diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index 9513814..7c325f7 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -44,6 +44,8 @@
     hash_info.c
     hkdf.c
     hmac_drbg.c
+    lmots.c
+    lms.c
     md.c
     md5.c
     memory_buffer_alloc.c
diff --git a/library/Makefile b/library/Makefile
index 9c3af3b..624773d 100644
--- a/library/Makefile
+++ b/library/Makefile
@@ -109,6 +109,8 @@
 	     hash_info.o \
 	     hkdf.o \
 	     hmac_drbg.o \
+	     lmots.o \
+	     lms.o \
 	     md.o \
 	     md5.o \
 	     memory_buffer_alloc.o \
diff --git a/library/lmots.c b/library/lmots.c
new file mode 100644
index 0000000..7319d29
--- /dev/null
+++ b/library/lmots.c
@@ -0,0 +1,684 @@
+/*
+ * The LM-OTS one-time public-key signature scheme
+ *
+ * Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+/*
+ *  The following sources were referenced in the design of this implementation
+ *  of the LM-OTS algorithm:
+ *
+ *  [1] IETF RFC8554
+ *      D. McGrew, M. Curcio, S.Fluhrer
+ *      https://datatracker.ietf.org/doc/html/rfc8554
+ *
+ *  [2] NIST Special Publication 800-208
+ *      David A. Cooper et. al.
+ *      https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-208.pdf
+ */
+
+#include "common.h"
+
+#ifdef MBEDTLS_LMOTS_C
+
+#include <string.h>
+
+#include "mbedtls/lmots.h"
+#include "mbedtls/md.h"
+#include "mbedtls/platform_util.h"
+#include "mbedtls/error.h"
+
+#define W_SYMBOL_BIT_LEN      (8)
+#define CHECKSUM_LEN          (2)
+#define I_SYMBOL_IDX_LEN      (2)
+#define J_HASH_IDX_LEN        (1)
+#define D_CONST_LEN           (2)
+
+#define SYMBOL_MAX_VAL        ((1 << W_SYMBOL_BIT_LEN) - 1)
+
+#define D_PBLC_CONSTANT       (0x8080)
+#define D_MESG_CONSTANT       (0x8181)
+
+static void val_to_network_bytes(unsigned int val, size_t len, unsigned char *bytes)
+{
+    size_t idx;
+
+    for (idx = 0; idx < len; idx++) {
+        bytes[idx] = (val >> ((len - 1 - idx) * 8)) & 0xFF;
+    }
+}
+
+static unsigned int network_bytes_to_val(size_t len, const unsigned char *bytes)
+{
+    size_t idx;
+    unsigned int val = 0;
+
+    for (idx = 0; idx < len; idx++) {
+        val |= ((unsigned int)bytes[idx]) << (8 * (len - 1 - idx));
+    }
+
+    return val;
+}
+
+static unsigned short lmots_checksum_generate( const unsigned char* digest )
+{
+    size_t idx;
+    unsigned short sum = 0;
+
+    for ( idx = 0; idx < MBEDTLS_LMOTS_N_HASH_LEN; idx++ )
+    {
+        sum += ( 1 << W_SYMBOL_BIT_LEN ) - 1 - digest[idx];
+    }
+
+    return sum;
+}
+
+static int create_symbol_array( const unsigned char I_key_identifier[MBEDTLS_LMOTS_I_KEY_ID_LEN],
+                                const unsigned char q_leaf_identifier[MBEDTLS_LMOTS_Q_LEAF_ID_LEN],
+                                const unsigned char *msg,
+                                size_t msg_len,
+                                const unsigned char C_random_value[MBEDTLS_LMOTS_C_RANDOM_VALUE_LEN],
+                                unsigned char out[MBEDTLS_LMOTS_P_SIG_SYMBOL_LEN] )
+{
+    mbedtls_md_context_t hash_ctx;
+    unsigned char D_MESG_BYTES[D_CONST_LEN];
+    unsigned short checksum;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    mbedtls_md_init( &hash_ctx );
+    ret = mbedtls_md_setup( &hash_ctx, mbedtls_md_info_from_type( MBEDTLS_MD_SHA256 ), 0 );
+    if( ret )
+    {
+        goto out;
+    }
+    ret = mbedtls_md_starts( &hash_ctx );
+    if ( ret )
+    {
+        goto out;
+    }
+
+    ret = mbedtls_md_update( &hash_ctx, I_key_identifier, MBEDTLS_LMOTS_I_KEY_ID_LEN );
+    if ( ret )
+    {
+        goto out;
+    }
+
+    ret = mbedtls_md_update( &hash_ctx, q_leaf_identifier, MBEDTLS_LMOTS_Q_LEAF_ID_LEN );
+    if ( ret )
+    {
+        goto out;
+    }
+
+    val_to_network_bytes( D_MESG_CONSTANT, D_CONST_LEN, D_MESG_BYTES );
+    ret = mbedtls_md_update( &hash_ctx, D_MESG_BYTES, sizeof( D_MESG_BYTES ) );
+    if ( ret )
+    {
+        goto out;
+    }
+
+    ret = mbedtls_md_update( &hash_ctx, C_random_value, MBEDTLS_LMOTS_C_RANDOM_VALUE_LEN );
+    if ( ret )
+    {
+        goto out;
+    }
+
+    ret = mbedtls_md_update( &hash_ctx, msg, msg_len );
+    if ( ret )
+    {
+        goto out;
+    }
+
+    ret = mbedtls_md_finish( &hash_ctx, out );
+    if ( ret )
+    {
+        goto out;
+    }
+
+    checksum = lmots_checksum_generate( out );
+    val_to_network_bytes( checksum, CHECKSUM_LEN, out + MBEDTLS_LMOTS_N_HASH_LEN );
+
+out:
+    mbedtls_md_free( &hash_ctx );
+
+    return( ret );
+}
+
+static int hash_symbol_array( const unsigned char I_key_identifier[MBEDTLS_LMOTS_I_KEY_ID_LEN],
+                              const unsigned char q_leaf_identifier[MBEDTLS_LMOTS_Q_LEAF_ID_LEN],
+                              const unsigned char x_symbol_array[MBEDTLS_LMOTS_P_SIG_SYMBOL_LEN][32],
+                              const unsigned char hash_idx_min_values[MBEDTLS_LMOTS_P_SIG_SYMBOL_LEN],
+                              const unsigned char hash_idx_max_values[MBEDTLS_LMOTS_P_SIG_SYMBOL_LEN],
+                              unsigned char output[MBEDTLS_LMOTS_P_SIG_SYMBOL_LEN][32] )
+{
+    unsigned char i_symbol_idx;
+    unsigned char j_hash_idx;
+    unsigned char i_symbol_idx_bytes[I_SYMBOL_IDX_LEN];
+    unsigned char j_hash_idx_bytes[1];
+    unsigned short j_hash_idx_min;
+    unsigned short j_hash_idx_max;
