| /********************************************************************** |
| * 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 <string.h> |
| #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; |
| } |
| |
| |