Mercurial > dropbear
comparison libtomcrypt/src/pk/asn1/der/bit/der_encode_raw_bit_string.c @ 1471:6dba84798cd5
Update to libtomcrypt 1.18.1, merged with Dropbear changes
author | Matt Johnston <matt@ucc.asn.au> |
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date | Fri, 09 Feb 2018 21:44:05 +0800 |
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1470:8bba51a55704 | 1471:6dba84798cd5 |
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1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis | |
2 * | |
3 * LibTomCrypt is a library that provides various cryptographic | |
4 * algorithms in a highly modular and flexible manner. | |
5 * | |
6 * The library is free for all purposes without any express | |
7 * guarantee it works. | |
8 */ | |
9 #include "tomcrypt.h" | |
10 | |
11 /** | |
12 @file der_encode_bit_string.c | |
13 ASN.1 DER, encode a BIT STRING, Tom St Denis | |
14 */ | |
15 | |
16 | |
17 #ifdef LTC_DER | |
18 | |
19 #define getbit(n, k) (((n) & ( 1 << (k) )) >> (k)) | |
20 | |
21 /** | |
22 Store a BIT STRING | |
23 @param in The array of bits to store (8 per char) | |
24 @param inlen The number of bits to store | |
25 @param out [out] The destination for the DER encoded BIT STRING | |
26 @param outlen [in/out] The max size and resulting size of the DER BIT STRING | |
27 @return CRYPT_OK if successful | |
28 */ | |
29 int der_encode_raw_bit_string(const unsigned char *in, unsigned long inlen, | |
30 unsigned char *out, unsigned long *outlen) | |
31 { | |
32 unsigned long len, x, y; | |
33 unsigned char buf; | |
34 int err; | |
35 | |
36 LTC_ARGCHK(in != NULL); | |
37 LTC_ARGCHK(out != NULL); | |
38 LTC_ARGCHK(outlen != NULL); | |
39 | |
40 /* avoid overflows */ | |
41 if ((err = der_length_bit_string(inlen, &len)) != CRYPT_OK) { | |
42 return err; | |
43 } | |
44 | |
45 if (len > *outlen) { | |
46 *outlen = len; | |
47 return CRYPT_BUFFER_OVERFLOW; | |
48 } | |
49 | |
50 /* store header (include bit padding count in length) */ | |
51 x = 0; | |
52 y = (inlen >> 3) + ((inlen&7) ? 1 : 0) + 1; | |
53 | |
54 out[x++] = 0x03; | |
55 if (y < 128) { | |
56 out[x++] = (unsigned char)y; | |
57 } else if (y < 256) { | |
58 out[x++] = 0x81; | |
59 out[x++] = (unsigned char)y; | |
60 } else if (y < 65536) { | |
61 out[x++] = 0x82; | |
62 out[x++] = (unsigned char)((y>>8)&255); | |
63 out[x++] = (unsigned char)(y&255); | |
64 } | |
65 | |
66 /* store number of zero padding bits */ | |
67 out[x++] = (unsigned char)((8 - inlen) & 7); | |
68 | |
69 /* store the bits in big endian format */ | |
70 for (y = buf = 0; y < inlen; y++) { | |
71 buf |= (getbit(in[y/8],7-y%8)?1:0) << (7 - (y & 7)); | |
72 if ((y & 7) == 7) { | |
73 out[x++] = buf; | |
74 buf = 0; | |
75 } | |
76 } | |
77 /* store last byte */ | |
78 if (inlen & 7) { | |
79 out[x++] = buf; | |
80 } | |
81 | |
82 *outlen = x; | |
83 return CRYPT_OK; | |
84 } | |
85 | |
86 #endif | |
87 | |
88 /* ref: $Format:%D$ */ | |
89 /* git commit: $Format:%H$ */ | |
90 /* commit time: $Format:%ai$ */ |