chacha20+poly1305 authenticated encryption
Loganaden Velvindron
loganaden at gmail.com
Sat Nov 16 02:48:44 EST 2013
On Fri, Nov 15, 2013 at 2:55 PM, Loganaden Velvindron
<loganaden at gmail.com> wrote:
> On Fri, Nov 15, 2013 at 2:03 PM, Damien Miller <djm at mindrot.org> wrote:
>> On Thu, 14 Nov 2013, James Cloos wrote:
>>
>>> >>>>> "DM" == Damien Miller <djm at mindrot.org> writes:
>>>
>>> DM> Here's a diff to implement ChaCha20+Poly1305 as an authenticated
>>> DM> encryption mode. It authenticates the packet length and payload,
>>> DM> and uses a separate ChaCh20 instance to encrypt the packet length
>>> DM> to preserve privacy of packet lengths* while avoiding any decryption
>>> DM> oracle for the main packet payload.
>>>
>>> Cool.
>>>
>>> I'd like to test it out, but for logistics reasons I'll have to do so on
>>> a linux box. Is anything written on what is needed to convert from the
>>> openbsd cvs tree to the portable tree? Or do you have a version of the
>>> patch applicable to the portable's cvs?
>>
>> Here's one that applies to portable OpenSSH. Also available at
>> http://www.mindrot.org/files/chachapoly1305_04_portable.diff
>
> What kind of test case are you expecting ?
An include file seems to be missing for
chacha20poly1305aead.c:72:3: warning: implicit declaration of function
‘timingsafe_bcmp’ [-Wimplicit-function-declaration]
--- chacha20poly1305aead.c.orig 2013-11-15 19:48:01.977031397 +0400
+++ chacha20poly1305aead.c 2013-11-15 19:44:16.359912632 +0400
@@ -23,6 +23,7 @@
#include "log.h"
#include "misc.h"
#include "chacha20poly1305aead.h"
+#include "openbsd-compat/openbsd-compat.h"
void cp_aead_init(struct chacha_poly_aead_ctx *ctx,
const u_char *key, u_int keylen)
>
>
>>
>> Index: Makefile.in
>> ===================================================================
>> RCS file: /var/cvs/openssh/Makefile.in,v
>> retrieving revision 1.344
>> diff -u -p -r1.344 Makefile.in
>> --- Makefile.in 8 Nov 2013 13:17:41 -0000 1.344
>> +++ Makefile.in 15 Nov 2013 00:08:29 -0000
>> @@ -74,7 +74,8 @@ LIBSSH_OBJS=authfd.o authfile.o bufaux.o
>> kexdh.o kexgex.o kexdhc.o kexgexc.o bufec.o kexecdh.o kexecdhc.o \
>> msg.o progressmeter.o dns.o entropy.o gss-genr.o umac.o umac128.o \
>> jpake.o schnorr.o ssh-pkcs11.o krl.o smult_curve25519_ref.o \
>> - kexc25519.o kexc25519c.o
>> + kexc25519.o kexc25519c.o chacha.o chacha20poly1305aead.o \
>> + poly1305-donna-unrolled.o
>>
>> SSHOBJS= ssh.o readconf.o clientloop.o sshtty.o \
>> sshconnect.o sshconnect1.o sshconnect2.o mux.o \
>> Index: PROTOCOL
>> ===================================================================
>> RCS file: /var/cvs/openssh/PROTOCOL,v
>> retrieving revision 1.20
>> diff -u -p -r1.20 PROTOCOL
>> --- PROTOCOL 17 Oct 2013 00:48:53 -0000 1.20
>> +++ PROTOCOL 15 Nov 2013 00:08:29 -0000
>> @@ -91,6 +91,11 @@ an MAC algorithm. Additionally, if AES-G
>> the exchanged MAC algorithms are ignored and there doesn't have to be
>> a matching MAC.
>>
>> +1.7 transport: chacha20-poly1305 at openssh.com authenticated encryption
>> +
>> +OpenSSH supports authenticated encryption using ChaCha20 and Poly1305
>> +as described in PROTOCOL.chacha20poly1305.
>> +
>> 2. Connection protocol changes
>>
>> 2.1. connection: Channel write close extension "eow at openssh.com"
>> Index: PROTOCOL.chacha20poly1305
>> ===================================================================
>> RCS file: PROTOCOL.chacha20poly1305
>> diff -N PROTOCOL.chacha20poly1305
>> --- /dev/null 1 Jan 1970 00:00:00 -0000
>> +++ PROTOCOL.chacha20poly1305 15 Nov 2013 00:08:29 -0000
>> @@ -0,0 +1,99 @@
>> +This document describes the chacha20-poly1305 at openssh.com authenticated
>> +encryption cipher supported by OpenSSH.
>> +
>> +Background
>> +----------
>> +
>> +ChaCha20 is a stream cipher designed by Daniel Bernstein and described
>> +in [1]. It operates by permuting 128 fixed bits, 128 or 256 bits of key,
>> +a 64 bit nonce and a 64 bit counter into 64 bytes of stream output.
>> +
>> +Poly1305[2] also by Daniel Bernstien is a one-time Carter-Wegman MAC
>> +that computes a 128 bit integrity tag given a message and a 256 bit key.
>> +
>> +The chacha20-poly1305 at openssh.com combines these two primitives into an
>> +autenticated encryption mode. The construction used is based on that
>> +proposed for TLS by Adam Langley in [3], but differs in the layout of
>> +data passed to the MAC and in the addition of encyption of the packet
>> +lengths.
>> +
>> +Negotiation
>> +-----------
>> +
>> +The chacha20-poly1305 at openssh.com offers both encryption and
>> +authentication. As such, no separate MAC is required. If the
>> +chacha20-poly1305 at openssh.com cipher is selected in key exchange,
>> +the offered MAC algorithms are ignored and no MAC is required to be
>> +negotiated.
>> +
>> +Detailed Construction
>> +---------------------
>> +
>> +The chacha20-poly1305 at openssh.com cipher required 512 bits of key
>> +material as output from the SSH key exchange. This forms two 256 bit
>> +keys (K_1 and K_2), used by two separate instances of chacha20.
>> +
>> +The instance keyed by K_1 is a pure stream cipher that is used only
>> +to encrypt the 4 byte packet length field. The second instance,
>> +keyed by K_2, is used in conjunction with poly1305 to build an AEAD
>> +(Authenticated Encryption with Associated Data) that is used to encrypt
>> +and authenticate entire packet.
>> +
>> +Two separate cipher instances are used here so as to keep the packet
>> +lengths confidential but not create an oracle for the packet payload
>> +encryption by decrypting and using the packet length prior to checking
>> +the MAC. By using an independently-keyed cipher instance to encrypt the
>> +length, an active attacker seeking to exploit the packet input handling
>> +as a decryption oracle can learn nothing about the payload contents or
>> +its MAC (assuming key derivation is secure).
>> +
>> +The AEAD is constructed as follows: for each packet, generate a Poly1305
>> +key by taking the first 256 bits of ChaCha20 stream output generated
>> +using K_2, an IV consisting of the packet sequence number encoded as an
>> +uint64 under the SSH wire encoding rules and a ChaCha20 block counter of
>> +zero. The K_2 ChaCha20 block counter is then set to the little-endian
>> +encoding of 1 (i.e. {1, 0, 0, 0, 0, 0, 0, 0}) and this instance is used
>> +for encryption of the packet payload.
>> +
>> +Packet Handling
>> +---------------
>> +
>> +When receiving a packet, the length must be decrypted first. When 4
>> +bytes of ciphertext length have been received, they may be decrypted
>> +using K_1 to obtain the plaintext length.
>> +
>> +Once the entire packet has been received, the MAC MUST be checked
>> +before decryption. A per-packet Poly1305 key is generated as described
>> +above and the MAC tag calculated using Poly1305 with this key over the
>> +ciphertext of the packet length and the payload together. The calculated
>> +MAC is then compared with the one appended to the packet and the packet
>> +decrypted using ChaCha20 as described above (with K_2, the packet
>> +sequence number as nonce and a starting block counter of 1).
>> +
>> +To send a packet, first encode the 4 byte length and encrypt it using
>> +K_1. Encrypt the packet payload (using K_2) and append it to the
>> +encrypted length. Finally, calculate a MAC tag and append it.
>> +
>> +Rekeying
>> +--------
>> +
>> +ChaCha20 must never reuse a {key, nonce} for encryption nor may it be
>> +used to encrypt more than 2^70 bytes under the same {key, nonce}. The
>> +SSH Transport protocol (RFC4253) recommends rekeying every 1GB of data
>> +sent or received. If this recommendation is followed, then
>> +chacha20-poly1305 at openssh.com requires no special handling in this area.
>> +
>> +References
>> +----------
>> +
>> +[1] "ChaCha, a variant of Salsa20", Daniel Bernstein
>> + http://cr.yp.to/chacha/chacha-20080128.pdf
>> +
>> +[2] "The Poly1305-AES message-authentication code", Daniel Bernstein
>> + http://cr.yp.to/mac/poly1305-20050329.pdf
>> +
>> +[3] "ChaCha20 and Poly1305 based Cipher Suites for TLS", Adam Langley
>> + http://tools.ietf.org/html/draft-agl-tls-chacha20poly1305-03
>> +
>> +$OpenBSD$
>> +
>> Index: authfile.c
>> ===================================================================
>> RCS file: /var/cvs/openssh/authfile.c,v
>> retrieving revision 1.101
>> diff -u -p -r1.101 authfile.c
>> --- authfile.c 1 Jun 2013 21:31:18 -0000 1.101
>> +++ authfile.c 15 Nov 2013 00:08:29 -0000
>> @@ -149,7 +149,7 @@ key_private_rsa1_to_blob(Key *key, Buffe
>>
>> cipher_set_key_string(&ciphercontext, cipher, passphrase,
>> CIPHER_ENCRYPT);
>> - cipher_crypt(&ciphercontext, cp,
>> + cipher_crypt(&ciphercontext, 0, cp,
>> buffer_ptr(&buffer), buffer_len(&buffer), 0, 0);
>> cipher_cleanup(&ciphercontext);
>> memset(&ciphercontext, 0, sizeof(ciphercontext));
>> @@ -473,7 +473,7 @@ key_parse_private_rsa1(Buffer *blob, con
>> /* Rest of the buffer is encrypted. Decrypt it using the passphrase. */
>> cipher_set_key_string(&ciphercontext, cipher, passphrase,
>> CIPHER_DECRYPT);
>> - cipher_crypt(&ciphercontext, cp,
>> + cipher_crypt(&ciphercontext, 0, cp,
>> buffer_ptr(©), buffer_len(©), 0, 0);
>> cipher_cleanup(&ciphercontext);
>> memset(&ciphercontext, 0, sizeof(ciphercontext));
>> Index: chacha.c
>> ===================================================================
>> RCS file: chacha.c
>> diff -N chacha.c
>> --- /dev/null 1 Jan 1970 00:00:00 -0000
>> +++ chacha.c 15 Nov 2013 00:08:29 -0000
>> @@ -0,0 +1,217 @@
>> +/*
>> +chacha-merged.c version 20080118
>> +D. J. Bernstein
>> +Public domain.
>> +*/
>> +#include <stddef.h>
>> +#include "chacha.h"
>> +
>> +/* $OpenBSD$ */
>> +
>> +typedef unsigned char u8;
>> +typedef unsigned int u32;
>> +
>> +typedef struct chacha_ctx chacha_ctx;
>> +
>> +#define U8C(v) (v##U)
>> +#define U32C(v) (v##U)
>> +
>> +#define U8V(v) ((u8)(v) & U8C(0xFF))
>> +#define U32V(v) ((u32)(v) & U32C(0xFFFFFFFF))
>> +
>> +#define ROTL32(v, n) \
>> + (U32V((v) << (n)) | ((v) >> (32 - (n))))
>> +
>> +#define U8TO32_LITTLE(p) \
>> + (((u32)((p)[0]) ) | \
>> + ((u32)((p)[1]) << 8) | \
>> + ((u32)((p)[2]) << 16) | \
>> + ((u32)((p)[3]) << 24))
>> +
>> +#define U32TO8_LITTLE(p, v) \
>> + do { \
>> + (p)[0] = U8V((v) ); \
>> + (p)[1] = U8V((v) >> 8); \
>> + (p)[2] = U8V((v) >> 16); \
>> + (p)[3] = U8V((v) >> 24); \
>> + } while (0)
>> +
>> +#define ROTATE(v,c) (ROTL32(v,c))
>> +#define XOR(v,w) ((v) ^ (w))
>> +#define PLUS(v,w) (U32V((v) + (w)))
>> +#define PLUSONE(v) (PLUS((v),1))
>> +
>> +#define QUARTERROUND(a,b,c,d) \
>> + a = PLUS(a,b); d = ROTATE(XOR(d,a),16); \
>> + c = PLUS(c,d); b = ROTATE(XOR(b,c),12); \
>> + a = PLUS(a,b); d = ROTATE(XOR(d,a), 8); \
>> + c = PLUS(c,d); b = ROTATE(XOR(b,c), 7);
>> +
>> +static const char sigma[16] = "expand 32-byte k";
