Mercurial > dropbear
diff libtomcrypt/src/pk/asn1/der/bit/der_decode_raw_bit_string.c @ 1511:5916af64acd4 fuzz
merge from main
author | Matt Johnston <matt@ucc.asn.au> |
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date | Sat, 17 Feb 2018 19:29:51 +0800 |
parents | 6dba84798cd5 |
children |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/libtomcrypt/src/pk/asn1/der/bit/der_decode_raw_bit_string.c Sat Feb 17 19:29:51 2018 +0800 @@ -0,0 +1,107 @@ +/* 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_bit_string.c + ASN.1 DER, encode a BIT STRING, Tom St Denis +*/ + + +#ifdef LTC_DER + +#define SETBIT(v, n) (v=((unsigned char)(v) | (1U << (unsigned char)(n)))) +#define CLRBIT(v, n) (v=((unsigned char)(v) & ~(1U << (unsigned char)(n)))) + +/** + Store a BIT STRING + @param in The DER encoded BIT STRING + @param inlen The size of the DER BIT STRING + @param out [out] The array of bits stored (8 per char) + @param outlen [in/out] The number of bits stored + @return CRYPT_OK if successful +*/ +int der_decode_raw_bit_string(const unsigned char *in, unsigned long inlen, + unsigned char *out, unsigned long *outlen) +{ + unsigned long dlen, blen, x, y; + + LTC_ARGCHK(in != NULL); + LTC_ARGCHK(out != NULL); + LTC_ARGCHK(outlen != NULL); + + /* packet must be at least 4 bytes */ + if (inlen < 4) { + return CRYPT_INVALID_ARG; + } + + /* check for 0x03 */ + if ((in[0]&0x1F) != 0x03) { + return CRYPT_INVALID_PACKET; + } + + /* offset in the data */ + x = 1; + + /* get the length of the data */ + if (in[x] & 0x80) { + /* long format get number of length bytes */ + y = in[x++] & 0x7F; + + /* invalid if 0 or > 2 */ + if (y == 0 || y > 2) { + return CRYPT_INVALID_PACKET; + } + + /* read the data len */ + dlen = 0; + while (y--) { + dlen = (dlen << 8) | (unsigned long)in[x++]; + } + } else { + /* short format */ + dlen = in[x++] & 0x7F; + } + + /* is the data len too long or too short? */ + if ((dlen == 0) || (dlen + x > inlen)) { + return CRYPT_INVALID_PACKET; + } + + /* get padding count */ + blen = ((dlen - 1) << 3) - (in[x++] & 7); + + /* too many bits? */ + if (blen > *outlen) { + *outlen = blen; + return CRYPT_BUFFER_OVERFLOW; + } + + /* decode/store the bits */ + for (y = 0; y < blen; y++) { + if (in[x] & (1 << (7 - (y & 7)))) { + SETBIT(out[y/8], 7-(y%8)); + } else { + CLRBIT(out[y/8], 7-(y%8)); + } + if ((y & 7) == 7) { + ++x; + } + } + + /* we done */ + *outlen = blen; + return CRYPT_OK; +} + +#endif + +/* ref: $Format:%D$ */ +/* git commit: $Format:%H$ */ +/* commit time: $Format:%ai$ */