stun

commit 2adfcd8bcdd0469b809690660e95f1f609827e86
parent 36d736adf16ec63c3703ec02915e0cf77e168691
Author: sin <sin@2f30.org>
Date:   Thu, 31 Mar 2016 17:59:29 +0100

some comments

Diffstat:
M
stun.c
 | 
11
++++++++++-

1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/stun.c b/stun.c
@@ -268,18 +268,23 @@ aesenc(EVP_CIPHER_CTX *ctx, unsigned char *ct, unsigned char *pt, int ptlen,
 {
 	int len, flen;
 
+	/* initialize encryption operation with the given key and iv */
 	if (EVP_EncryptInit_ex(ctx, EVP_aes_256_gcm(), NULL, key, iv) != 1)
 		logerr("EVP_EncryptInit_ex failed");
 
+	/* encrypt additional authentication data */
 	if (EVP_EncryptUpdate(ctx, NULL, &len, aad, aadlen) != 1)
 		logerr("EVP_EncryptUpdate failed");
 
+	/* encrypt payload */
 	if (EVP_EncryptUpdate(ctx, ct, &len, pt, ptlen) != 1)
 		logerr("EVP_EncryptUpdate failed");
 
+	/* finalize encryption */
 	if (EVP_EncryptFinal_ex(ctx, ct + len, &flen) != 1)
 		logerr("EVP_EncryptFinal_ex failed");
 
+	/* get the tag */
 	if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, TAGLEN, tag) != 1)
 		logerr("EVP_CTRL_GCM_GET_TAG failed");
 
@@ -293,19 +298,23 @@ aesdec(EVP_CIPHER_CTX *ctx, unsigned char *pt, unsigned char *ct, int ctlen,
 {
 	int len, flen;
 
+	/* initialize decryption operation with the given key and iv */
 	if (EVP_DecryptInit_ex(ctx, EVP_aes_256_gcm(), NULL, key, iv) != 1)
 		logerr("EVP_DecryptInit_ex failed");
 
+	/* decrypt additional authentication data */
 	if (EVP_DecryptUpdate(ctx, NULL, &len, aad, aadlen) != 1)
 		logerr("EVP_DecryptUpdate failed");
 
+	/* decrypt payload */
 	if (EVP_DecryptUpdate(ctx, pt, &len, ct, ctlen) != 1)
 		logerr("EVP_DecryptUpdate failed");
 
+	/* set the tag */
 	if (EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_TAG, TAGLEN, tag) != 1)
 		logerr("EVP_CTRL_GCM_SET_TAG failed");
 
-	/* if this fails, someone has tampered with the packet in transit */
+	/* finalize decryption and check if the tag matches */
 	if (EVP_DecryptFinal_ex(ctx, pt + len, &flen) != 1)
 		return -1;