+    mbedtls_md_context_t hash_ctx;
+    unsigned char tmp_hash[32];
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    for ( i_symbol_idx = 0; i_symbol_idx < MBEDTLS_LMOTS_P_SIG_SYMBOL_LEN; i_symbol_idx++ )
+    {
+
+        memcpy( tmp_hash, &x_symbol_array[i_symbol_idx], MBEDTLS_LMOTS_N_HASH_LEN );
+
+        j_hash_idx_min = hash_idx_min_values != NULL ? hash_idx_min_values[i_symbol_idx] : 0;
+        j_hash_idx_max = hash_idx_max_values != NULL ? hash_idx_max_values[i_symbol_idx] : SYMBOL_MAX_VAL;
+
+        for ( j_hash_idx = (unsigned char)j_hash_idx_min; j_hash_idx < j_hash_idx_max; j_hash_idx++ )
+        {
+            mbedtls_md_init( &hash_ctx );
+            ret = mbedtls_md_setup( &hash_ctx, mbedtls_md_info_from_type( MBEDTLS_MD_SHA256 ), 0 );
+            if( ret )
+            {
+                goto out;
+            }
+            ret = mbedtls_md_starts( &hash_ctx );
+            if ( ret )
+            {
+                goto out;
+            }
+
+            ret = mbedtls_md_update( &hash_ctx, I_key_identifier, MBEDTLS_LMOTS_I_KEY_ID_LEN );
+            if ( ret )
+            {
+                goto out;
+            }
+
+            ret = mbedtls_md_update( &hash_ctx, q_leaf_identifier, MBEDTLS_LMOTS_Q_LEAF_ID_LEN );
+            if ( ret )
+            {
+                goto out;
+            }
+
+            val_to_network_bytes( i_symbol_idx, I_SYMBOL_IDX_LEN, i_symbol_idx_bytes );
+            ret = mbedtls_md_update( &hash_ctx, i_symbol_idx_bytes, I_SYMBOL_IDX_LEN );
+            if ( ret )
+            {
+                goto out;
+            }
+
+            val_to_network_bytes( j_hash_idx, J_HASH_IDX_LEN, j_hash_idx_bytes );
+            ret = mbedtls_md_update( &hash_ctx, j_hash_idx_bytes, J_HASH_IDX_LEN );
+            if ( ret )
+            {
+                goto out;
+            }
+
+            ret = mbedtls_md_update( &hash_ctx, tmp_hash, MBEDTLS_LMOTS_N_HASH_LEN );
+            if ( ret )
+            {
+                goto out;
+            }
+
+            ret = mbedtls_md_finish( &hash_ctx, tmp_hash );
+            if ( ret )
+            {
+                goto out;
+            }
+
+            mbedtls_md_free( &hash_ctx );
+        }
+
+        memcpy( &output[i_symbol_idx], tmp_hash, MBEDTLS_LMOTS_N_HASH_LEN );
+    }
+
+out:
+    if( ret )
+    {
+        mbedtls_md_free( &hash_ctx );
+        return( ret );
+    }
+
+    return ret;
+}
+
+static int public_key_from_hashed_symbol_array( const unsigned char I_key_identifier[MBEDTLS_LMOTS_I_KEY_ID_LEN],
+                                                const unsigned char q_leaf_identifier[MBEDTLS_LMOTS_Q_LEAF_ID_LEN],
+                                                const unsigned char  y_hashed_symbols[MBEDTLS_LMOTS_P_SIG_SYMBOL_LEN][32],
+                                                unsigned char *pub_key )
+{
+    unsigned char D_PBLC_bytes[D_CONST_LEN];
+    mbedtls_md_context_t hash_ctx;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    mbedtls_md_init( &hash_ctx );
+    ret = mbedtls_md_setup( &hash_ctx, mbedtls_md_info_from_type( MBEDTLS_MD_SHA256 ), 0 );
+    if( ret )
+    {
+        goto out;
+    }
+    ret = mbedtls_md_starts( &hash_ctx );
+    if ( ret )
+    {
+        goto out;
+    }
+
+    ret = mbedtls_md_update( &hash_ctx, I_key_identifier,
+                             MBEDTLS_LMOTS_I_KEY_ID_LEN );
+    if ( ret )
+    {
+        goto out;
+    }
+
+    ret = mbedtls_md_update( &hash_ctx, q_leaf_identifier,
+                             MBEDTLS_LMOTS_Q_LEAF_ID_LEN );
+    if ( ret )
+    {
+        goto out;
+    }
+
+    val_to_network_bytes( D_PBLC_CONSTANT, D_CONST_LEN, D_PBLC_bytes );
+    ret = mbedtls_md_update( &hash_ctx, D_PBLC_bytes, D_CONST_LEN );
+    if ( ret )
+    {
+        goto out;
+    }
+
+    ret = mbedtls_md_update( &hash_ctx, ( unsigned char * )y_hashed_symbols,
+                             MBEDTLS_LMOTS_P_SIG_SYMBOL_LEN * MBEDTLS_LMOTS_N_HASH_LEN );
+    if ( ret )
+    {
+        goto out;
+    }
+
+    ret = mbedtls_md_finish( &hash_ctx, pub_key );
+
+out:
+    mbedtls_md_free( &hash_ctx );
+    return( ret );
+}
+
+void mbedtls_lmots_init( mbedtls_lmots_context *ctx )
+{
+    if( ctx == NULL ) {
+        return;
+    }
+
+    mbedtls_platform_zeroize( ctx, sizeof( mbedtls_lmots_context  ) ) ;
+}
+
+void mbedtls_lmots_free( mbedtls_lmots_context *ctx )
+{
+    if( ctx == NULL )
+    {
+        return;
+    }
+
+    mbedtls_platform_zeroize( ctx, sizeof( mbedtls_lmots_context  ) ) ;
+}
+
+int mbedtls_lmots_set_algorithm_type( mbedtls_lmots_context *ctx,
+                                      mbedtls_lmots_algorithm_type_t type )
+{
+    if( ctx == NULL )
+    {
+        return( MBEDTLS_ERR_LMOTS_BAD_INPUT_DATA );
+    }
+
+    ctx->MBEDTLS_PRIVATE(type) = type;
+
+    return( 0 );
+}
+
+int mbedtls_lmots_generate_pub_key_candidate( const unsigned char I_key_identifier[MBEDTLS_LMOTS_I_KEY_ID_LEN],
+                                              const unsigned char q_leaf_identifier[MBEDTLS_LMOTS_Q_LEAF_ID_LEN],
+                                              const unsigned char  *msg,
+                                              size_t msg_len,
+                                              const unsigned char *sig,
+                                              unsigned char *out )
