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1// SPDX-License-Identifier: GPL-2.0-or-later2 3#include <crypto/curve25519.h>4#include <crypto/internal/kpp.h>5#include <crypto/kpp.h>6#include <linux/module.h>7#include <linux/scatterlist.h>8 9static int curve25519_set_secret(struct crypto_kpp *tfm, const void *buf,10 unsigned int len)11{12 u8 *secret = kpp_tfm_ctx(tfm);13 14 if (!len)15 curve25519_generate_secret(secret);16 else if (len == CURVE25519_KEY_SIZE &&17 crypto_memneq(buf, curve25519_null_point, CURVE25519_KEY_SIZE))18 memcpy(secret, buf, CURVE25519_KEY_SIZE);19 else20 return -EINVAL;21 return 0;22}23 24static int curve25519_compute_value(struct kpp_request *req)25{26 struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);27 const u8 *secret = kpp_tfm_ctx(tfm);28 u8 public_key[CURVE25519_KEY_SIZE];29 u8 buf[CURVE25519_KEY_SIZE];30 int copied, nbytes;31 u8 const *bp;32 33 if (req->src) {34 copied = sg_copy_to_buffer(req->src,35 sg_nents_for_len(req->src,36 CURVE25519_KEY_SIZE),37 public_key, CURVE25519_KEY_SIZE);38 if (copied != CURVE25519_KEY_SIZE)39 return -EINVAL;40 bp = public_key;41 } else {42 bp = curve25519_base_point;43 }44 45 curve25519_generic(buf, secret, bp);46 47 /* might want less than we've got */48 nbytes = min_t(size_t, CURVE25519_KEY_SIZE, req->dst_len);49 copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst,50 nbytes),51 buf, nbytes);52 if (copied != nbytes)53 return -EINVAL;54 return 0;55}56 57static unsigned int curve25519_max_size(struct crypto_kpp *tfm)58{59 return CURVE25519_KEY_SIZE;60}61 62static struct kpp_alg curve25519_alg = {63 .base.cra_name = "curve25519",64 .base.cra_driver_name = "curve25519-generic",65 .base.cra_priority = 100,66 .base.cra_module = THIS_MODULE,67 .base.cra_ctxsize = CURVE25519_KEY_SIZE,68 69 .set_secret = curve25519_set_secret,70 .generate_public_key = curve25519_compute_value,71 .compute_shared_secret = curve25519_compute_value,72 .max_size = curve25519_max_size,73};74 75static int __init curve25519_init(void)76{77 return crypto_register_kpp(&curve25519_alg);78}79 80static void __exit curve25519_exit(void)81{82 crypto_unregister_kpp(&curve25519_alg);83}84 85subsys_initcall(curve25519_init);86module_exit(curve25519_exit);87 88MODULE_ALIAS_CRYPTO("curve25519");89MODULE_ALIAS_CRYPTO("curve25519-generic");90MODULE_DESCRIPTION("Curve25519 elliptic curve (RFC7748)");91MODULE_LICENSE("GPL");92