X-Git-Url: https://git.openssl.org/?a=blobdiff_plain;f=crypto%2Fec%2Fcurve448%2Feddsa.c;h=556edf07b91cbf2b3d29e456ea383fbeb2a36e38;hb=9fd3c858b4ceea7ff0b176c7c0a2438475898598;hp=9f68e31177171546787eb29b24d5454f6e4f65bd;hpb=a2039c87f5923b10f148dea8fb725df03b90011b;p=openssl.git

diff --git a/crypto/ec/curve448/eddsa.c b/crypto/ec/curve448/eddsa.c
index 9f68e31177..556edf07b9 100644
--- a/crypto/ec/curve448/eddsa.c
+++ b/crypto/ec/curve448/eddsa.c
@@ -1,327 +1,359 @@
-/**
- * @file ed448goldilocks/eddsa.c
- * @author Mike Hamburg
+/*
+ * Copyright 2017-2018 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 2015-2016 Cryptography Research, Inc.
  *
- * @copyright
- *   Copyright (c) 2015-2016 Cryptography Research, Inc.  \n
- *   Released under the MIT License.  See LICENSE.txt for license information.
+ * Licensed under the OpenSSL license (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
  *
- * @cond internal
- * @brief EdDSA routines.
- *
- * @warning This file was automatically generated in Python.
- * Please do not edit it.
+ * Originally written by Mike Hamburg
  */
+#include <openssl/crypto.h>
+#include <openssl/evp.h>
+
+#include "curve448_lcl.h"
 #include "word.h"
 #include "ed448.h"
-#include "shake.h"
 #include <string.h>
+#include "internal/numbers.h"
 
-#define API_NAME "decaf_448"
-#define API_NS(_id) decaf_448_##_id
+#define COFACTOR 4
 
-#define hash_ctx_t   decaf_shake256_ctx_t
-#define hash_init    decaf_shake256_init
-#define hash_update  decaf_shake256_update
-#define hash_final   decaf_shake256_final
-#define hash_destroy decaf_shake256_destroy
-#define hash_hash    decaf_shake256_hash
+static c448_error_t oneshot_hash(uint8_t *out, size_t outlen,
+                                 const uint8_t *in, size_t inlen)
+{
+    EVP_MD_CTX *hashctx = EVP_MD_CTX_new();
 
-#define NO_CONTEXT DECAF_EDDSA_448_SUPPORTS_CONTEXTLESS_SIGS
-#define EDDSA_USE_SIGMA_ISOGENY 0
-#define COFACTOR 4
-#define EDDSA_PREHASH_BYTES 64
+    if (hashctx == NULL)
+        return C448_FAILURE;
 
-#if NO_CONTEXT
-const uint8_t NO_CONTEXT_POINTS_HERE = 0;
-const uint8_t * const DECAF_ED448_NO_CONTEXT = &NO_CONTEXT_POINTS_HERE;
-#endif
+    if (!EVP_DigestInit_ex(hashctx, EVP_shake256(), NULL)
+            || !EVP_DigestUpdate(hashctx, in, inlen)
+            || !EVP_DigestFinalXOF(hashctx, out, outlen)) {
+        EVP_MD_CTX_free(hashctx);
+        return C448_FAILURE;
+    }
 
-/* EDDSA_BASE_POINT_RATIO = 1 or 2
- * Because EdDSA25519 is not on E_d but on the isogenous E_sigma_d,
- * its base point is twice ours.
- */
-#define EDDSA_BASE_POINT_RATIO (1+EDDSA_USE_SIGMA_ISOGENY) /* TODO: remove */
+    EVP_MD_CTX_free(hashctx);
+    return C448_SUCCESS;
+}
+
+static void clamp(uint8_t secret_scalar_ser[EDDSA_448_PRIVATE_BYTES])
+{
+    uint8_t hibit = (1 << 0) >> 1;
 
