chacha20+poly1305 authenticated encryption

Damien Miller djm at mindrot.org
Fri Nov 15 21:03:11 EST 2013


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

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(&copy), buffer_len(&copy), 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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