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/*
* Copyright 2006-2016 The OpenSSL Project Authors. All Rights Reserved.
*
* 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
*/
#include <stdio.h>
#include "internal/cryptlib.h"
#include <openssl/x509.h>
#include <openssl/ec.h>
#include <openssl/rand.h>
#include "internal/asn1_int.h"
#include "internal/evp_int.h"
#include "ec_lcl.h"
#define X25519_KEYLEN 32
#define X25519_BITS 253
#define X25519_SECURITY_BITS 128
typedef struct {
unsigned char pubkey[X25519_KEYLEN];
unsigned char *privkey;
} X25519_KEY;
typedef enum {
X25519_PUBLIC,
X25519_PRIVATE,
X25519_KEYGEN
} ecx_key_op_t;
/* Setup EVP_PKEY using public, private or generation */
static int ecx_key_op(EVP_PKEY *pkey, const X509_ALGOR *palg,
const unsigned char *p, int plen, ecx_key_op_t op)
{
X25519_KEY *xkey;
if (op != X25519_KEYGEN) {
if (palg != NULL) {
int ptype;
/* Algorithm parameters must be absent */
X509_ALGOR_get0(NULL, &ptype, NULL, palg);
if (ptype != V_ASN1_UNDEF) {
ECerr(EC_F_ECX_KEY_OP, EC_R_INVALID_ENCODING);
return 0;
}
}
if (p == NULL || plen != X25519_KEYLEN) {
ECerr(EC_F_ECX_KEY_OP, EC_R_INVALID_ENCODING);
return 0;
}
}
xkey = OPENSSL_zalloc(sizeof(*xkey));
if (xkey == NULL) {
ECerr(EC_F_ECX_KEY_OP, ERR_R_MALLOC_FAILURE);
return 0;
}
if (op == X25519_PUBLIC) {
memcpy(xkey->pubkey, p, plen);
} else {
xkey->privkey = OPENSSL_secure_malloc(X25519_KEYLEN);
if (xkey->privkey == NULL) {
ECerr(EC_F_ECX_KEY_OP, ERR_R_MALLOC_FAILURE);
OPENSSL_free(xkey);
return 0;
}
if (op == X25519_KEYGEN) {
if (RAND_bytes(xkey->privkey, X25519_KEYLEN) <= 0) {
OPENSSL_secure_free(xkey->privkey);
OPENSSL_free(xkey);
return 0;
}
xkey->privkey[0] &= 248;
xkey->privkey[31] &= 127;
xkey->privkey[31] |= 64;
} else {
memcpy(xkey->privkey, p, X25519_KEYLEN);
}
X25519_public_from_private(xkey->pubkey, xkey->privkey);
}
EVP_PKEY_assign(pkey, NID_X25519, xkey);
return 1;
}
static int ecx_pub_encode(X509_PUBKEY *pk, const EVP_PKEY *pkey)
{
const X25519_KEY *xkey = pkey->pkey.ptr;
unsigned char *penc;
if (xkey == NULL) {
ECerr(EC_F_ECX_PUB_ENCODE, EC_R_INVALID_KEY);
return 0;
}
penc = OPENSSL_memdup(xkey->pubkey, X25519_KEYLEN);
if (penc == NULL) {
ECerr(EC_F_ECX_PUB_ENCODE, ERR_R_MALLOC_FAILURE);
return 0;
}
if (!X509_PUBKEY_set0_param(pk, OBJ_nid2obj(NID_X25519), V_ASN1_UNDEF,
NULL, penc, X25519_KEYLEN)) {
OPENSSL_free(penc);
ECerr(EC_F_ECX_PUB_ENCODE, ERR_R_MALLOC_FAILURE);
return 0;
}
return 1;
}
static int ecx_pub_decode(EVP_PKEY *pkey, X509_PUBKEY *pubkey)
{
const unsigned char *p;
int pklen;
