96 lines
3.0 KiB
C
96 lines
3.0 KiB
C
/* LibTomCrypt, modular cryptographic library -- Tom St Denis */
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/* SPDX-License-Identifier: Unlicense */
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#include "tomcrypt_private.h"
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/**
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@file rsa_decrypt_key.c
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RSA PKCS #1 Decryption, Tom St Denis and Andreas Lange
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*/
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#ifdef LTC_MRSA
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/**
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PKCS #1 decrypt then v1.5 or OAEP depad
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@param in The ciphertext
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@param inlen The length of the ciphertext (octets)
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@param out [out] The plaintext
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@param outlen [in/out] The max size and resulting size of the plaintext (octets)
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@param lparam The system "lparam" value
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@param lparamlen The length of the lparam value (octets)
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@param mgf_hash The hash algorithm used for the MGF
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@param lparam_hash The hash algorithm used when hashing the lparam (can be -1)
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@param padding Type of padding (LTC_PKCS_1_OAEP or LTC_PKCS_1_V1_5)
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@param stat [out] Result of the decryption, 1==valid, 0==invalid
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@param key The corresponding private RSA key
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@return CRYPT_OK if succcessul (even if invalid)
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*/
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int rsa_decrypt_key_ex(const unsigned char *in, unsigned long inlen,
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unsigned char *out, unsigned long *outlen,
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const unsigned char *lparam, unsigned long lparamlen,
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int mgf_hash, int lparam_hash,
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int padding,
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int *stat, const rsa_key *key)
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{
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unsigned long modulus_bitlen, modulus_bytelen, x;
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int err;
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unsigned char *tmp;
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LTC_ARGCHK(in != NULL);
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LTC_ARGCHK(out != NULL);
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LTC_ARGCHK(outlen != NULL);
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LTC_ARGCHK(key != NULL);
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LTC_ARGCHK(stat != NULL);
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/* default to invalid */
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*stat = 0;
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/* valid padding? */
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if ((padding != LTC_PKCS_1_V1_5) &&
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(padding != LTC_PKCS_1_OAEP)) {
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return CRYPT_PK_INVALID_PADDING;
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}
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if (padding == LTC_PKCS_1_OAEP) {
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/* valid hash ? */
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if ((err = hash_is_valid(mgf_hash)) != CRYPT_OK) {
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return err;
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}
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}
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/* get modulus len in bits */
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modulus_bitlen = ltc_mp_count_bits( (key->N));
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/* outlen must be at least the size of the modulus */
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modulus_bytelen = ltc_mp_unsigned_bin_size( (key->N));
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if (modulus_bytelen != inlen) {
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return CRYPT_INVALID_PACKET;
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}
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/* allocate ram */
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tmp = XMALLOC(inlen);
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if (tmp == NULL) {
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return CRYPT_MEM;
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}
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/* rsa decode the packet */
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x = inlen;
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if ((err = ltc_mp.rsa_me(in, inlen, tmp, &x, PK_PRIVATE, key)) != CRYPT_OK) {
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XFREE(tmp);
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return err;
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}
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if (padding == LTC_PKCS_1_OAEP) {
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/* now OAEP decode the packet */
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err = pkcs_1_oaep_decode(tmp, x, lparam, lparamlen, modulus_bitlen, mgf_hash,
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lparam_hash, out, outlen, stat);
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} else {
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/* now PKCS #1 v1.5 depad the packet */
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err = pkcs_1_v1_5_decode(tmp, x, LTC_PKCS_1_EME, modulus_bitlen, out, outlen, stat);
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}
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XFREE(tmp);
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return err;
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}
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#endif /* LTC_MRSA */
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