>> +static const char tau[16] = "expand 16-byte k";
>> +
>> +void
>> +chacha_keysetup(chacha_ctx *x,const u8 *k,u32 kbits)
>> +{
>> + const char *constants;
>> +
>> + x->input[4] = U8TO32_LITTLE(k + 0);
>> + x->input[5] = U8TO32_LITTLE(k + 4);
>> + x->input[6] = U8TO32_LITTLE(k + 8);
>> + x->input[7] = U8TO32_LITTLE(k + 12);
>> + if (kbits == 256) { /* recommended */
>> + k += 16;
>> + constants = sigma;
>> + } else { /* kbits == 128 */
>> + constants = tau;
>> + }
>> + x->input[8] = U8TO32_LITTLE(k + 0);
>> + x->input[9] = U8TO32_LITTLE(k + 4);
>> + x->input[10] = U8TO32_LITTLE(k + 8);
>> + x->input[11] = U8TO32_LITTLE(k + 12);
>> + x->input[0] = U8TO32_LITTLE(constants + 0);
>> + x->input[1] = U8TO32_LITTLE(constants + 4);
>> + x->input[2] = U8TO32_LITTLE(constants + 8);
>> + x->input[3] = U8TO32_LITTLE(constants + 12);
>> +}
>> +
>> +void
>> +chacha_ivsetup(chacha_ctx *x, const u8 *iv, const u8 *counter)
>> +{
>> + x->input[12] = counter == NULL ? 0 : U8TO32_LITTLE(counter + 0);
>> + x->input[13] = counter == NULL ? 0 : U8TO32_LITTLE(counter + 4);
>> + x->input[14] = U8TO32_LITTLE(iv + 0);
>> + x->input[15] = U8TO32_LITTLE(iv + 4);
>> +}
>> +
>> +void
>> +chacha_encrypt_bytes(chacha_ctx *x,const u8 *m,u8 *c,u32 bytes)
>> +{
>> + u32 x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, x10, x11, x12, x13, x14, x15;
>> + u32 j0, j1, j2, j3, j4, j5, j6, j7, j8, j9, j10, j11, j12, j13, j14, j15;
>> + u8 *ctarget = NULL;
>> + u8 tmp[64];
>> + u_int i;
>> +
>> + if (!bytes) return;
>> +
>> + j0 = x->input[0];
>> + j1 = x->input[1];
>> + j2 = x->input[2];
>> + j3 = x->input[3];
>> + j4 = x->input[4];
>> + j5 = x->input[5];
>> + j6 = x->input[6];
>> + j7 = x->input[7];
>> + j8 = x->input[8];
>> + j9 = x->input[9];
>> + j10 = x->input[10];
>> + j11 = x->input[11];
>> + j12 = x->input[12];
>> + j13 = x->input[13];
>> + j14 = x->input[14];
>> + j15 = x->input[15];
>> +
>> + for (;;) {
>> + if (bytes < 64) {
>> + for (i = 0;i < bytes;++i) tmp[i] = m[i];
>> + m = tmp;
>> + ctarget = c;
>> + c = tmp;
>> + }
>> + x0 = j0;
>> + x1 = j1;
>> + x2 = j2;
>> + x3 = j3;
>> + x4 = j4;
>> + x5 = j5;
>> + x6 = j6;
>> + x7 = j7;
>> + x8 = j8;
>> + x9 = j9;
>> + x10 = j10;
>> + x11 = j11;
>> + x12 = j12;
>> + x13 = j13;
>> + x14 = j14;
>> + x15 = j15;
>> + for (i = 20;i > 0;i -= 2) {
>> + QUARTERROUND( x0, x4, x8,x12)
>> + QUARTERROUND( x1, x5, x9,x13)
>> + QUARTERROUND( x2, x6,x10,x14)
>> + QUARTERROUND( x3, x7,x11,x15)
>> + QUARTERROUND( x0, x5,x10,x15)
>> + QUARTERROUND( x1, x6,x11,x12)
>> + QUARTERROUND( x2, x7, x8,x13)
>> + QUARTERROUND( x3, x4, x9,x14)
>> + }
>> + x0 = PLUS(x0,j0);
>> + x1 = PLUS(x1,j1);
>> + x2 = PLUS(x2,j2);
>> + x3 = PLUS(x3,j3);
>> + x4 = PLUS(x4,j4);
>> + x5 = PLUS(x5,j5);
>> + x6 = PLUS(x6,j6);
>> + x7 = PLUS(x7,j7);
>> + x8 = PLUS(x8,j8);
>> + x9 = PLUS(x9,j9);
>> + x10 = PLUS(x10,j10);
>> + x11 = PLUS(x11,j11);
>> + x12 = PLUS(x12,j12);
>> + x13 = PLUS(x13,j13);
>> + x14 = PLUS(x14,j14);
>> + x15 = PLUS(x15,j15);
>> +
>> + x0 = XOR(x0,U8TO32_LITTLE(m + 0));
>> + x1 = XOR(x1,U8TO32_LITTLE(m + 4));
>> + x2 = XOR(x2,U8TO32_LITTLE(m + 8));
>> + x3 = XOR(x3,U8TO32_LITTLE(m + 12));
>> + x4 = XOR(x4,U8TO32_LITTLE(m + 16));
>> + x5 = XOR(x5,U8TO32_LITTLE(m + 20));
>> + x6 = XOR(x6,U8TO32_LITTLE(m + 24));
>> + x7 = XOR(x7,U8TO32_LITTLE(m + 28));
>> + x8 = XOR(x8,U8TO32_LITTLE(m + 32));
>> + x9 = XOR(x9,U8TO32_LITTLE(m + 36));
>> + x10 = XOR(x10,U8TO32_LITTLE(m + 40));
>> + x11 = XOR(x11,U8TO32_LITTLE(m + 44));
>> + x12 = XOR(x12,U8TO32_LITTLE(m + 48));
>> + x13 = XOR(x13,U8TO32_LITTLE(m + 52));
>> + x14 = XOR(x14,U8TO32_LITTLE(m + 56));
>> + x15 = XOR(x15,U8TO32_LITTLE(m + 60));
>> +
>> + j12 = PLUSONE(j12);
>> + if (!j12) {
>> + j13 = PLUSONE(j13);
>> + /* stopping at 2^70 bytes per nonce is user's responsibility */
>> + }
>> +
>> + U32TO8_LITTLE(c + 0,x0);
>> + U32TO8_LITTLE(c + 4,x1);
>> + U32TO8_LITTLE(c + 8,x2);
>> + U32TO8_LITTLE(c + 12,x3);
>> + U32TO8_LITTLE(c + 16,x4);
>> + U32TO8_LITTLE(c + 20,x5);
>> + U32TO8_LITTLE(c + 24,x6);
>> + U32TO8_LITTLE(c + 28,x7);
>> + U32TO8_LITTLE(c + 32,x8);
>> + U32TO8_LITTLE(c + 36,x9);
>> + U32TO8_LITTLE(c + 40,x10);
>> + U32TO8_LITTLE(c + 44,x11);
>> + U32TO8_LITTLE(c + 48,x12);
>> + U32TO8_LITTLE(c + 52,x13);
>> + U32TO8_LITTLE(c + 56,x14);
>> + U32TO8_LITTLE(c + 60,x15);
>> +
>> + if (bytes <= 64) {
>> + if (bytes < 64) {
>> + for (i = 0;i < bytes;++i) ctarget[i] = c[i];
>> + }
>> + x->input[12] = j12;
>> + x->input[13] = j13;
>> + return;
>> + }
>> + bytes -= 64;
>> + c += 64;
>> + m += 64;
>> + }
>> +}
>> Index: chacha.h
>> ===================================================================
>> RCS file: chacha.h
>> diff -N chacha.h
>> --- /dev/null 1 Jan 1970 00:00:00 -0000
>> +++ chacha.h 15 Nov 2013 00:08:29 -0000
>> @@ -0,0 +1,35 @@
>> +/* $OpenBSD$ */
>> +
>> +/*
>> +chacha-merged.c version 20080118
>> +D. J. Bernstein
>> +Public domain.
>> +*/
>> +
>> +#ifndef CHACHA_H
>> +#define CHACHA_H
>> +
>> +#include <sys/types.h>
>> +
>> +struct chacha_ctx {
>> + u_int input[16];
>> +};
>> +
>> +#define CHACHA_MINKEYLEN 16
>> +#define CHACHA_NONCELEN 8
>> +#define CHACHA_CTRLEN 8
>> +#define CHACHA_STATELEN (CHACHA_NONCELEN+CHACHA_CTRLEN)
>> +#define CHACHA_BLOCKLEN 64
>> +
>> +void chacha_keysetup(struct chacha_ctx *x, const u_char *k, u_int kbits)
>> + __attribute__((__bounded__(__minbytes__, 2, CHACHA_MINKEYLEN)));
>> +void chacha_ivsetup(struct chacha_ctx *x, const u_char *iv, const u_char *ctr)
>> + __attribute__((__bounded__(__minbytes__, 2, CHACHA_NONCELEN)))
>> + __attribute__((__bounded__(__minbytes__, 3, CHACHA_CTRLEN)));
>> +void chacha_encrypt_bytes(struct chacha_ctx *x, const u_char *m,
>> + u_char *c, u_int bytes)
>> + __attribute__((__bounded__(__buffer__, 2, 4)))
>> + __attribute__((__bounded__(__buffer__, 3, 4)));
>> +
>> +#endif /* CHACHA_H */
>> +
>> Index: chacha20poly1305aead.c
>> ===================================================================
>> RCS file: chacha20poly1305aead.c
>> diff -N chacha20poly1305aead.c
>> --- /dev/null 1 Jan 1970 00:00:00 -0000
>> +++ chacha20poly1305aead.c 15 Nov 2013 00:08:29 -0000
>> @@ -0,0 +1,111 @@
>> +/*
>> + * Copyright (c) 2013 Damien Miller <djm at mindrot.org>
>> + *
>> + * Permission to use, copy, modify, and distribute this software for any
>> + * purpose with or without fee is hereby granted, provided that the above
>> + * copyright notice and this permission notice appear in all copies.
>> + *
>> + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
>> + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
>> + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
>> + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
>> + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
>> + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
>> + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
>> + */
>> +
>> +#include <sys/types.h>
>> +#include <sys/time.h> /* needed for misc.h */
>> +#include <stdarg.h> /* needed for log.h */
>> +#include <string.h>
>> +#include <stdio.h> /* needed for misc.h */
>> +
>> +#include "log.h"
>> +#include "misc.h"
>> +#include "chacha20poly1305aead.h"
>> +
>> +void cp_aead_init(struct chacha_poly_aead_ctx *ctx,
>> + const u_char *key, u_int keylen)
>> +{
>> + if (keylen != (32 + 32)) /* 2 x 256 bit keys */
>> + fatal("%s: invalid keylen %u", __func__, keylen);
>> + chacha_keysetup(&ctx->main_ctx, key, 256);
>> + chacha_keysetup(&ctx->header_ctx, key + 32, 256);
>> +}
>> +
>> +/*
>> + * cp_aead_crypt() operates as following:
>> + * Copy 'aadlen' bytes (without en/decryption) from 'src' to 'dest'.
>> + * Theses bytes are treated as additional authenticated data.
>> + * En/Decrypt 'len' bytes at offset 'aadlen' from 'src' to 'dest'.
>> + * Use POLY1305_TAGLEN bytes at offset 'len'+'aadlen' as the
>> + * authentication tag.
>> + * This tag is written on encryption and verified on decryption.
>> + * Both 'aadlen' and 'authlen' can be set to 0.
>> + */
>> +int
>> +cp_aead_crypt(struct chacha_poly_aead_ctx *ctx, u_int seqnr, u_char *dest,
>> + const u_char *src, u_int len, u_int aadlen, u_int authlen, int do_encrypt)
>> +{
>> + u_char seqbuf[8];
>> + u_char one[8] = { 1, 0, 0, 0, 0, 0, 0, 0 }; /* NB. little-endian */
>> + u_char expected_tag[POLY1305_TAGLEN], poly_key[POLY1305_KEYLEN];
>> + int r = -1;
>> +
>> + /*
>> + * Run ChaCha20 once to generate the Poly1305 key. The IV is the
>> + * packet sequence number.
