/src/openssl30/crypto/ec/curve448/eddsa.c

Source (jump to first uncovered line)
/*
 * Copyright 2017-2021 The OpenSSL Project Authors. All Rights Reserved.
 * Copyright 2015-2016 Cryptography Research, Inc.
 *
 * Licensed under the Apache License 2.0 (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
 *
 * Originally written by Mike Hamburg
 */
#include <string.h>
#include <openssl/crypto.h>
#include <openssl/evp.h>
#include "crypto/ecx.h"
#include "curve448_local.h"
#include "word.h"
#include "ed448.h"
#include "internal/numbers.h"

#define COFACTOR 4

static c448_error_t oneshot_hash(OSSL_LIB_CTX *ctx, uint8_t *out, size_t outlen,
                                 const uint8_t *in, size_t inlen,
                                 const char *propq)
{
    EVP_MD_CTX *hashctx = EVP_MD_CTX_new();
    EVP_MD *shake256 = NULL;
    c448_error_t ret = C448_FAILURE;

    if (hashctx == NULL)
        return C448_FAILURE;

    shake256 = EVP_MD_fetch(ctx, "SHAKE256", propq);
    if (shake256 == NULL)
        goto err;

    if (!EVP_DigestInit_ex(hashctx, shake256, NULL)
            || !EVP_DigestUpdate(hashctx, in, inlen)
            || !EVP_DigestFinalXOF(hashctx, out, outlen))
        goto err;

    ret = C448_SUCCESS;
 err:
    EVP_MD_CTX_free(hashctx);
    EVP_MD_free(shake256);
    return ret;
}

static void clamp(uint8_t secret_scalar_ser[EDDSA_448_PRIVATE_BYTES])
{
    secret_scalar_ser[0] &= -COFACTOR;
    secret_scalar_ser[EDDSA_448_PRIVATE_BYTES - 1] = 0;
    secret_scalar_ser[EDDSA_448_PRIVATE_BYTES - 2] |= 0x80;
}

static c448_error_t hash_init_with_dom(OSSL_LIB_CTX *ctx, EVP_MD_CTX *hashctx,
                                       uint8_t prehashed,
                                       uint8_t for_prehash,
                                       const uint8_t *context,
                                       size_t context_len,
                                       const char *propq)
{
#ifdef CHARSET_EBCDIC
    const char dom_s[] = {0x53, 0x69, 0x67, 0x45,
                          0x64, 0x34, 0x34, 0x38, 0x00};
#else
    const char dom_s[] = "SigEd448";
#endif
    uint8_t dom[2];
    EVP_MD *shake256 = NULL;

    if (context_len > UINT8_MAX)
        return C448_FAILURE;

    dom[0] = (uint8_t)(2 - (prehashed == 0 ? 1 : 0)
                       - (for_prehash == 0 ? 1 : 0));
    dom[1] = (uint8_t)context_len;

    shake256 = EVP_MD_fetch(ctx, "SHAKE256", propq);
    if (shake256 == NULL)
        return C448_FAILURE;

    if (!EVP_DigestInit_ex(hashctx, shake256, NULL)
            || !EVP_DigestUpdate(hashctx, dom_s, strlen(dom_s))
            || !EVP_DigestUpdate(hashctx, dom, sizeof(dom))
            || !EVP_DigestUpdate(hashctx, context, context_len)) {
        EVP_MD_free(shake256);
        return C448_FAILURE;
    }

    EVP_MD_free(shake256);
    return C448_SUCCESS;
}

/* In this file because it uses the hash */
c448_error_t
ossl_c448_ed448_convert_private_key_to_x448(
                            OSSL_LIB_CTX *ctx,
                            uint8_t x[X448_PRIVATE_BYTES],
                            const uint8_t ed [EDDSA_448_PRIVATE_BYTES],
                            const char *propq)
{
    /* pass the private key through oneshot_hash function */
    /* and keep the first X448_PRIVATE_BYTES bytes */
    return oneshot_hash(ctx, x, X448_PRIVATE_BYTES, ed,
                        EDDSA_448_PRIVATE_BYTES, propq);
}