-static void clamp (
-    uint8_t secret_scalar_ser[DECAF_EDDSA_448_PRIVATE_BYTES]
-) {
     /* Blarg */
     secret_scalar_ser[0] &= -COFACTOR;
-    uint8_t hibit = (1<<0)>>1;
     if (hibit == 0) {
-        secret_scalar_ser[DECAF_EDDSA_448_PRIVATE_BYTES - 1] = 0;
-        secret_scalar_ser[DECAF_EDDSA_448_PRIVATE_BYTES - 2] |= 0x80;
+        secret_scalar_ser[EDDSA_448_PRIVATE_BYTES - 1] = 0;
+        secret_scalar_ser[EDDSA_448_PRIVATE_BYTES - 2] |= 0x80;
     } else {
-        secret_scalar_ser[DECAF_EDDSA_448_PRIVATE_BYTES - 1] &= hibit-1;
-        secret_scalar_ser[DECAF_EDDSA_448_PRIVATE_BYTES - 1] |= hibit;
+        secret_scalar_ser[EDDSA_448_PRIVATE_BYTES - 1] &= hibit - 1;
+        secret_scalar_ser[EDDSA_448_PRIVATE_BYTES - 1] |= hibit;
     }
 }
 
-static void hash_init_with_dom(
-    hash_ctx_t hash,
-    uint8_t prehashed,
-    uint8_t for_prehash,
-    const uint8_t *context,
-    uint8_t context_len
-) {
-    hash_init(hash);
-
-#if NO_CONTEXT
-    if (context_len == 0 && context == DECAF_ED448_NO_CONTEXT) {
-        (void)prehashed;
-        (void)for_prehash;
-        (void)context;
-        (void)context_len;
-        return;
-    }
-#endif
+static c448_error_t hash_init_with_dom(EVP_MD_CTX *hashctx, uint8_t prehashed,
+                                       uint8_t for_prehash,
+                                       const uint8_t *context,
+                                       size_t context_len)
+{
     const char *dom_s = "SigEd448";
-    const uint8_t dom[2] = {2+word_is_zero(prehashed)+word_is_zero(for_prehash), context_len};
-    hash_update(hash,(const unsigned char *)dom_s, strlen(dom_s));
-    hash_update(hash,dom,2);
-    hash_update(hash,context,context_len);
-}
+    uint8_t dom[2];
+
+    dom[0] = 2 + word_is_zero(prehashed) + word_is_zero(for_prehash);
+    dom[1] = (uint8_t)context_len;
+
+    if (context_len > UINT8_MAX)
+        return C448_FAILURE;
+
+    if (!EVP_DigestInit_ex(hashctx, EVP_shake256(), NULL)
+            || !EVP_DigestUpdate(hashctx, dom_s, strlen(dom_s))
+            || !EVP_DigestUpdate(hashctx, dom, sizeof(dom))
+            || !EVP_DigestUpdate(hashctx, context, context_len))
+        return C448_FAILURE;
 
-void decaf_ed448_prehash_init (
-    hash_ctx_t hash
-) {
-    hash_init(hash);
+    return C448_SUCCESS;
 }
 