>> + */
>> + bzero(poly_key, sizeof(poly_key));
>> + put_u64(seqbuf, seqnr);
>> + chacha_ivsetup(&ctx->main_ctx, seqbuf, NULL);
>> + chacha_encrypt_bytes(&ctx->main_ctx,
>> + poly_key, poly_key, sizeof(poly_key));
>> + /* Set Chacha's block counter to 1 */
>> + chacha_ivsetup(&ctx->main_ctx, seqbuf, one);
>> +
>> + /* If decrypting, check tag before anything else */
>> + if (!do_encrypt) {
>> + const u_char *tag = src + aadlen + len;
>> +
>> + poly1305_auth(expected_tag, src, aadlen + len, poly_key);
>> + if (!timingsafe_bcmp(expected_tag, tag, POLY1305_TAGLEN))
>> + goto out;
>> + }
>> + /* Crypt additional data */
>> + if (aadlen) {
>> + chacha_ivsetup(&ctx->header_ctx, seqbuf, NULL);
>> + chacha_encrypt_bytes(&ctx->header_ctx, src, dest, aadlen);
>> + }
>> + chacha_encrypt_bytes(&ctx->main_ctx, src + aadlen,
>> + dest + aadlen, len);
>> +
>> + /* If encrypting, calculate and append tag */
>> + if (do_encrypt) {
>> + poly1305_auth(dest + aadlen + len, dest, aadlen + len,
>> + poly_key);
>> + }
>> + r = 0;
>> +
>> + out:
>> + bzero(expected_tag, sizeof(expected_tag));
>> + bzero(seqbuf, sizeof(seqbuf));
>> + bzero(poly_key, sizeof(poly_key));
>> + return r;
>> +}
>> +
>> +int
>> +cp_aead_get_length(struct chacha_poly_aead_ctx *ctx,
>> + u_int *plenp, u_int seqnr, const u_char *cp, u_int len)
>> +{
>> + u_char buf[4], seqbuf[8];
>> +
>> + if (len < 4)
>> + return -1; /* Insufficient length */
>> + put_u64(seqbuf, seqnr);
>> + chacha_ivsetup(&ctx->header_ctx, seqbuf, NULL);
>> + chacha_encrypt_bytes(&ctx->header_ctx, cp, buf, 4);
>> + *plenp = get_u32(buf);
>> + return 0;
>> +}
>> +
>> Index: chacha20poly1305aead.h
>> ===================================================================
>> RCS file: chacha20poly1305aead.h
>> diff -N chacha20poly1305aead.h
>> --- /dev/null 1 Jan 1970 00:00:00 -0000
>> +++ chacha20poly1305aead.h 15 Nov 2013 00:08:29 -0000
>> @@ -0,0 +1,41 @@
>> +/* $OpenBSD$ */
>> +
>> +/*
>> + * Copyright (c) Damien Miller 2013 <djm at mindrot.org>
>> + *
>> + * Permission to use, copy, modify, and distribute this software for any
>> + * purpose with or without fee is hereby granted, provided that the above
>> + * copyright notice and this permission notice appear in all copies.
>> + *
>> + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
>> + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
>> + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
>> + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
>> + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
>> + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
>> + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
>> + */
>> +#ifndef CHACHA_POLY_AEAD_H
>> +#define CHACHA_POLY_AEAD_H
>> +
>> +#include <sys/types.h>
>> +#include "chacha.h"
>> +#include "poly1305-donna-unrolled.h"
>> +
>> +#define CHACHA_KEYLEN 32 /* Only 256 bit keys used here */
>> +
>> +struct chacha_poly_aead_ctx {
>> + struct chacha_ctx main_ctx, header_ctx;
>> +};
>> +
>> +void cp_aead_init(struct chacha_poly_aead_ctx *cpctx,
>> + const u_char *key, u_int keylen)
>> + __attribute__((__bounded__(__buffer__, 2, 3)));
>> +int cp_aead_crypt(struct chacha_poly_aead_ctx *cpctx, u_int seqnr,
>> + u_char *dest, const u_char *src, u_int len, u_int aadlen, u_int authlen,
>> + int do_encrypt);
>> +int cp_aead_get_length(struct chacha_poly_aead_ctx *cpctx,
>> + u_int *plenp, u_int seqnr, const u_char *cp, u_int len)
>> + __attribute__((__bounded__(__buffer__, 4, 5)));
>> +
>> +#endif /* CHACHA_POLY_AEAD_H */
>> Index: cipher.c
>> ===================================================================
>> RCS file: /var/cvs/openssh/cipher.c,v
>> retrieving revision 1.97
>> diff -u -p -r1.97 cipher.c
>> --- cipher.c 8 Nov 2013 01:16:50 -0000 1.97
>> +++ cipher.c 15 Nov 2013 00:08:29 -0000
>> @@ -43,9 +43,11 @@
>>
>> #include <string.h>
>> #include <stdarg.h>
>> +#include <stdio.h>
>>
>> #include "xmalloc.h"
>> #include "log.h"
>> +#include "misc.h"
>> #include "cipher.h"
>>
>> /* compatibility with old or broken OpenSSL versions */
>> @@ -63,7 +65,9 @@ struct Cipher {
>> u_int iv_len; /* defaults to block_size */
>> u_int auth_len;
>> u_int discard_len;
>> - u_int cbc_mode;
>> + u_int flags;
>> +#define CFLAG_CBC (1<<0)
>> +#define CFLAG_CP_AEAD (1<<1)
>> const EVP_CIPHER *(*evptype)(void);
>> };
>>
>> @@ -95,6 +99,8 @@ static const struct Cipher ciphers[] = {
>> { "aes256-gcm at openssh.com",
>> SSH_CIPHER_SSH2, 16, 32, 12, 16, 0, 0, EVP_aes_256_gcm },
>> #endif
>> + { "chacha20-poly1305 at openssh.com",
>> + SSH_CIPHER_SSH2, 8, 64, 0, 8, 0, CFLAG_CP_AEAD, NULL },
>> { NULL, SSH_CIPHER_INVALID, 0, 0, 0, 0, 0, 0, NULL }
>> };
>>
>> @@ -142,7 +148,12 @@ cipher_authlen(const Cipher *c)
>> u_int
>> cipher_ivlen(const Cipher *c)
>> {
>> - return (c->iv_len ? c->iv_len : c->block_size);
>> + /*
>> + * Default is cipher block size, except for chacha20+poly1305 that
>> + * needs no IV. XXX make iv_len == -1 default?
>> + */
>> + return (c->iv_len != 0 || (c->flags & CFLAG_CP_AEAD) != 0) ?
>> + c->iv_len : c->block_size;
>> }
>>
>> u_int
>> @@ -154,7 +165,7 @@ cipher_get_number(const Cipher *c)
>> u_int
>> cipher_is_cbc(const Cipher *c)
>> {
>> - return (c->cbc_mode);
>> + return (c->flags & CFLAG_CBC) != 0;
>> }
>>
>> u_int
>> @@ -274,8 +285,11 @@ cipher_init(CipherContext *cc, const Cip
>> ivlen, cipher->name);
>> cc->cipher = cipher;
>>
>> + if ((cc->cipher->flags & CFLAG_CP_AEAD) != 0) {
>> + cp_aead_init(&cc->cp_ctx, key, keylen);
>> + return;
>> + }
>> type = (*cipher->evptype)();
>> -
>> EVP_CIPHER_CTX_init(&cc->evp);
>> #ifdef SSH_OLD_EVP
>> if (type->key_len > 0 && type->key_len != keylen) {
>> @@ -330,9 +344,15 @@ cipher_init(CipherContext *cc, const Cip
>> * Both 'aadlen' and 'authlen' can be set to 0.