c448_error_t
ossl_c448_ed448_derive_public_key(
                        OSSL_LIB_CTX *ctx,
                        uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
                        const uint8_t privkey[EDDSA_448_PRIVATE_BYTES],
                        const char *propq)
{
    /* only this much used for keygen */
    uint8_t secret_scalar_ser[EDDSA_448_PRIVATE_BYTES];
    curve448_scalar_t secret_scalar;
    unsigned int c;
    curve448_point_t p;

    if (!oneshot_hash(ctx, secret_scalar_ser, sizeof(secret_scalar_ser),
                      privkey,
                      EDDSA_448_PRIVATE_BYTES,
                      propq))
        return C448_FAILURE;

    clamp(secret_scalar_ser);

    ossl_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 (c = 1; c < C448_EDDSA_ENCODE_RATIO; c <<= 1)
        ossl_curve448_scalar_halve(secret_scalar, secret_scalar);

    ossl_curve448_precomputed_scalarmul(p, ossl_curve448_precomputed_base,
                                        secret_scalar);

    ossl_curve448_point_mul_by_ratio_and_encode_like_eddsa(pubkey, p);

    /* Cleanup */
    ossl_curve448_scalar_destroy(secret_scalar);
    ossl_curve448_point_destroy(p);
    OPENSSL_cleanse(secret_scalar_ser, sizeof(secret_scalar_ser));

    return C448_SUCCESS;
}

c448_error_t
ossl_c448_ed448_sign(OSSL_LIB_CTX *ctx,
                     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, const char *propq)
{
    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, First EDDSA_448_PRIVATE_BYTES is serialized
         * secret scalar,next EDDSA_448_PRIVATE_BYTES bytes is the seed.
         */
        uint8_t expanded[EDDSA_448_PRIVATE_BYTES * 2];

        if (!oneshot_hash(ctx, expanded, sizeof(expanded), privkey,
                          EDDSA_448_PRIVATE_BYTES, propq))
            goto err;
        clamp(expanded);
        ossl_curve448_scalar_decode_long(secret_scalar, expanded,
                                         EDDSA_448_PRIVATE_BYTES);

        /* Hash to create the nonce */
        if (!hash_init_with_dom(ctx, hashctx, prehashed, 0, context,
                                context_len, propq)
                || !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 */
    {
        uint8_t nonce[2 * EDDSA_448_PRIVATE_BYTES];

        if (!EVP_DigestFinalXOF(hashctx, nonce, sizeof(nonce)))
            goto err;
        ossl_curve448_scalar_decode_long(nonce_scalar, nonce, sizeof(nonce));
        OPENSSL_cleanse(nonce, sizeof(nonce));
    }

    {
        /* Scalarmul to create the nonce-point */
        curve448_scalar_t nonce_scalar_2;
        curve448_point_t p;

        ossl_curve448_scalar_halve(nonce_scalar_2, nonce_scalar);
        for (c = 2; c < C448_EDDSA_ENCODE_RATIO; c <<= 1)
            ossl_curve448_scalar_halve(nonce_scalar_2, nonce_scalar_2);

        ossl_curve448_precomputed_scalarmul(p, ossl_curve448_precomputed_base,
                                            nonce_scalar_2);
        ossl_curve448_point_mul_by_ratio_and_encode_like_eddsa(nonce_point, p);
        ossl_curve448_point_destroy(p);
        ossl_curve448_scalar_destroy(nonce_scalar_2);
    }

    {
        uint8_t challenge[2 * EDDSA_448_PRIVATE_BYTES];

        /* Compute the challenge */
        if (!hash_init_with_dom(ctx, hashctx, prehashed, 0, context, context_len,
                                propq)
                || !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;

        ossl_curve448_scalar_decode_long(challenge_scalar, challenge,
                                         sizeof(challenge));
        OPENSSL_cleanse(challenge, sizeof(challenge));
    }

    ossl_curve448_scalar_mul(challenge_scalar, challenge_scalar, secret_scalar);
    ossl_curve448_scalar_add(challenge_scalar, challenge_scalar, nonce_scalar);