 /* In this file because it uses the hash */
-void decaf_ed448_convert_private_key_to_x448 (
-    uint8_t x[DECAF_X448_PRIVATE_BYTES],
-    const uint8_t ed[DECAF_EDDSA_448_PRIVATE_BYTES]
-) {
-    /* pass the private key through hash_hash function */
-    /* and keep the first DECAF_X448_PRIVATE_BYTES bytes */
-    hash_hash(
-        x,
-        DECAF_X448_PRIVATE_BYTES,
-        ed,
-        DECAF_EDDSA_448_PRIVATE_BYTES
-    );
+c448_error_t c448_ed448_convert_private_key_to_x448(
+                            uint8_t x[X448_PRIVATE_BYTES],
+                            const uint8_t ed [EDDSA_448_PRIVATE_BYTES])
+{
+    /* pass the private key through oneshot_hash function */
+    /* and keep the first X448_PRIVATE_BYTES bytes */
+    return oneshot_hash(x, X448_PRIVATE_BYTES, ed,
+                        EDDSA_448_PRIVATE_BYTES);
 }
-    
-void decaf_ed448_derive_public_key (
-    uint8_t pubkey[DECAF_EDDSA_448_PUBLIC_BYTES],
-    const uint8_t privkey[DECAF_EDDSA_448_PRIVATE_BYTES]
-) {
+
+c448_error_t c448_ed448_derive_public_key(
+                        uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
+                        const uint8_t privkey[EDDSA_448_PRIVATE_BYTES])
+{
     /* only this much used for keygen */
-    uint8_t secret_scalar_ser[DECAF_EDDSA_448_PRIVATE_BYTES];
-    
-    hash_hash(
-        secret_scalar_ser,
-        sizeof(secret_scalar_ser),
-        privkey,
-        DECAF_EDDSA_448_PRIVATE_BYTES
-    );
+    uint8_t secret_scalar_ser[EDDSA_448_PRIVATE_BYTES];
+    curve448_scalar_t secret_scalar;
+    unsigned int c;
+    curve448_point_t p;
+
+    if (!oneshot_hash(secret_scalar_ser, sizeof(secret_scalar_ser), privkey,
+                      EDDSA_448_PRIVATE_BYTES))
+        return C448_FAILURE;
+
     clamp(secret_scalar_ser);
-        
-    API_NS(scalar_t) secret_scalar;
-    API_NS(scalar_decode_long)(secret_scalar, secret_scalar_ser, sizeof(secret_scalar_ser));
-    
-    /* Since we are going to mul_by_cofactor during encoding, divide by it here.
-     * However, the EdDSA base point is not the same as the decaf base point if
-     * the sigma isogeny is in use: the EdDSA base point is on Etwist_d/(1-d) and
-     * the decaf base point is on Etwist_d, and when converted it effectively
-     * picks up a factor of 2 from the isogenies.  So we might start at 2 instead of 1. 
+
+    curve448_scalar_decode_long(secret_scalar, secret_scalar_ser,
+                                sizeof(secret_scalar_ser));
+
+    /*
+     * Since we are going to mul_by_cofactor during encoding, divide by it
+     * here. However, the EdDSA base point is not the same as the decaf base
+     * point if the sigma isogeny is in use: the EdDSA base point is on
+     * Etwist_d/(1-d) and the decaf base point is on Etwist_d, and when
+     * converted it effectively picks up a factor of 2 from the isogenies.  So
+     * we might start at 2 instead of 1.
      */
-    for (unsigned int c=1; c<DECAF_448_EDDSA_ENCODE_RATIO; c <<= 1) {
-        API_NS(scalar_halve)(secret_scalar,secret_scalar);
-    }
-    
-    API_NS(point_t) p;
-    API_NS(precomputed_scalarmul)(p,API_NS(precomputed_base),secret_scalar);
-    
-    API_NS(point_mul_by_ratio_and_encode_like_eddsa)(pubkey, p);
-        
+    for (c = 1; c < C448_EDDSA_ENCODE_RATIO; c <<= 1)
+        curve448_scalar_halve(secret_scalar, secret_scalar);
+
+    curve448_precomputed_scalarmul(p, curve448_precomputed_base, secret_scalar);
+
+    curve448_point_mul_by_ratio_and_encode_like_eddsa(pubkey, p);
+
     /* Cleanup */
-    API_NS(scalar_destroy)(secret_scalar);
-    API_NS(point_destroy)(p);
-    decaf_bzero(secret_scalar_ser, sizeof(secret_scalar_ser));
+    curve448_scalar_destroy(secret_scalar);
+    curve448_point_destroy(p);
+    OPENSSL_cleanse(secret_scalar_ser, sizeof(secret_scalar_ser));
+
+    return C448_SUCCESS;
 }
 
