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annotate libtomcrypt/src/encauth/chachapoly/chacha20poly1305_decrypt.c @ 1930:299f4f19ba19

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Add /usr/sbin and /sbin to default root PATH When dropbear is used in a very restricted environment (such as in a initrd), the default user shell is often also very restricted and doesn't take care of setting the PATH so the user ends up with the PATH set by dropbear. Unfortunately, dropbear always sets "/usr/bin:/bin" as default PATH even for the root user which should have /usr/sbin and /sbin too. For a concrete instance of this problem, see the "Remote Unlocking" section in this tutorial: https://paxswill.com/blog/2013/11/04/encrypted-raspberry-pi/ It speaks of a bug in the initramfs script because it's written "blkid" instead of "/sbin/blkid"... this is just because the scripts from the initramfs do not expect to have a PATH without the sbin directories and because dropbear is not setting the PATH appropriately for the root user. I'm thus suggesting to use the attached patch to fix this misbehaviour (I did not test it, but it's easy enough). It might seem anecdotic but multiple Kali users have been bitten by this. From https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=903403
author Raphael Hertzog <hertzog@debian.org>
date Mon, 09 Jul 2018 16:27:53 +0200
parents 6dba84798cd5
children
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1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
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2 *
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3 * LibTomCrypt is a library that provides various cryptographic
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4 * algorithms in a highly modular and flexible manner.
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5 *
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6 * The library is free for all purposes without any express
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7 * guarantee it works.
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8 */
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9
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10 #include "tomcrypt.h"
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11
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12 #ifdef LTC_CHACHA20POLY1305_MODE
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13
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14 /**
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15 Decrypt bytes of ciphertext with ChaCha20Poly1305
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16 @param st The ChaCha20Poly1305 state
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17 @param in The ciphertext
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18 @param inlen The length of the input (octets)
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19 @param out [out] The plaintext (length inlen)
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20 @return CRYPT_OK if successful
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21 */
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22 int chacha20poly1305_decrypt(chacha20poly1305_state *st, const unsigned char *in, unsigned long inlen, unsigned char *out)
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23 {
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24 unsigned char padzero[16] = { 0 };
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25 unsigned long padlen;
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26 int err;
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27
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28 if (inlen == 0) return CRYPT_OK; /* nothing to do */
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29 LTC_ARGCHK(st != NULL);
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30
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31 if (st->aadflg) {
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32 padlen = 16 - (unsigned long)(st->aadlen % 16);
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33 if (padlen < 16) {
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34 if ((err = poly1305_process(&st->poly, padzero, padlen)) != CRYPT_OK) return err;
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35 }
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36 st->aadflg = 0; /* no more AAD */
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37 }
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38 if (st->aadflg) st->aadflg = 0; /* no more AAD */
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39 if ((err = poly1305_process(&st->poly, in, inlen)) != CRYPT_OK) return err;
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40 if ((err = chacha_crypt(&st->chacha, in, inlen, out)) != CRYPT_OK) return err;
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41 st->ctlen += (ulong64)inlen;
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42 return CRYPT_OK;
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43 }
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44
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45 #endif
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46
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47 /* ref: $Format:%D$ */
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48 /* git commit: $Format:%H$ */
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49 /* commit time: $Format:%ai$ */