    OPENSSL_cleanse(signature, EDDSA_448_SIGNATURE_BYTES);
    memcpy(signature, nonce_point, sizeof(nonce_point));
    ossl_curve448_scalar_encode(&signature[EDDSA_448_PUBLIC_BYTES],
                                challenge_scalar);

    ossl_curve448_scalar_destroy(secret_scalar);
    ossl_curve448_scalar_destroy(nonce_scalar);
    ossl_curve448_scalar_destroy(challenge_scalar);

    ret = C448_SUCCESS;
 err:
    EVP_MD_CTX_free(hashctx);
    return ret;
}

c448_error_t
ossl_c448_ed448_sign_prehash(
                        OSSL_LIB_CTX *ctx,
                        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, const char *propq)
{
    return ossl_c448_ed448_sign(ctx, signature, privkey, pubkey, hash, 64, 1,
                                context, context_len, propq);
}

c448_error_t
ossl_c448_ed448_verify(
                    OSSL_LIB_CTX *ctx,
                    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, const char *propq)
{
    curve448_point_t pk_point, r_point;
    c448_error_t error;
    curve448_scalar_t challenge_scalar;
    curve448_scalar_t response_scalar;
    /* Order in little endian format */
    static const uint8_t order[] = {
        0xF3, 0x44, 0x58, 0xAB, 0x92, 0xC2, 0x78, 0x23, 0x55, 0x8F, 0xC5, 0x8D,
        0x72, 0xC2, 0x6C, 0x21, 0x90, 0x36, 0xD6, 0xAE, 0x49, 0xDB, 0x4E, 0xC4,
        0xE9, 0x23, 0xCA, 0x7C, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
        0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
        0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x3F, 0x00
    };
    int i;

    /*
     * Check that s (second 57 bytes of the sig) is less than the order. Both
     * s and the order are in little-endian format. This can be done in
     * variable time, since if this is not the case the signature if publicly
     * invalid.
     */
    for (i = EDDSA_448_PUBLIC_BYTES - 1; i >= 0; i--) {
        if (signature[i + EDDSA_448_PUBLIC_BYTES] > order[i])
            return C448_FAILURE;
        if (signature[i + EDDSA_448_PUBLIC_BYTES] < order[i])
            break;
    }
    if (i < 0)
        return C448_FAILURE;

    error =
        ossl_curve448_point_decode_like_eddsa_and_mul_by_ratio(pk_point, pubkey);

    if (C448_SUCCESS != error)
        return error;

    error =
        ossl_curve448_point_decode_like_eddsa_and_mul_by_ratio(r_point, signature);
    if (C448_SUCCESS != error)
        return error;

    {
        /* Compute the challenge */
        EVP_MD_CTX *hashctx = EVP_MD_CTX_new();
        uint8_t challenge[2 * EDDSA_448_PRIVATE_BYTES];

        if (hashctx == NULL
                || !hash_init_with_dom(ctx, hashctx, prehashed, 0, context,
                                       context_len, propq)
                || !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);
        ossl_curve448_scalar_decode_long(challenge_scalar, challenge,
                                         sizeof(challenge));
        OPENSSL_cleanse(challenge, sizeof(challenge));
    }
    ossl_curve448_scalar_sub(challenge_scalar, ossl_curve448_scalar_zero,
                             challenge_scalar);

    ossl_curve448_scalar_decode_long(response_scalar,
                                     &signature[EDDSA_448_PUBLIC_BYTES],
                                     EDDSA_448_PRIVATE_BYTES);

    /* pk_point = -c(x(P)) + (cx + k)G = kG */
    ossl_curve448_base_double_scalarmul_non_secret(pk_point,
                                                   response_scalar,
                                                   pk_point, challenge_scalar);
    return c448_succeed_if(ossl_curve448_point_eq(pk_point, r_point));
}

c448_error_t
ossl_c448_ed448_verify_prehash(
                    OSSL_LIB_CTX *ctx,
                    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, const char *propq)
{
    return ossl_c448_ed448_verify(ctx, signature, pubkey, hash, 64, 1, context,
                                  context_len, propq);
}

int
ossl_ed448_sign(OSSL_LIB_CTX *ctx, 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, const char *propq)
{
    return ossl_c448_ed448_sign(ctx, out_sig, private_key, public_key, message,
                                message_len, 0, context, context_len,
                                propq) == C448_SUCCESS;
}

int
ossl_ed448_verify(OSSL_LIB_CTX *ctx, 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, const char *propq)
{
    return ossl_c448_ed448_verify(ctx, signature, public_key, message,
                                  message_len, 0, context, (uint8_t)context_len,
                                  propq) == C448_SUCCESS;
}

