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2340bcd3 JVH |
1 | #include <stdlib.h> |
2 | #include <stdio.h> | |
3 | #include <string.h> | |
4 | #include <ctype.h> | |
5 | ||
6 | #include "rsapem.h" | |
7 | #include "base64.h" | |
8 | ||
9 | #define RSAPRIVHEADER "-----BEGIN RSA PRIVATE KEY-----" | |
10 | #define RSAPRIVFOOTER "-----END RSA PRIVATE KEY-----" | |
11 | ||
12 | struct rsapem_s { | |
13 | unsigned char *data; | |
14 | unsigned int datalen; | |
15 | unsigned int datapos; | |
16 | }; | |
17 | ||
18 | rsapem_t * | |
19 | rsapem_init(const char *pemstr) | |
20 | { | |
21 | rsapem_t *rsapem=NULL; | |
22 | const char *header; | |
23 | const char *footer; | |
24 | base64_t *b64dec; | |
25 | unsigned char *data; | |
26 | int datalen; | |
27 | ||
28 | header = strstr(pemstr, RSAPRIVHEADER); | |
29 | footer = strstr(pemstr, RSAPRIVFOOTER); | |
30 | if (!header || !footer) { | |
31 | return NULL; | |
32 | } | |
33 | ||
34 | ||
35 | /* Base64 decode the whole input excluding header and footer */ | |
36 | b64dec = base64_init(NULL, 0, 1); | |
37 | datalen = base64_decode(b64dec, &data, pemstr+sizeof(RSAPRIVHEADER), | |
38 | (footer-header)-sizeof(RSAPRIVHEADER)); | |
39 | base64_destroy(b64dec); | |
40 | b64dec = NULL; | |
41 | ||
42 | if (datalen < 0) { | |
43 | return NULL; | |
44 | } | |
45 | ||
46 | #ifdef RSAPEM_DEBUG | |
47 | { | |
48 | int i; | |
49 | printf("Decoded output:\n"); | |
50 | for (i=0; i<datalen; i++) { | |
51 | printf("%02x", data[i]); | |
52 | } | |
53 | printf("\n"); | |
54 | } | |
55 | #endif | |
56 | ||
57 | /* Check that first 4 bytes are all valid */ | |
58 | if (datalen < 4 || data[0] != 0x30 || data[1] != 0x82) { | |
59 | free(data); | |
60 | return NULL; | |
61 | } else if (((data[2] << 8) | data[3]) != datalen-4) { | |
62 | free(data); | |
63 | return NULL; | |
64 | } | |
65 | ||
66 | rsapem = calloc(1, sizeof(rsapem_t)); | |
67 | if (!rsapem) { | |
68 | free(data); | |
69 | return NULL; | |
70 | } | |
71 | ||
72 | /* Initialize the data */ | |
73 | rsapem->data = data; | |
74 | rsapem->datalen = datalen; | |
75 | rsapem->datapos = 4; | |
76 | ||
77 | data = NULL; | |
78 | datalen = rsapem_read_vector(rsapem, &data); | |
79 | if (datalen != 1 && data[0] != 0x00) { | |
80 | free(data); | |
81 | rsapem_destroy(rsapem); | |
82 | return NULL; | |
83 | } | |
84 | free(data); | |
85 | return rsapem; | |
86 | } | |
87 | ||
88 | void | |
89 | rsapem_destroy(rsapem_t *rsapem) | |
90 | { | |
91 | if (rsapem) { | |
92 | free(rsapem->data); | |
93 | free(rsapem); | |
94 | } | |
95 | } | |
96 | ||
97 | int | |
98 | rsapem_read_vector(rsapem_t *rsapem, unsigned char **data) | |
99 | { | |
100 | unsigned int length; | |
101 | unsigned char *ptr; | |
102 | ||
103 | if (rsapem->datalen-rsapem->datapos < 2) { | |
104 | return -1; | |
105 | } | |
106 | if (rsapem->data[rsapem->datapos] != 0x02) { | |
107 | return -2; | |
108 | } | |
109 | ||
110 | /* Read vector length */ | |
111 | length = rsapem->data[rsapem->datapos+1]; | |
112 | if (length <= 0x80) { | |
113 | rsapem->datapos += 2; | |
114 | } else if (length == 0x81) { | |
115 | if (rsapem->datalen-rsapem->datapos < 3) { | |
116 | return -3; | |
117 | } | |
118 | length = rsapem->data[rsapem->datapos+2]; | |
119 | rsapem->datapos += 3; | |
120 | } else if (length == 0x82) { | |
121 | if (rsapem->datalen-rsapem->datapos < 4) { | |
122 | return -3; | |
123 | } | |
124 | length = (rsapem->data[rsapem->datapos+2] << 8) | | |
125 | rsapem->data[rsapem->datapos+3]; | |
126 | rsapem->datapos += 4; | |
127 | } else { | |
128 | return -3; | |
129 | } | |
130 | ||
131 | /* Check that we have enough data available */ | |
132 | if (rsapem->datalen-rsapem->datapos < length) { | |
133 | return -4; | |
134 | } | |
135 | ||
136 | /* Allocate data buffer and read bytes */ | |
137 | ptr = malloc(length); | |
138 | if (!ptr) { | |
139 | return -5; | |
140 | } | |
141 | memcpy(ptr, rsapem->data+rsapem->datapos, length); | |
142 | rsapem->datapos += length; | |
143 | ||
144 | /* Return buffer and length */ | |
145 | *data = ptr; | |
146 | return length; | |
147 | } | |
148 |