>> */
>> void
>> -cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src,
>> +cipher_crypt(CipherContext *cc, u_int seqnr, u_char *dest, const u_char *src,
>> u_int len, u_int aadlen, u_int authlen)
>> {
>> + if ((cc->cipher->flags & CFLAG_CP_AEAD) != 0) {
>> + if (cp_aead_crypt(&cc->cp_ctx, seqnr, dest, src, len, aadlen,
>> + authlen, cc->encrypt) != 0)
>> + fatal("Decryption integrity check failed");
>> + return;
>> + }
>> if (authlen) {
>> u_char lastiv[1];
>>
>> @@ -374,10 +394,29 @@ cipher_crypt(CipherContext *cc, u_char *
>> }
>> }
>>
>> +/*
>> + * Extract the packet length for an AEAD cipher, including any decryption
>> + * necessary beforehand.
>> + */
>> +int
>> +cipher_aead_get_length(CipherContext *cc, u_int *plenp, u_int seqnr,
>> + const u_char *cp, u_int len)
>> +{
>> + if ((cc->cipher->flags & CFLAG_CP_AEAD) != 0)
>> + return cp_aead_get_length(&cc->cp_ctx, plenp, seqnr,
>> + cp, len);
>> + if (len < 4)
>> + return -1;
>> + *plenp = get_u32(cp);
>> + return 0;
>> +}
>> +
>> void
>> cipher_cleanup(CipherContext *cc)
>> {
>> - if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
>> + if ((cc->cipher->flags & CFLAG_CP_AEAD) != 0)
>> + bzero(&cc->cp_ctx, sizeof(&cc->cp_ctx));
>> + else if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
>> error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
>> }
>>
>> @@ -417,6 +456,8 @@ cipher_get_keyiv_len(const CipherContext
>>
>> if (c->number == SSH_CIPHER_3DES)
>> ivlen = 24;
>> + else if ((cc->cipher->flags & CFLAG_CP_AEAD) != 0)
>> + ivlen = 0;
>> else
>> ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
>> return (ivlen);
>> @@ -428,6 +469,12 @@ cipher_get_keyiv(CipherContext *cc, u_ch
>> const Cipher *c = cc->cipher;
>> int evplen;
>>
>> + if ((cc->cipher->flags & CFLAG_CP_AEAD) != 0) {
>> + if (len != 0)
>> + fatal("%s: wrong iv length %d != %d", __func__, len, 0);
>> + return;
>> + }
>> +
>> switch (c->number) {
>> case SSH_CIPHER_SSH2:
>> case SSH_CIPHER_DES:
>> @@ -463,6 +510,9 @@ cipher_set_keyiv(CipherContext *cc, u_ch
>> {
>> const Cipher *c = cc->cipher;
>> int evplen = 0;
>> +
>> + if ((cc->cipher->flags & CFLAG_CP_AEAD) != 0)
>> + return;
>>
>> switch (c->number) {
>> case SSH_CIPHER_SSH2:
>> Index: cipher.h
>> ===================================================================
>> RCS file: /var/cvs/openssh/cipher.h,v
>> retrieving revision 1.37
>> diff -u -p -r1.37 cipher.h
>> --- cipher.h 8 Nov 2013 01:16:50 -0000 1.37
>> +++ cipher.h 15 Nov 2013 00:08:29 -0000
>> @@ -38,6 +38,8 @@
>> #define CIPHER_H
>>
>> #include <openssl/evp.h>
>> +#include "chacha20poly1305aead.h"
>> +
>> /*
>> * Cipher types for SSH-1. New types can be added, but old types should not
>> * be removed for compatibility. The maximum allowed value is 31.
>> @@ -65,7 +67,9 @@ struct Cipher;
>> struct CipherContext {
>> int plaintext;
>> int encrypt;
>> + int is_cp_aead;
>> EVP_CIPHER_CTX evp;
>> + struct chacha_poly_aead_ctx cp_ctx; /* XXX union with evp? */
>> const Cipher *cipher;
>> };
>>
>> @@ -78,8 +82,10 @@ int ciphers_valid(const char *);
>> char *cipher_alg_list(char);
>> void cipher_init(CipherContext *, const Cipher *, const u_char *, u_int,
>> const u_char *, u_int, int);
>> -void cipher_crypt(CipherContext *, u_char *, const u_char *,
>> +void cipher_crypt(CipherContext *, u_int, u_char *, const u_char *,
>> u_int, u_int, u_int);
>> +int cipher_aead_get_length(CipherContext *, u_int *, u_int,
>> + const u_char *, u_int);
>> void cipher_cleanup(CipherContext *);
>> void cipher_set_key_string(CipherContext *, const Cipher *, const char *, int);
>> u_int cipher_blocksize(const Cipher *);
>> Index: myproposal.h
>> ===================================================================
>> RCS file: /var/cvs/openssh/myproposal.h,v
>> retrieving revision 1.43
>> diff -u -p -r1.43 myproposal.h
>> --- myproposal.h 9 Nov 2013 07:39:25 -0000 1.43
>> +++ myproposal.h 15 Nov 2013 00:08:30 -0000
>> @@ -104,6 +104,7 @@
>> "aes128-ctr,aes192-ctr,aes256-ctr," \
>> "arcfour256,arcfour128," \
>> AESGCM_CIPHER_MODES \
>> + "chacha20-poly1305 at openssh.com," \
>> "aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc," \
>> "aes192-cbc,aes256-cbc,arcfour,rijndael-cbc at lysator.liu.se"
>>
>> Index: packet.c
>> ===================================================================
>> RCS file: /var/cvs/openssh/packet.c,v
>> retrieving revision 1.196
>> diff -u -p -r1.196 packet.c
>> --- packet.c 8 Nov 2013 01:19:57 -0000 1.196
>> +++ packet.c 15 Nov 2013 00:08:30 -0000
>> @@ -713,7 +713,7 @@ packet_send1(void)
>> buffer_append(&active_state->output, buf, 4);
>> cp = buffer_append_space(&active_state->output,