int
ossl_ed448ph_sign(OSSL_LIB_CTX *ctx, 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, const char *propq)
{
    return ossl_c448_ed448_sign_prehash(ctx, out_sig, private_key, public_key,
                                        hash, context, context_len,
                                        propq) == C448_SUCCESS;
}

int
ossl_ed448ph_verify(OSSL_LIB_CTX *ctx, const uint8_t hash[64],
                    const uint8_t signature[114], const uint8_t public_key[57],
                    const uint8_t *context, size_t context_len,
                    const char *propq)
{
    return ossl_c448_ed448_verify_prehash(ctx, signature, public_key, hash,
                                          context, (uint8_t)context_len,
                                          propq) == C448_SUCCESS;
}

int
ossl_ed448_public_from_private(OSSL_LIB_CTX *ctx, uint8_t out_public_key[57],
                               const uint8_t private_key[57], const char *propq)
{
    return ossl_c448_ed448_derive_public_key(ctx, out_public_key, private_key,
                                             propq) == C448_SUCCESS;
}

Coverage Report

Created: 2023-06-08 06:40

Line	Count	Source (jump to first uncovered line)
1		/*
2		* Copyright 2017-2021 The OpenSSL Project Authors. All Rights Reserved.
3		* Copyright 2015-2016 Cryptography Research, Inc.
4		*
5		* Licensed under the Apache License 2.0 (the "License"). You may not use
6		* this file except in compliance with the License. You can obtain a copy
7		* in the file LICENSE in the source distribution or at
8		* https://www.openssl.org/source/license.html
9		*
10		* Originally written by Mike Hamburg
11		*/
12		#include <string.h>
13		#include <openssl/crypto.h>
14		#include <openssl/evp.h>
15		#include "crypto/ecx.h"
16		#include "curve448_local.h"
17		#include "word.h"
18		#include "ed448.h"
19		#include "internal/numbers.h"
20
21	0	#define COFACTOR 4
22
23		static c448_error_t oneshot_hash(OSSL_LIB_CTX ctx, uint8_t out, size_t outlen,
24		const uint8_t *in, size_t inlen,
25		const char *propq)
26	0	{
27	0	EVP_MD_CTX *hashctx = EVP_MD_CTX_new();
28	0	EVP_MD *shake256 = NULL;
29	0	c448_error_t ret = C448_FAILURE;
30
31	0	if (hashctx == NULL)
32	0	return C448_FAILURE;
33
34	0	shake256 = EVP_MD_fetch(ctx, "SHAKE256", propq);
35	0	if (shake256 == NULL)
36	0	goto err;
37
38	0	if (!EVP_DigestInit_ex(hashctx, shake256, NULL)
39	0	\|\| !EVP_DigestUpdate(hashctx, in, inlen)
40	0	\|\| !EVP_DigestFinalXOF(hashctx, out, outlen))
41	0	goto err;
42
43	0	ret = C448_SUCCESS;
44	0	err:
45	0	EVP_MD_CTX_free(hashctx);
46	0	EVP_MD_free(shake256);
47	0	return ret;
48	0	}
49
50		static void clamp(uint8_t secret_scalar_ser[EDDSA_448_PRIVATE_BYTES])
51	0	{
52	0	secret_scalar_ser[0] &= -COFACTOR;
53	0	secret_scalar_ser[EDDSA_448_PRIVATE_BYTES - 1] = 0;
54	0	secret_scalar_ser[EDDSA_448_PRIVATE_BYTES - 2] \|= 0x80;
55	0	}
56
57		static c448_error_t hash_init_with_dom(OSSL_LIB_CTX ctx, EVP_MD_CTX hashctx,
58		uint8_t prehashed,
59		uint8_t for_prehash,
60		const uint8_t *context,
61		size_t context_len,
62		const char *propq)
63	0	{
64		#ifdef CHARSET_EBCDIC
65		const char dom_s[] = {0x53, 0x69, 0x67, 0x45,
