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109 lines
3.4 KiB
109 lines
3.4 KiB
/**********************************************************************
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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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/* 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, 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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{
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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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{
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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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{
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s1+=k;
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}
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else
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{
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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, const unsigned char *ukm,
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const unsigned char *sessionKey, 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, 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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{
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return 0;
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}
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return 1;
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}
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