From eb7a8f7cfd290d925bfcf6904ca54081559b78d9 Mon Sep 17 00:00:00 2001
From: wipedlife <potatolivingstonei2p@gmail.com>
Date: Tue, 22 Jun 2021 05:00:27 +0300
Subject: [PATCH] x25519 preinit

---
 libbacteria/encdec/async/x25519.c | 137 ++++++++++++++++++++++++++++++
 1 file changed, 137 insertions(+)
 create mode 100644 libbacteria/encdec/async/x25519.c

diff --git a/libbacteria/encdec/async/x25519.c b/libbacteria/encdec/async/x25519.c
new file mode 100644
index 0000000..727de4f
--- /dev/null
+++ b/libbacteria/encdec/async/x25519.c
@@ -0,0 +1,137 @@
+#include<openssl/crypto.h>
+#include <openssl/evp.h>
+
+#include<stdio.h>
+#include<string.h>
+
+#define LENKEY 32
+static size_t len_key = LENKEY;
+struct keysPair{
+	EVP_PKEY * privKey;	//, *pubKey ;
+	unsigned char pubKey[LENKEY+1];
+	EVP_PKEY_CTX * pKeyCtx;//just ctx
+};
+
+
+struct keysPair createKeyPair(const uint8_t * priv, const uint8_t * pub){
+	struct keysPair ret;
+	bzero(ret.pubKey,sizeof(ret.pubKey));
+	EVP_PKEY_CTX * ctx = /*(EVP_CIPHER_CTX*)*/EVP_PKEY_CTX_new_id (NID_X25519, NULL);
+ 	if (!ctx){
+		fprintf(stderr,"Cant create x25519 pair\n");
+		return ret;
+	}
+	EVP_PKEY * privKey = EVP_PKEY_new_raw_private_key (EVP_PKEY_X25519, NULL, priv, len_key);
+       	EVP_PKEY_get_raw_public_key(privKey, ret.pubKey, &len_key);
+	ret.privKey = privKey;
+	//ret.pubKey = pubKey;
+	ret.pKeyCtx=ctx;
+	return ret;
+}
+
+void freeKeyPair(struct keysPair * pair){
+	EVP_PKEY_CTX_free( pair->pKeyCtx );
+	EVP_PKEY_free(pair->privKey);
+//	EVP_PKEY_free(pair->pubKey);
+}
+void freeSharedKeys(uint8_t * w, ...){
+	va_list ap;
+	va_start(ap,w);
+	while(*w){
+		OPENSSL_free(w);
+	}
+	va_end(ap);
+}
+
+struct keysPair generateKeyPair(void){
+	struct keysPair ret;
+	EVP_PKEY_CTX *ctx;
+ 	EVP_PKEY *pkey = NULL;
+ 	ctx = EVP_PKEY_CTX_new_id(NID_X25519, NULL);
+ 	if (!ctx){
+		fprintf(stderr,"Cant create x25519 pair\n");
+		return ret;
+	}
+ 	if (EVP_PKEY_keygen_init(ctx) <= 0){
+		fprintf(stderr, "can't keygen x25519 pair\n");
+		EVP_PKEY_CTX_free(ctx);
+		return ret;
+	}
+	EVP_PKEY_keygen (ctx, &pkey);
+	EVP_PKEY_CTX_free(ctx);
+	ctx = EVP_PKEY_CTX_new (pkey, NULL);
+	bzero(ret.pubKey,sizeof(ret.pubKey));
+	EVP_PKEY_get_raw_public_key (pkey, ret.pubKey, &len_key);
+	//EVP_PKEY_CTX_free (ctx);
+
+	ret.privKey=pkey;
+	//ret.pubKey=pubKey;
+	ret.pKeyCtx=ctx;
+	return ret;
+}
+
+uint8_t * getSharedKey( struct keysPair * pair, const uint8_t * pubPeer, size_t * skeylen ){
+	if (!pubPeer || (pubPeer[31] & 0x80)){
+		 fprintf(stderr,"Is not pubkey!\n");
+		 return NULL;
+	}// not x25519 key
+
+	if(EVP_PKEY_derive_init(pair->pKeyCtx) <= 0){
+		fprintf(stderr,"derive init error\n");
+		return NULL;
+	}
+
+
+	EVP_PKEY * pkey = EVP_PKEY_new_raw_public_key (NID_X25519, NULL, pubPeer, len_key);
+
+	if (EVP_PKEY_derive_set_peer(pair->pKeyCtx, pkey) <= 0)
+	{
+		fprintf(stderr,"Seet peer key error\n");
+		EVP_PKEY_free (pkey);
+		return NULL;
+	}
+	if( EVP_PKEY_derive (pair->pKeyCtx, NULL, skeylen) <= 0){
+		fprintf(stderr, "buffer length derive err\n");
+		EVP_PKEY_free (pkey);
+		return NULL;
+	}	
+	uint8_t * ret = OPENSSL_malloc(*skeylen);
+	if(ret == 0){
+		fprintf(stderr,"OPENSSL malloc err\n");
+		EVP_PKEY_free (pkey);
+		return NULL;
+	}
+	if( EVP_PKEY_derive (pair->pKeyCtx, ret, skeylen) <= 0){
+		fprintf(stderr, "shared key write err\n");
+		EVP_PKEY_free (pkey);
+		return NULL;
+	}	
+	EVP_PKEY_free (pkey);
+	return ret;
+}
+
+int test(void){
+	struct keysPair pair = generateKeyPair();
+	struct keysPair pair1 = generateKeyPair();
+	if(pair.pKeyCtx == NULL || pair1.pKeyCtx == NULL ) {
+		return fprintf(stderr,"can't CTX init\n");
+	}	
+	printf("pubKey: %s\nLen(strlen): %d\n", pair.pubKey,strlen(pair.pubKey));	
+	printf("pubKey1: %s\nLen(strlen): %d\n", pair1.pubKey,strlen(pair1.pubKey));	
+	puts("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~");
+	size_t skeylen,skeylen1; 
+	
+	//bzero(shared0,sizeof(shared0));
+	//bzero(shared1,sizeof(shared0));
+	uint8_t * shared0 = getSharedKey(&pair, pair1.pubKey,&skeylen);
+	uint8_t * shared1 = getSharedKey(&pair1, pair.pubKey, &skeylen1);
+	printf("shared0: %s \nshared1: %s \n",shared0,shared1);
+	freeSharedKeys(shared0,shared1,NULL);
+	freeKeyPair(&pair);freeKeyPair(&pair1);
+}
+
+int main(void){
+	puts("Start test");
+	test();
+	puts("Test is done");
+}