+{
+    unsigned char tmp_symbol_array[MBEDTLS_LMOTS_P_SIG_SYMBOL_LEN];
+    unsigned char y_hashed_symbols[MBEDTLS_LMOTS_P_SIG_SYMBOL_LEN][32];
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    if (I_key_identifier == NULL || msg == NULL || sig == NULL || out == NULL)
+    {
+        return( MBEDTLS_ERR_LMOTS_BAD_INPUT_DATA );
+    }
+
+    ret = create_symbol_array( I_key_identifier, q_leaf_identifier, msg, msg_len,
+                               sig + MBEDTLS_LMOTS_SIG_C_RANDOM_OFFSET, tmp_symbol_array );
+    if ( ret )
+    {
+        return ( ret );
+    }
+
+    ret = hash_symbol_array( I_key_identifier, q_leaf_identifier,
+                             ( const unsigned char( *)[32] )(sig + MBEDTLS_LMOTS_SIG_SIGNATURE_OFFSET),
+                             tmp_symbol_array, NULL, y_hashed_symbols );
+    if ( ret )
+    {
+        return ( ret );
+    }
+
+    ret = public_key_from_hashed_symbol_array( I_key_identifier, q_leaf_identifier,
+                                               ( const unsigned char( *)[32] )y_hashed_symbols,
+                                               out );
+    if ( ret )
+    {
+        return ( ret );
+    }
+
+    return( 0 );
+}
+
+int mbedtls_lmots_sign( mbedtls_lmots_context *ctx,
+                        int (*f_rng)(void *, unsigned char *, size_t),
+                        void *p_rng, const unsigned char *msg, size_t msg_len,
+                        unsigned char *sig )
+{
+    unsigned char tmp_symbol_array[MBEDTLS_LMOTS_P_SIG_SYMBOL_LEN];
+    unsigned char tmp_sig[MBEDTLS_LMOTS_P_SIG_SYMBOL_LEN][MBEDTLS_LMOTS_N_HASH_LEN];
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    if( ctx == NULL || f_rng == NULL || p_rng == NULL || msg == NULL || sig == NULL)
+    {
+        return( MBEDTLS_ERR_LMOTS_BAD_INPUT_DATA );
+    }
+
+    /* Check that a private key is loaded */
+    if ( !ctx->MBEDTLS_PRIVATE(have_privkey) )
+    {
+        return( MBEDTLS_ERR_LMOTS_BAD_INPUT_DATA );
+    }
+
+    ret = f_rng( p_rng, sig + MBEDTLS_LMOTS_SIG_C_RANDOM_OFFSET, MBEDTLS_LMOTS_N_HASH_LEN );
+    if ( ret )
+    {
+        return( ret );
+    }
+
+    ret = create_symbol_array( ctx->MBEDTLS_PRIVATE(I_key_identifier),
+                               ctx->MBEDTLS_PRIVATE(q_leaf_identifier_bytes),
+                               msg, msg_len, sig + MBEDTLS_LMOTS_SIG_C_RANDOM_OFFSET,
+                               tmp_symbol_array );
+    if ( ret )
+    {
+        return( ret );
+    }
+
+    ret = hash_symbol_array( ctx->MBEDTLS_PRIVATE(I_key_identifier),
+                             ctx->MBEDTLS_PRIVATE(q_leaf_identifier_bytes),
+                             ( const unsigned char( *)[32] )(ctx->MBEDTLS_PRIVATE(priv_key)),
+                             NULL, tmp_symbol_array, tmp_sig );
+    if ( ret )
+    {
+        return( ret );
+    }
+
+    val_to_network_bytes( ctx->MBEDTLS_PRIVATE(type), MBEDTLS_LMOTS_TYPE_LEN,
+                          sig + MBEDTLS_LMOTS_SIG_TYPE_OFFSET );
+
+    /* We've got a valid signature now, so it's time to make sure the private
+     * key can't be reused.
+     */
+    ctx->MBEDTLS_PRIVATE(have_privkey) = 0;
+    mbedtls_platform_zeroize(ctx->MBEDTLS_PRIVATE(priv_key),
+                             sizeof(ctx->MBEDTLS_PRIVATE(priv_key)));
+
+    memcpy(sig + MBEDTLS_LMOTS_SIG_SIGNATURE_OFFSET, tmp_sig,
+           MBEDTLS_LMOTS_P_SIG_SYMBOL_LEN * MBEDTLS_LMOTS_N_HASH_LEN);
+
+    return( 0 );
+}
+
+int mbedtls_lmots_verify( mbedtls_lmots_context *ctx, const unsigned char *msg,
+                          size_t msg_len, const unsigned char *sig )
+{
+    unsigned char Kc_public_key_candidate[32];
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    if( ctx == NULL || msg == NULL || sig == NULL)
+    {
+        return( MBEDTLS_ERR_LMOTS_BAD_INPUT_DATA );
+    }
+
+    if ( !ctx->MBEDTLS_PRIVATE(have_pubkey) )
+    {
+        return( MBEDTLS_ERR_LMOTS_BAD_INPUT_DATA );
+    }
+
+    if( ctx->MBEDTLS_PRIVATE(type ) != MBEDTLS_LMOTS_SHA256_N32_W8 )
+    {
+        return( MBEDTLS_ERR_LMOTS_BAD_INPUT_DATA );
+    }
+
+    if ( network_bytes_to_val( MBEDTLS_LMOTS_TYPE_LEN,
+                               sig + MBEDTLS_LMOTS_SIG_TYPE_OFFSET ) != MBEDTLS_LMOTS_SHA256_N32_W8 )
+    {
+        return( MBEDTLS_ERR_LMOTS_VERIFY_FAILED );
+    }
+
+    ret = mbedtls_lmots_generate_pub_key_candidate( ctx->MBEDTLS_PRIVATE(I_key_identifier),
+                                                    ctx->MBEDTLS_PRIVATE(q_leaf_identifier_bytes),
+                                                    msg, msg_len, sig,
+                                                    Kc_public_key_candidate );
+    if ( ret )
+    {
+        return( ret );
+    }
+
+    if ( memcmp( &Kc_public_key_candidate, ctx->MBEDTLS_PRIVATE(pub_key),
+                 sizeof( ctx->MBEDTLS_PRIVATE(pub_key) ) ) )
+    {
+        return( MBEDTLS_ERR_LMOTS_VERIFY_FAILED );
+    }
+
+    return( 0 );
+}
+
+int mbedtls_lmots_import_pubkey( mbedtls_lmots_context *ctx,
+                                 const unsigned char *key )
+{
+    if ( ctx == NULL || key == NULL)
+    {
+        return( MBEDTLS_ERR_LMOTS_BAD_INPUT_DATA );
+    }
+
+    ctx->MBEDTLS_PRIVATE(type) = network_bytes_to_val( MBEDTLS_LMOTS_TYPE_LEN,
+                                                       key + MBEDTLS_LMOTS_SIG_TYPE_OFFSET );
