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Add zero padding

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Manuel Pégourié-Gonnard 2013-07-26 16:05:14 +02:00 • committed by Paul Bakker
parent 8d4291b52a
commit 0e7d2c0f95
7 changed files with 299 additions and 3 deletions
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34
library/cipher.c
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@ -630,6 +630,33 @@ static int get_zeros_and_len_padding( unsigned char *input, size_t input_len,
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 @@ int cipher_set_padding_mode( cipher_context_t *ctx, cipher_padding_t mode )
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;
}