/**
Decodes a UTC time structure in DER format (reads all 6 valid encoding formats)
@param in Input buffer
@param inlen Length of input buffer in octets
@param out [out] Destination of UTC time structure
@return CRYPT_OK if successful
*/
int der_decode_utctime(const unsigned char *in, unsigned long *inlen,
ltc_utctime *out)
{
unsigned char buf[32];
unsigned long x;
int y;
LTC_ARGCHK(in != NULL);
LTC_ARGCHK(inlen != NULL);
LTC_ARGCHK(out != NULL);
/* check header */
if (*inlen < 2UL || (in[1] >= sizeof(buf)) || ((in[1] + 2UL) > *inlen)) {
return CRYPT_INVALID_PACKET;
}
/* decode the string */
for (x = 0; x < in[1]; x++) {
y = der_ia5_value_decode(in[x+2]);
if (y == -1) {
return CRYPT_INVALID_PACKET;
}
buf[x] = y;
}
*inlen = 2 + x;
/* possible encodings are
YYMMDDhhmmZ
YYMMDDhhmm+hh'mm'
YYMMDDhhmm-hh'mm'
YYMMDDhhmmssZ
YYMMDDhhmmss+hh'mm'
YYMMDDhhmmss-hh'mm'
So let's do a trivial decode upto [including] mm
*/
x = 0;
DECODE_V(out->YY, 100);
DECODE_V(out->MM, 13);
DECODE_V(out->DD, 32);
DECODE_V(out->hh, 24);
DECODE_V(out->mm, 60);
/* clear timezone and seconds info */
out->off_dir = out->off_hh = out->off_mm = out->ss = 0;
/* now is it Z, +, - or 0-9 */
if (buf[x] == 'Z') {
return CRYPT_OK;
} else if (buf[x] == '+' || buf[x] == '-') {
out->off_dir = (buf[x++] == '+') ? 0 : 1;
DECODE_V(out->off_hh, 24);
DECODE_V(out->off_mm, 60);
return CRYPT_OK;
}
/* decode seconds */
DECODE_V(out->ss, 60);
/* now is it Z, +, - */
if (buf[x] == 'Z') {
return CRYPT_OK;
} else if (buf[x] == '+' || buf[x] == '-') {
out->off_dir = (buf[x++] == '+') ? 0 : 1;
DECODE_V(out->off_hh, 24);
DECODE_V(out->off_mm, 60);
return CRYPT_OK;
} else {
return CRYPT_INVALID_PACKET;
}
}
/**
Decodes a Generalized time structure in DER format (reads all 6 valid encoding formats)
@param in Input buffer
@param inlen Length of input buffer in octets
@param out [out] Destination of Generalized time structure
@return CRYPT_OK if successful
*/
int der_decode_generalizedtime(const unsigned char *in, unsigned long *inlen,
ltc_generalizedtime *out)
{
unsigned char buf[32];
unsigned long x;
int y;
LTC_ARGCHK(in != NULL);
LTC_ARGCHK(inlen != NULL);
LTC_ARGCHK(out != NULL);
/* check header */
if (*inlen < 2UL || (in[1] >= sizeof(buf)) || ((in[1] + 2UL) > *inlen)) {
return CRYPT_INVALID_PACKET;
}
/* decode the string */
for (x = 0; x < in[1]; x++) {
y = der_ia5_value_decode(in[x+2]);
if (y == -1) {
return CRYPT_INVALID_PACKET;
}
if (!((y >= '0' && y <= '9')
|| y == 'Z' || y == '.'
|| y == '+' || y == '-')) {
return CRYPT_INVALID_PACKET;
}
buf[x] = y;
}
*inlen = 2 + x;
if (x < 15) {
return CRYPT_INVALID_PACKET;
}
/* possible encodings are
YYYYMMDDhhmmssZ
YYYYMMDDhhmmss+hh'mm'
YYYYMMDDhhmmss-hh'mm'
YYYYMMDDhhmmss.fsZ
YYYYMMDDhhmmss.fs+hh'mm'
YYYYMMDDhhmmss.fs-hh'mm'
So let's do a trivial decode upto [including] ss
*/
x = 0;
DECODE_V4(out->YYYY, 10000);
DECODE_V(out->MM, 13);
DECODE_V(out->DD, 32);
DECODE_V(out->hh, 24);
DECODE_V(out->mm, 60);
DECODE_V(out->ss, 60);
/* clear fractional seconds info */
out->fs = 0;
/* now is it Z or . */
if (buf[x] == 'Z') {
return CRYPT_OK;
} else if (buf[x] == '.') {
x++;
while (buf[x] >= '0' && buf[x] <= '9') {
unsigned fs = out->fs;
if (x >= sizeof(buf)) return CRYPT_INVALID_PACKET;
out->fs *= 10;
out->fs += _char_to_int(buf[x]);
if (fs > out->fs) return CRYPT_OVERFLOW;
x++;
}
}
/* now is it Z, +, - */
if (buf[x] == 'Z') {
return CRYPT_OK;
} else if (buf[x] == '+' || buf[x] == '-') {
out->off_dir = (buf[x++] == '+') ? 0 : 1;
DECODE_V(out->off_hh, 24);
DECODE_V(out->off_mm, 60);
return CRYPT_OK;
} else {
return CRYPT_INVALID_PACKET;
}
}
