| // SPDX-License-Identifier: BSD-2-Clause |
| /* 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_private.h" |
| |
| #ifdef LTC_CHACHA20POLY1305_MODE |
| |
| /** |
| Decrypt bytes of ciphertext with ChaCha20Poly1305 |
| @param st The ChaCha20Poly1305 state |
| @param in The ciphertext |
| @param inlen The length of the input (octets) |
| @param out [out] The plaintext (length inlen) |
| @return CRYPT_OK if successful |
| */ |
| int chacha20poly1305_decrypt(chacha20poly1305_state *st, const unsigned char *in, unsigned long inlen, unsigned char *out) |
| { |
| unsigned char padzero[16] = { 0 }; |
| unsigned long padlen; |
| int err; |
| |
| LTC_ARGCHK(st != NULL); |
| |
| if (st->aadflg) { |
| padlen = 16 - (unsigned long)(st->aadlen % 16); |
| if (padlen < 16) { |
| if ((err = poly1305_process(&st->poly, padzero, padlen)) != CRYPT_OK) return err; |
| } |
| st->aadflg = 0; /* no more AAD */ |
| } |
| if (st->aadflg) st->aadflg = 0; /* no more AAD */ |
| if ((err = poly1305_process(&st->poly, in, inlen)) != CRYPT_OK) return err; |
| if ((err = chacha_crypt(&st->chacha, in, inlen, out)) != CRYPT_OK) return err; |
| st->ctlen += (ulong64)inlen; |
| return CRYPT_OK; |
| } |
| |
| #endif |
| |
| /* ref: $Format:%D$ */ |
| /* git commit: $Format:%H$ */ |
| /* commit time: $Format:%ai$ */ |