Add zero padding
diff --git a/library/cipher.c b/library/cipher.c
index 1abc47d..bbde944 100644
--- a/library/cipher.c
+++ b/library/cipher.c
@@ -630,6 +630,33 @@
return 0;
}
+/*
+ * Zero padding: fill with 00 ... 00
+ */
+static void add_zeros_padding( unsigned char *output,
+ size_t output_len, size_t data_len )
+{
+ unsigned char i;
+
+ for( i = data_len; i < output_len; i++ )
+ output[i] = 0x00;
+}
+
+static int get_zeros_padding( unsigned char *input, size_t input_len,
+ size_t *data_len )
+{
+ unsigned char *p = input + input_len - 1;
+ if( NULL == input || NULL == data_len )
+ return POLARSSL_ERR_CIPHER_BAD_INPUT_DATA;
+
+ while( *p == 0x00 && p > input )
+ --p;
+
+ *data_len = *p == 0x00 ? 0 : p - input + 1;
+
+ return 0;
+}
+
int cipher_finish( cipher_context_t *ctx, unsigned char *output, size_t *olen)
{
int ret = 0;
@@ -709,6 +736,13 @@
return 0;
}
+ if( POLARSSL_PADDING_ZEROS == mode )
+ {
+ ctx->add_padding = add_zeros_padding;
+ ctx->get_padding = get_zeros_padding;
+ return 0;
+ }
+
return POLARSSL_ERR_CIPHER_BAD_INPUT_DATA;
}
