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-rw-r--r--crypto/curve25519-generic.c90
1 files changed, 90 insertions, 0 deletions
diff --git a/crypto/curve25519-generic.c b/crypto/curve25519-generic.c
new file mode 100644
index 000000000..d055b0784
--- /dev/null
+++ b/crypto/curve25519-generic.c
@@ -0,0 +1,90 @@
+// 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_LICENSE("GPL");