66		0x64, 0x34, 0x34, 0x38, 0x00};
67		#else
68	0	const char dom_s[] = "SigEd448";
69	0	#endif
70	0	uint8_t dom[2];
71	0	EVP_MD *shake256 = NULL;
72
73	0	if (context_len > UINT8_MAX)
74	0	return C448_FAILURE;
75
76	0	dom[0] = (uint8_t)(2 - (prehashed == 0 ? 1 : 0)
77	0	- (for_prehash == 0 ? 1 : 0));
78	0	dom[1] = (uint8_t)context_len;
79
80	0	shake256 = EVP_MD_fetch(ctx, "SHAKE256", propq);
81	0	if (shake256 == NULL)
82	0	return C448_FAILURE;
83
84	0	if (!EVP_DigestInit_ex(hashctx, shake256, NULL)
85	0	\|\| !EVP_DigestUpdate(hashctx, dom_s, strlen(dom_s))
86	0	\|\| !EVP_DigestUpdate(hashctx, dom, sizeof(dom))
87	0	\|\| !EVP_DigestUpdate(hashctx, context, context_len)) {
88	0	EVP_MD_free(shake256);
89	0	return C448_FAILURE;
90	0	}
91
92	0	EVP_MD_free(shake256);
93	0	return C448_SUCCESS;
94	0	}
95
96		/* In this file because it uses the hash */
97		c448_error_t
98		ossl_c448_ed448_convert_private_key_to_x448(
99		OSSL_LIB_CTX *ctx,
100		uint8_t x[X448_PRIVATE_BYTES],
101		const uint8_t ed [EDDSA_448_PRIVATE_BYTES],
102		const char *propq)
103	0	{
104		/* pass the private key through oneshot_hash function */
105		/* and keep the first X448_PRIVATE_BYTES bytes */
106	0	return oneshot_hash(ctx, x, X448_PRIVATE_BYTES, ed,
107	0	EDDSA_448_PRIVATE_BYTES, propq);
108	0	}
109
110		c448_error_t
111		ossl_c448_ed448_derive_public_key(
112		OSSL_LIB_CTX *ctx,
113		uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
114		const uint8_t privkey[EDDSA_448_PRIVATE_BYTES],
115		const char *propq)
116	0	{
117		/* only this much used for keygen */
118	0	uint8_t secret_scalar_ser[EDDSA_448_PRIVATE_BYTES];
119	0	curve448_scalar_t secret_scalar;
120	0	unsigned int c;
121	0	curve448_point_t p;
122
123	0	if (!oneshot_hash(ctx, secret_scalar_ser, sizeof(secret_scalar_ser),
124	0	privkey,
125	0	EDDSA_448_PRIVATE_BYTES,
126	0	propq))
127	0	return C448_FAILURE;
128
129	0	clamp(secret_scalar_ser);
130
131	0	ossl_curve448_scalar_decode_long(secret_scalar, secret_scalar_ser,
132	0	sizeof(secret_scalar_ser));
133
134		/*
135		* Since we are going to mul_by_cofactor during encoding, divide by it
136		* here. However, the EdDSA base point is not the same as the decaf base
137		* point if the sigma isogeny is in use: the EdDSA base point is on
138		* Etwist_d/(1-d) and the decaf base point is on Etwist_d, and when
139		* converted it effectively picks up a factor of 2 from the isogenies. So
140		* we might start at 2 instead of 1.
141		*/
142	0	for (c = 1; c < C448_EDDSA_ENCODE_RATIO; c <<= 1)
143	0	ossl_curve448_scalar_halve(secret_scalar, secret_scalar);
144
145	0	ossl_curve448_precomputed_scalarmul(p, ossl_curve448_precomputed_base,
146	0	secret_scalar);
147
148	0	ossl_curve448_point_mul_by_ratio_and_encode_like_eddsa(pubkey, p);
149
150		/* Cleanup */
151	0	ossl_curve448_scalar_destroy(secret_scalar);
152	0	ossl_curve448_point_destroy(p);
153	0	OPENSSL_cleanse(secret_scalar_ser, sizeof(secret_scalar_ser));
154
155	0	return C448_SUCCESS;
156	0	}
157
158		c448_error_t
159		ossl_c448_ed448_sign(OSSL_LIB_CTX *ctx,
160		uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
161		const uint8_t privkey[EDDSA_448_PRIVATE_BYTES],
