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107 lines
3.9 KiB
C
107 lines
3.9 KiB
C
/**********************************************************************
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* keywrap.c *
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* Copyright (c) 2005-2006 Cryptocom LTD *
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* This file is distributed under the same license as OpenSSL *
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* *
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* Implementation of CryptoPro key wrap algorithm, as defined in *
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* RFC 4357 p 6.3 and 6.4 *
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* Doesn't need OpenSSL *
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**********************************************************************/
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#include <string.h>
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#include "gost89.h"
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#include "gost_keywrap.h"
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/*-
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* Diversifies key using random UserKey Material
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* Implements RFC 4357 p 6.5 key diversification algorithm
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*
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* inputKey - 32byte key to be diversified
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* ukm - 8byte user key material
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* outputKey - 32byte buffer to store diversified key
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*
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*/
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void keyDiversifyCryptoPro(gost_ctx * ctx, const unsigned char *inputKey,
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const unsigned char *ukm, unsigned char *outputKey)
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{
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u4 k, s1, s2;
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int i, j, mask;
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unsigned char S[8];
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memcpy(outputKey, inputKey, 32);
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for (i = 0; i < 8; i++) {
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/* Make array of integers from key */
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/* Compute IV S */
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s1 = 0, s2 = 0;
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for (j = 0, mask = 1; j < 8; j++, mask <<= 1) {
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k = ((u4) outputKey[4 * j]) | (outputKey[4 * j + 1] << 8) |
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(outputKey[4 * j + 2] << 16) | (outputKey[4 * j + 3] << 24);
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if (mask & ukm[i]) {
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s1 += k;
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} else {
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s2 += k;
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}
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}
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S[0] = (unsigned char)(s1 & 0xff);
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S[1] = (unsigned char)((s1 >> 8) & 0xff);
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S[2] = (unsigned char)((s1 >> 16) & 0xff);
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S[3] = (unsigned char)((s1 >> 24) & 0xff);
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S[4] = (unsigned char)(s2 & 0xff);
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S[5] = (unsigned char)((s2 >> 8) & 0xff);
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S[6] = (unsigned char)((s2 >> 16) & 0xff);
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S[7] = (unsigned char)((s2 >> 24) & 0xff);
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gost_key(ctx, outputKey);
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gost_enc_cfb(ctx, S, outputKey, outputKey, 4);
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}
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}
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/*-
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* Wraps key using RFC 4357 6.3
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* ctx - gost encryption context, initialized with some S-boxes
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* keyExchangeKey (KEK) 32-byte (256-bit) shared key
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* ukm - 8 byte (64 bit) user key material,
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* sessionKey - 32-byte (256-bit) key to be wrapped
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* wrappedKey - 44-byte buffer to store wrapped key
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*/
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int keyWrapCryptoPro(gost_ctx * ctx, const unsigned char *keyExchangeKey,
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const unsigned char *ukm,
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const unsigned char *sessionKey,
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unsigned char *wrappedKey)
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{
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unsigned char kek_ukm[32];
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keyDiversifyCryptoPro(ctx, keyExchangeKey, ukm, kek_ukm);
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gost_key(ctx, kek_ukm);
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memcpy(wrappedKey, ukm, 8);
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gost_enc(ctx, sessionKey, wrappedKey + 8, 4);
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gost_mac_iv(ctx, 32, ukm, sessionKey, 32, wrappedKey + 40);
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return 1;
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}
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/*-
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* Unwraps key using RFC 4357 6.4
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* ctx - gost encryption context, initialized with some S-boxes
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* keyExchangeKey 32-byte shared key
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* wrappedKey 44 byte key to be unwrapped (concatenation of 8-byte UKM,
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* 32 byte encrypted key and 4 byte MAC
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*
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* sessionKEy - 32byte buffer to store sessionKey in
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* Returns 1 if key is decrypted successfully, and 0 if MAC doesn't match
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*/
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int keyUnwrapCryptoPro(gost_ctx * ctx, const unsigned char *keyExchangeKey,
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const unsigned char *wrappedKey,
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unsigned char *sessionKey)
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{
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unsigned char kek_ukm[32], cek_mac[4];
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keyDiversifyCryptoPro(ctx, keyExchangeKey, wrappedKey
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/* First 8 bytes of wrapped Key is ukm */
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, kek_ukm);
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gost_key(ctx, kek_ukm);
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gost_dec(ctx, wrappedKey + 8, sessionKey, 4);
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gost_mac_iv(ctx, 32, wrappedKey, sessionKey, 32, cek_mac);
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if (memcmp(cek_mac, wrappedKey + 40, 4)) {
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return 0;
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}
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return 1;
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}
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