+
+    memcpy( ctx->MBEDTLS_PRIVATE(I_key_identifier), key + MBEDTLS_LMOTS_PUBKEY_I_KEY_ID_OFFSET,
+            MBEDTLS_LMOTS_I_KEY_ID_LEN );
+
+    memcpy( ctx->MBEDTLS_PRIVATE(q_leaf_identifier_bytes), key + MBEDTLS_LMOTS_PUBKEY_Q_LEAF_ID_OFFSET,
+            MBEDTLS_LMOTS_Q_LEAF_ID_LEN );
+    ctx->MBEDTLS_PRIVATE(q_leaf_identifier) = network_bytes_to_val( MBEDTLS_LMOTS_Q_LEAF_ID_LEN,
+                                                                    ctx->MBEDTLS_PRIVATE(q_leaf_identifier_bytes) );
+
+    memcpy( ctx->MBEDTLS_PRIVATE(pub_key), key + MBEDTLS_LMOTS_PUBKEY_KEY_HASH_OFFSET, MBEDTLS_LMOTS_N_HASH_LEN );
+
+    ctx->MBEDTLS_PRIVATE(have_pubkey) = 1;
+
+    return( 0 );
+}
+
+int mbedtls_lmots_export_pubkey( mbedtls_lmots_context *ctx,
+                                 unsigned char *key )
+{
+    if ( ctx == NULL || key == NULL)
+    {
+        return( MBEDTLS_ERR_LMOTS_BAD_INPUT_DATA );
+    }
+
+    if ( ! ctx->MBEDTLS_PRIVATE(have_pubkey) )
+    {
+        return( MBEDTLS_ERR_LMOTS_BAD_INPUT_DATA );
+    }
+
+    val_to_network_bytes( ctx->MBEDTLS_PRIVATE(type), MBEDTLS_LMOTS_TYPE_LEN,
+                          key + MBEDTLS_LMOTS_SIG_TYPE_OFFSET );
+
+    memcpy( key + MBEDTLS_LMOTS_PUBKEY_I_KEY_ID_OFFSET, ctx->MBEDTLS_PRIVATE(I_key_identifier),
+            MBEDTLS_LMOTS_I_KEY_ID_LEN );
+
+    memcpy( key + MBEDTLS_LMOTS_PUBKEY_Q_LEAF_ID_OFFSET, ctx->MBEDTLS_PRIVATE(q_leaf_identifier_bytes),
+            MBEDTLS_LMOTS_Q_LEAF_ID_LEN );
+
+    memcpy( key + MBEDTLS_LMOTS_PUBKEY_KEY_HASH_OFFSET, ctx->MBEDTLS_PRIVATE(pub_key),
+            MBEDTLS_LMOTS_N_HASH_LEN );
+
+    return( 0 );
+}
+
+
+int mbedtls_lmots_gen_pubkey( mbedtls_lmots_context *ctx )
+{
+    unsigned char y_hashed_symbols[MBEDTLS_LMOTS_P_SIG_SYMBOL_LEN][32];
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    if( ctx == NULL )
+    {
+        return( MBEDTLS_ERR_LMOTS_BAD_INPUT_DATA );
+    }
+
+    /* Check that a private key is loaded */
+    if ( !ctx->MBEDTLS_PRIVATE(have_privkey) )
+    {
+        return( MBEDTLS_ERR_LMOTS_BAD_INPUT_DATA );
+    }
+
+    ret = hash_symbol_array( ctx->MBEDTLS_PRIVATE(I_key_identifier),
+                             ctx->MBEDTLS_PRIVATE(q_leaf_identifier_bytes),
+                             ( const unsigned char( *)[32] )(ctx->MBEDTLS_PRIVATE(priv_key)),
+                             NULL, NULL, y_hashed_symbols );
+    if ( ret )
+    {
+        return( ret );
+    }
+
+    ret = public_key_from_hashed_symbol_array( ctx->MBEDTLS_PRIVATE(I_key_identifier),
+                                               ctx->MBEDTLS_PRIVATE(q_leaf_identifier_bytes),
+                                               ( const unsigned char( *)[32] )y_hashed_symbols,
+                                               ctx->MBEDTLS_PRIVATE(pub_key) );
+    if ( ret )
+    {
+        return( ret );
+    }
+
+    ctx->MBEDTLS_PRIVATE(have_pubkey = 1);
+
+    return( ret );
+}
+
+int mbedtls_lmots_gen_privkey( mbedtls_lmots_context *ctx,
+                               const unsigned char I_key_identifier[MBEDTLS_LMOTS_I_KEY_ID_LEN],
+                               unsigned int q_leaf_identifier,
+                               const unsigned char *seed,
+                               size_t seed_len )
+{
+    mbedtls_md_context_t hash_ctx;
+    unsigned int i_symbol_idx;
+    unsigned char i_symbol_idx_bytes[2];
+    unsigned char const_bytes[1];
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    if( ctx == NULL || I_key_identifier == NULL || seed == NULL)
+    {
+        return( MBEDTLS_ERR_LMOTS_BAD_INPUT_DATA );
+    }
+
+    if ( ctx->MBEDTLS_PRIVATE(have_privkey) )
+    {
+        return( MBEDTLS_ERR_LMOTS_BAD_INPUT_DATA );
+    }
+
+    if ( ctx->MBEDTLS_PRIVATE(type) != MBEDTLS_LMOTS_SHA256_N32_W8 ) {
+        return( MBEDTLS_ERR_LMOTS_BAD_INPUT_DATA );
+    }
+
+    memcpy( ctx->MBEDTLS_PRIVATE(I_key_identifier), I_key_identifier,
+            sizeof( ctx->MBEDTLS_PRIVATE(I_key_identifier) ) );
+
+    ctx->MBEDTLS_PRIVATE(q_leaf_identifier) = q_leaf_identifier;
+
+    val_to_network_bytes( ctx->MBEDTLS_PRIVATE(q_leaf_identifier), MBEDTLS_LMOTS_Q_LEAF_ID_LEN,
+                          ctx->MBEDTLS_PRIVATE(q_leaf_identifier_bytes) );
+
+    val_to_network_bytes( 0xFF, sizeof( const_bytes ), const_bytes );
+
+    for ( i_symbol_idx = 0; i_symbol_idx < MBEDTLS_LMOTS_P_SIG_SYMBOL_LEN; i_symbol_idx++ )
+    {
+        mbedtls_md_init( &hash_ctx );
+        ret = mbedtls_md_setup( &hash_ctx, mbedtls_md_info_from_type( MBEDTLS_MD_SHA256 ), 0 );
+        if( ret )
+        {
+            goto out;
+        }
+        ret = mbedtls_md_starts( &hash_ctx );
+        if ( ret )
+        {
+            goto out;
+        }
+
+        ret = mbedtls_md_update( &hash_ctx, ctx->MBEDTLS_PRIVATE(I_key_identifier),
+                                 sizeof( ctx->MBEDTLS_PRIVATE(I_key_identifier) ) );
+        if ( ret ) {
+            goto out;
+        }
+
+        ret = mbedtls_md_update( &hash_ctx, ctx->MBEDTLS_PRIVATE(q_leaf_identifier_bytes),
+                                 sizeof( ctx->MBEDTLS_PRIVATE(q_leaf_identifier_bytes) ) );
+        if ( ret )
+        {
+            goto out;
+        }
+
+        val_to_network_bytes( i_symbol_idx, I_SYMBOL_IDX_LEN, i_symbol_idx_bytes );
