ccm_decrypt_message: length argument is cleartext (dst) length

Also updated related functions.

7 files changed, 33 insertions, 19 deletions

diff --git a/ChangeLog b/ChangeLog
index 12ddbc70..2a43a3cb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2014-04-25  Niels Möller  <nisse@lysator.liu.se>
+
+	* testsuite/ccm-test.c (test_cipher_ccm): And tests.
+
+	* ccm.c (ccm_decrypt_message): Change length argument, should now
+	be clear text (dst) length.
+	* ccm-aes128.c (ccm_aes128_decrypt_message): Likewise.
+	* ccm-aes192.c (ccm_aes192_decrypt_message): Likewise.
+	* ccm-aes256.c (ccm_aes256_decrypt_message): Likewise.
+	* ccm.h: Updated prototypes.
+
 2014-04-22  Niels Möller  <nisse@lysator.liu.se>
 
 	* nettle.texinfo (Recommended hash functions): Document additional
diff --git a/ccm-aes128.c b/ccm-aes128.c
index c47249ea..74ae51f4 100644
--- a/ccm-aes128.c
+++ b/ccm-aes128.c
@@ -105,10 +105,10 @@ ccm_aes128_decrypt_message(struct ccm_aes128_ctx *ctx,
 			   size_t nlength, const uint8_t *nonce,
 			   size_t alength, const uint8_t *adata,
 			   size_t tlength,
-			   size_t clength, uint8_t *dst, const uint8_t *src)
+			   size_t mlength, uint8_t *dst, const uint8_t *src)
 {
   return ccm_decrypt_message(&ctx->cipher,
 			     (nettle_cipher_func *) aes128_encrypt,
 			     nlength, nonce, alength, adata,
-			     tlength, clength, dst, src);
+			     tlength, mlength, dst, src);
 }
diff --git a/ccm-aes192.c b/ccm-aes192.c
index 01d406a0..6b6ebed9 100644
--- a/ccm-aes192.c
+++ b/ccm-aes192.c
@@ -105,10 +105,10 @@ ccm_aes192_decrypt_message(struct ccm_aes192_ctx *ctx,
 			   size_t nlength, const uint8_t *nonce,
 			   size_t alength, const uint8_t *adata,
 			   size_t tlength,
-			   size_t clength, uint8_t *dst, const uint8_t *src)
+			   size_t mlength, uint8_t *dst, const uint8_t *src)
 {
   return ccm_decrypt_message(&ctx->cipher,
 			     (nettle_cipher_func *) aes192_encrypt,
 			     nlength, nonce, alength, adata,
-			     tlength, clength, dst, src);
+			     tlength, mlength, dst, src);
 }
diff --git a/ccm-aes256.c b/ccm-aes256.c
index 9a58ceab..211c411b 100644
--- a/ccm-aes256.c
+++ b/ccm-aes256.c
@@ -106,9 +106,9 @@ ccm_aes256_decrypt_message(struct ccm_aes256_ctx *ctx,
 			   size_t nlength, const uint8_t *nonce,
 			   size_t alength, const uint8_t *adata,
 			   size_t tlength,
-			   size_t clength, uint8_t *dst, const uint8_t *src)
+			   size_t mlength, uint8_t *dst, const uint8_t *src)
 {
   return ccm_decrypt_message(&ctx->cipher, (nettle_cipher_func *) aes256_encrypt,
 			     nlength, nonce, alength, adata,
-			     tlength, clength, dst, src);
+			     tlength, mlength, dst, src);
 }
diff --git a/ccm.c b/ccm.c
index 49655914..00f3f26e 100644
--- a/ccm.c
+++ b/ccm.c
@@ -250,14 +250,13 @@ int
 ccm_decrypt_message(const void *cipher, nettle_cipher_func *f,
 		    size_t nlength, const uint8_t *nonce,
 		    size_t alength, const uint8_t *adata, size_t tlength,
-		    size_t clength, uint8_t *dst, const uint8_t *src)
+		    size_t mlength, uint8_t *dst, const uint8_t *src)
 {
   struct ccm_ctx ctx;
   uint8_t tag[CCM_BLOCK_SIZE];
-  assert(clength >= tlength);
-  ccm_set_nonce(&ctx, cipher, f, nlength, nonce, alength, clength-tlength, tlength);
+  ccm_set_nonce(&ctx, cipher, f, nlength, nonce, alength, mlength, tlength);
   ccm_update(&ctx, cipher, f, alength, adata);
-  ccm_decrypt(&ctx, cipher, f, clength-tlength, dst, src);
+  ccm_decrypt(&ctx, cipher, f, mlength, dst, src);
   ccm_digest(&ctx, cipher, f, tlength, tag);
-  return (memcmp(tag, src + (clength-tlength), tlength) == 0);
+  return (memcmp(tag, src + mlength, tlength) == 0);
 }
diff --git a/ccm.h b/ccm.h
index b215360d..9827e45d 100644
--- a/ccm.h
+++ b/ccm.h
@@ -150,7 +150,7 @@ ccm_decrypt_message(const void *cipher, nettle_cipher_func *f,
 		    size_t nlength, const uint8_t *nonce,
 		    size_t alength, const uint8_t *adata,
 		    size_t tlength,
-		    size_t clength, uint8_t *dst, const uint8_t *src);
+		    size_t mlength, uint8_t *dst, const uint8_t *src);
 
