diff --git a/pkcs1-rsa-md5.c b/pkcs1-rsa-md5.c
new file mode 100644
index 0000000000000000000000000000000000000000..5273ee8ed84113f465c3a901d56b9719085e3e74
--- /dev/null
+++ b/pkcs1-rsa-md5.c
@@ -0,0 +1,92 @@
+/* pkcs1-rsa-md5.c
+ *
+ * PKCS stuff for rsa-md5.
+ */
+
+/* nettle, low-level cryptographics library
+ *
+ * Copyright (C) 2001, 2003 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.
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#if WITH_PUBLIC_KEY
+
+#include "rsa.h"
+
+#include "bignum.h"
+#include "pkcs1.h"
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* From pkcs-1v2
+ *
+ * md5 OBJECT IDENTIFIER ::=
+ * {iso(1) member-body(2) US(840) rsadsi(113549) digestAlgorithm(2) 5}
+ *
+ * The parameters part of the algorithm identifier is NULL:
+ *
+ * md5Identifier ::= AlgorithmIdentifier {md5, NULL}
+ */
+
+static const uint8_t
+md5_prefix[] =
+{
+ /* 18 octets prefix, 16 octets hash, 34 total. */
+ 0x30, 32, /* SEQUENCE */
+ 0x30, 12, /* SEQUENCE */
+ 0x06, 8, /* OBJECT IDENTIFIER */
+ 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x02, 0x05,
+ 0x05, 0, /* NULL */
+ 0x04, 16 /* OCTET STRING */
+ /* Here comes the raw hash value */
+};
+
+void
+pkcs1_rsa_md5_encode(mpz_t m, unsigned length, struct md5_ctx *hash)
+{
+ uint8_t *em = alloca(length);
+
+ assert(length >= MD5_DIGEST_SIZE);
+ pkcs1_signature_prefix(length - MD5_DIGEST_SIZE, em,
+ sizeof(md5_prefix),
+ md5_prefix);
+
+ md5_digest(hash, MD5_DIGEST_SIZE, em + length - MD5_DIGEST_SIZE);
+ nettle_mpz_set_str_256_u(m, length, em);
+}
+
+void
+pkcs1_rsa_md5_encode_digest(mpz_t m, unsigned length, const uint8_t *digest)
+{
+ uint8_t *em = alloca(length);
+
+ assert(length >= MD5_DIGEST_SIZE);
+ pkcs1_signature_prefix(length - MD5_DIGEST_SIZE, em,
+ sizeof(md5_prefix),
+ md5_prefix);
+
+ memcpy(em + length - MD5_DIGEST_SIZE, digest, MD5_DIGEST_SIZE);
+ nettle_mpz_set_str_256_u(m, length, em);
+}
+
+#endif /* WITH_PUBLIC_KEY */
diff --git a/pkcs1-rsa-sha1.c b/pkcs1-rsa-sha1.c
new file mode 100644
index 0000000000000000000000000000000000000000..9517411945e06f9a81ef95d1b3ad3fea3b0ce983
--- /dev/null
+++ b/pkcs1-rsa-sha1.c
@@ -0,0 +1,92 @@
+/* pkcs1-rsa-md5.c
+ *
+ * PKCS stuff for rsa-md5.
+ */
+
+/* nettle, low-level cryptographics library
+ *
+ * Copyright (C) 2001, 2003 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.
