/** 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; } }