 /* CCM Mode with AES-128 */
 struct ccm_aes128_ctx {
@@ -194,7 +194,7 @@ ccm_aes128_decrypt_message(struct ccm_aes128_ctx *ctx,
 			   size_t nlength, const uint8_t *nonce,
 			   size_t alength, const uint8_t *adata,
 			   size_t tlength,
-			   size_t clength, uint8_t *dst, const uint8_t *src);
+			   size_t mlength, uint8_t *dst, const uint8_t *src);
 
 struct ccm_aes192_ctx {
     struct ccm_ctx      ccm;
@@ -238,7 +238,7 @@ ccm_aes192_decrypt_message(struct ccm_aes192_ctx *ctx,
 			   size_t nlength, const uint8_t *nonce,
 			   size_t alength, const uint8_t *adata,
 			   size_t tlength,
-			   size_t clength, uint8_t *dst, const uint8_t *src);
+			   size_t mlength, uint8_t *dst, const uint8_t *src);
 
 /* CCM Mode with AES-256 */
 struct ccm_aes256_ctx {
@@ -282,7 +282,7 @@ ccm_aes256_decrypt_message(struct ccm_aes256_ctx *ctx,
 			   size_t nlength, const uint8_t *nonce,
 			   size_t alength, const uint8_t *adata,
 			   size_t tlength,
-			   size_t clength, uint8_t *dst, const uint8_t *src);
+			   size_t mlength, uint8_t *dst, const uint8_t *src);
 
 #ifdef __cplusplus
 }
diff --git a/testsuite/ccm-test.c b/testsuite/ccm-test.c
index 9a7161b9..4176cc7f 100644
--- a/testsuite/ccm-test.c
+++ b/testsuite/ccm-test.c
@@ -156,10 +156,12 @@ test_cipher_ccm(const struct nettle_cipher *cipher,
     memset(de_digest, 0, sizeof(de_digest));
 
     ccm_encrypt_message(ctx, cipher->encrypt, nonce->length, nonce->data,
-			authdata->length, authdata->data, tlength, ciphertext->length, en_data, cleartext->data);
+			authdata->length, authdata->data, tlength,
+			ciphertext->length, en_data, cleartext->data);
 
     ret = ccm_decrypt_message(ctx, cipher->encrypt, nonce->length, nonce->data,
-			      authdata->length, authdata->data, tlength, ciphertext->length, de_data, ciphertext->data);
+			      authdata->length, authdata->data, tlength,
+			      cleartext->length, de_data, ciphertext->data);
 
     if (ret != 1) fprintf(stderr, "ccm_decrypt_message failed to validate message\n");
     test_compare_results("CCM_MSG", authdata,
@@ -169,13 +171,15 @@ test_cipher_ccm(const struct nettle_cipher *cipher,
     if (tlength) {
       en_data[0] ^= 1;
       ret = ccm_decrypt_message(ctx, cipher->encrypt, nonce->length, nonce->data,
-				authdata->length, authdata->data, tlength, ciphertext->length, de_data, en_data);
+				authdata->length, authdata->data, tlength,
+				cleartext->length, de_data, en_data);
       if (ret != 0) fprintf(stderr, "ccm_decrypt_message failed to detect corrupted message\n");
     }
     /* Ensure we can detect corrupted adata. */
     if (tlength && authdata->length) {
       ret = ccm_decrypt_message(ctx, cipher->encrypt, nonce->length, nonce->data,
-				authdata->length-1, authdata->data, tlength, ciphertext->length, de_data, ciphertext->data);
+				authdata->length-1, authdata->data, tlength,
+				cleartext->length, de_data, ciphertext->data);
       if (ret != 0) fprintf(stderr, "ccm_decrypt_message failed to detect corrupted message\n");
     }
   }