+        ret = mbedtls_md_update( &hash_ctx, i_symbol_idx_bytes, I_SYMBOL_IDX_LEN );
+        if ( ret )
+        {
+            goto out;
+        }
+
+        ret = mbedtls_md_update( &hash_ctx, const_bytes, sizeof( const_bytes) );
+        if ( ret )
+        {
+            goto out;
+        }
+
+        ret = mbedtls_md_update( &hash_ctx, seed, seed_len );
+        if ( ret )
+        {
+            goto out;
+        }
+
+        ret = mbedtls_md_finish( &hash_ctx, ctx->MBEDTLS_PRIVATE(priv_key)[i_symbol_idx] );
+        if ( ret )
+        {
+            goto out;
+        }
+
+        mbedtls_md_free( &hash_ctx);
+    }
+
+    ctx->MBEDTLS_PRIVATE(have_privkey) = 1;
+
+out:
+    if( ret )
+    {
+        mbedtls_md_free( &hash_ctx );
+        return( ret );
+    }
+
+    return ret;
+}
+
+#endif /* MBEDTLS_LMOTS_C */
diff --git a/library/lms.c b/library/lms.c
new file mode 100644
index 0000000..e1ac7b9
--- /dev/null
+++ b/library/lms.c
@@ -0,0 +1,718 @@
+/*
+ *  The LMS stateful-hash public-key signature scheme
+ *
+ *  Copyright The Mbed TLS Contributors
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+/*
+ *  The following sources were referenced in the design of this implementation
+ *  of the LMS algorithm:
+ *
+ *  [1] IETF RFC8554
+ *      D. McGrew, M. Curcio, S.Fluhrer
+ *      https://datatracker.ietf.org/doc/html/rfc8554
+ *
+ *  [2] NIST Special Publication 800-208
+ *      David A. Cooper et. al.
+ *      https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-208.pdf
+ */
+
+#include "common.h"
+
+#ifdef MBEDTLS_LMS_C
+
+#include <string.h>
+
+#include "mbedtls/lms.h"
+#include "mbedtls/lmots.h"
+#include "mbedtls/md.h"
+#include "mbedtls/error.h"
+#include "mbedtls/platform_util.h"
+
+#if defined(MBEDTLS_PLATFORM_C)
+#include "mbedtls/platform.h"
+#else
+#include <stdlib.h>
+#include <stdio.h>
+#define mbedtls_printf printf
+#define mbedtls_calloc calloc
+#define mbedtls_free   free
+#endif
+
+#define MERKLE_TREE_NODE_AM (1 << (MBEDTLS_LMS_H_TREE_HEIGHT + 1))
+#define MERKLE_TREE_LEAF_AM (1 << MBEDTLS_LMS_H_TREE_HEIGHT)
+#define MERKLE_TREE_INTR_AM (1 << MBEDTLS_LMS_H_TREE_HEIGHT)
+
+#define D_CONST_LEN           (2)
+
+#define D_LEAF_CONSTANT     (0x8282)
+#define D_INTR_CONSTANT     (0x8383)
+
+static void val_to_network_bytes(unsigned int val, size_t len, unsigned char *bytes)
+{
+    size_t idx;
+
+    for (idx = 0; idx < len; idx++) {
+        bytes[idx] = (val >> ((len - 1 - idx) * 8)) & 0xFF;
+    }
+}
+
+static unsigned int network_bytes_to_val(size_t len, const unsigned char *bytes)
+{
+    size_t idx;
+    unsigned int val = 0;
+
+    for (idx = 0; idx < len; idx++) {
+        val |= ((unsigned int)bytes[idx]) << (8 * (len - 1 - idx));
+    }
+
+    return val;
+}
+
+static int create_merkle_leaf_node( const mbedtls_lms_context *ctx,
+                                    unsigned char pub_key[MBEDTLS_LMOTS_N_HASH_LEN],
+                                    unsigned int r_node_idx,
+                                    unsigned char out[32] )
+{
+    mbedtls_md_context_t hash_ctx;
+    unsigned char D_LEAF_bytes[D_CONST_LEN];
+    unsigned char r_node_idx_bytes[4];
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    mbedtls_md_init( &hash_ctx );
+    ret = mbedtls_md_setup( &hash_ctx, mbedtls_md_info_from_type( MBEDTLS_MD_SHA256 ), 0 );
+    if( ret )
+    {
+        goto out;
+    }
+    ret = mbedtls_md_starts( &hash_ctx );
+    if( ret )
+    {
+        goto out;
+    }
+
+    ret = mbedtls_md_update( &hash_ctx,
+                             ctx->MBEDTLS_PRIVATE(I_key_identifier),
+                             MBEDTLS_LMOTS_I_KEY_ID_LEN );
+    if( ret )
+    {
+        goto out;
+    }
+
+    val_to_network_bytes( r_node_idx, 4, r_node_idx_bytes );
+    ret = mbedtls_md_update( &hash_ctx, r_node_idx_bytes, 4 );
+    if( ret )
+    {
+        goto out;
+    }
+
+    val_to_network_bytes( D_LEAF_CONSTANT, D_CONST_LEN, D_LEAF_bytes );
+    ret = mbedtls_md_update( &hash_ctx, D_LEAF_bytes, D_CONST_LEN );
+    if( ret )
+    {
+        goto out;
+    }
+
+    ret = mbedtls_md_update( &hash_ctx, pub_key, MBEDTLS_LMOTS_N_HASH_LEN );
+    if( ret )
+    {
+        goto out;
+    }
+
+    ret = mbedtls_md_finish( &hash_ctx, out );
+    if( ret )
+    {
+        goto out;
+    }
+
+out:
+    mbedtls_md_free( &hash_ctx );
+
+    return( ret );
+}
+
+static int create_merkle_intr_node( const mbedtls_lms_context *ctx,
+                                    const unsigned char left_node[32],
+                                    const unsigned char rght_node[32],
+                                    unsigned int r_node_idx,
+                                    unsigned char out[32] )
+{
+    mbedtls_md_context_t hash_ctx;
+    unsigned char D_INTR_bytes[D_CONST_LEN];
+    unsigned char r_node_idx_bytes[4];
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    mbedtls_md_init( &hash_ctx );
+    ret = mbedtls_md_setup( &hash_ctx, mbedtls_md_info_from_type( MBEDTLS_MD_SHA256 ), 0 );
+    if( ret )
+    {
+        goto out;
+    }
+    ret = mbedtls_md_starts( &hash_ctx );
+    if( ret )
+    {
+        goto out;
+    }
+
+    ret = mbedtls_md_update( &hash_ctx, ctx->MBEDTLS_PRIVATE(I_key_identifier),
+                             MBEDTLS_LMOTS_I_KEY_ID_LEN );
+    if( ret )
+    {
+        goto out;
+    }
+