-void decaf_ed448_sign (
-    uint8_t signature[DECAF_EDDSA_448_SIGNATURE_BYTES],
-    const uint8_t privkey[DECAF_EDDSA_448_PRIVATE_BYTES],
-    const uint8_t pubkey[DECAF_EDDSA_448_PUBLIC_BYTES],
-    const uint8_t *message,
-    size_t message_len,
-    uint8_t prehashed,
-    const uint8_t *context,
-    uint8_t context_len
-) {
-    API_NS(scalar_t) secret_scalar;
-    hash_ctx_t hash;
+c448_error_t c448_ed448_sign(
+                        uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
+                        const uint8_t privkey[EDDSA_448_PRIVATE_BYTES],
+                        const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
+                        const uint8_t *message, size_t message_len,
+                        uint8_t prehashed, const uint8_t *context,
+                        size_t context_len)
+{
+    curve448_scalar_t secret_scalar;
+    EVP_MD_CTX *hashctx = EVP_MD_CTX_new();
+    c448_error_t ret = C448_FAILURE;
+    curve448_scalar_t nonce_scalar;
+    uint8_t nonce_point[EDDSA_448_PUBLIC_BYTES] = { 0 };
+    unsigned int c;
+    curve448_scalar_t challenge_scalar;
+
+    if (hashctx == NULL)
+        return C448_FAILURE;
+
     {
-        /* Schedule the secret key */
-        struct {
-            uint8_t secret_scalar_ser[DECAF_EDDSA_448_PRIVATE_BYTES];
-            uint8_t seed[DECAF_EDDSA_448_PRIVATE_BYTES];
-        } __attribute__((packed)) expanded;
-        hash_hash(
-            (uint8_t *)&expanded,
-            sizeof(expanded),
-            privkey,
-            DECAF_EDDSA_448_PRIVATE_BYTES
-        );
-        clamp(expanded.secret_scalar_ser);   
-        API_NS(scalar_decode_long)(secret_scalar, expanded.secret_scalar_ser, sizeof(expanded.secret_scalar_ser));
-    
+        /*
+         * Schedule the secret key, First EDDSA_448_PRIVATE_BYTES is serialised
+         * secret scalar,next EDDSA_448_PRIVATE_BYTES bytes is the seed.
+         */
+        uint8_t expanded[EDDSA_448_PRIVATE_BYTES * 2];
+
+        if (!oneshot_hash(expanded, sizeof(expanded), privkey,
+                          EDDSA_448_PRIVATE_BYTES))
+            goto err;
+        clamp(expanded);
+        curve448_scalar_decode_long(secret_scalar, expanded,
+                                    EDDSA_448_PRIVATE_BYTES);
+
         /* Hash to create the nonce */
-        hash_init_with_dom(hash,prehashed,0,context,context_len);
-        hash_update(hash,expanded.seed,sizeof(expanded.seed));
-        hash_update(hash,message,message_len);
-        decaf_bzero(&expanded, sizeof(expanded));
+        if (!hash_init_with_dom(hashctx, prehashed, 0, context, context_len)
+                || !EVP_DigestUpdate(hashctx,
+                                     expanded + EDDSA_448_PRIVATE_BYTES,
+                                     EDDSA_448_PRIVATE_BYTES)
+                || !EVP_DigestUpdate(hashctx, message, message_len)) {
+            OPENSSL_cleanse(expanded, sizeof(expanded));
+            goto err;
+        }
+        OPENSSL_cleanse(expanded, sizeof(expanded));
     }
-    
+
     /* Decode the nonce */
-    API_NS(scalar_t) nonce_scalar;
     {
-        uint8_t nonce[2*DECAF_EDDSA_448_PRIVATE_BYTES];
-        hash_final(hash,nonce,sizeof(nonce));
-        API_NS(scalar_decode_long)(nonce_scalar, nonce, sizeof(nonce));
-        decaf_bzero(nonce, sizeof(nonce));
+        uint8_t nonce[2 * EDDSA_448_PRIVATE_BYTES];
+
+        if (!EVP_DigestFinalXOF(hashctx, nonce, sizeof(nonce)))
+            goto err;
+        curve448_scalar_decode_long(nonce_scalar, nonce, sizeof(nonce));
+        OPENSSL_cleanse(nonce, sizeof(nonce));
     }
-    
-    uint8_t nonce_point[DECAF_EDDSA_448_PUBLIC_BYTES] = {0};
+
     {
         /* Scalarmul to create the nonce-point */
-        API_NS(scalar_t) nonce_scalar_2;
-        API_NS(scalar_halve)(nonce_scalar_2,nonce_scalar);
-        for (unsigned int c = 2; c < DECAF_448_EDDSA_ENCODE_RATIO; c <<= 1) {
-            API_NS(scalar_halve)(nonce_scalar_2,nonce_scalar_2);
-        }
-        
-        API_NS(point_t) p;
-        API_NS(precomputed_scalarmul)(p,API_NS(precomputed_base),nonce_scalar_2);
-        API_NS(point_mul_by_ratio_and_encode_like_eddsa)(nonce_point, p);
-        API_NS(point_destroy)(p);
-        API_NS(scalar_destroy)(nonce_scalar_2);
+        curve448_scalar_t nonce_scalar_2;
+        curve448_point_t p;
+
+        curve448_scalar_halve(nonce_scalar_2, nonce_scalar);
+        for (c = 2; c < C448_EDDSA_ENCODE_RATIO; c <<= 1)
+            curve448_scalar_halve(nonce_scalar_2, nonce_scalar_2);
+
+        curve448_precomputed_scalarmul(p, curve448_precomputed_base,
+                                       nonce_scalar_2);
+        curve448_point_mul_by_ratio_and_encode_like_eddsa(nonce_point, p);
+        curve448_point_destroy(p);
+        curve448_scalar_destroy(nonce_scalar_2);
     }
-    
-    API_NS(scalar_t) challenge_scalar;
+
     {
+        uint8_t challenge[2 * EDDSA_448_PRIVATE_BYTES];
+
         /* Compute the challenge */
-        hash_init_with_dom(hash,prehashed,0,context,context_len);
-        hash_update(hash,nonce_point,sizeof(nonce_point));
-        hash_update(hash,pubkey,DECAF_EDDSA_448_PUBLIC_BYTES);
-        hash_update(hash,message,message_len);
-        uint8_t challenge[2*DECAF_EDDSA_448_PRIVATE_BYTES];
-        hash_final(hash,challenge,sizeof(challenge));
-        hash_destroy(hash);
-        API_NS(scalar_decode_long)(challenge_scalar,challenge,sizeof(challenge));
-        decaf_bzero(challenge,sizeof(challenge));
+        if (!hash_init_with_dom(hashctx, prehashed, 0, context, context_len)
+                || !EVP_DigestUpdate(hashctx, nonce_point, sizeof(nonce_point))
+                || !EVP_DigestUpdate(hashctx, pubkey, EDDSA_448_PUBLIC_BYTES)
+                || !EVP_DigestUpdate(hashctx, message, message_len)
+                || !EVP_DigestFinalXOF(hashctx, challenge, sizeof(challenge)))
+            goto err;
+
+        curve448_scalar_decode_long(challenge_scalar, challenge,
+                                    sizeof(challenge));
+        OPENSSL_cleanse(challenge, sizeof(challenge));
     }
-    
-    API_NS(scalar_mul)(challenge_scalar,challenge_scalar,secret_scalar);
-    API_NS(scalar_add)(challenge_scalar,challenge_scalar,nonce_scalar);
-    
-    decaf_bzero(signature,DECAF_EDDSA_448_SIGNATURE_BYTES);
-    memcpy(signature,nonce_point,sizeof(nonce_point));
-    API_NS(scalar_encode)(&signature[DECAF_EDDSA_448_PUBLIC_BYTES],challenge_scalar);
-    
-    API_NS(scalar_destroy)(secret_scalar);
-    API_NS(scalar_destroy)(nonce_scalar);
-    API_NS(scalar_destroy)(challenge_scalar);
-}
 
