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Diffstat (limited to 'libtomcrypt/src/pk/asn1/der/generalizedtime/der_decode_generalizedtime.c')
| -rw-r--r-- | libtomcrypt/src/pk/asn1/der/generalizedtime/der_decode_generalizedtime.c | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/libtomcrypt/src/pk/asn1/der/generalizedtime/der_decode_generalizedtime.c b/libtomcrypt/src/pk/asn1/der/generalizedtime/der_decode_generalizedtime.c new file mode 100644 index 0000000..016a4c2 --- /dev/null +++ b/libtomcrypt/src/pk/asn1/der/generalizedtime/der_decode_generalizedtime.c @@ -0,0 +1,144 @@ +/* LibTomCrypt, modular cryptographic library -- Tom St Denis + * + * LibTomCrypt is a library that provides various cryptographic + * algorithms in a highly modular and flexible manner. + * + * The library is free for all purposes without any express + * guarantee it works. + */ +#include "tomcrypt.h" + +/** + @file der_decode_generalizedtime.c + ASN.1 DER, decode a GeneralizedTime, Steffen Jaeckel + Based on der_decode_utctime.c +*/ + +#ifdef LTC_DER + +static int _char_to_int(unsigned char x) +{ + switch (x) { + case '0': return 0; + case '1': return 1; + case '2': return 2; + case '3': return 3; + case '4': return 4; + case '5': return 5; + case '6': return 6; + case '7': return 7; + case '8': return 8; + case '9': return 9; + default: return 100; + } +} + +#define DECODE_V(y, max) do {\ + y = _char_to_int(buf[x])*10 + _char_to_int(buf[x+1]); \ + if (y >= max) return CRYPT_INVALID_PACKET; \ + x += 2; \ +} while(0) + +#define DECODE_V4(y, max) do {\ + y = _char_to_int(buf[x])*1000 + _char_to_int(buf[x+1])*100 + _char_to_int(buf[x+2])*10 + _char_to_int(buf[x+3]); \ + if (y >= max) return CRYPT_INVALID_PACKET; \ + x += 4; \ +} while(0) + +/** + 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; + } +} + +#endif + +/* ref: $Format:%D$ */ +/* git commit: $Format:%H$ */ +/* commit time: $Format:%ai$ */ |