+    val_to_network_bytes( r_node_idx, 4, r_node_idx_bytes );
+    ret = mbedtls_md_update( &hash_ctx, r_node_idx_bytes, 4 );
+    if( ret )
+    {
+        goto out;
+    }
+
+    val_to_network_bytes( D_INTR_CONSTANT, D_CONST_LEN, D_INTR_bytes );
+    ret = mbedtls_md_update( &hash_ctx, D_INTR_bytes, D_CONST_LEN );
+    if( ret )
+    {
+        goto out;
+    }
+
+    ret = mbedtls_md_update( &hash_ctx, left_node, MBEDTLS_LMOTS_N_HASH_LEN );
+    if( ret )
+    {
+        goto out;
+    }
+
+    ret = mbedtls_md_update( &hash_ctx, rght_node, MBEDTLS_LMOTS_N_HASH_LEN );
+    if( ret )
+    {
+        goto out;
+    }
+
+    ret = mbedtls_md_finish( &hash_ctx, out );
+    if( ret )
+    {
+        goto out;
+    }
+
+out:
+    mbedtls_md_free( &hash_ctx );
+
+    return ret;
+}
+
+static int generate_merkle_tree( mbedtls_lms_context *ctx,
+                                 unsigned char tree[MERKLE_TREE_NODE_AM][32] )
+{
+    unsigned int priv_key_idx;
+    unsigned int r_node_idx;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    /* First create the leaf nodes, in ascending order */
+    for( priv_key_idx = 0; priv_key_idx < MERKLE_TREE_INTR_AM; priv_key_idx++ )
+    {
+        r_node_idx = MERKLE_TREE_INTR_AM + priv_key_idx;
+
+        ret = create_merkle_leaf_node( ctx, ctx->MBEDTLS_PRIVATE(priv_keys)[priv_key_idx].pub_key,
+                                       r_node_idx, tree[r_node_idx] );
+        if( ret )
+        {
+            return( ret );
+        }
+    }
+
+    /* Then the internal nodes, in reverse order so that we can guarantee the
+     * parent has been created */
+    for( r_node_idx = MERKLE_TREE_INTR_AM - 1; r_node_idx > 0; r_node_idx-- )
+    {
+        ret = create_merkle_intr_node( ctx, tree[(r_node_idx * 2)],
+                                       tree[(r_node_idx * 2 + 1)],
+                                       r_node_idx, tree[r_node_idx] );
+        if( ret )
+        {
+            return( ret );
+        }
+    }
+
+    return( 0 );
+}
+
+static int get_merkle_path( mbedtls_lms_context *ctx,
+                            unsigned int leaf_node_id, unsigned char path[MBEDTLS_LMS_H_TREE_HEIGHT][32] )
+{
+    unsigned char tree[MERKLE_TREE_NODE_AM][32];
+    unsigned int curr_node_id = leaf_node_id;
+    unsigned int parent_node_id;
+    unsigned char sibling_relative_id;
+    unsigned int adjacent_node_id;
+    unsigned int height;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    ret = generate_merkle_tree( ctx, tree);
+    if( ret )
+    {
+        return( ret );
+    }
+
+    for( height = 0; height < MBEDTLS_LMS_H_TREE_HEIGHT; height++ )
+    {
+        parent_node_id = ( curr_node_id / 2 );
+
+        /* 0 if the node is a left child, 1 if the node is a right child */
+        sibling_relative_id = curr_node_id & 1;
+
+        adjacent_node_id = ( parent_node_id * 2 ) + ( 1 - sibling_relative_id );
+
+        memcpy( &path[height], &tree[adjacent_node_id], MBEDTLS_LMOTS_N_HASH_LEN );
+
+        curr_node_id = parent_node_id;
+    }
+
+    return( 0 );
+}
+
+void mbedtls_lms_init( mbedtls_lms_context *ctx )
+{
+    if( ctx == NULL )
+    {
+        return;
+    }
+
+    mbedtls_platform_zeroize( ctx, sizeof( mbedtls_lms_context ) ) ;
+}
+
+void mbedtls_lms_free( mbedtls_lms_context *ctx )
+{
+    unsigned int idx;
+
+    if( ctx == NULL )
+    {
+        return;
+    }
+
+    if( ctx->MBEDTLS_PRIVATE(have_privkey) )
+    {
+        for( idx = 0; idx < MERKLE_TREE_LEAF_AM; idx++ )
+        {
+            mbedtls_lmots_free( &ctx->MBEDTLS_PRIVATE(priv_keys)[idx] );
+        }
+
+        mbedtls_free( ctx->MBEDTLS_PRIVATE(priv_keys) );
+    }
+
+    mbedtls_platform_zeroize( ctx, sizeof( mbedtls_lms_context ) );
+}
+
+int mbedtls_lms_set_algorithm_type( mbedtls_lms_context *ctx,
+                                    mbedtls_lms_algorithm_type_t type,
+                                    mbedtls_lmots_algorithm_type_t otstype )
+{
+    if( ctx == NULL )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    ctx->MBEDTLS_PRIVATE(type) = type;
+    ctx->MBEDTLS_PRIVATE(otstype) = otstype;
+
+    return( 0 );
+}
+
+int mbedtls_lms_sign( mbedtls_lms_context *ctx,
+                      int ( *f_rng)(void *, unsigned char *, size_t),
+                      void* p_rng, unsigned char *msg, unsigned int msg_len,
+                      unsigned char *sig )
+{
+    unsigned int q_leaf_identifier;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    if( ctx == NULL )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    if( ! ctx->MBEDTLS_PRIVATE(have_privkey) )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    if( msg == NULL )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    if( sig == NULL )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+
+    if( ctx->MBEDTLS_PRIVATE(type) != MBEDTLS_LMS_SHA256_M32_H10 )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    if( ctx->MBEDTLS_PRIVATE(otstype) != MBEDTLS_LMOTS_SHA256_N32_W8 )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+
+    if( ctx->MBEDTLS_PRIVATE(q_next_usable_key) >= MERKLE_TREE_LEAF_AM )
+    {
+        return( MBEDTLS_ERR_LMS_OUT_OF_PRIV_KEYS );
+    }
+
+
+    q_leaf_identifier = ctx->MBEDTLS_PRIVATE(q_next_usable_key);
+    /* This new value must _always_ be written back to the disk before the
+     * signature is returned.