162		const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
163		const uint8_t *message, size_t message_len,
164		uint8_t prehashed, const uint8_t *context,
165		size_t context_len, const char *propq)
166	0	{
167	0	curve448_scalar_t secret_scalar;
168	0	EVP_MD_CTX *hashctx = EVP_MD_CTX_new();
169	0	c448_error_t ret = C448_FAILURE;
170	0	curve448_scalar_t nonce_scalar;
171	0	uint8_t nonce_point[EDDSA_448_PUBLIC_BYTES] = { 0 };
172	0	unsigned int c;
173	0	curve448_scalar_t challenge_scalar;
174
175	0	if (hashctx == NULL)
176	0	return C448_FAILURE;
177
178	0	{
179		/*
180		* Schedule the secret key, First EDDSA_448_PRIVATE_BYTES is serialized
181		* secret scalar,next EDDSA_448_PRIVATE_BYTES bytes is the seed.
182		*/
183	0	uint8_t expanded[EDDSA_448_PRIVATE_BYTES * 2];
184
185	0	if (!oneshot_hash(ctx, expanded, sizeof(expanded), privkey,
186	0	EDDSA_448_PRIVATE_BYTES, propq))
187	0	goto err;
188	0	clamp(expanded);
189	0	ossl_curve448_scalar_decode_long(secret_scalar, expanded,
190	0	EDDSA_448_PRIVATE_BYTES);
191
192		/* Hash to create the nonce */
193	0	if (!hash_init_with_dom(ctx, hashctx, prehashed, 0, context,
194	0	context_len, propq)
195	0	\|\| !EVP_DigestUpdate(hashctx,
196	0	expanded + EDDSA_448_PRIVATE_BYTES,
197	0	EDDSA_448_PRIVATE_BYTES)
198	0	\|\| !EVP_DigestUpdate(hashctx, message, message_len)) {
199	0	OPENSSL_cleanse(expanded, sizeof(expanded));
200	0	goto err;
201	0	}
202	0	OPENSSL_cleanse(expanded, sizeof(expanded));
203	0	}
204
205		/* Decode the nonce */
206	0	{
207	0	uint8_t nonce[2 * EDDSA_448_PRIVATE_BYTES];
208
209	0	if (!EVP_DigestFinalXOF(hashctx, nonce, sizeof(nonce)))
210	0	goto err;
211	0	ossl_curve448_scalar_decode_long(nonce_scalar, nonce, sizeof(nonce));
212	0	OPENSSL_cleanse(nonce, sizeof(nonce));
213	0	}
214
215	0	{
216		/* Scalarmul to create the nonce-point */
217	0	curve448_scalar_t nonce_scalar_2;
218	0	curve448_point_t p;
219
220	0	ossl_curve448_scalar_halve(nonce_scalar_2, nonce_scalar);
221	0	for (c = 2; c < C448_EDDSA_ENCODE_RATIO; c <<= 1)
222	0	ossl_curve448_scalar_halve(nonce_scalar_2, nonce_scalar_2);
223
224	0	ossl_curve448_precomputed_scalarmul(p, ossl_curve448_precomputed_base,
225	0	nonce_scalar_2);
226	0	ossl_curve448_point_mul_by_ratio_and_encode_like_eddsa(nonce_point, p);
227	0	ossl_curve448_point_destroy(p);
228	0	ossl_curve448_scalar_destroy(nonce_scalar_2);
229	0	}
230
231	0	{
232	0	uint8_t challenge[2 * EDDSA_448_PRIVATE_BYTES];
233
234		/* Compute the challenge */
235	0	if (!hash_init_with_dom(ctx, hashctx, prehashed, 0, context, context_len,
236	0	propq)
237	0	\|\| !EVP_DigestUpdate(hashctx, nonce_point, sizeof(nonce_point))
238	0	\|\| !EVP_DigestUpdate(hashctx, pubkey, EDDSA_448_PUBLIC_BYTES)
239	0	\|\| !EVP_DigestUpdate(hashctx, message, message_len)
240	0	\|\| !EVP_DigestFinalXOF(hashctx, challenge, sizeof(challenge)))
241	0	goto err;
242
243	0	ossl_curve448_scalar_decode_long(challenge_scalar, challenge,
244	0	sizeof(challenge));
245	0	OPENSSL_cleanse(challenge, sizeof(challenge));
246	0	}
247
248	0	ossl_curve448_scalar_mul(challenge_scalar, challenge_scalar, secret_scalar);
249	0	ossl_curve448_scalar_add(challenge_scalar, challenge_scalar, nonce_scalar);
250
251	0	OPENSSL_cleanse(signature, EDDSA_448_SIGNATURE_BYTES);
252	0	memcpy(signature, nonce_point, sizeof(nonce_point));
253	0	ossl_curve448_scalar_encode(&signature[EDDSA_448_PUBLIC_BYTES],
254	0	challenge_scalar);
255
256	0	ossl_curve448_scalar_destroy(secret_scalar);
257	0	ossl_curve448_scalar_destroy(nonce_scalar);
258	0	ossl_curve448_scalar_destroy(challenge_scalar);
259
260	0	ret = C448_SUCCESS;
261	0	err:
262	0	EVP_MD_CTX_free(hashctx);
263	0	return ret;
264	0	}
265
266		c448_error_t
267		ossl_c448_ed448_sign_prehash(
268		OSSL_LIB_CTX *ctx,
269		uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
270		const uint8_t privkey[EDDSA_448_PRIVATE_BYTES],
271		const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
272		const uint8_t hash[64], const uint8_t *context,
273		size_t context_len, const char *propq)
274	0	{
275	0	return ossl_c448_ed448_sign(ctx, signature, privkey, pubkey, hash, 64, 1,
276	0	context, context_len, propq);
277	0	}
278
279		c448_error_t
280		ossl_c448_ed448_verify(
281		OSSL_LIB_CTX *ctx,
282		const uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
283		const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
284		const uint8_t *message, size_t message_len,
285		uint8_t prehashed, const uint8_t *context,
286		uint8_t context_len, const char *propq)
287	0	{
288	0	curve448_point_t pk_point, r_point;
289	0	c448_error_t error;
290	0	curve448_scalar_t challenge_scalar;
291	0	curve448_scalar_t response_scalar;
292		/* Order in little endian format */
293	0	static const uint8_t order[] = {
294	0	0xF3, 0x44, 0x58, 0xAB, 0x92, 0xC2, 0x78, 0x23, 0x55, 0x8F, 0xC5, 0x8D,
295	0	0x72, 0xC2, 0x6C, 0x21, 0x90, 0x36, 0xD6, 0xAE, 0x49, 0xDB, 0x4E, 0xC4,
296	0	0xE9, 0x23, 0xCA, 0x7C, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
297	0	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
298	0	0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x3F, 0x00
299	0	};
300	0	int i;
301
302		/*
303		* Check that s (second 57 bytes of the sig) is less than the order. Both
304		* s and the order are in little-endian format. This can be done in
305		* variable time, since if this is not the case the signature if publicly
306		* invalid.
307		*/
308	0	for (i = EDDSA_448_PUBLIC_BYTES - 1; i >= 0; i--) {
309	0	if (signature[i + EDDSA_448_PUBLIC_BYTES] > order[i])
310	0	return C448_FAILURE;
311	0	if (signature[i + EDDSA_448_PUBLIC_BYTES] < order[i])
312	0	break;
313	0	}
314	0	if (i < 0)
315	0	return C448_FAILURE;
316
317	0	error =
318	0	ossl_curve448_point_decode_like_eddsa_and_mul_by_ratio(pk_point, pubkey);
319
320	0	if (C448_SUCCESS != error)
321	0	return error;
322
323	0	error =
324	0	ossl_curve448_point_decode_like_eddsa_and_mul_by_ratio(r_point, signature);
325	0	if (C448_SUCCESS != error)
326	0	return error;
327
328	0	{
329		/* Compute the challenge */
330	0	EVP_MD_CTX *hashctx = EVP_MD_CTX_new();
331	0	uint8_t challenge[2 * EDDSA_448_PRIVATE_BYTES];
332
333	0	if (hashctx == NULL
334	0	\|\| !hash_init_with_dom(ctx, hashctx, prehashed, 0, context,
335	0	context_len, propq)
336	0	\|\| !EVP_DigestUpdate(hashctx, signature, EDDSA_448_PUBLIC_BYTES)
337	0	\|\| !EVP_DigestUpdate(hashctx, pubkey, EDDSA_448_PUBLIC_BYTES)
