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// SPDX-License-Identifier: GPL-2.0-or-later #include <crypto/curve25519.h> #include <crypto/internal/kpp.h> #include <crypto/kpp.h> #include <linux/module.h> #include <linux/scatterlist.h> static int curve25519_set_secret(struct crypto_kpp *tfm, const void *buf, unsigned int len) { u8 *secret = kpp_tfm_ctx(tfm); if (!len) curve25519_generate_secret(secret); else if (len == CURVE25519_KEY_SIZE && crypto_memneq(buf, curve25519_null_point, CURVE25519_KEY_SIZE)) memcpy(secret, buf, CURVE25519_KEY_SIZE); else return -EINVAL; return 0; } static int curve25519_compute_value(struct kpp_request *req) { struct crypto_kpp *tfm = crypto_kpp_reqtfm(req); const u8 *secret = kpp_tfm_ctx(tfm); u8 public_key[CURVE25519_KEY_SIZE]; u8 buf[CURVE25519_KEY_SIZE]; int copied, nbytes; u8 const *bp; if (req->src) { copied = sg_copy_to_buffer(req->src, sg_nents_for_len(req->src, CURVE25519_KEY_SIZE), public_key, CURVE25519_KEY_SIZE); if (copied != CURVE25519_KEY_SIZE) return -EINVAL; bp = public_key; } else { bp = curve25519_base_point; } curve25519_generic(buf, secret, bp); /* might want less than we've got */ nbytes = min_t(size_t, CURVE25519_KEY_SIZE, req->dst_len); copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst, nbytes), buf, nbytes); if (copied != nbytes) return -EINVAL; return 0; } static unsigned int curve25519_max_size(struct crypto_kpp *tfm) { return CURVE25519_KEY_SIZE; } static struct kpp_alg curve25519_alg = { .base.cra_name = "curve25519", .base.cra_driver_name = "curve25519-generic", .base.cra_priority = 100, .base.cra_module = THIS_MODULE, .base.cra_ctxsize = CURVE25519_KEY_SIZE, .set_secret = curve25519_set_secret, .generate_public_key = curve25519_compute_value, .compute_shared_secret = curve25519_compute_value, .max_size = curve25519_max_size, }; static int __init curve25519_init(void) { return crypto_register_kpp(&curve25519_alg); } static void __exit curve25519_exit(void) { crypto_unregister_kpp(&curve25519_alg); } subsys_initcall(curve25519_init); module_exit(curve25519_exit); MODULE_ALIAS_CRYPTO("curve25519"); MODULE_ALIAS_CRYPTO("curve25519-generic"); MODULE_DESCRIPTION("Curve25519 elliptic curve (RFC7748)"); MODULE_LICENSE("GPL");