+     */
+    ctx->MBEDTLS_PRIVATE(q_next_usable_key) += 1;
+
+    ret = mbedtls_lmots_sign( &ctx->MBEDTLS_PRIVATE(priv_keys)[q_leaf_identifier],
+                              f_rng, p_rng, msg, msg_len,
+                              sig + MBEDTLS_LMS_SIG_OTS_SIG_OFFSET );
+    if( ret )
+    {
+        return( ret );
+    }
+
+    val_to_network_bytes( ctx->MBEDTLS_PRIVATE(type), MBEDTLS_LMS_TYPE_LEN,
+                          sig + MBEDTLS_LMS_SIG_TYPE_OFFSET );
+    val_to_network_bytes( q_leaf_identifier, MBEDTLS_LMOTS_Q_LEAF_ID_LEN,
+                          sig + MBEDTLS_LMS_SIG_Q_LEAF_ID_OFFSET);
+
+    ret = get_merkle_path( ctx, MERKLE_TREE_INTR_AM + q_leaf_identifier,
+                           ( unsigned char( * )[32] )( sig + MBEDTLS_LMS_SIG_PATH_OFFSET ) );
+    if( ret )
+    {
+        return( ret );
+    }
+
+    return( 0 );
+}
+
+int mbedtls_lms_verify( const mbedtls_lms_context *ctx,
+                        const unsigned char *msg, unsigned int msg_len,
+                        const unsigned char *sig )
+{
+    unsigned int q_leaf_identifier;
+    unsigned char Kc_candidate_ots_pub_key[MBEDTLS_LMOTS_N_HASH_LEN];
+    unsigned char Tc_candidate_root_node[32];
+    unsigned int height;
+    unsigned int curr_node_id;
+    unsigned int parent_node_id;
+    const unsigned char* left_node;
+    const unsigned char* rght_node;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    if( ctx == NULL )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    if( ! ctx->MBEDTLS_PRIVATE(have_pubkey) )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    if( msg == NULL)
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    if( sig == NULL)
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    if( ctx->MBEDTLS_PRIVATE(type) != MBEDTLS_LMS_SHA256_M32_H10 )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    if( ctx->MBEDTLS_PRIVATE(otstype) != MBEDTLS_LMOTS_SHA256_N32_W8 )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+
+    if( network_bytes_to_val( MBEDTLS_LMS_TYPE_LEN,
+                              sig + MBEDTLS_LMS_SIG_TYPE_OFFSET) != MBEDTLS_LMS_SHA256_M32_H10 )
+    {
+        return( MBEDTLS_ERR_LMS_VERIFY_FAILED );
+    }
+
+    if( network_bytes_to_val( MBEDTLS_LMOTS_TYPE_LEN,
+                              sig + MBEDTLS_LMS_SIG_OTS_SIG_OFFSET + MBEDTLS_LMOTS_SIG_TYPE_OFFSET)
+        != MBEDTLS_LMOTS_SHA256_N32_W8 )
+    {
+        return( MBEDTLS_ERR_LMS_VERIFY_FAILED );
+    }
+
+
+    q_leaf_identifier = network_bytes_to_val( MBEDTLS_LMOTS_Q_LEAF_ID_LEN,
+                                              sig + MBEDTLS_LMS_SIG_Q_LEAF_ID_OFFSET );
+
+    if( q_leaf_identifier >= MERKLE_TREE_LEAF_AM )
+    {
+        return( MBEDTLS_ERR_LMS_VERIFY_FAILED );
+    }
+
+    ret = mbedtls_lmots_generate_pub_key_candidate( ctx->MBEDTLS_PRIVATE(I_key_identifier),
+                                                    sig + MBEDTLS_LMS_SIG_Q_LEAF_ID_OFFSET,
+                                                    msg, msg_len,
+                                                    sig + MBEDTLS_LMS_SIG_OTS_SIG_OFFSET,
+                                                    Kc_candidate_ots_pub_key );
+    if( ret )
+    {
+        return( ret );
+    }
+
+    create_merkle_leaf_node( ctx, Kc_candidate_ots_pub_key,
+                             MERKLE_TREE_INTR_AM + q_leaf_identifier,
+                             Tc_candidate_root_node );
+
+    curr_node_id = MERKLE_TREE_INTR_AM + q_leaf_identifier;
+
+    for( height = 0; height < MBEDTLS_LMS_H_TREE_HEIGHT; height++ )
+    {
+        parent_node_id = curr_node_id / 2;
+
+        /* Left/right node ordering matters for the hash */
+        if( curr_node_id & 1 )
+        {
+            left_node = ( ( const unsigned char( * )[32] )( sig + MBEDTLS_LMS_SIG_PATH_OFFSET ) )[height];
+            rght_node = Tc_candidate_root_node;
+        }
+        else
+        {
+            left_node = Tc_candidate_root_node;
+            rght_node = ( ( const unsigned char( * )[32] )( sig + MBEDTLS_LMS_SIG_PATH_OFFSET ) )[height];
+        }
+
+        create_merkle_intr_node( ctx, left_node, rght_node, parent_node_id,
+                                 Tc_candidate_root_node);
+
+        curr_node_id /= 2;
+    }
+
+    if( memcmp( Tc_candidate_root_node, ctx->MBEDTLS_PRIVATE(T_1_pub_key),
+                MBEDTLS_LMOTS_N_HASH_LEN) )
+    {
+        return( MBEDTLS_ERR_LMS_VERIFY_FAILED );
+    }
+
+    return( 0 );
+}
+
+int mbedtls_lms_import_pubkey( mbedtls_lms_context *ctx,
+                               const unsigned char *key )
+{
+    mbedtls_lms_algorithm_type_t type;
+    mbedtls_lmots_algorithm_type_t otstype;
+
+    if( ctx == NULL )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    if( key == NULL )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    type = network_bytes_to_val( MBEDTLS_LMS_TYPE_LEN, key + MBEDTLS_LMS_PUBKEY_TYPE_OFFSET );
+    if( type != MBEDTLS_LMS_SHA256_M32_H10 )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+    ctx->MBEDTLS_PRIVATE(type) = type;