X509_ALGOR *palg;
if (!X509_PUBKEY_get0_param(NULL, &p, &pklen, &palg, pubkey))
return 0;
return ecx_key_op(pkey, palg, p, pklen, X25519_PUBLIC);
}
static int ecx_pub_cmp(const EVP_PKEY *a, const EVP_PKEY *b)
{
const X25519_KEY *akey = a->pkey.ptr;
const X25519_KEY *bkey = b->pkey.ptr;
if (akey == NULL || bkey == NULL)
return -2;
return !CRYPTO_memcmp(akey->pubkey, bkey->pubkey, X25519_KEYLEN);
}
static int ecx_priv_decode(EVP_PKEY *pkey, const PKCS8_PRIV_KEY_INFO *p8)
{
const unsigned char *p;
int plen;
ASN1_OCTET_STRING *oct = NULL;
const X509_ALGOR *palg;
int rv;
if (!PKCS8_pkey_get0(NULL, &p, &plen, &palg, p8))
return 0;
oct = d2i_ASN1_OCTET_STRING(NULL, &p, plen);
if (oct == NULL) {
p = NULL;
plen = 0;
} else {
p = ASN1_STRING_get0_data(oct);
plen = ASN1_STRING_length(oct);
}
rv = ecx_key_op(pkey, palg, p, plen, X25519_PRIVATE);
ASN1_OCTET_STRING_free(oct);
return rv;
}
static int ecx_priv_encode(PKCS8_PRIV_KEY_INFO *p8, const EVP_PKEY *pkey)
{
const X25519_KEY *xkey = pkey->pkey.ptr;
ASN1_OCTET_STRING oct;
unsigned char *penc = NULL;
int penclen;
if (xkey == NULL || xkey->privkey == NULL) {
ECerr(EC_F_ECX_PRIV_ENCODE, EC_R_INVALID_PRIVATE_KEY);
return 0;
}
oct.data = xkey->privkey;
oct.length = X25519_KEYLEN;
oct.flags = 0;
penclen = i2d_ASN1_OCTET_STRING(&oct, &penc);
if (penclen < 0) {
ECerr(EC_F_ECX_PRIV_ENCODE, ERR_R_MALLOC_FAILURE);
return 0;
}
if (!PKCS8_pkey_set0(p8, OBJ_nid2obj(NID_X25519), 0,
V_ASN1_UNDEF, NULL, penc, penclen)) {
OPENSSL_clear_free(penc, penclen);
ECerr(EC_F_ECX_PRIV_ENCODE, ERR_R_MALLOC_FAILURE);
return 0;
}
return 1;
}
static int ecx_size(const EVP_PKEY *pkey)
{
return X25519_KEYLEN;
}
static int ecx_bits(const EVP_PKEY *pkey)
{
return X25519_BITS;
}
static int ecx_security_bits(const EVP_PKEY *pkey)
{
return X25519_SECURITY_BITS;
}
static void ecx_free(EVP_PKEY *pkey)
{
X25519_KEY *xkey = pkey->pkey.ptr;
if (xkey)
OPENSSL_secure_free(xkey->privkey);
OPENSSL_free(xkey);
}
/* "parameters" are always equal */
static int ecx_cmp_parameters(const EVP_PKEY *a, const EVP_PKEY *b)
{
return 1;
}
static int ecx_key_print(BIO *bp, const EVP_PKEY *pkey, int indent,
ASN1_PCTX *ctx, ecx_key_op_t op)
{
const X25519_KEY *xkey = pkey->pkey.ptr;
if (op == X25519_PRIVATE) {
if (xkey == NULL || xkey->privkey == NULL) {
if (BIO_printf(bp, "%*s<INVALID PRIVATE KEY>\n", indent, "") <= 0)
return 0;
return 1;
}
if (BIO_printf(bp, "%*sX25519 Private-Key:\n", indent, "") <= 0)
return 0;
if (BIO_printf(bp, "%*spriv:\n", indent, "") <= 0)
return 0
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