diff options
Diffstat (limited to 'libotr/libgcrypt-1.8.7/cipher/cipher-poly1305.c')
| -rw-r--r-- | libotr/libgcrypt-1.8.7/cipher/cipher-poly1305.c | 334 |
1 files changed, 334 insertions, 0 deletions
diff --git a/libotr/libgcrypt-1.8.7/cipher/cipher-poly1305.c b/libotr/libgcrypt-1.8.7/cipher/cipher-poly1305.c new file mode 100644 index 0000000..a2a74e8 --- /dev/null +++ b/libotr/libgcrypt-1.8.7/cipher/cipher-poly1305.c @@ -0,0 +1,334 @@ +/* cipher-poly1305.c - Poly1305 based AEAD cipher mode, RFC-7539 + * Copyright (C) 2014 Jussi Kivilinna <jussi.kivilinna@iki.fi> + * + * This file is part of Libgcrypt. + * + * Libgcrypt is free software; you can redistribute it and/or modify + * it under the terms of the GNU Lesser general Public License as + * published by the Free Software Foundation; either version 2.1 of + * the License, or (at your option) any later version. + * + * Libgcrypt is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this program; if not, see <http://www.gnu.org/licenses/>. + */ + +#include <config.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <errno.h> + +#include "g10lib.h" +#include "cipher.h" +#include "bufhelp.h" +#include "./cipher-internal.h" +#include "./poly1305-internal.h" + + +static inline int +poly1305_bytecounter_add (u32 ctr[2], size_t add) +{ + int overflow = 0; + + if (sizeof(add) > sizeof(u32)) + { + u32 high_add = ((add >> 31) >> 1) & 0xffffffff; + ctr[1] += high_add; + if (ctr[1] < high_add) + overflow = 1; + } + + ctr[0] += add; + if (ctr[0] >= add) + return overflow; + + ctr[1] += 1; + return (ctr[1] < 1) || overflow; +} + + +static void +poly1305_fill_bytecounts (gcry_cipher_hd_t c) +{ + u32 lenbuf[4]; + + lenbuf[0] = le_bswap32(c->u_mode.poly1305.aadcount[0]); + lenbuf[1] = le_bswap32(c->u_mode.poly1305.aadcount[1]); + lenbuf[2] = le_bswap32(c->u_mode.poly1305.datacount[0]); + lenbuf[3] = le_bswap32(c->u_mode.poly1305.datacount[1]); + _gcry_poly1305_update (&c->u_mode.poly1305.ctx, (byte*)lenbuf, + sizeof(lenbuf)); + + wipememory(lenbuf, sizeof(lenbuf)); +} + + +static void +poly1305_do_padding (gcry_cipher_hd_t c, u32 ctr[2]) +{ + static const byte zero_padding_buf[15] = {}; + u32 padding_count; + + /* Padding to 16 byte boundary. */ + if (ctr[0] % 16 > 0) + { + padding_count = 16 - ctr[0] % 16; + + _gcry_poly1305_update (&c->u_mode.poly1305.ctx, zero_padding_buf, + padding_count); + } +} + + +static void +poly1305_aad_finish (gcry_cipher_hd_t c) +{ + /* After AAD, feed padding bytes so we get 16 byte alignment. */ + poly1305_do_padding (c, c->u_mode.poly1305.aadcount); + + /* Start of encryption marks end of AAD stream. */ + c->u_mode.poly1305.aad_finalized = 1; + + c->u_mode.poly1305.datacount[0] = 0; + c->u_mode.poly1305.datacount[1] = 0; +} + + +static gcry_err_code_t +poly1305_set_zeroiv (gcry_cipher_hd_t c) +{ + byte zero[8] = { 0, }; + + return _gcry_cipher_poly1305_setiv (c, zero, sizeof(zero)); +} + + +gcry_err_code_t +_gcry_cipher_poly1305_authenticate (gcry_cipher_hd_t c, + const byte * aadbuf, size_t aadbuflen) +{ + if (c->u_mode.poly1305.bytecount_over_limits) + return GPG_ERR_INV_LENGTH; + if (c->u_mode.poly1305.aad_finalized) + return GPG_ERR_INV_STATE; + if (c->marks.tag) + return GPG_ERR_INV_STATE; + + if (!c->marks.iv) + poly1305_set_zeroiv(c); + + if (poly1305_bytecounter_add(c->u_mode.poly1305.aadcount, aadbuflen)) + { + c->u_mode.poly1305.bytecount_over_limits = 1; + return GPG_ERR_INV_LENGTH; + } + + _gcry_poly1305_update (&c->u_mode.poly1305.ctx, aadbuf, aadbuflen); + + return 0; +} + + +gcry_err_code_t +_gcry_cipher_poly1305_encrypt (gcry_cipher_hd_t c, + byte *outbuf, size_t outbuflen, + const byte *inbuf, size_t inbuflen) +{ + gcry_err_code_t err; + + if (outbuflen < inbuflen) + return GPG_ERR_BUFFER_TOO_SHORT; + if (c->marks.tag) + return GPG_ERR_INV_STATE; + if (c->u_mode.poly1305.bytecount_over_limits) + return GPG_ERR_INV_LENGTH; + + if (!c->marks.iv) + { + err = poly1305_set_zeroiv(c); + if (err) + return err; + } + + if (!c->u_mode.poly1305.aad_finalized) + poly1305_aad_finish(c); + + if (poly1305_bytecounter_add(c->u_mode.poly1305.datacount, inbuflen)) + { + c->u_mode.poly1305.bytecount_over_limits = 1; + return GPG_ERR_INV_LENGTH; + } + + c->spec->stencrypt(&c->context.c, outbuf, (byte*)inbuf, inbuflen); + + _gcry_poly1305_update (&c->u_mode.poly1305.ctx, outbuf, inbuflen); + + return 0; +} + + +gcry_err_code_t +_gcry_cipher_poly1305_decrypt (gcry_cipher_hd_t c, + byte *outbuf, size_t outbuflen, + const byte *inbuf, size_t inbuflen) +{ + gcry_err_code_t err; + + if (outbuflen < inbuflen) + return GPG_ERR_BUFFER_TOO_SHORT; + if (c->marks.tag) + return GPG_ERR_INV_STATE; + if (c->u_mode.poly1305.bytecount_over_limits) + return GPG_ERR_INV_LENGTH; + + if (!c->marks.iv) + { + err = poly1305_set_zeroiv(c); + if (err) + return err; + } + + if (!c->u_mode.poly1305.aad_finalized) + poly1305_aad_finish(c); + + if (poly1305_bytecounter_add(c->u_mode.poly1305.datacount, inbuflen)) + { + c->u_mode.poly1305.bytecount_over_limits = 1; + return GPG_ERR_INV_LENGTH; + } + + _gcry_poly1305_update (&c->u_mode.poly1305.ctx, inbuf, inbuflen); + + c->spec->stdecrypt(&c->context.c, outbuf, (byte*)inbuf, inbuflen); + return 0; +} + + +static gcry_err_code_t +_gcry_cipher_poly1305_tag (gcry_cipher_hd_t c, + byte * outbuf, size_t outbuflen, int check) +{ + gcry_err_code_t err; + + if (outbuflen < POLY1305_TAGLEN) + return GPG_ERR_BUFFER_TOO_SHORT; + if (c->u_mode.poly1305.bytecount_over_limits) + return GPG_ERR_INV_LENGTH; + + if (!c->marks.iv) + { + err = poly1305_set_zeroiv(c); + if (err) + return err; + } + + if (!c->u_mode.poly1305.aad_finalized) + poly1305_aad_finish(c); + + if (!c->marks.tag) + { + /* After data, feed padding bytes so we get 16 byte alignment. */ + poly1305_do_padding (c, c->u_mode.poly1305.datacount); + + /* Write byte counts to poly1305. */ + poly1305_fill_bytecounts(c); + + _gcry_poly1305_finish(&c->u_mode.poly1305.ctx, c->u_iv.iv); + + c->marks.tag = 1; + } + + if (!check) + { + memcpy (outbuf, c->u_iv.iv, POLY1305_TAGLEN); + } + else + { + /* OUTBUFLEN gives the length of the user supplied tag in OUTBUF + * and thus we need to compare its length first. */ + if (outbuflen != POLY1305_TAGLEN + || !buf_eq_const (outbuf, c->u_iv.iv, POLY1305_TAGLEN)) + return GPG_ERR_CHECKSUM; + } + + return 0; +} + + +gcry_err_code_t +_gcry_cipher_poly1305_get_tag (gcry_cipher_hd_t c, unsigned char *outtag, + size_t taglen) +{ + return _gcry_cipher_poly1305_tag (c, outtag, taglen, 0); +} + +gcry_err_code_t +_gcry_cipher_poly1305_check_tag (gcry_cipher_hd_t c, const unsigned char *intag, + size_t taglen) +{ + return _gcry_cipher_poly1305_tag (c, (unsigned char *) intag, taglen, 1); +} + + +void +_gcry_cipher_poly1305_setkey (gcry_cipher_hd_t c) +{ + c->u_mode.poly1305.aadcount[0] = 0; + c->u_mode.poly1305.aadcount[1] = 0; + + c->u_mode.poly1305.datacount[0] = 0; + c->u_mode.poly1305.datacount[1] = 0; + + c->u_mode.poly1305.bytecount_over_limits = 0; + c->u_mode.poly1305.aad_finalized = 0; + c->marks.tag = 0; + c->marks.iv = 0; +} + + +gcry_err_code_t +_gcry_cipher_poly1305_setiv (gcry_cipher_hd_t c, const byte *iv, size_t ivlen) +{ + byte tmpbuf[64]; /* size of ChaCha20 block */ + gcry_err_code_t err; + + /* IV must be 96-bits */ + if (!iv && ivlen != (96 / 8)) + return GPG_ERR_INV_ARG; + + memset(&c->u_mode.poly1305.ctx, 0, sizeof(c->u_mode.poly1305.ctx)); + + c->u_mode.poly1305.aadcount[0] = 0; + c->u_mode.poly1305.aadcount[1] = 0; + + c->u_mode.poly1305.datacount[0] = 0; + c->u_mode.poly1305.datacount[1] = 0; + + c->u_mode.poly1305.bytecount_over_limits = 0; + c->u_mode.poly1305.aad_finalized = 0; + c->marks.tag = 0; + c->marks.iv = 0; + + /* Set up IV for stream cipher. */ + c->spec->setiv (&c->context.c, iv, ivlen); + + /* Get the first block from ChaCha20. */ + memset(tmpbuf, 0, sizeof(tmpbuf)); + c->spec->stencrypt(&c->context.c, tmpbuf, tmpbuf, sizeof(tmpbuf)); + + /* Use the first 32-bytes as Poly1305 key. */ + err = _gcry_poly1305_init (&c->u_mode.poly1305.ctx, tmpbuf, POLY1305_KEYLEN); + + wipememory(tmpbuf, sizeof(tmpbuf)); + + if (err) + return err; + + c->marks.iv = 1; + return 0; +} |