+
+    otstype = network_bytes_to_val( MBEDTLS_LMOTS_TYPE_LEN,
+                                    key + MBEDTLS_LMS_PUBKEY_OTSTYPE_OFFSET );
+    if( otstype != MBEDTLS_LMOTS_SHA256_N32_W8 )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+    ctx->MBEDTLS_PRIVATE(otstype) = otstype;
+
+    memcpy( ctx->MBEDTLS_PRIVATE(I_key_identifier), key + MBEDTLS_LMS_PUBKEY_I_KEY_ID_OFFSET,
+            MBEDTLS_LMOTS_I_KEY_ID_LEN );
+    memcpy( ctx->MBEDTLS_PRIVATE(T_1_pub_key), key + MBEDTLS_LMS_PUBKEY_ROOT_NODE_OFFSET,
+            MBEDTLS_LMOTS_N_HASH_LEN );
+
+    ctx->MBEDTLS_PRIVATE(have_pubkey) = 1;
+
+    return( 0 );
+}
+
+int mbedtls_lms_export_pubkey( mbedtls_lms_context *ctx,
+                               unsigned char *key )
+{
+    if( ctx == NULL )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    if( key == NULL )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    if( ! ctx->MBEDTLS_PRIVATE(have_pubkey) )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    val_to_network_bytes( ctx->MBEDTLS_PRIVATE(type),
+                          MBEDTLS_LMS_TYPE_LEN, key + MBEDTLS_LMS_PUBKEY_TYPE_OFFSET );
+    val_to_network_bytes( ctx->MBEDTLS_PRIVATE(otstype),
+                          MBEDTLS_LMOTS_TYPE_LEN, key + MBEDTLS_LMS_PUBKEY_OTSTYPE_OFFSET );
+    memcpy( key + MBEDTLS_LMS_PUBKEY_I_KEY_ID_OFFSET,
+            ctx->MBEDTLS_PRIVATE(I_key_identifier),
+            MBEDTLS_LMOTS_I_KEY_ID_LEN );
+    memcpy( key + MBEDTLS_LMS_PUBKEY_ROOT_NODE_OFFSET,
+            ctx->MBEDTLS_PRIVATE(T_1_pub_key),
+            MBEDTLS_LMOTS_N_HASH_LEN );
+
+    return( 0 );
+}
+
+int mbedtls_lms_gen_pubkey( mbedtls_lms_context *ctx )
+{
+    unsigned char tree[MERKLE_TREE_NODE_AM][32];
+    unsigned int idx;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    if( ctx == NULL )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    if( ! ctx->MBEDTLS_PRIVATE( have_privkey ) )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    if( ctx->MBEDTLS_PRIVATE(type) != MBEDTLS_LMS_SHA256_M32_H10 )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    if( ctx->MBEDTLS_PRIVATE(otstype) != MBEDTLS_LMOTS_SHA256_N32_W8 )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    for( idx = 0; idx < MERKLE_TREE_LEAF_AM; idx++ )
+    {
+        ret = mbedtls_lmots_gen_pubkey( &ctx->MBEDTLS_PRIVATE(priv_keys)[idx] );
+        if( ret )
+        {
+            return( ret );
+        }
+    }
+
+    ret = generate_merkle_tree( ctx, tree);
+    if( ret )
+    {
+        return( ret );
+    }
+
+    /* Root node is always at position 1, due to 1-based indexing */
+    memcpy( ctx->MBEDTLS_PRIVATE(T_1_pub_key), &tree[1], MBEDTLS_LMOTS_N_HASH_LEN );
+
+    ctx->MBEDTLS_PRIVATE(have_pubkey) = 1;
+
+    return( 0 );
+}
+
+int mbedtls_lms_gen_privkey( mbedtls_lms_context *ctx,
+                             int ( *f_rng)(void *, unsigned char *, size_t),
+                             void* p_rng, unsigned char *seed,
+                             size_t seed_len )
+{
+    unsigned int idx;
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+
+    if( ctx == NULL )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    if( ctx->MBEDTLS_PRIVATE(type) != MBEDTLS_LMS_SHA256_M32_H10 )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    if( ctx->MBEDTLS_PRIVATE(otstype) != MBEDTLS_LMOTS_SHA256_N32_W8 )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    if( ctx->MBEDTLS_PRIVATE(have_privkey) )
+    {
+        return( MBEDTLS_ERR_LMS_BAD_INPUT_DATA );
+    }
+
+    f_rng( p_rng, ctx->MBEDTLS_PRIVATE(I_key_identifier),
+           sizeof( ctx->MBEDTLS_PRIVATE(I_key_identifier) ) );
+
+    ctx->MBEDTLS_PRIVATE(priv_keys) = mbedtls_calloc( MERKLE_TREE_LEAF_AM,
+                                                      sizeof( mbedtls_lmots_context));
+    if( ctx->MBEDTLS_PRIVATE(priv_keys) == NULL )
+    {
+        ret = MBEDTLS_ERR_LMS_ALLOC_FAILED;
+        goto out;
+    }
+
+    for( idx = 0; idx < MERKLE_TREE_LEAF_AM; idx++ )
+    {
+        mbedtls_lmots_init( &ctx->MBEDTLS_PRIVATE(priv_keys)[idx] );
+        ret = mbedtls_lmots_set_algorithm_type( &ctx->MBEDTLS_PRIVATE(priv_keys)[idx],
+                                                ctx->MBEDTLS_PRIVATE(otstype) );
+        if( ret)
+        {
+            goto out;
+        }
+    }
+
+
+    for( idx = 0; idx < MERKLE_TREE_LEAF_AM; idx++ )
+    {
+        ret = mbedtls_lmots_gen_privkey( &ctx->MBEDTLS_PRIVATE(priv_keys)[idx],
+                                         ctx->MBEDTLS_PRIVATE(I_key_identifier),
+                                         idx, seed, seed_len );
+        if( ret)
+        {
+            goto out;
+        }
+    }
+
+    ctx->MBEDTLS_PRIVATE(q_next_usable_key) = 0;
+    ctx->MBEDTLS_PRIVATE(have_privkey) = 1;
+
+out:
+    if( ret )
+    {
+        mbedtls_free( ctx->MBEDTLS_PRIVATE(priv_keys) );
+        return( ret );
+    }
+
+    return( 0 );
+}
+
+#endif /* MBEDTLS_LMS_C */