1f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* LibTomCrypt, modular cryptographic library -- Tom St Denis 2f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * 3f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * LibTomCrypt is a library that provides various cryptographic 4f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * algorithms in a highly modular and flexible manner. 5f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * 6f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * The library is free for all purposes without any express 7f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * guarantee it works. 8f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * 9f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com 10f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project */ 11f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#include "tomcrypt.h" 12f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 13f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/** 14f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @file katja_decrypt_key.c 15f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project Katja PKCS #1 OAEP Decryption, Tom St Denis 16f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project*/ 17f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 18f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#ifdef MKAT 19f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 20f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/** 21f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project (PKCS #1 v2.0) decrypt then OAEP depad 22f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param in The ciphertext 23f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param inlen The length of the ciphertext (octets) 24f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param out [out] The plaintext 25f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param outlen [in/out] The max size and resulting size of the plaintext (octets) 26f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param lparam The system "lparam" value 27f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param lparamlen The length of the lparam value (octets) 28f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param hash_idx The index of the hash desired 29f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param stat [out] Result of the decryption, 1==valid, 0==invalid 30f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @param key The corresponding private Katja key 31f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project @return CRYPT_OK if succcessul (even if invalid) 32f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project*/ 33f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Projectint katja_decrypt_key(const unsigned char *in, unsigned long inlen, 34f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project unsigned char *out, unsigned long *outlen, 35f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project const unsigned char *lparam, unsigned long lparamlen, 36f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project int hash_idx, int *stat, 37f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project katja_key *key) 38f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project{ 39f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project unsigned long modulus_bitlen, modulus_bytelen, x; 40f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project int err; 41f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project unsigned char *tmp; 42f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 43f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(out != NULL); 44f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(outlen != NULL); 45f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(key != NULL); 46f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project LTC_ARGCHK(stat != NULL); 47f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 48f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* default to invalid */ 49f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project *stat = 0; 50f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 51f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* valid hash ? */ 52f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) { 53f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return err; 54f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 55f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 56f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* get modulus len in bits */ 57f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project modulus_bitlen = mp_count_bits( (key->N)); 58f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 59f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* payload is upto pq, so we know q is 1/3rd the size of N and therefore pq is 2/3th the size */ 60f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project modulus_bitlen = ((modulus_bitlen << 1) / 3); 61f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 62f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* round down to next byte */ 63f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project modulus_bitlen -= (modulus_bitlen & 7) + 8; 64f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 65f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* outlen must be at least the size of the modulus */ 66f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project modulus_bytelen = mp_unsigned_bin_size( (key->N)); 67f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (modulus_bytelen != inlen) { 68f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return CRYPT_INVALID_PACKET; 69f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 70f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 71f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* allocate ram */ 72f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project tmp = XMALLOC(inlen); 73f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if (tmp == NULL) { 74f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return CRYPT_MEM; 75f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 76f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 77f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* rsa decode the packet */ 78f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project x = inlen; 79f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project if ((err = katja_exptmod(in, inlen, tmp, &x, PK_PRIVATE, key)) != CRYPT_OK) { 80f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project XFREE(tmp); 81f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return err; 82f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 83f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 84f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* shift right by modulus_bytelen - modulus_bitlen/8 bytes */ 85f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project for (x = 0; x < (modulus_bitlen >> 3); x++) { 86f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project tmp[x] = tmp[x+(modulus_bytelen-(modulus_bitlen>>3))]; 87f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project } 88f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 89f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project /* now OAEP decode the packet */ 90f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project err = pkcs_1_oaep_decode(tmp, x, lparam, lparamlen, modulus_bitlen, hash_idx, 91f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project out, outlen, stat); 92f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 93f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project XFREE(tmp); 94f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project return err; 95f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project} 96f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 97f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project#endif /* MRSA */ 98f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 99f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 100f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 101f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 102f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project 103f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Source: /cvs/libtom/libtomcrypt/src/pk/katja/katja_decrypt_key.c,v $ */ 104f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Revision: 1.4 $ */ 105f7fc46c63fdc8f39234fea409b8dbe116d73ebf8The Android Open Source Project/* $Date: 2006/03/31 14:15:35 $ */ 106