>> buffer_len(&active_state->outgoing_packet));
>> - cipher_crypt(&active_state->send_context, cp,
>> + cipher_crypt(&active_state->send_context, 0, cp,
>> buffer_ptr(&active_state->outgoing_packet),
>> buffer_len(&active_state->outgoing_packet), 0, 0);
>>
>> @@ -946,8 +946,8 @@ packet_send2_wrapped(void)
>> }
>> /* encrypt packet and append to output buffer. */
>> cp = buffer_append_space(&active_state->output, len + authlen);
>> - cipher_crypt(&active_state->send_context, cp,
>> - buffer_ptr(&active_state->outgoing_packet),
>> + cipher_crypt(&active_state->send_context, active_state->p_send.seqnr,
>> + cp, buffer_ptr(&active_state->outgoing_packet),
>> len - aadlen, aadlen, authlen);
>> /* append unencrypted MAC */
>> if (mac && mac->enabled) {
>> @@ -1208,7 +1208,7 @@ packet_read_poll1(void)
>> /* Decrypt data to incoming_packet. */
>> buffer_clear(&active_state->incoming_packet);
>> cp = buffer_append_space(&active_state->incoming_packet, padded_len);
>> - cipher_crypt(&active_state->receive_context, cp,
>> + cipher_crypt(&active_state->receive_context, 0, cp,
>> buffer_ptr(&active_state->input), padded_len, 0, 0);
>>
>> buffer_consume(&active_state->input, padded_len);
>> @@ -1279,10 +1279,12 @@ packet_read_poll2(u_int32_t *seqnr_p)
>> aadlen = (mac && mac->enabled && mac->etm) || authlen ? 4 : 0;
>>
>> if (aadlen && active_state->packlen == 0) {
>> - if (buffer_len(&active_state->input) < 4)
>> + if (cipher_aead_get_length(&active_state->receive_context,
>> + &active_state->packlen,
>> + active_state->p_read.seqnr,
>> + buffer_ptr(&active_state->input),
>> + buffer_len(&active_state->input)) != 0)
>> return SSH_MSG_NONE;
>> - cp = buffer_ptr(&active_state->input);
>> - active_state->packlen = get_u32(cp);
>> if (active_state->packlen < 1 + 4 ||
>> active_state->packlen > PACKET_MAX_SIZE) {
>> #ifdef PACKET_DEBUG
>> @@ -1302,7 +1304,8 @@ packet_read_poll2(u_int32_t *seqnr_p)
>> buffer_clear(&active_state->incoming_packet);
>> cp = buffer_append_space(&active_state->incoming_packet,
>> block_size);
>> - cipher_crypt(&active_state->receive_context, cp,
>> + cipher_crypt(&active_state->receive_context,
>> + active_state->p_read.seqnr, cp,
>> buffer_ptr(&active_state->input), block_size, 0, 0);
>> cp = buffer_ptr(&active_state->incoming_packet);
>> active_state->packlen = get_u32(cp);
>> @@ -1357,7 +1360,8 @@ packet_read_poll2(u_int32_t *seqnr_p)
>> macbuf = mac_compute(mac, active_state->p_read.seqnr,
>> buffer_ptr(&active_state->input), aadlen + need);
>> cp = buffer_append_space(&active_state->incoming_packet, aadlen + need);
>> - cipher_crypt(&active_state->receive_context, cp,
>> + cipher_crypt(&active_state->receive_context,
>> + active_state->p_read.seqnr, cp,
>> buffer_ptr(&active_state->input), need, aadlen, authlen);
>> buffer_consume(&active_state->input, aadlen + need + authlen);
>> /*
>> Index: poly1305-donna-unrolled.c
>> ===================================================================
>> RCS file: poly1305-donna-unrolled.c
>> diff -N poly1305-donna-unrolled.c
>> --- /dev/null 1 Jan 1970 00:00:00 -0000
>> +++ poly1305-donna-unrolled.c 15 Nov 2013 00:08:30 -0000
>> @@ -0,0 +1,154 @@
>> +/*
>> + * Public Domain poly1305-donna from Andrew M.
>> + * https://github.com/floodyberry/poly1305-donna
>> + */
>> +
>> +#include <sys/types.h>
>> +#include <stdint.h>
>> +
>> +#include "poly1305-donna-unrolled.h"
>> +
>> +#define mul32x32_64(a,b) ((uint64_t)(a) * (b))
>> +
>> +#define U8TO32_LE(p) \
>> + (((uint32_t)((p)[0])) | \
>> + ((uint32_t)((p)[1]) << 8) | \
>> + ((uint32_t)((p)[2]) << 16) | \
>> + ((uint32_t)((p)[3]) << 24))
>> +
>> +#define U32TO8_LE(p, v) \
>> + do { \
>> + (p)[0] = (uint8_t)((v)); \
>> + (p)[1] = (uint8_t)((v) >> 8); \
>> + (p)[2] = (uint8_t)((v) >> 16); \
>> + (p)[3] = (uint8_t)((v) >> 24); \
>> + } while (0)
>> +
>> +void
>> +poly1305_auth(unsigned char out[POLY1305_TAGLEN], const unsigned char *m, size_t inlen, const unsigned char key[POLY1305_KEYLEN]) {
>> + uint32_t t0,t1,t2,t3;
>> + uint32_t h0,h1,h2,h3,h4;
>> + uint32_t r0,r1,r2,r3,r4;
>> + uint32_t s1,s2,s3,s4;
>> + uint32_t b, nb;
>> + size_t j;
>> + uint64_t t[5];
>> + uint64_t f0,f1,f2,f3;
>> + uint32_t g0,g1,g2,g3,g4;
>> + uint64_t c;
>> + unsigned char mp[16];
>> +
>> + /* clamp key */
>> + t0 = U8TO32_LE(key+0);
>> + t1 = U8TO32_LE(key+4);
>> + t2 = U8TO32_LE(key+8);
>> + t3 = U8TO32_LE(key+12);
>> +
>> + /* precompute multipliers */
>> + r0 = t0 & 0x3ffffff; t0 >>= 26; t0 |= t1 << 6;
>> + r1 = t0 & 0x3ffff03; t1 >>= 20; t1 |= t2 << 12;
>> + r2 = t1 & 0x3ffc0ff; t2 >>= 14; t2 |= t3 << 18;
>> + r3 = t2 & 0x3f03fff; t3 >>= 8;
>> + r4 = t3 & 0x00fffff;
