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Add one-and-zeros (ISO/IEC 7816-4) padding

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Manuel Pégourié-Gonnard 2013-07-26 12:46:02 +02:00 • committed by Paul Bakker
parent 6c9789932e
commit 679f9e90ad
7 changed files with 305 additions and 0 deletions
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43
library/cipher.c
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@ -526,6 +526,9 @@ int cipher_update( cipher_context_t *ctx, const unsigned char *input, size_t ile
return POLARSSL_ERR_CIPHER_FEATURE_UNAVAILABLE;
}
/*
* PKCS7 (and PKCS5) padding: fill with ll bytes, with ll = padding_len
*/
static void add_pkcs_padding( unsigned char *output, size_t output_len,
size_t data_len )
{
@ -558,6 +561,39 @@ static int get_pkcs_padding( unsigned char *input, size_t input_len,
return 0;
}
/*
* One and zeros padding: fill with 80 00 ... 00
*/
static void add_one_and_zeros_padding( unsigned char *output,
size_t output_len, size_t data_len )
{
size_t padding_len = output_len - data_len;
unsigned char i = 0;
output[data_len] = 0x80;
for( i = 1; i < padding_len; i++ )
output[data_len + i] = 0x00;
}
static int get_one_and_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;
if( *p != 0x80 )
return POLARSSL_ERR_CIPHER_INVALID_PADDING;
*data_len = p - input;
return 0;
}
int cipher_finish( cipher_context_t *ctx, unsigned char *output, size_t *olen)
{
int ret = 0;
@ -623,6 +659,13 @@ int cipher_set_padding_mode( cipher_context_t *ctx, cipher_padding_t mode )
return 0;
}
if( POLARSSL_PADDING_ONE_AND_ZEROS == mode )
{
ctx->add_padding = add_one_and_zeros_padding;
ctx->get_padding = get_one_and_zeros_padding;
return 0;
}
return POLARSSL_ERR_CIPHER_BAD_INPUT_DATA;
}