Split cipher_set_iv() out of cipher_reset()
diff --git a/include/polarssl/cipher.h b/include/polarssl/cipher.h
index ef037be..e540c92 100644
--- a/include/polarssl/cipher.h
+++ b/include/polarssl/cipher.h
@@ -185,7 +185,8 @@
/** Name of the cipher */
const char * name;
- /** IV size, in bytes */
+ /** IV/NONCE size, in bytes, for ciphers with fixed-length IVs), or
+ * 0 for ciphers with variable-length IVs or not using IVs */
unsigned int iv_size;
/** block size, in bytes */
@@ -222,6 +223,9 @@
/** Current IV or NONCE_COUNTER for CTR-mode */
unsigned char iv[POLARSSL_MAX_IV_LENGTH];
+ /** IV size in bytes (for ciphers with variable-length IVs) */
+ size_t iv_size;
+
/** Cipher-specific context */
void *cipher_ctx;
} cipher_context_t;
@@ -315,18 +319,22 @@
}
/**
- * \brief Returns the size of the cipher's IV.
+ * \brief Returns the size of the cipher's IV/NONCE in bytes.
*
* \param ctx cipher's context. Must have been initialised.
*
- * \return size of the cipher's IV, or 0 if ctx has not been
- * initialised or accepts IV of various sizes.
+ * \return If IV has not been set yet: desired size for ciphers
+ * with fixed-size IVs, 0 for other ciphers.
+ * If IV has already been set: actual size.
*/
static inline int cipher_get_iv_size( const cipher_context_t *ctx )
{
if( NULL == ctx || NULL == ctx->cipher_info )
return 0;
+ if( ctx->iv_size != 0 )
+ return ctx->iv_size;
+
return ctx->cipher_info->iv_size;
}
@@ -428,12 +436,24 @@
int cipher_set_padding_mode( cipher_context_t *ctx, cipher_padding_t mode );
/**
+ * \brief Set the initialization vector (IV) or nonce
+ *
+ * \param iv IV to use (or NONCE_COUNTER for CTR-mode ciphers)
+ * \param iv_len IV length for ciphers with variable-size IV,
+ * Discarded by ciphers with fixed-size IV.
+ *
+ * \returns O on success, or POLARSSL_ERR_CIPHER_BAD_INPUT_DATA
+ *
+ * \note Some ciphers don't use IVs nor NONCE. For these
+ * ciphers, this function has no effect.
+ */
+int cipher_set_iv( cipher_context_t *ctx,
+ const unsigned char *iv, size_t iv_len );
+
+/**
* \brief Reset the given context, setting the IV to iv
*
* \param ctx generic cipher context
- * \param iv IV to use or NONCE_COUNTER in the case of a CTR-mode cipher
- * \param iv_len IV length for ciphers with variable-size IV,
- * Discared by ciphers with fixed-size IV.
* \param ad Additional data for AEAD ciphers, or discarded.
* May be NULL only if ad_len is 0.
* \param ad_len Length of ad for AEAD ciphers, or discarded.
@@ -442,7 +462,6 @@
* if parameter verification fails.
*/
int cipher_reset( cipher_context_t *ctx,
- const unsigned char *iv, size_t iv_len,
const unsigned char *ad, size_t ad_len );
/**