>> +
>> + s1 = r1 * 5;
>> + s2 = r2 * 5;
>> + s3 = r3 * 5;
>> + s4 = r4 * 5;
>> +
>> + /* init state */
>> + h0 = 0;
>> + h1 = 0;
>> + h2 = 0;
>> + h3 = 0;
>> + h4 = 0;
>> +
>> + /* full blocks */
>> + if (inlen < 16) goto poly1305_donna_atmost15bytes;
>> +poly1305_donna_16bytes:
>> + m += 16;
>> + inlen -= 16;
>> +
>> + t0 = U8TO32_LE(m-16);
>> + t1 = U8TO32_LE(m-12);
>> + t2 = U8TO32_LE(m-8);
>> + t3 = U8TO32_LE(m-4);
>> +
>> + h0 += t0 & 0x3ffffff;
>> + h1 += ((((uint64_t)t1 << 32) | t0) >> 26) & 0x3ffffff;
>> + h2 += ((((uint64_t)t2 << 32) | t1) >> 20) & 0x3ffffff;
>> + h3 += ((((uint64_t)t3 << 32) | t2) >> 14) & 0x3ffffff;
>> + h4 += (t3 >> 8) | (1 << 24);
>> +
>> +
>> +poly1305_donna_mul:
>> + t[0] = mul32x32_64(h0,r0) + mul32x32_64(h1,s4) + mul32x32_64(h2,s3) + mul32x32_64(h3,s2) + mul32x32_64(h4,s1);
>> + t[1] = mul32x32_64(h0,r1) + mul32x32_64(h1,r0) + mul32x32_64(h2,s4) + mul32x32_64(h3,s3) + mul32x32_64(h4,s2);
>> + t[2] = mul32x32_64(h0,r2) + mul32x32_64(h1,r1) + mul32x32_64(h2,r0) + mul32x32_64(h3,s4) + mul32x32_64(h4,s3);
>> + t[3] = mul32x32_64(h0,r3) + mul32x32_64(h1,r2) + mul32x32_64(h2,r1) + mul32x32_64(h3,r0) + mul32x32_64(h4,s4);
>> + t[4] = mul32x32_64(h0,r4) + mul32x32_64(h1,r3) + mul32x32_64(h2,r2) + mul32x32_64(h3,r1) + mul32x32_64(h4,r0);
>> +
>> + h0 = (uint32_t)t[0] & 0x3ffffff; c = (t[0] >> 26);
>> + t[1] += c; h1 = (uint32_t)t[1] & 0x3ffffff; b = (uint32_t)(t[1] >> 26);
>> + t[2] += b; h2 = (uint32_t)t[2] & 0x3ffffff; b = (uint32_t)(t[2] >> 26);
>> + t[3] += b; h3 = (uint32_t)t[3] & 0x3ffffff; b = (uint32_t)(t[3] >> 26);
>> + t[4] += b; h4 = (uint32_t)t[4] & 0x3ffffff; b = (uint32_t)(t[4] >> 26);
>> + h0 += b * 5;
>> +
>> + if (inlen >= 16) goto poly1305_donna_16bytes;
>> +
>> + /* final bytes */
>> +poly1305_donna_atmost15bytes:
>> + if (!inlen) goto poly1305_donna_finish;
>> +
>> + for (j = 0; j < inlen; j++) mp[j] = m[j];
>> + mp[j++] = 1;
>> + for (; j < 16; j++) mp[j] = 0;
>> + inlen = 0;
>> +
>> + t0 = U8TO32_LE(mp+0);
>> + t1 = U8TO32_LE(mp+4);
>> + t2 = U8TO32_LE(mp+8);
>> + t3 = U8TO32_LE(mp+12);
>> +
>> + h0 += t0 & 0x3ffffff;
>> + h1 += ((((uint64_t)t1 << 32) | t0) >> 26) & 0x3ffffff;
>> + h2 += ((((uint64_t)t2 << 32) | t1) >> 20) & 0x3ffffff;
>> + h3 += ((((uint64_t)t3 << 32) | t2) >> 14) & 0x3ffffff;
>> + h4 += (t3 >> 8);
>> +
>> + goto poly1305_donna_mul;
>> +
>> +poly1305_donna_finish:
>> + b = h0 >> 26; h0 = h0 & 0x3ffffff;
>> + h1 += b; b = h1 >> 26; h1 = h1 & 0x3ffffff;
>> + h2 += b; b = h2 >> 26; h2 = h2 & 0x3ffffff;
>> + h3 += b; b = h3 >> 26; h3 = h3 & 0x3ffffff;
>> + h4 += b; b = h4 >> 26; h4 = h4 & 0x3ffffff;
>> + h0 += b * 5; b = h0 >> 26; h0 = h0 & 0x3ffffff;
>> + h1 += b;
>> +
>> + g0 = h0 + 5; b = g0 >> 26; g0 &= 0x3ffffff;
>> + g1 = h1 + b; b = g1 >> 26; g1 &= 0x3ffffff;
>> + g2 = h2 + b; b = g2 >> 26; g2 &= 0x3ffffff;
>> + g3 = h3 + b; b = g3 >> 26; g3 &= 0x3ffffff;
>> + g4 = h4 + b - (1 << 26);
>> +
>> + b = (g4 >> 31) - 1;
>> + nb = ~b;
>> + h0 = (h0 & nb) | (g0 & b);
>> + h1 = (h1 & nb) | (g1 & b);
>> + h2 = (h2 & nb) | (g2 & b);
>> + h3 = (h3 & nb) | (g3 & b);
>> + h4 = (h4 & nb) | (g4 & b);
>> +
>> + f0 = ((h0 ) | (h1 << 26)) + (uint64_t)U8TO32_LE(&key[16]);
>> + f1 = ((h1 >> 6) | (h2 << 20)) + (uint64_t)U8TO32_LE(&key[20]);
>> + f2 = ((h2 >> 12) | (h3 << 14)) + (uint64_t)U8TO32_LE(&key[24]);
>> + f3 = ((h3 >> 18) | (h4 << 8)) + (uint64_t)U8TO32_LE(&key[28]);
>> +
>> + U32TO8_LE(&out[ 0], f0); f1 += (f0 >> 32);
>> + U32TO8_LE(&out[ 4], f1); f2 += (f1 >> 32);
>> + U32TO8_LE(&out[ 8], f2); f3 += (f2 >> 32);
>> + U32TO8_LE(&out[12], f3);
>> +}
>> Index: poly1305-donna-unrolled.h
>> ===================================================================
>> RCS file: poly1305-donna-unrolled.h
>> diff -N poly1305-donna-unrolled.h
>> --- /dev/null 1 Jan 1970 00:00:00 -0000
>> +++ poly1305-donna-unrolled.h 15 Nov 2013 00:08:30 -0000
>> @@ -0,0 +1,22 @@
>> +/* $OpenBSD$ */
>> +
>> +/*
>> + * Public Domain poly1305-donna from Andrew M.
>> + * https://github.com/floodyberry/poly1305-donna
>> + */
>> +
>> +#ifndef POLY1305_H
>> +#define POLY1305_H
>> +
>> +#include <sys/types.h>
>> +
>> +#define POLY1305_KEYLEN 32
>> +#define POLY1305_TAGLEN 16
>> +
>> +void poly1305_auth(u_char out[POLY1305_TAGLEN], const u_char *m, size_t inlen,
>> + const u_char key[POLY1305_KEYLEN])
>> + __attribute__((__bounded__(__minbytes__, 1, POLY1305_TAGLEN)))
>> + __attribute__((__bounded__(__buffer__, 2, 3)))
>> + __attribute__((__bounded__(__minbytes__, 4, POLY1305_KEYLEN)));
>> +
>> +#endif /* POLY1305_H */
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>
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