338	0	\|\| !EVP_DigestUpdate(hashctx, message, message_len)
339	0	\|\| !EVP_DigestFinalXOF(hashctx, challenge, sizeof(challenge))) {
340	0	EVP_MD_CTX_free(hashctx);
341	0	return C448_FAILURE;
342	0	}
343
344	0	EVP_MD_CTX_free(hashctx);
345	0	ossl_curve448_scalar_decode_long(challenge_scalar, challenge,
346	0	sizeof(challenge));
347	0	OPENSSL_cleanse(challenge, sizeof(challenge));
348	0	}
349	0	ossl_curve448_scalar_sub(challenge_scalar, ossl_curve448_scalar_zero,
350	0	challenge_scalar);
351
352	0	ossl_curve448_scalar_decode_long(response_scalar,
353	0	&signature[EDDSA_448_PUBLIC_BYTES],
354	0	EDDSA_448_PRIVATE_BYTES);
355
356		/* pk_point = -c(x(P)) + (cx + k)G = kG */
357	0	ossl_curve448_base_double_scalarmul_non_secret(pk_point,
358	0	response_scalar,
359	0	pk_point, challenge_scalar);
360	0	return c448_succeed_if(ossl_curve448_point_eq(pk_point, r_point));
361	0	}
362
363		c448_error_t
364		ossl_c448_ed448_verify_prehash(
365		OSSL_LIB_CTX *ctx,
366		const uint8_t signature[EDDSA_448_SIGNATURE_BYTES],
367		const uint8_t pubkey[EDDSA_448_PUBLIC_BYTES],
368		const uint8_t hash[64], const uint8_t *context,
369		uint8_t context_len, const char *propq)
370	0	{
371	0	return ossl_c448_ed448_verify(ctx, signature, pubkey, hash, 64, 1, context,
372	0	context_len, propq);
373	0	}
374
375		int
376		ossl_ed448_sign(OSSL_LIB_CTX ctx, uint8_t out_sig, const uint8_t *message,
377		size_t message_len, const uint8_t public_key[57],
378		const uint8_t private_key[57], const uint8_t *context,
379		size_t context_len, const char *propq)
380	0	{
381	0	return ossl_c448_ed448_sign(ctx, out_sig, private_key, public_key, message,
382	0	message_len, 0, context, context_len,
383	0	propq) == C448_SUCCESS;
384	0	}
385
386		int
387		ossl_ed448_verify(OSSL_LIB_CTX ctx, const uint8_t message, size_t message_len,
388		const uint8_t signature[114], const uint8_t public_key[57],
389		const uint8_t context, size_t context_len, const char propq)
390	0	{
391	0	return ossl_c448_ed448_verify(ctx, signature, public_key, message,
392	0	message_len, 0, context, (uint8_t)context_len,
393	0	propq) == C448_SUCCESS;
394	0	}
395
396		int
397		ossl_ed448ph_sign(OSSL_LIB_CTX ctx, uint8_t out_sig, const uint8_t hash[64],
398		const uint8_t public_key[57], const uint8_t private_key[57],
399		const uint8_t context, size_t context_len, const char propq)
400	0	{
401	0	return ossl_c448_ed448_sign_prehash(ctx, out_sig, private_key, public_key,
402	0	hash, context, context_len,
403	0	propq) == C448_SUCCESS;
404	0	}
405
406		int
407		ossl_ed448ph_verify(OSSL_LIB_CTX *ctx, const uint8_t hash[64],
408		const uint8_t signature[114], const uint8_t public_key[57],
409		const uint8_t *context, size_t context_len,
410		const char *propq)
411	0	{
412	0	return ossl_c448_ed448_verify_prehash(ctx, signature, public_key, hash,
413	0	context, (uint8_t)context_len,
414	0	propq) == C448_SUCCESS;
415	0	}
416
417		int
418		ossl_ed448_public_from_private(OSSL_LIB_CTX *ctx, uint8_t out_public_key[57],
419		const uint8_t private_key[57], const char *propq)
420	0	{
421	0	return ossl_c448_ed448_derive_public_key(ctx, out_public_key, private_key,
422	0	propq) == C448_SUCCESS;
423	0	}