Mercurial > dropbear
view libtomcrypt/src/pk/pkcs1/pkcs_1_v1_5_encode.c @ 652:17962b2a6b8f
- Make sure we don't use channel-specific data after it has been freed
with a ChanType->closehandler()
author | Matt Johnston <matt@ucc.asn.au> |
---|---|
date | Sun, 04 Dec 2011 05:27:29 +0800 (2011-12-03) |
parents | 0cbe8f6dbf9e |
children | f849a5ca2efc |
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis * * LibTomCrypt is a library that provides various cryptographic * algorithms in a highly modular and flexible manner. * * The library is free for all purposes without any express * guarantee it works. * * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com */ #include "tomcrypt.h" /*! \file pkcs_1_v1_5_encode.c * * PKCS #1 v1.5 Padding (Andreas Lange) */ #ifdef PKCS_1 /*! \brief PKCS #1 v1.5 encode. * * \param msg The data to encode * \param msglen The length of the data to encode (octets) * \param block_type Block type to use in padding (\sa ltc_pkcs_1_v1_5_blocks) * \param modulus_bitlen The bit length of the RSA modulus * \param prng An active PRNG state (only for LTC_PKCS_1_EME) * \param prng_idx The index of the PRNG desired (only for LTC_PKCS_1_EME) * \param out [out] The destination for the encoded data * \param outlen [in/out] The max size and resulting size of the encoded data * * \return CRYPT_OK if successful */ int pkcs_1_v1_5_encode(const unsigned char *msg, unsigned long msglen, int block_type, unsigned long modulus_bitlen, prng_state *prng, int prng_idx, unsigned char *out, unsigned long *outlen) { unsigned long modulus_len, ps_len, i; unsigned char *ps; int result; /* valid block_type? */ if ((block_type != LTC_PKCS_1_EMSA) && (block_type != LTC_PKCS_1_EME)) { return CRYPT_PK_INVALID_PADDING; } if (block_type == LTC_PKCS_1_EME) { /* encryption padding, we need a valid PRNG */ if ((result = prng_is_valid(prng_idx)) != CRYPT_OK) { return result; } } modulus_len = (modulus_bitlen >> 3) + (modulus_bitlen & 7 ? 1 : 0); /* test message size */ if ((msglen + 11) > modulus_len) { return CRYPT_PK_INVALID_SIZE; } if (*outlen < modulus_len) { *outlen = modulus_len; result = CRYPT_BUFFER_OVERFLOW; goto bail; } /* generate an octets string PS */ ps = &out[2]; ps_len = modulus_len - msglen - 3; if (block_type == LTC_PKCS_1_EME) { /* now choose a random ps */ if (prng_descriptor[prng_idx].read(ps, ps_len, prng) != ps_len) { result = CRYPT_ERROR_READPRNG; goto bail; } /* transform zero bytes (if any) to non-zero random bytes */ for (i = 0; i < ps_len; i++) { while (ps[i] == 0) { if (prng_descriptor[prng_idx].read(&ps[i], 1, prng) != 1) { result = CRYPT_ERROR_READPRNG; goto bail; } } } } else { XMEMSET(ps, 0xFF, ps_len); } /* create string of length modulus_len */ out[0] = 0x00; out[1] = (unsigned char)block_type; /* block_type 1 or 2 */ out[2 + ps_len] = 0x00; XMEMCPY(&out[2 + ps_len + 1], msg, msglen); *outlen = modulus_len; result = CRYPT_OK; bail: return result; } /* pkcs_1_v1_5_encode */ #endif /* #ifdef PKCS_1 */ /* $Source: /cvs/libtom/libtomcrypt/src/pk/pkcs1/pkcs_1_v1_5_encode.c,v $ */ /* $Revision: 1.2 $ */ /* $Date: 2006/11/01 09:12:06 $ */