+    curve448_scalar_mul(challenge_scalar, challenge_scalar, secret_scalar);
+    curve448_scalar_add(challenge_scalar, challenge_scalar, nonce_scalar);
 
-void decaf_ed448_sign_prehash (
-    uint8_t signature[DECAF_EDDSA_448_SIGNATURE_BYTES],
-    const uint8_t privkey[DECAF_EDDSA_448_PRIVATE_BYTES],
-    const uint8_t pubkey[DECAF_EDDSA_448_PUBLIC_BYTES],
-    const decaf_ed448_prehash_ctx_t hash,
-    const uint8_t *context,
-    uint8_t context_len
-) {
-    uint8_t hash_output[EDDSA_PREHASH_BYTES];
-    {
-        decaf_ed448_prehash_ctx_t hash_too;
-        memcpy(hash_too,hash,sizeof(hash_too));
-        hash_final(hash_too,hash_output,sizeof(hash_output));
-        hash_destroy(hash_too);
-    }
+    OPENSSL_cleanse(signature, EDDSA_448_SIGNATURE_BYTES);
+    memcpy(signature, nonce_point, sizeof(nonce_point));
+    curve448_scalar_encode(&signature[EDDSA_448_PUBLIC_BYTES],
+                           challenge_scalar);
+
+    curve448_scalar_destroy(secret_scalar);
+    curve448_scalar_destroy(nonce_scalar);
+    curve448_scalar_destroy(challenge_scalar);
 