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#if WITH_PUBLIC_KEY
+
+#include "rsa.h"
+
+#include "bignum.h"
+#include "pkcs1.h"
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* From pkcs-1v2
+ *
+ * id-sha1 OBJECT IDENTIFIER ::=
+ * {iso(1) identified-organization(3) oiw(14) secsig(3)
+ * algorithms(2) 26}
+ *
+ * The default hash function is SHA-1:
+ * sha1Identifier ::= AlgorithmIdentifier {id-sha1, NULL}
+ */
+
+static const uint8_t
+sha1_prefix[] =
+{
+ /* 15 octets prefix, 20 octets hash, total 35 */
+ 0x30, 33, /* SEQUENCE */
+ 0x30, 9, /* SEQUENCE */
+ 0x06, 5, /* OBJECT IDENTIFIER */
+ 0x2b, 0x0e, 0x03, 0x02, 0x1a,
+ 0x05, 0, /* NULL */
+ 0x04, 20 /* OCTET STRING */
+ /* Here comes the raw hash value */
+};
+
+void
+pkcs1_rsa_sha1_encode(mpz_t m, unsigned length, struct sha1_ctx *hash)
+{
+ uint8_t *em = alloca(length);
+
+ assert(length >= SHA1_DIGEST_SIZE);
+ pkcs1_signature_prefix(length - SHA1_DIGEST_SIZE, em,
+ sizeof(sha1_prefix),
+ sha1_prefix);
+
+ sha1_digest(hash, SHA1_DIGEST_SIZE, em + length - SHA1_DIGEST_SIZE);
+ nettle_mpz_set_str_256_u(m, length, em);
+}
+
+void
+pkcs1_rsa_sha1_encode_digest(mpz_t m, unsigned length, const uint8_t *digest)
+{
+ uint8_t *em = alloca(length);
+
+ assert(length >= SHA1_DIGEST_SIZE);
+ pkcs1_signature_prefix(length - SHA1_DIGEST_SIZE, em,
+ sizeof(sha1_prefix),
+ sha1_prefix);
+
+ memcpy(em + length - SHA1_DIGEST_SIZE, digest, SHA1_DIGEST_SIZE);
+ nettle_mpz_set_str_256_u(m, length, em);
+}
+
+#endif /* WITH_PUBLIC_KEY */
diff --git a/pkcs1.c b/pkcs1.c
new file mode 100644
index 0000000000000000000000000000000000000000..104af2acb158e5bde4f21dc8411fe3ab1ade4b14
--- /dev/null
+++ b/pkcs1.c
@@ -0,0 +1,55 @@
+/* pkcs1.c
+ *
+ * PKCS1 embedding.
+ */
+
+/* nettle, low-level cryptographics library
+ *
+ * Copyright (C) 2003 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.
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#if WITH_PUBLIC_KEY
+
+#include "pkcs1.h"
+
+#include <assert.h>
+#include <string.h>
+
+void
+pkcs1_signature_prefix(unsigned length,
+ uint8_t *buffer,
+ unsigned id_length,
+ const uint8_t *id)
+{
+ assert(length >= id_length);
+ length -= id_length;
+ memcpy(buffer + length, id, id_length);
+
+ assert(length);
+ buffer[--length] = 0;
+
+ assert(length >= 9);
+ memset(buffer + 1, 0xff, length - 1);
+ buffer[0] = 1;
+}
+
+#endif /* WITH_PUBLIC_KEY */
diff --git a/pkcs1.h b/pkcs1.h
new file mode 100644
index 0000000000000000000000000000000000000000..3671f8018c3ea259beb51dbb3efab55c6f3d0403
--- /dev/null
+++ b/pkcs1.h
@@ -0,0 +1,53 @@
+/* pkcs1.h
+ *
+ * PKCS1 embedding.
+ */
+
+/* nettle, low-level cryptographics library
+ *
+ * Copyright (C) 2003 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_PKCS1_H_INCLUDED
+#define NETTLE_PKCS1_H_INCLUDED
+
+#include <inttypes.h>
+#include <gmp.h>
+
+struct md5_ctx;
+struct sha1_ctx;
+
+void
+pkcs1_signature_prefix(unsigned length,
+ uint8_t *buffer,
+ unsigned id_length,
+ const uint8_t *id);
+
+void
+pkcs1_rsa_md5_encode(mpz_t m, unsigned length, struct md5_ctx *hash);
+
+void
+pkcs1_rsa_md5_encode_digest(mpz_t m, unsigned length, const uint8_t *digest);
+
+void
+pkcs1_rsa_sha1_encode(mpz_t m, unsigned length, struct sha1_ctx *hash);
+
+void
+pkcs1_rsa_sha1_encode_digest(mpz_t m, unsigned length, const uint8_t *digest);
+
+#endif /* NETTLE_PKCS1_H_INCLUDED */