cryptodev: clarify API for AES-CCM

[dpdk.git] / lib / librte_cryptodev / rte_crypto_sym.h

diff --git a/lib/librte_cryptodev/rte_crypto_sym.h b/lib/librte_cryptodev/rte_crypto_sym.h
index 0ceaa91..5f859ec 100644 (file)
--- a/lib/librte_cryptodev/rte_crypto_sym.h
+++ b/lib/librte_cryptodev/rte_crypto_sym.h
@@ -196,7 +196,9 @@ struct rte_crypto_cipher_xform {
                 * space for the implementation to write in the flags
                 * in the first byte). Note that a full 16 bytes should
                 * be allocated, even though the length field will
-                * have a value less than this.
+                * have a value less than this. Note that the PMDs may
+                * modify the memory reserved (the first byte and the
+                * final padding)
                 *
                 * - For AES-XTS, this is the 128bit tweak, i, from
                 * IEEE Std 1619-2007.
@@ -555,20 +557,19 @@ struct rte_crypto_sym_op {
                                 * Specifically for CCM (@ref RTE_CRYPTO_AEAD_AES_CCM),
                                 * the caller should setup this field as follows:
                                 *
-                                * - the nonce should be written starting at an offset
-                                * of one byte into the array, leaving room for the
-                                * implementation to write in the flags to the first
-                                * byte.
-                                *
-                                * - the additional  authentication data itself should
+                                * - the additional authentication data itself should
                                 * be written starting at an offset of 18 bytes into
-                                * the array, leaving room for the length encoding in
-                                * the first two bytes of the second block.
+                                * the array, leaving room for the first block (16 bytes)
+                                * and the length encoding in the first two bytes of the
+                                * second block.
                                 *
                                 * - the array should be big enough to hold the above
-                                *  fields, plus any padding to round this up to the
-                                *  nearest multiple of the block size (16 bytes).
-                                *  Padding will be added by the implementation.
+                                * fields, plus any padding to round this up to the
+                                * nearest multiple of the block size (16 bytes).
+                                * Padding will be added by the implementation.
+                                *
+                                * - Note that PMDs may modify the memory reserved
+                                * (first 18 bytes and the final padding).
                                 *
                                 * Finally, for GCM (@ref RTE_CRYPTO_AEAD_AES_GCM), the
                                 * caller should setup this field as follows: