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Diffstat (limited to 'gost_keywrap.c')
-rw-r--r-- | gost_keywrap.c | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/gost_keywrap.c b/gost_keywrap.c new file mode 100644 index 0000000..502a83c --- /dev/null +++ b/gost_keywrap.c @@ -0,0 +1,106 @@ +/********************************************************************** + * 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; +} |