contrib/lax_der_privatekey_parsing.c

   1 /***********************************************************************
   2  * Copyright (c) 2014, 2015 Pieter Wuille                              *
   3  * Distributed under the MIT software license, see the accompanying    *
   4  * file COPYING or https://www.opensource.org/licenses/mit-license.php.*
   5  ***********************************************************************/
   6
   7 #include <string.h>
   8 #include <secp256k1.h>
   9
  10 #include "lax_der_privatekey_parsing.h"
  11
  12 int ec_privkey_import_der(const secp256k1_context* ctx, unsigned char *out32, const unsigned char *privkey, size_t privkeylen) {
  13     const unsigned char *end = privkey + privkeylen;
  14     int lenb = 0;
  15     int len = 0;
  16     memset(out32, 0, 32);
  17     /* sequence header */
  18     if (end < privkey+1 || *privkey != 0x30) {
  19         return 0;
  20     }
  21     privkey++;
  22     /* sequence length constructor */
  23     if (end < privkey+1 || !(*privkey & 0x80)) {
  24         return 0;
  25     }
  26     lenb = *privkey & ~0x80; privkey++;
  27     if (lenb < 1 || lenb > 2) {
  28         return 0;
  29     }
  30     if (end < privkey+lenb) {
  31         return 0;
  32     }
  33     /* sequence length */
  34     len = privkey[lenb-1] | (lenb > 1 ? privkey[lenb-2] << 8 : 0);
  35     privkey += lenb;
  36     if (end < privkey+len) {
  37         return 0;
  38     }
  39     /* sequence element 0: version number (=1) */
  40     if (end < privkey+3 || privkey[0] != 0x02 || privkey[1] != 0x01 || privkey[2] != 0x01) {
  41         return 0;
  42     }
  43     privkey += 3;
  44     /* sequence element 1: octet string, up to 32 bytes */
  45     if (end < privkey+2 || privkey[0] != 0x04 || privkey[1] > 0x20 || end < privkey+2+privkey[1]) {
  46         return 0;
  47     }
  48     memcpy(out32 + 32 - privkey[1], privkey + 2, privkey[1]);
  49     if (!secp256k1_ec_seckey_verify(ctx, out32)) {
  50         memset(out32, 0, 32);
  51         return 0;
  52     }
  53     return 1;
  54 }
  55
  56 int ec_privkey_export_der(const secp256k1_context *ctx, unsigned char *privkey, size_t *privkeylen, const unsigned char *key32, int compressed) {
  57     secp256k1_pubkey pubkey;
  58     size_t pubkeylen = 0;
  59     if (!secp256k1_ec_pubkey_create(ctx, &pubkey, key32)) {
  60         *privkeylen = 0;
  61         return 0;
  62     }
  63     if (compressed) {
  64         static const unsigned char begin[] = {
  65             0x30,0x81,0xD3,0x02,0x01,0x01,0x04,0x20
  66         };
  67         static const unsigned char middle[] = {
  68             0xA0,0x81,0x85,0x30,0x81,0x82,0x02,0x01,0x01,0x30,0x2C,0x06,0x07,0x2A,0x86,0x48,
  69             0xCE,0x3D,0x01,0x01,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
  70             0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
  71             0xFF,0xFF,0xFE,0xFF,0xFF,0xFC,0x2F,0x30,0x06,0x04,0x01,0x00,0x04,0x01,0x07,0x04,
  72             0x21,0x02,0x79,0xBE,0x66,0x7E,0xF9,0xDC,0xBB,0xAC,0x55,0xA0,0x62,0x95,0xCE,0x87,
  73             0x0B,0x07,0x02,0x9B,0xFC,0xDB,0x2D,0xCE,0x28,0xD9,0x59,0xF2,0x81,0x5B,0x16,0xF8,
  74             0x17,0x98,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
  75             0xFF,0xFF,0xFF,0xFF,0xFE,0xBA,0xAE,0xDC,0xE6,0xAF,0x48,0xA0,0x3B,0xBF,0xD2,0x5E,
  76             0x8C,0xD0,0x36,0x41,0x41,0x02,0x01,0x01,0xA1,0x24,0x03,0x22,0x00
  77         };
  78         unsigned char *ptr = privkey;
  79         memcpy(ptr, begin, sizeof(begin)); ptr += sizeof(begin);
  80         memcpy(ptr, key32, 32); ptr += 32;
  81         memcpy(ptr, middle, sizeof(middle)); ptr += sizeof(middle);
  82         pubkeylen = 33;
  83         secp256k1_ec_pubkey_serialize(ctx, ptr, &pubkeylen, &pubkey, SECP256K1_EC_COMPRESSED);
  84         ptr += pubkeylen;
  85         *privkeylen = ptr - privkey;
  86     } else {
  87         static const unsigned char begin[] = {
  88             0x30,0x82,0x01,0x13,0x02,0x01,0x01,0x04,0x20
  89         };
  90         static const unsigned char middle[] = {
  91             0xA0,0x81,0xA5,0x30,0x81,0xA2,0x02,0x01,0x01,0x30,0x2C,0x06,0x07,0x2A,0x86,0x48,
  92             0xCE,0x3D,0x01,0x01,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
  93             0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
  94             0xFF,0xFF,0xFE,0xFF,0xFF,0xFC,0x2F,0x30,0x06,0x04,0x01,0x00,0x04,0x01,0x07,0x04,
  95             0x41,0x04,0x79,0xBE,0x66,0x7E,0xF9,0xDC,0xBB,0xAC,0x55,0xA0,0x62,0x95,0xCE,0x87,
  96             0x0B,0x07,0x02,0x9B,0xFC,0xDB,0x2D,0xCE,0x28,0xD9,0x59,0xF2,0x81,0x5B,0x16,0xF8,
  97             0x17,0x98,0x48,0x3A,0xDA,0x77,0x26,0xA3,0xC4,0x65,0x5D,0xA4,0xFB,0xFC,0x0E,0x11,
  98             0x08,0xA8,0xFD,0x17,0xB4,0x48,0xA6,0x85,0x54,0x19,0x9C,0x47,0xD0,0x8F,0xFB,0x10,
  99             0xD4,0xB8,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
 100             0xFF,0xFF,0xFF,0xFF,0xFE,0xBA,0xAE,0xDC,0xE6,0xAF,0x48,0xA0,0x3B,0xBF,0xD2,0x5E,
 101             0x8C,0xD0,0x36,0x41,0x41,0x02,0x01,0x01,0xA1,0x44,0x03,0x42,0x00
 102         };
 103         unsigned char *ptr = privkey;
 104         memcpy(ptr, begin, sizeof(begin)); ptr += sizeof(begin);
 105         memcpy(ptr, key32, 32); ptr += 32;
 106         memcpy(ptr, middle, sizeof(middle)); ptr += sizeof(middle);
 107         pubkeylen = 65;
 108         secp256k1_ec_pubkey_serialize(ctx, ptr, &pubkeylen, &pubkey, SECP256K1_EC_UNCOMPRESSED);
 109         ptr += pubkeylen;
 110         *privkeylen = ptr - privkey;
 111     }
 112     return 1;
 113 }