1b3c89cd1e
Found by coverity. This is an artifact left over from the original decaf import which generated the source code for different curves. For curve 448 this is dead. Reviewed-by: Rich Salz <rsalz@openssl.org> (Merged from https://github.com/openssl/openssl/pull/6373)
349 lines
13 KiB
C
349 lines
13 KiB
C
/*
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* Copyright 2017-2018 The OpenSSL Project Authors. All Rights Reserved.
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* Copyright 2015-2016 Cryptography Research, Inc.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*
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* Originally written by Mike Hamburg
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*/
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#include <string.h>
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#include <openssl/crypto.h>
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#include <openssl/evp.h>
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#include "curve448_lcl.h"
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#include "word.h"
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#include "ed448.h"
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#include "internal/numbers.h"
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#define COFACTOR 4
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static c448_error_t oneshot_hash(uint8_t *out, size_t outlen,
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const uint8_t *in, size_t inlen)
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{
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EVP_MD_CTX *hashctx = EVP_MD_CTX_new();
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if (hashctx == NULL)
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return C448_FAILURE;
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if (!EVP_DigestInit_ex(hashctx, EVP_shake256(), NULL)
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|| !EVP_DigestUpdate(hashctx, in, inlen)
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|| !EVP_DigestFinalXOF(hashctx, out, outlen)) {
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EVP_MD_CTX_free(hashctx);
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return C448_FAILURE;
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}
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EVP_MD_CTX_free(hashctx);
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return C448_SUCCESS;
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}
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static void clamp(uint8_t secret_scalar_ser[EDDSA_448_PRIVATE_BYTES])
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{
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secret_scalar_ser[0] &= -COFACTOR;
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secret_scalar_ser[EDDSA_448_PRIVATE_BYTES - 1] = 0;
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secret_scalar_ser[EDDSA_448_PRIVATE_BYTES - 2] |= 0x80;
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}
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static c448_error_t hash_init_with_dom(EVP_MD_CTX *hashctx, uint8_t prehashed,
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uint8_t for_prehash,
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const uint8_t *context,
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size_t context_len)
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{
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const char *dom_s = "SigEd448";
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uint8_t dom[2];
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if (context_len > UINT8_MAX)
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return C448_FAILURE;
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dom[0] = (uint8_t)(2 - (prehashed == 0 ? 1 : 0)
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- (for_prehash == 0 ? 1 : 0));
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dom[1] = (uint8_t)context_len;
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if (!EVP_DigestInit_ex(hashctx, EVP_shake256(), NULL)
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|| !EVP_DigestUpdate(hashctx, dom_s, strlen(dom_s))
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|| !EVP_DigestUpdate(hashctx, dom, sizeof(dom))
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|| (context_len > 0
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&& !EVP_DigestUpdate(hashctx, context, context_len)))
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return C448_FAILURE;
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return C448_SUCCESS;
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}
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/* In this file because it uses the hash */
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c448_error_t c448_ed448_convert_private_key_to_x448(
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uint8_t x[X448_PRIVATE_BYTES],
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const uint8_t ed [EDDSA_448_PRIVATE_BYTES])
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{
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/* pass the private key through oneshot_hash function */
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/* and keep the first X448_PRIVATE_BYTES bytes */
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return oneshot_hash(x, X448_PRIVATE_BYTES, ed,
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EDDSA_448_PRIVATE_BYTES);
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}
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c448_error_t c448_ed448_derive_public_key(
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uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
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const uint8_t privkey[EDDSA_448_PRIVATE_BYTES])
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{
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/* only this much used for keygen */
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uint8_t secret_scalar_ser[EDDSA_448_PRIVATE_BYTES];
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curve448_scalar_t secret_scalar;
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unsigned int c;
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curve448_point_t p;
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if (!oneshot_hash(secret_scalar_ser, sizeof(secret_scalar_ser), privkey,
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EDDSA_448_PRIVATE_BYTES))
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return C448_FAILURE;
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clamp(secret_scalar_ser);
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curve448_scalar_decode_long(secret_scalar, secret_scalar_ser,
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sizeof(secret_scalar_ser));
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/*
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* Since we are going to mul_by_cofactor during encoding, divide by it
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* here. However, the EdDSA base point is not the same as the decaf base
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* point if the sigma isogeny is in use: the EdDSA base point is on
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* Etwist_d/(1-d) and the decaf base point is on Etwist_d, and when
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* converted it effectively picks up a factor of 2 from the isogenies. So
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* we might start at 2 instead of 1.
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*/
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for (c = 1; c < C448_EDDSA_ENCODE_RATIO; c <<= 1)
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curve448_scalar_halve(secret_scalar, secret_scalar);
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curve448_precomputed_scalarmul(p, curve448_precomputed_base, secret_scalar);
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curve448_point_mul_by_ratio_and_encode_like_eddsa(pubkey, p);
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/* Cleanup */
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curve448_scalar_destroy(secret_scalar);
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curve448_point_destroy(p);
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OPENSSL_cleanse(secret_scalar_ser, sizeof(secret_scalar_ser));
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return C448_SUCCESS;
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}
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c448_error_t c448_ed448_sign(
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uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
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const uint8_t privkey[EDDSA_448_PRIVATE_BYTES],
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const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
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const uint8_t *message, size_t message_len,
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uint8_t prehashed, const uint8_t *context,
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size_t context_len)
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{
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curve448_scalar_t secret_scalar;
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EVP_MD_CTX *hashctx = EVP_MD_CTX_new();
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c448_error_t ret = C448_FAILURE;
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curve448_scalar_t nonce_scalar;
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uint8_t nonce_point[EDDSA_448_PUBLIC_BYTES] = { 0 };
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unsigned int c;
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curve448_scalar_t challenge_scalar;
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if (hashctx == NULL)
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return C448_FAILURE;
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{
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/*
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* Schedule the secret key, First EDDSA_448_PRIVATE_BYTES is serialised
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* secret scalar,next EDDSA_448_PRIVATE_BYTES bytes is the seed.
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*/
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uint8_t expanded[EDDSA_448_PRIVATE_BYTES * 2];
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if (!oneshot_hash(expanded, sizeof(expanded), privkey,
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EDDSA_448_PRIVATE_BYTES))
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goto err;
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clamp(expanded);
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curve448_scalar_decode_long(secret_scalar, expanded,
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EDDSA_448_PRIVATE_BYTES);
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/* Hash to create the nonce */
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if (!hash_init_with_dom(hashctx, prehashed, 0, context, context_len)
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|| !EVP_DigestUpdate(hashctx,
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expanded + EDDSA_448_PRIVATE_BYTES,
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EDDSA_448_PRIVATE_BYTES)
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|| (message_len > 0
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&& !EVP_DigestUpdate(hashctx, message, message_len))) {
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OPENSSL_cleanse(expanded, sizeof(expanded));
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goto err;
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}
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OPENSSL_cleanse(expanded, sizeof(expanded));
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}
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/* Decode the nonce */
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{
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uint8_t nonce[2 * EDDSA_448_PRIVATE_BYTES];
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if (!EVP_DigestFinalXOF(hashctx, nonce, sizeof(nonce)))
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goto err;
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curve448_scalar_decode_long(nonce_scalar, nonce, sizeof(nonce));
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OPENSSL_cleanse(nonce, sizeof(nonce));
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}
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{
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/* Scalarmul to create the nonce-point */
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curve448_scalar_t nonce_scalar_2;
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curve448_point_t p;
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curve448_scalar_halve(nonce_scalar_2, nonce_scalar);
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for (c = 2; c < C448_EDDSA_ENCODE_RATIO; c <<= 1)
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curve448_scalar_halve(nonce_scalar_2, nonce_scalar_2);
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curve448_precomputed_scalarmul(p, curve448_precomputed_base,
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nonce_scalar_2);
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curve448_point_mul_by_ratio_and_encode_like_eddsa(nonce_point, p);
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curve448_point_destroy(p);
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curve448_scalar_destroy(nonce_scalar_2);
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}
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{
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uint8_t challenge[2 * EDDSA_448_PRIVATE_BYTES];
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/* Compute the challenge */
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if (!hash_init_with_dom(hashctx, prehashed, 0, context, context_len)
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|| !EVP_DigestUpdate(hashctx, nonce_point, sizeof(nonce_point))
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|| !EVP_DigestUpdate(hashctx, pubkey, EDDSA_448_PUBLIC_BYTES)
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|| (message_len > 0
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&& !EVP_DigestUpdate(hashctx, message, message_len))
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|| !EVP_DigestFinalXOF(hashctx, challenge, sizeof(challenge)))
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goto err;
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curve448_scalar_decode_long(challenge_scalar, challenge,
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sizeof(challenge));
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OPENSSL_cleanse(challenge, sizeof(challenge));
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}
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curve448_scalar_mul(challenge_scalar, challenge_scalar, secret_scalar);
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curve448_scalar_add(challenge_scalar, challenge_scalar, nonce_scalar);
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OPENSSL_cleanse(signature, EDDSA_448_SIGNATURE_BYTES);
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memcpy(signature, nonce_point, sizeof(nonce_point));
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curve448_scalar_encode(&signature[EDDSA_448_PUBLIC_BYTES],
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challenge_scalar);
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curve448_scalar_destroy(secret_scalar);
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curve448_scalar_destroy(nonce_scalar);
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curve448_scalar_destroy(challenge_scalar);
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ret = C448_SUCCESS;
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err:
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EVP_MD_CTX_free(hashctx);
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return ret;
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}
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c448_error_t c448_ed448_sign_prehash(
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uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
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const uint8_t privkey[EDDSA_448_PRIVATE_BYTES],
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const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
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const uint8_t hash[64], const uint8_t *context,
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size_t context_len)
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{
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return c448_ed448_sign(signature, privkey, pubkey, hash, 64, 1, context,
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context_len);
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}
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c448_error_t c448_ed448_verify(
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const uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
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const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
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const uint8_t *message, size_t message_len,
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uint8_t prehashed, const uint8_t *context,
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uint8_t context_len)
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{
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curve448_point_t pk_point, r_point;
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c448_error_t error =
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curve448_point_decode_like_eddsa_and_mul_by_ratio(pk_point, pubkey);
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curve448_scalar_t challenge_scalar;
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curve448_scalar_t response_scalar;
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if (C448_SUCCESS != error)
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return error;
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error =
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curve448_point_decode_like_eddsa_and_mul_by_ratio(r_point, signature);
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if (C448_SUCCESS != error)
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return error;
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{
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/* Compute the challenge */
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EVP_MD_CTX *hashctx = EVP_MD_CTX_new();
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uint8_t challenge[2 * EDDSA_448_PRIVATE_BYTES];
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if (hashctx == NULL
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|| !hash_init_with_dom(hashctx, prehashed, 0, context,
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context_len)
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|| !EVP_DigestUpdate(hashctx, signature, EDDSA_448_PUBLIC_BYTES)
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|| !EVP_DigestUpdate(hashctx, pubkey, EDDSA_448_PUBLIC_BYTES)
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|| !EVP_DigestUpdate(hashctx, message, message_len)
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|| !EVP_DigestFinalXOF(hashctx, challenge, sizeof(challenge))) {
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EVP_MD_CTX_free(hashctx);
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return C448_FAILURE;
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}
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EVP_MD_CTX_free(hashctx);
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curve448_scalar_decode_long(challenge_scalar, challenge,
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sizeof(challenge));
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OPENSSL_cleanse(challenge, sizeof(challenge));
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}
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curve448_scalar_sub(challenge_scalar, curve448_scalar_zero,
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challenge_scalar);
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curve448_scalar_decode_long(response_scalar,
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&signature[EDDSA_448_PUBLIC_BYTES],
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EDDSA_448_PRIVATE_BYTES);
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/* pk_point = -c(x(P)) + (cx + k)G = kG */
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curve448_base_double_scalarmul_non_secret(pk_point,
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response_scalar,
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pk_point, challenge_scalar);
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return c448_succeed_if(curve448_point_eq(pk_point, r_point));
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}
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c448_error_t c448_ed448_verify_prehash(
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const uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
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const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
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const uint8_t hash[64], const uint8_t *context,
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uint8_t context_len)
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{
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return c448_ed448_verify(signature, pubkey, hash, 64, 1, context,
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context_len);
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}
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int ED448_sign(uint8_t *out_sig, const uint8_t *message, size_t message_len,
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const uint8_t public_key[57], const uint8_t private_key[57],
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const uint8_t *context, size_t context_len)
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{
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return c448_ed448_sign(out_sig, private_key, public_key, message,
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message_len, 0, context, context_len)
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== C448_SUCCESS;
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}
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int ED448_verify(const uint8_t *message, size_t message_len,
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const uint8_t signature[114], const uint8_t public_key[57],
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const uint8_t *context, size_t context_len)
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{
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return c448_ed448_verify(signature, public_key, message, message_len, 0,
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context, (uint8_t)context_len) == C448_SUCCESS;
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}
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int ED448ph_sign(uint8_t *out_sig, const uint8_t hash[64],
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const uint8_t public_key[57], const uint8_t private_key[57],
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const uint8_t *context, size_t context_len)
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{
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return c448_ed448_sign_prehash(out_sig, private_key, public_key, hash,
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context, context_len) == C448_SUCCESS;
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}
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int ED448ph_verify(const uint8_t hash[64], const uint8_t signature[114],
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const uint8_t public_key[57], const uint8_t *context,
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size_t context_len)
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{
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return c448_ed448_verify_prehash(signature, public_key, hash, context,
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(uint8_t)context_len) == C448_SUCCESS;
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}
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int ED448_public_from_private(uint8_t out_public_key[57],
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const uint8_t private_key[57])
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{
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return c448_ed448_derive_public_key(out_public_key, private_key)
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== C448_SUCCESS;
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}
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