Add SHA256/512 ($5$ and $6$) to crypt(3). Used in linux-world, doesn't

hurt us.

PR:		misc/124164
Submitted by:	KIMURA Yasuhiro < yasu utahime org >
MFC after:	1 month

6 files changed, 1009 insertions, 1 deletions

diff --git a/lib/libcrypt/Makefile b/lib/libcrypt/Makefile
index 285f672..0b77f73 100644
--- a/lib/libcrypt/Makefile
+++ b/lib/libcrypt/Makefile
@@ -12,7 +12,9 @@ LIB=		crypt
 .PATH:		${.CURDIR}/../libmd
 SRCS=		crypt.c misc.c \
 		crypt-md5.c md5c.c \
-		crypt-nthash.c md4c.c
+		crypt-nthash.c md4c.c \
+		crypt-sha256.c sha256c.c \
+		crypt-sha512.c sha512c.c
 MAN=		crypt.3
 MLINKS=		crypt.3 crypt_get_format.3 crypt.3 crypt_set_format.3
 CFLAGS+=	-I${.CURDIR}/../libmd -I${.CURDIR}/../libutil
diff --git a/lib/libcrypt/crypt-sha256.c b/lib/libcrypt/crypt-sha256.c
new file mode 100644
index 0000000..d9e4ea6
--- /dev/null
+++ b/lib/libcrypt/crypt-sha256.c
@@ -0,0 +1,477 @@
+/*
+ * Copyright (c) 2011 The FreeBSD Project. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/* Based on:
+ * SHA256-based Unix crypt implementation. Released into the Public Domain by
+ * Ulrich Drepper <drepper@redhat.com>. */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/endian.h>
+#include <sys/param.h>
+
+#include <errno.h>
+#include <limits.h>
+#include <sha256.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "crypt.h"
+
+/* Define our magic string to mark salt for SHA256 "encryption" replacement. */
+static const char sha256_salt_prefix[] = "$5$";
+
+/* Prefix for optional rounds specification. */
+static const char sha256_rounds_prefix[] = "rounds=";
+
+/* Maximum salt string length. */
+#define SALT_LEN_MAX 16
+/* Default number of rounds if not explicitly specified. */
+#define ROUNDS_DEFAULT 5000
+/* Minimum number of rounds. */
+#define ROUNDS_MIN 1000
+/* Maximum number of rounds. */
+#define ROUNDS_MAX 999999999
+
+static char *
+sha256_crypt_r(const char *key, const char *salt, char *buffer, int buflen)
+{
+	u_long srounds;
+	int n;
+	uint8_t alt_result[32], temp_result[32];
+	SHA256_CTX ctx, alt_ctx;
+	size_t salt_len, key_len, cnt, rounds;
+	char *cp, *copied_key, *copied_salt, *p_bytes, *s_bytes, *endp;
+	const char *num;
+	bool rounds_custom;
+
+	copied_key = NULL;
+	copied_salt = NULL;
+
+	/* Default number of rounds. */
+	rounds = ROUNDS_DEFAULT;
+	rounds_custom = false;
+
+	/* Find beginning of salt string. The prefix should normally always
+	 * be present. Just in case it is not. */
+	if (strncmp(sha256_salt_prefix, salt, sizeof(sha256_salt_prefix) - 1) == 0)
+		/* Skip salt prefix. */
+		salt += sizeof(sha256_salt_prefix) - 1;
+
+	if (strncmp(salt, sha256_rounds_prefix, sizeof(sha256_rounds_prefix) - 1)
+	    == 0) {
+		num = salt + sizeof(sha256_rounds_prefix) - 1;
+		srounds = strtoul(num, &endp, 10);
+
+		if (*endp == '$') {
+			salt = endp + 1;
+			rounds = MAX(ROUNDS_MIN, MIN(srounds, ROUNDS_MAX));
+			rounds_custom = true;
+		}
+	}
+
+	salt_len = MIN(strcspn(salt, "$"), SALT_LEN_MAX);
+	key_len = strlen(key);
+
+	/* Prepare for the real work. */
+	SHA256_Init(&ctx);
+
+	/* Add the key string. */
+	SHA256_Update(&ctx, key, key_len);
+
+	/* The last part is the salt string. This must be at most 8
+	 * characters and it ends at the first `$' character (for
+	 * compatibility with existing implementations). */
+	SHA256_Update(&ctx, salt, salt_len);
+
+	/* Compute alternate SHA256 sum with input KEY, SALT, and KEY. The
+	 * final result will be added to the first context. */
+	SHA256_Init(&alt_ctx);
+
+	/* Add key. */
+	SHA256_Update(&alt_ctx, key, key_len);
+
+	/* Add salt. */
+	SHA256_Update(&alt_ctx, salt, salt_len);
+
+	/* Add key again. */
+	SHA256_Update(&alt_ctx, key, key_len);
+
+	/* Now get result of this (32 bytes) and add it to the other context. */
+	SHA256_Final(alt_result, &alt_ctx);
+
+	/* Add for any character in the key one byte of the alternate sum. */
+	for (cnt = key_len; cnt > 32; cnt -= 32)
+		SHA256_Update(&ctx, alt_result, 32);
+	SHA256_Update(&ctx, alt_result, cnt);
+
+	/* Take the binary representation of the length of the key and for
+	 * every 1 add the alternate sum, for every 0 the key. */
+	for (cnt = key_len; cnt > 0; cnt >>= 1)
+		if ((cnt & 1) != 0)
+			SHA256_Update(&ctx, alt_result, 32);
+		else
+			SHA256_Update(&ctx, key, key_len);
+
+	/* Create intermediate result. */
+	SHA256_Final(alt_result, &ctx);
+
+	/* Start computation of P byte sequence. */
+	SHA256_Init(&alt_ctx);
+
+	/* For every character in the password add the entire password. */
+	for (cnt = 0; cnt < key_len; ++cnt)
+		SHA256_Update(&alt_ctx, key, key_len);
+
+	/* Finish the digest. */
+	SHA256_Final(temp_result, &alt_ctx);
+
+	/* Create byte sequence P. */
+	cp = p_bytes = alloca(key_len);
+	for (cnt = key_len; cnt >= 32; cnt -= 32) {
+		memcpy(cp, temp_result, 32);
+		cp += 32;
+	}
+	memcpy(cp, temp_result, cnt);
+
+	/* Start computation of S byte sequence. */
+	SHA256_Init(&alt_ctx);
+
+	/* For every character in the password add the entire password. */
+	for (cnt = 0; cnt < 16 + alt_result[0]; ++cnt)
+		SHA256_Update(&alt_ctx, salt, salt_len);
+
+	/* Finish the digest. */
+	SHA256_Final(temp_result, &alt_ctx);
+
+	/* Create byte sequence S. */
+	cp = s_bytes = alloca(salt_len);
+	for (cnt = salt_len; cnt >= 32; cnt -= 32) {
+		memcpy(cp, temp_result, 32);
+		cp += 32;
+	}
+	memcpy(cp, temp_result, cnt);
+
+	/* Repeatedly run the collected hash value through SHA256 to burn CPU
+	 * cycles. */
+	for (cnt = 0; cnt < rounds; ++cnt) {
+		/* New context. */
+		SHA256_Init(&ctx);
+
+		/* Add key or last result. */
+		if ((cnt & 1) != 0)
+			SHA256_Update(&ctx, p_bytes, key_len);
+		else
+			SHA256_Update(&ctx, alt_result, 32);
+
+		/* Add salt for numbers not divisible by 3. */
+		if (cnt % 3 != 0)
+			SHA256_Update(&ctx, s_bytes, salt_len);
+
+		/* Add key for numbers not divisible by 7. */
+		if (cnt % 7 != 0)
+			SHA256_Update(&ctx, p_bytes, key_len);
+
+		/* Add key or last result. */
+		if ((cnt & 1) != 0)
+			SHA256_Update(&ctx, alt_result, 32);
+		else
+			SHA256_Update(&ctx, p_bytes, key_len);