-    decaf_ed448_sign(signature,privkey,pubkey,hash_output,sizeof(hash_output),1,context,context_len);
-    decaf_bzero(hash_output,sizeof(hash_output));
+    ret = C448_SUCCESS;
+ err:
+    EVP_MD_CTX_free(hashctx);
+    return ret;
 }
 
-decaf_error_t decaf_ed448_verify (
-    const uint8_t signature[DECAF_EDDSA_448_SIGNATURE_BYTES],
-    const uint8_t pubkey[DECAF_EDDSA_448_PUBLIC_BYTES],
-    const uint8_t *message,
-    size_t message_len,
-    uint8_t prehashed,
-    const uint8_t *context,
-    uint8_t context_len
-) { 
-    API_NS(point_t) pk_point, r_point;
-    decaf_error_t error = API_NS(point_decode_like_eddsa_and_mul_by_ratio)(pk_point,pubkey);
-    if (DECAF_SUCCESS != error) { return error; }
-    
-    error = API_NS(point_decode_like_eddsa_and_mul_by_ratio)(r_point,signature);
-    if (DECAF_SUCCESS != error) { return error; }
-    
-    API_NS(scalar_t) challenge_scalar;
+c448_error_t c448_ed448_sign_prehash(
+                        uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
+                        const uint8_t privkey[EDDSA_448_PRIVATE_BYTES],
+                        const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
+                        const uint8_t hash[64], const uint8_t *context,
+                        size_t context_len)
+{
+    return c448_ed448_sign(signature, privkey, pubkey, hash, 64, 1, context,
+                           context_len);
+}
+
+c448_error_t c448_ed448_verify(
+                    const uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
+                    const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
+                    const uint8_t *message, size_t message_len,
+                    uint8_t prehashed, const uint8_t *context,
+                    uint8_t context_len)
+{
+    curve448_point_t pk_point, r_point;
+    c448_error_t error =
+        curve448_point_decode_like_eddsa_and_mul_by_ratio(pk_point, pubkey);
+    curve448_scalar_t challenge_scalar;
+    curve448_scalar_t response_scalar;
+    unsigned int c;
+
+    if (C448_SUCCESS != error)
+        return error;
+
+    error =
+        curve448_point_decode_like_eddsa_and_mul_by_ratio(r_point, signature);
+    if (C448_SUCCESS != error)
+        return error;
+
     {
         /* Compute the challenge */
-        hash_ctx_t hash;
-        hash_init_with_dom(hash,prehashed,0,context,context_len);
-        hash_update(hash,signature,DECAF_EDDSA_448_PUBLIC_BYTES);
-        hash_update(hash,pubkey,DECAF_EDDSA_448_PUBLIC_BYTES);
-        hash_update(hash,message,message_len);
-        uint8_t challenge[2*DECAF_EDDSA_448_PRIVATE_BYTES];
-        hash_final(hash,challenge,sizeof(challenge));
-        hash_destroy(hash);
-        API_NS(scalar_decode_long)(challenge_scalar,challenge,sizeof(challenge));
-        decaf_bzero(challenge,sizeof(challenge));
-    }
-    API_NS(scalar_sub)(challenge_scalar, API_NS(scalar_zero), challenge_scalar);
-    
-    API_NS(scalar_t) response_scalar;
-    API_NS(scalar_decode_long)(
-        response_scalar,
-        &signature[DECAF_EDDSA_448_PUBLIC_BYTES],
-        DECAF_EDDSA_448_PRIVATE_BYTES
-    );
-    
-    for (unsigned c=1; c<DECAF_448_EDDSA_DECODE_RATIO; c<<=1) {
-        API_NS(scalar_add)(response_scalar,response_scalar,response_scalar);
+        EVP_MD_CTX *hashctx = EVP_MD_CTX_new();
+        uint8_t challenge[2 * EDDSA_448_PRIVATE_BYTES];
+
+        if (hashctx == NULL
+                || !hash_init_with_dom(hashctx, prehashed, 0, context,
+                                       context_len)
+                || !EVP_DigestUpdate(hashctx, signature, EDDSA_448_PUBLIC_BYTES)
+                || !EVP_DigestUpdate(hashctx, pubkey, EDDSA_448_PUBLIC_BYTES)
+                || !EVP_DigestUpdate(hashctx, message, message_len)
+                || !EVP_DigestFinalXOF(hashctx, challenge, sizeof(challenge))) {
+            EVP_MD_CTX_free(hashctx);
+            return C448_FAILURE;
+        }
+
+        EVP_MD_CTX_free(hashctx);
+        curve448_scalar_decode_long(challenge_scalar, challenge,
+                                    sizeof(challenge));
+        OPENSSL_cleanse(challenge, sizeof(challenge));
     }
-    
-    
+    curve448_scalar_sub(challenge_scalar, curve448_scalar_zero,
+                        challenge_scalar);
+
+    curve448_scalar_decode_long(response_scalar,
+                                &signature[EDDSA_448_PUBLIC_BYTES],
+                                EDDSA_448_PRIVATE_BYTES);
+
+    for (c = 1; c < C448_EDDSA_DECODE_RATIO; c <<= 1)
+        curve448_scalar_add(response_scalar, response_scalar, response_scalar);
+
     /* pk_point = -c(x(P)) + (cx + k)G = kG */
-    API_NS(base_double_scalarmul_non_secret)(
-        pk_point,
-        response_scalar,
-        pk_point,
-        challenge_scalar
-    );
-    return decaf_succeed_if(API_NS(point_eq(pk_point,r_point)));
+    curve448_base_double_scalarmul_non_secret(pk_point,
+                                              response_scalar,
+                                              pk_point, challenge_scalar);
+    return c448_succeed_if(curve448_point_eq(pk_point, r_point));
 }
 
