Mercurial > dropbear
view libtomcrypt/src/pk/katja/katja_decrypt_key.c @ 1653:76189c9ffea2
External Public-Key Authentication API (#72)
* Implemented dynamic loading of an external plug-in shared library to delegate public key authentication
* Moved conditional compilation of the plugin infrastructure into the configure.ac script to be able to add -ldl to dropbear build only when the flag is enabled
* Added tags file to the ignore list
* Updated API to have the constructor to return function pointers in the pliugin instance. Added support for passing user name to the checkpubkey function. Added options to the session returned by the plugin and have dropbear to parse and process them
* Added -rdynamic to the linker flags when EPKA is enabled
* Changed the API to pass a previously created session to the checkPubKey function (created during preauth)
* Added documentation to the API
* Added parameter addrstring to plugin creation function
* Modified the API to retrieve the auth options. Instead of having them as field of the EPKASession struct, they are stored internally (plugin-dependent) in the plugin/session and retrieved through a pointer to a function (in the session)
* Changed option string to be a simple char * instead of unsigned char *
author | fabriziobertocci <fabriziobertocci@gmail.com> |
---|---|
date | Wed, 15 May 2019 09:43:57 -0400 (2019-05-15) |
parents | 6dba84798cd5 |
children |
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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. */ #include "tomcrypt.h" /** @file katja_decrypt_key.c Katja PKCS #1 OAEP Decryption, Tom St Denis */ #ifdef LTC_MKAT /** (PKCS #1 v2.0) decrypt then OAEP depad @param in The ciphertext @param inlen The length of the ciphertext (octets) @param out [out] The plaintext @param outlen [in/out] The max size and resulting size of the plaintext (octets) @param lparam The system "lparam" value @param lparamlen The length of the lparam value (octets) @param hash_idx The index of the hash desired @param stat [out] Result of the decryption, 1==valid, 0==invalid @param key The corresponding private Katja key @return CRYPT_OK if succcessul (even if invalid) */ int katja_decrypt_key(const unsigned char *in, unsigned long inlen, unsigned char *out, unsigned long *outlen, const unsigned char *lparam, unsigned long lparamlen, int hash_idx, int *stat, katja_key *key) { unsigned long modulus_bitlen, modulus_bytelen, x; int err; unsigned char *tmp; LTC_ARGCHK(out != NULL); LTC_ARGCHK(outlen != NULL); LTC_ARGCHK(key != NULL); LTC_ARGCHK(stat != NULL); /* default to invalid */ *stat = 0; /* valid hash ? */ if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) { return err; } /* get modulus len in bits */ modulus_bitlen = mp_count_bits( (key->N)); /* payload is upto pq, so we know q is 1/3rd the size of N and therefore pq is 2/3th the size */ modulus_bitlen = ((modulus_bitlen << 1) / 3); /* round down to next byte */ modulus_bitlen -= (modulus_bitlen & 7) + 8; /* outlen must be at least the size of the modulus */ modulus_bytelen = mp_unsigned_bin_size( (key->N)); if (modulus_bytelen != inlen) { return CRYPT_INVALID_PACKET; } /* allocate ram */ tmp = XMALLOC(inlen); if (tmp == NULL) { return CRYPT_MEM; } /* rsa decode the packet */ x = inlen; if ((err = katja_exptmod(in, inlen, tmp, &x, PK_PRIVATE, key)) != CRYPT_OK) { XFREE(tmp); return err; } /* shift right by modulus_bytelen - modulus_bitlen/8 bytes */ for (x = 0; x < (modulus_bitlen >> 3); x++) { tmp[x] = tmp[x+(modulus_bytelen-(modulus_bitlen>>3))]; } /* now OAEP decode the packet */ err = pkcs_1_oaep_decode(tmp, x, lparam, lparamlen, modulus_bitlen, hash_idx, out, outlen, stat); XFREE(tmp); return err; } #endif /* LTC_MRSA */ /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */