diff --git a/arctwo-meta.c b/arctwo-meta.c
new file mode 100644
index 0000000000000000000000000000000000000000..3401b9d35f6b24ee974c3cf0b15f7ebe407937fc
--- /dev/null
+++ b/arctwo-meta.c
@@ -0,0 +1,48 @@
+/* arctwo-meta.c */
+
+/* nettle, low-level cryptographics library
+ *
+ * Copyright (C) 2004 Simon Josefsson
+ *
+ * The nettle library 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.
+ *
+ * The nettle library 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 the nettle library; see the file COPYING.LIB. If not, write to
+ * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+#if HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include "nettle-meta.h"
+
+#include "arctwo.h"
+
+const struct nettle_cipher nettle_arctwo40
+= _NETTLE_CIPHER (arctwo, ARCTWO, 40);
+
+const struct nettle_cipher nettle_arctwo64
+= _NETTLE_CIPHER (arctwo, ARCTWO, 64);
+
+const struct nettle_cipher nettle_arctwo128
+= _NETTLE_CIPHER (arctwo, ARCTWO, 128);
+
+/* Map Gutmann variant. */
+#define arctwo_gutmann_ctx arctwo_ctx
+#define arctwo_gutmann_encrypt arctwo_encrypt
+#define arctwo_gutmann_decrypt arctwo_decrypt
+#define arctwo_gutmann_ctx arctwo_ctx
+#define arctwo_gutmann_set_key arctwo_set_key_gutmann
+
+const struct nettle_cipher nettle_arctwo_gutmann128
+= _NETTLE_CIPHER (arctwo_gutmann, ARCTWO, 128);
diff --git a/arctwo.c b/arctwo.c
new file mode 100644
index 0000000000000000000000000000000000000000..a84cc250622ef955dddff57bedeebf112b259c0f
--- /dev/null
+++ b/arctwo.c
@@ -0,0 +1,230 @@
+/* arctwo.c
+ *
+ * The cipher described in rfc2268; aka Ron's Cipher 2.
+ */
+
+/* nettle, low-level cryptographics library
+ *
+ * Copyright (C) 2004 Simon Josefsson
+ * Copyright (C) 2003 Nikos Mavroyanopoulos
+ * Copyright (C) 2004 Free Software Foundation, Inc.
+ * Copyright (C) 2004 Niels Möller
+ *
+ * The nettle library 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.
+ *
+ * The nettle library 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 the nettle library; see the file COPYING.LIB. If not, write to
+ * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+/* This implementation was written by Nikos Mavroyanopoulos for GNUTLS
+ * as a Libgcrypt module (gnutls/lib/x509/rc2.c) and later adapted for
+ * direct use by Libgcrypt by Werner Koch and later adapted for direct
+ * use by Nettle by Simon Josefsson and Niels Möller.
+ *
+ * The implementation here is based on Peter Gutmann's RRC.2 paper and
+ * RFC 2268.
+ */
+
+#if HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <assert.h>
+
+#include "arctwo.h"
+
+#include "macros.h"
+
+static const uint8_t arctwo_sbox[] = {
+ 0xd9, 0x78, 0xf9, 0xc4, 0x19, 0xdd, 0xb5, 0xed,
+ 0x28, 0xe9, 0xfd, 0x79, 0x4a, 0xa0, 0xd8, 0x9d,
+ 0xc6, 0x7e, 0x37, 0x83, 0x2b, 0x76, 0x53, 0x8e,
+ 0x62, 0x4c, 0x64, 0x88, 0x44, 0x8b, 0xfb, 0xa2,
+ 0x17, 0x9a, 0x59, 0xf5, 0x87, 0xb3, 0x4f, 0x13,
+ 0x61, 0x45, 0x6d, 0x8d, 0x09, 0x81, 0x7d, 0x32,
+ 0xbd, 0x8f, 0x40, 0xeb, 0x86, 0xb7, 0x7b, 0x0b,
+ 0xf0, 0x95, 0x21, 0x22, 0x5c, 0x6b, 0x4e, 0x82,
+ 0x54, 0xd6, 0x65, 0x93, 0xce, 0x60, 0xb2, 0x1c,
+ 0x73, 0x56, 0xc0, 0x14, 0xa7, 0x8c, 0xf1, 0xdc,
+ 0x12, 0x75, 0xca, 0x1f, 0x3b, 0xbe, 0xe4, 0xd1,
+ 0x42, 0x3d, 0xd4, 0x30, 0xa3, 0x3c, 0xb6, 0x26,
+ 0x6f, 0xbf, 0x0e, 0xda, 0x46, 0x69, 0x07, 0x57,
+ 0x27, 0xf2, 0x1d, 0x9b, 0xbc, 0x94, 0x43, 0x03,
+ 0xf8, 0x11, 0xc7, 0xf6, 0x90, 0xef, 0x3e, 0xe7,
+ 0x06, 0xc3, 0xd5, 0x2f, 0xc8, 0x66, 0x1e, 0xd7,
+ 0x08, 0xe8, 0xea, 0xde, 0x80, 0x52, 0xee, 0xf7,
+ 0x84, 0xaa, 0x72, 0xac, 0x35, 0x4d, 0x6a, 0x2a,
+ 0x96, 0x1a, 0xd2, 0x71, 0x5a, 0x15, 0x49, 0x74,
+ 0x4b, 0x9f, 0xd0, 0x5e, 0x04, 0x18, 0xa4, 0xec,
+ 0xc2, 0xe0, 0x41, 0x6e, 0x0f, 0x51, 0xcb, 0xcc,
+ 0x24, 0x91, 0xaf, 0x50, 0xa1, 0xf4, 0x70, 0x39,
+ 0x99, 0x7c, 0x3a, 0x85, 0x23, 0xb8, 0xb4, 0x7a,
+ 0xfc, 0x02, 0x36, 0x5b, 0x25, 0x55, 0x97, 0x31,
+ 0x2d, 0x5d, 0xfa, 0x98, 0xe3, 0x8a, 0x92, 0xae,
+ 0x05, 0xdf, 0x29, 0x10, 0x67, 0x6c, 0xba, 0xc9,
+ 0xd3, 0x00, 0xe6, 0xcf, 0xe1, 0x9e, 0xa8, 0x2c,
+ 0x63, 0x16, 0x01, 0x3f, 0x58, 0xe2, 0x89, 0xa9,
+ 0x0d, 0x38, 0x34, 0x1b, 0xab, 0x33, 0xff, 0xb0,
+ 0xbb, 0x48, 0x0c, 0x5f, 0xb9, 0xb1, 0xcd, 0x2e,
+ 0xc5, 0xf3, 0xdb, 0x47, 0xe5, 0xa5, 0x9c, 0x77,
+ 0x0a, 0xa6, 0x20, 0x68, 0xfe, 0x7f, 0xc1, 0xad
+};
+
+#define rotl16(x,n) (((x) << ((uint16_t)(n))) | ((x) >> (16 - (uint16_t)(n))))
+#define rotr16(x,n) (((x) >> ((uint16_t)(n))) | ((x) << (16 - (uint16_t)(n))))
+
+void
+arctwo_encrypt (struct arctwo_ctx *ctx,
+ unsigned length, uint8_t *dst, const uint8_t *src)
+{
+ FOR_BLOCKS (length, dst, src, ARCTWO_BLOCK_SIZE)
+ {
+ register unsigned i;
+ uint16_t w0, w1, w2, w3;
+
+ w0 = LE_READ_UINT16 (&src[0]);
+ w1 = LE_READ_UINT16 (&src[2]);
+ w2 = LE_READ_UINT16 (&src[4]);
+ w3 = LE_READ_UINT16 (&src[6]);
+
+ for (i = 0; i < 16; i++)
+ {
+ register unsigned j = i * 4;
+ /* For some reason I cannot combine those steps. */
+ w0 += (w1 & ~w3) + (w2 & w3) + ctx->S[j];
+ w0 = rotl16 (w0, 1);
+
+ w1 += (w2 & ~w0) + (w3 & w0) + ctx->S[j + 1];
+ w1 = rotl16 (w1, 2);
+
+ w2 += (w3 & ~w1) + (w0 & w1) + ctx->S[j + 2];
+ w2 = rotl16 (w2, 3);
+
+ w3 += (w0 & ~w2) + (w1 & w2) + ctx->S[j + 3];
+ w3 = rotl16 (w3, 5);
+
+ if (i == 4 || i == 10)
+ {
+ w0 += ctx->S[w3 & 63];
+ w1 += ctx->S[w0 & 63];
+ w2 += ctx->S[w1 & 63];
+ w3 += ctx->S[w2 & 63];
+ }
+ }
+ LE_WRITE_UINT16 (&dst[0], w0);
+ LE_WRITE_UINT16 (&dst[2], w1);
+ LE_WRITE_UINT16 (&dst[4], w2);
+ LE_WRITE_UINT16 (&dst[6], w3);
+ }
+}
+
+void
+arctwo_decrypt (struct arctwo_ctx *ctx,
+ unsigned length, uint8_t *dst, const uint8_t *src)
+{
+ FOR_BLOCKS (length, dst, src, ARCTWO_BLOCK_SIZE)
+ {
+ register unsigned i;
+ uint16_t w0, w1, w2, w3;
+
+ w0 = LE_READ_UINT16 (&src[0]);
+ w1 = LE_READ_UINT16 (&src[2]);
+ w2 = LE_READ_UINT16 (&src[4]);
+ w3 = LE_READ_UINT16 (&src[6]);
+
+ for (i = 16; i-- > 0; )
+ {
+ register unsigned j = i * 4;
+
+ w3 = rotr16 (w3, 5);
+ w3 -= (w0 & ~w2) + (w1 & w2) + ctx->S[j + 3];
+
+ w2 = rotr16 (w2, 3);
+ w2 -= (w3 & ~w1) + (w0 & w1) + ctx->S[j + 2];
+
+ w1 = rotr16 (w1, 2);
+ w1 -= (w2 & ~w0) + (w3 & w0) + ctx->S[j + 1];
+
+ w0 = rotr16 (w0, 1);
+ w0 -= (w1 & ~w3) + (w2 & w3) + ctx->S[j];
+
+ if (i == 5 || i == 11)
+ {
+ w3 = w3 - ctx->S[w2 & 63];
+ w2 = w2 - ctx->S[w1 & 63];
+ w1 = w1 - ctx->S[w0 & 63];
+ w0 = w0 - ctx->S[w3 & 63];
+ }
+
+ }
+ LE_WRITE_UINT16 (&dst[0], w0);
+ LE_WRITE_UINT16 (&dst[2], w1);
+ LE_WRITE_UINT16 (&dst[4], w2);
+ LE_WRITE_UINT16 (&dst[6], w3);
+ }
+}
+
+void
+arctwo_set_key_ebk (struct arctwo_ctx *ctx,
+ unsigned length, const uint8_t *key, unsigned ebk)
+{
+ unsigned i;
+ /* Expanded key, treated as octets */
+ uint8_t S[128];
+ uint8_t x;
+
+ assert (length >= ARCTWO_MIN_KEY_SIZE);
+ assert (length <= ARCTWO_MAX_KEY_SIZE);
+ assert (ebk <= 1024);
+
+ for (i = 0; i < length; i++)
+ S[i] = key[i];
+
+ /* Phase 1: Expand input key to 128 bytes */
+ for (i = length; i < ARCTWO_MAX_KEY_SIZE; i++)
+ S[i] = arctwo_sbox[(S[i - length] + S[i - 1]) & 255];
+
+ S[0] = arctwo_sbox[S[0]];
+
+ /* Reduce effective key size to ebk bits, if requested by caller. */
+ if (ebk > 0 && ebk < 1024)
+ {
+ int len = (ebk + 7) >> 3;
+ i = 128 - len;
+ x = arctwo_sbox[S[i] & (255 >> (7 & -ebk))];
+ S[i] = x;
+
+ while (i--)
+ {
+ x = arctwo_sbox[x ^ S[i + len]];
+ S[i] = x;
+ }
+ }
+
+ /* Make the expanded key endian independent. */
+ for (i = 0; i < 64; i++)
+ ctx->S[i] = LE_READ_UINT16(S + i * 2);
+}
+
+void
+arctwo_set_key (struct arctwo_ctx *ctx, unsigned length, const uint8_t *key)
+{
+ arctwo_set_key_ebk (ctx, length, key, 8 * length);
+}
+
+void
+arctwo_set_key_gutmann (struct arctwo_ctx *ctx,
+ unsigned length, const uint8_t *key)
+{
+ arctwo_set_key_ebk (ctx, length, key, 0);
+}
diff --git a/arctwo.h b/arctwo.h
new file mode 100644
index 0000000000000000000000000000000000000000..4f2a93f40a4e31450a974d10870b3ccdddc07622
--- /dev/null
+++ b/arctwo.h
@@ -0,0 +1,76 @@
+/* arctwo.h
+ *
+ * The arctwo/rfc2268 block cipher.
+ */
+
+/* nettle, low-level cryptographics library
+ *
+ * Copyright (C) 2004 Simon Josefsson
+ * Copyright (C) 2002, 2004 Niels Möller
+ *
+ * The nettle library 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.
+ *
+ * The nettle library 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 the nettle library; see the file COPYING.LIB. If not, write to
+ * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+#ifndef NETTLE_ARCTWO_H_INCLUDED
+#define NETTLE_ARCTWO_H_INCLUDED
+
+#include "nettle-types.h"
+
+/* Name mangling */
+#define arctwo_set_key nettle_arctwo_set_key
+#define arctwo_set_key_ebk nettle_arctwo_set_key_ebk
+#define arctwo_encrypt nettle_arctwo_encrypt
+#define arctwo_decrypt nettle_arctwo_decrypt
+#define arctwo_set_key_gutmann nettle_arctwo_set_key_gutmann
+
+#define ARCTWO_BLOCK_SIZE 8
+
+/* Variable key size from 1 byte to 128 bytes. */
+#define ARCTWO_MIN_KEY_SIZE 1
+#define ARCTWO_MAX_KEY_SIZE 128
+
+#define ARCTWO_KEY_SIZE 8
+
+struct arctwo_ctx
+{
+ uint16_t S[64];
+};
+
+/* Key expansion function that takes the "effective key bits", 1-1024,
+ as an explicit argument. 0 means maximum key bits. */
+void
+arctwo_set_key_ebk (struct arctwo_ctx *ctx,
+ unsigned length, const uint8_t * key, unsigned ebk);
+
+/* Equvivalent to arctwo_set_key_ebk, with ebk = 8 * length */
+void
+arctwo_set_key (struct arctwo_ctx *ctx, unsigned length, const uint8_t *key);
+
+/* Equvivalent to arctwo_set_key_ebk, with ebk = 1024 */
+/* FIXME: Is this function really needed, and if so, what's the right
+ name for it? */
+void
+arctwo_set_key_gutmann (struct arctwo_ctx *ctx,
+ unsigned length, const uint8_t *key);
+
+void
+arctwo_encrypt (struct arctwo_ctx *ctx,
+ unsigned length, uint8_t *dst, const uint8_t *src);
+void
+arctwo_decrypt (struct arctwo_ctx *ctx,
+ unsigned length, uint8_t *dst, const uint8_t *src);
+
+#endif /* NETTLE_ARCTWO_H_INCLUDED */
diff --git a/testsuite/arctwo-test.c b/testsuite/arctwo-test.c
new file mode 100644
index 0000000000000000000000000000000000000000..6a363ed6cc9ed90d85c932f4cc25b84db9f979d1
--- /dev/null
+++ b/testsuite/arctwo-test.c
@@ -0,0 +1,115 @@
+/* nettle, low-level cryptographics library
+ *
+ * Copyright (C) 2004 Simon Josefsson
+ * Copyright (C) 2004 Niels Möller
+ *
+ * The nettle library 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.
+ *
+ * The nettle library 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 the nettle library; see the file COPYING.LIB. If not, write to
+ * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+#include "testutils.h"
+#include "arctwo.h"
+
+/* For tests with obscure values of ebk. */
+static void
+test_arctwo(unsigned ebk,
+ unsigned key_length,
+ const uint8_t *key,
+ unsigned length,
+ const uint8_t *cleartext,
+ const uint8_t *ciphertext)
+{
+ struct arctwo_ctx ctx;
+ uint8_t *data = xalloc(length);
+
+ arctwo_set_key_ebk(&ctx, key_length, key, ebk);
+ arctwo_encrypt(&ctx, length, data, cleartext);
+
+ if (!MEMEQ(length, data, ciphertext))
+ FAIL();
+
+ arctwo_decrypt(&ctx, length, data, data);
+
+ if (!MEMEQ(length, data, cleartext))
+ FAIL();
+
+ free(data);
+}
+
+int
+test_main(void)
+{
+ /* Test vectors from Peter Gutmann's paper. */
+ test_cipher(&nettle_arctwo_gutmann128,
+ HL("00000000 00000000 00000000 00000000"),
+ HL("00000000 00000000"),
+ H ("1c198a83 8df028b7"));
+
+ test_cipher(&nettle_arctwo_gutmann128,
+ HL("00010203 04050607 08090a0b 0c0d0e0f"),
+ HL("00000000 00000000"),
+ H ("50dc0162 bd757f31"));
+
+ /* This one was checked against libmcrypt's RFC2268. */
+ test_cipher(&nettle_arctwo_gutmann128,
+ HL("30000000 00000000 00000000 00000000"),
+ HL("10000000 00000000"),
+ H ("8fd10389 336bf95e"));
+
+ /* Test vectors from RFC 2268. */
+ test_cipher(&nettle_arctwo64,
+ HL("ffffffff ffffffff"),
+ HL("ffffffff ffffffff"),
+ H ("278b27e4 2e2f0d49"));
+
+ test_cipher(&nettle_arctwo64,
+ HL("30000000 00000000"),
+ HL("10000000 00000001"),
+ H ("30649edf 9be7d2c2"));
+
+ test_cipher(&nettle_arctwo128,
+ HL("88bca90e 90875a7f 0f79c384 627bafb2"),
+ HL("00000000 00000000"),
+ H ("2269552a b0f85ca6"));
+
+ /* More obscure tests from RFC 2286 */
+ test_arctwo(63,
+ HL("00000000 00000000"),
+ HL("00000000 00000000"),
+ H ("ebb773f9 93278eff"));
+
+ test_arctwo(64,
+ HL("88"),
+ HL("00000000 00000000"),
+ H ("61a8a244 adacccf0"));
+
+ test_arctwo(64,
+ HL("88bca90e 90875a"),
+ HL("00000000 00000000"),
+ H ("6ccf4308 974c267f"));
+
+ test_arctwo(64,
+ HL("88bca90e 90875a7f 0f79c384 627bafb2"),
+ HL("00000000 00000000"),
+ H ("1a807d27 2bbe5db1"));
+
+ test_arctwo(129,
+ HL("88bca90e 90875a7f 0f79c384 627bafb2"
+ "16f80a6f 85920584 c42fceb0 be255daf 1e"),
+ HL("00000000 00000000"),
+ H ("5b78d3a4 3dfff1f1"));
+
+ SUCCESS ();
+}