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