+c448_error_t c448_ed448_verify_prehash(
+                    const uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
+                    const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
+                    const uint8_t hash[64], const uint8_t *context,
+                    uint8_t context_len)
+{
+    return c448_ed448_verify(signature, pubkey, hash, 64, 1, context,
+                             context_len);
+}
 
-decaf_error_t decaf_ed448_verify_prehash (
-    const uint8_t signature[DECAF_EDDSA_448_SIGNATURE_BYTES],
-    const uint8_t pubkey[DECAF_EDDSA_448_PUBLIC_BYTES],
-    const decaf_ed448_prehash_ctx_t hash,
-    const uint8_t *context,
-    uint8_t context_len
-) {
-    decaf_error_t ret;
-    
-    uint8_t hash_output[EDDSA_PREHASH_BYTES];
-    {
-        decaf_ed448_prehash_ctx_t hash_too;
-        memcpy(hash_too,hash,sizeof(hash_too));
-        hash_final(hash_too,hash_output,sizeof(hash_output));
-        hash_destroy(hash_too);
-    }
-    
-    ret = decaf_ed448_verify(signature,pubkey,hash_output,sizeof(hash_output),1,context,context_len);
-    
-    return ret;
+int ED448_sign(uint8_t *out_sig, const uint8_t *message, size_t message_len,
+               const uint8_t public_key[57], const uint8_t private_key[57],
+               const uint8_t *context, size_t context_len)
+{
+
+    return c448_ed448_sign(out_sig, private_key, public_key, message,
+                           message_len, 0, context, context_len)
+        == C448_SUCCESS;
+}
+
+int ED448_verify(const uint8_t *message, size_t message_len,
+                 const uint8_t signature[114], const uint8_t public_key[57],
+                 const uint8_t *context, size_t context_len)
+{
+    return c448_ed448_verify(signature, public_key, message, message_len, 0,
+                             context, (uint8_t)context_len) == C448_SUCCESS;
+}
+
+int ED448ph_sign(uint8_t *out_sig, const uint8_t hash[64],
+                 const uint8_t public_key[57], const uint8_t private_key[57],
+                 const uint8_t *context, size_t context_len)
+{
+    return c448_ed448_sign_prehash(out_sig, private_key, public_key, hash,
+                                   context, context_len) == C448_SUCCESS;
+
+}
+
+int ED448ph_verify(const uint8_t hash[64], const uint8_t signature[114],
+                   const uint8_t public_key[57], const uint8_t *context,
+                   size_t context_len)
+{
+    return c448_ed448_verify_prehash(signature, public_key, hash, context,
+                                     (uint8_t)context_len) == C448_SUCCESS;
+}
+
+int ED448_public_from_private(uint8_t out_public_key[57],
+                              const uint8_t private_key[57])
+{
+    return c448_ed448_derive_public_key(out_public_key, private_key)
+        == C448_SUCCESS;
 }