+
+		/* Create intermediate result. */
+		SHA256_Final(alt_result, &ctx);
+	}
+
+	/* Now we can construct the result string. It consists of three
+	 * parts. */
+	cp = stpncpy(buffer, sha256_salt_prefix, MAX(0, buflen));
+	buflen -= sizeof(sha256_salt_prefix) - 1;
+
+	if (rounds_custom) {
+		n = snprintf(cp, MAX(0, buflen), "%s%zu$",
+			 sha256_rounds_prefix, rounds);
+
+		cp += n;
+		buflen -= n;
+	}
+
+	cp = stpncpy(cp, salt, MIN((size_t)MAX(0, buflen), salt_len));
+	buflen -= MIN((size_t)MAX(0, buflen), salt_len);
+
+	if (buflen > 0) {
+		*cp++ = '$';
+		--buflen;
+	}
+
+	b64_from_24bit(alt_result[0], alt_result[10], alt_result[20], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[21], alt_result[1], alt_result[11], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[12], alt_result[22], alt_result[2], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[3], alt_result[13], alt_result[23], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[24], alt_result[4], alt_result[14], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[15], alt_result[25], alt_result[5], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[6], alt_result[16], alt_result[26], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[27], alt_result[7], alt_result[17], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[18], alt_result[28], alt_result[8], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[9], alt_result[19], alt_result[29], 4, &buflen, &cp);
+	b64_from_24bit(0, alt_result[31], alt_result[30], 3, &buflen, &cp);
+	if (buflen <= 0) {
+		errno = ERANGE;
+		buffer = NULL;
+	}
+	else
+		*cp = '\0';	/* Terminate the string. */
+
+	/* Clear the buffer for the intermediate result so that people
+	 * attaching to processes or reading core dumps cannot get any
+	 * information. We do it in this way to clear correct_words[] inside
+	 * the SHA256 implementation as well. */
+	SHA256_Init(&ctx);
+	SHA256_Final(alt_result, &ctx);
+	memset(temp_result, '\0', sizeof(temp_result));
+	memset(p_bytes, '\0', key_len);
+	memset(s_bytes, '\0', salt_len);
+	memset(&ctx, '\0', sizeof(ctx));
+	memset(&alt_ctx, '\0', sizeof(alt_ctx));
+	if (copied_key != NULL)
+		memset(copied_key, '\0', key_len);
+	if (copied_salt != NULL)
+		memset(copied_salt, '\0', salt_len);
+
+	return buffer;
+}
+
+/* This entry point is equivalent to crypt(3). */
+char *
+sha256_crypt(const char *key, const char *salt)
+{
+	/* We don't want to have an arbitrary limit in the size of the
+	 * password. We can compute an upper bound for the size of the
+	 * result in advance and so we can prepare the buffer we pass to
+	 * `sha256_crypt_r'. */
+	static char *buffer;
+	static int buflen;
+	int needed;
+	char *new_buffer;
+
+	needed = (sizeof(sha256_salt_prefix) - 1
+	      + sizeof(sha256_rounds_prefix) + 9 + 1
+	      + strlen(salt) + 1 + 43 + 1);
+
+	if (buflen < needed) {
+		new_buffer = (char *)realloc(buffer, needed);
+
+		if (new_buffer == NULL)
+			return NULL;
+
+		buffer = new_buffer;
+		buflen = needed;
+	}
+
