nettleif

commit 682e2bff0cd7118c454c552377b9ed45fe8a02a8
parent 7f142b1eb0f5738d4ad7cdfa70a012a5a9e18fc9
Author: Dominik Schmidt <dominik@schm1dt.ch>
Date:   Tue, 25 Dec 2018 13:05:22 +0100

Introduce the iv_inband KV switch, that uses the first BLOCK_SIZE bytes of the input as IV

Diffstat:
nettle.c
 | 
56
+++++++++++++++++++++++++++++++++++++++++++++-----------

1 file changed, 45 insertions(+), 11 deletions(-)
diff --git a/nettle.c b/nettle.c
@@ -39,7 +39,7 @@ struct EncStage{
 	uint8_t* dst;
 	String key;
 	String iv;
-	
+	int iv_inband;
 };
 
 String readFile(FILE *f, size_t maxSize){
@@ -245,6 +245,13 @@ int parseKV(struct EncStage *es, char *args){
 			else if(strcmp("iv", k)==0){
 				es->iv=argString(v);
 			}
+			else if(strcmp("iv_inband", k)==0){
+				es->iv_inband=atoi(v);
+				if(es->iv_inband!=0 && es->iv_inband!=1){
+					fprintf(stderr, "iv_inband has to be either 1 or 0, not %s\n", v);
+					return 1;
+				}
+			}
 			else{
 				fprintf(stderr, "Key %s not known\n", k);
 				return 1;
@@ -326,7 +333,12 @@ const char *encDirToString(enum DIRECTION ed){
 }
 
 void fprintEncStage(FILE *f, struct EncStage *es){
-	fprintf(f, "%s using cipher %s in %s-Mode with key \"%s\" and IV \"%s\"\n", encDirToString(es->dir), es->cipher->name, modeToString(es->mode), es->key.str, es->iv.str);
+	if(es->iv_inband==0){
+		fprintf(f, "%s using cipher %s in %s-Mode with key \"%s\" and IV \"%s\"\n", encDirToString(es->dir), es->cipher->name, modeToString(es->mode), es->key.str, es->iv.str);
+	}
+	else{
+		fprintf(f, "%s using cipher %s in %s-Mode with key \"%s\" and IV the first %u bytes from input\n", encDirToString(es->dir), es->cipher->name, modeToString(es->mode), es->key.str, es->cipher->block_size);
+	}
 }
 
 void usage(){
@@ -379,15 +391,28 @@ void CFBDecrypt(void *state, struct EncStage *es){
 
 
 int execute(struct EncStage *es){
-	size_t ctx_s=es->cipher->context_size;
-	void *ctx=malloc(ctx_s);
-	memset(ctx, 0, ctx_s);
-	
-	if(es->iv.len == 0){
+	int free_iv=0;
+	if(es->iv_inband == 1){
+		es->iv.len=es->cipher->block_size;
+		es->iv.str=es->src;
+		es->src+=es->iv.len;
+		es->len-=es->iv.len;
+		es->dst+=es->iv.len;
+	}
+	else if(es->iv.len == 0){
 		es->iv.len=es->cipher->block_size;
 		es->iv.str=malloc(es->iv.len);
 		memset(es->iv.str, 0, es->iv.len);
+		free_iv=1;
+	}
+	else if(es->iv.len != es->cipher->block_size){
+		fprintf(stderr, "IV has to be exactly one block size, is %lu\n", es->iv.len);
+		return 1;
 	}
+	size_t ctx_s=es->cipher->context_size;
+	void *ctx=malloc(ctx_s);
+	memset(ctx, 0, ctx_s);
+	
 	
 	switch(es->dir){
 		case ENCRYPT:
@@ -412,6 +437,10 @@ int execute(struct EncStage *es){
 			if(es->dir==ENCRYPT) CFBEncrypt(ctx, es); else CFBDecrypt(ctx, es);
 			break;
 	}
+	if(free_iv){
+		free(es->iv.str);
+		es->iv.len=0;
+	}
 	free(ctx);
 	return 0;
 }
@@ -427,8 +456,10 @@ int main(int argc, char **argv){
 	String s=readFile(stdin, SIZE_MAX);
 	String s2;
 	char *in=s.str;
-	char *out=NULL;
+	char *out=s.str;
+	size_t len=s.len;
 	for(i=1; i<argc; i++){
+		
 		memset(&es, 0, sizeof(typeof(es)));
 		ret=fillEncStage(&es, argv[i]);
 		if(ret!=0){
@@ -438,17 +469,20 @@ int main(int argc, char **argv){
 		fprintEncStage(stderr, &es);
 		//char *out=malloc(s.len);
 		//memset(out, 0x00, s.len);
-		es.len=s.len;
+		es.len=len;
 		es.src=in;
-		es.dst=in;
+		es.dst=out;
 		
 		if(execute(&es)!=0){
 			return 1;
 		}
+		len=es.len;
+		in=es.src;
+		out=es.dst;
 		//char *tmp=in;
 		//in=out;
 		//free(tmp);
 	}
-	fwrite(in, 1, s.len, stdout);
+	fwrite(es.dst, 1, es.len, stdout);
 	return 0;
 }