| 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 | |