+    unsigned char *pk, const unsigned char *sk_seed,
+    const unsigned char *pub_seed, uint32_t addr[8]);
+
+/**
+ * Takes a n-byte message and the 32-byte seed for the private key to compute a
+ * signature that is placed at 'sig'.
+ */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_wots_sign(
+    unsigned char *sig, const unsigned char *msg,
+    const unsigned char *sk_seed, const unsigned char *pub_seed,
+    uint32_t addr[8]);
+
+/**
+ * Takes a WOTS signature and an n-byte message, computes a WOTS public key.
+ *
+ * Writes the computed public key to 'pk'.
+ */
+void PQCLEAN_SPHINCSSHAKE256128FSIMPLE_CLEAN_wots_pk_from_sig(
+    unsigned char *pk,
+    const unsigned char *sig, const unsigned char *msg,
+    const unsigned char *pub_seed, uint32_t addr[8]);
+
+#endif