+	return sha256_crypt_r(key, salt, buffer, buflen);
+}
+
+#ifdef TEST
+
+static const struct {
+	const char *input;
+	const char result[32];
+} tests[] =
+{
+	/* Test vectors from FIPS 180-2: appendix B.1. */
+	{
+		"abc",
+		"\xba\x78\x16\xbf\x8f\x01\xcf\xea\x41\x41\x40\xde\x5d\xae\x22\x23"
+		"\xb0\x03\x61\xa3\x96\x17\x7a\x9c\xb4\x10\xff\x61\xf2\x00\x15\xad"
+	},
+	/* Test vectors from FIPS 180-2: appendix B.2. */
+	{
+		"abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq",
+		"\x24\x8d\x6a\x61\xd2\x06\x38\xb8\xe5\xc0\x26\x93\x0c\x3e\x60\x39"
+		"\xa3\x3c\xe4\x59\x64\xff\x21\x67\xf6\xec\xed\xd4\x19\xdb\x06\xc1"
+	},
+	/* Test vectors from the NESSIE project. */
+	{
+		"",
+		"\xe3\xb0\xc4\x42\x98\xfc\x1c\x14\x9a\xfb\xf4\xc8\x99\x6f\xb9\x24"
+		"\x27\xae\x41\xe4\x64\x9b\x93\x4c\xa4\x95\x99\x1b\x78\x52\xb8\x55"
+	},
+	{
+		"a",
+		"\xca\x97\x81\x12\xca\x1b\xbd\xca\xfa\xc2\x31\xb3\x9a\x23\xdc\x4d"
+		"\xa7\x86\xef\xf8\x14\x7c\x4e\x72\xb9\x80\x77\x85\xaf\xee\x48\xbb"
+	},
+	{
+		"message digest",
+		"\xf7\x84\x6f\x55\xcf\x23\xe1\x4e\xeb\xea\xb5\xb4\xe1\x55\x0c\xad"
+		"\x5b\x50\x9e\x33\x48\xfb\xc4\xef\xa3\xa1\x41\x3d\x39\x3c\xb6\x50"
+	},
+	{
+		"abcdefghijklmnopqrstuvwxyz",
+		"\x71\xc4\x80\xdf\x93\xd6\xae\x2f\x1e\xfa\xd1\x44\x7c\x66\xc9\x52"
+		"\x5e\x31\x62\x18\xcf\x51\xfc\x8d\x9e\xd8\x32\xf2\xda\xf1\x8b\x73"
+	},
+	{
+		"abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq",
+		"\x24\x8d\x6a\x61\xd2\x06\x38\xb8\xe5\xc0\x26\x93\x0c\x3e\x60\x39"
+		"\xa3\x3c\xe4\x59\x64\xff\x21\x67\xf6\xec\xed\xd4\x19\xdb\x06\xc1"
+	},
+	{
+		"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789",
+		"\xdb\x4b\xfc\xbd\x4d\xa0\xcd\x85\xa6\x0c\x3c\x37\xd3\xfb\xd8\x80"
+		"\x5c\x77\xf1\x5f\xc6\xb1\xfd\xfe\x61\x4e\xe0\xa7\xc8\xfd\xb4\xc0"
+	},
+	{
+		"123456789012345678901234567890123456789012345678901234567890"
+		"12345678901234567890",
+		"\xf3\x71\xbc\x4a\x31\x1f\x2b\x00\x9e\xef\x95\x2d\xd8\x3c\xa8\x0e"
+		"\x2b\x60\x02\x6c\x8e\x93\x55\x92\xd0\xf9\xc3\x08\x45\x3c\x81\x3e"
+	}
+};
+
+#define ntests (sizeof (tests) / sizeof (tests[0]))
+
+static const struct {
+	const char *salt;
+	const char *input;
+	const char *expected;
+} tests2[] =
+{
+	{
+		"$5$saltstring", "Hello world!",
+		"$5$saltstring$5B8vYYiY.CVt1RlTTf8KbXBH3hsxY/GNooZaBBGWEc5"
+	},
+	{
+		"$5$rounds=10000$saltstringsaltstring", "Hello world!",
+		"$5$rounds=10000$saltstringsaltst$3xv.VbSHBb41AL9AvLeujZkZRBAwqFMz2."
+		"opqey6IcA"
+	},
+	{
+		"$5$rounds=5000$toolongsaltstring", "This is just a test",
+		"$5$rounds=5000$toolongsaltstrin$Un/5jzAHMgOGZ5.mWJpuVolil07guHPvOW8"
+		"mGRcvxa5"
+	},
+	{
+		"$5$rounds=1400$anotherlongsaltstring",
+		"a very much longer text to encrypt.  This one even stretches over more"
+		"than one line.",
+		"$5$rounds=1400$anotherlongsalts$Rx.j8H.h8HjEDGomFU8bDkXm3XIUnzyxf12"
+		"oP84Bnq1"
+	},
+	{
+		"$5$rounds=77777$short",
+		"we have a short salt string but not a short password",
+		"$5$rounds=77777$short$JiO1O3ZpDAxGJeaDIuqCoEFysAe1mZNJRs3pw0KQRd/"
+	},
+	{
+		"$5$rounds=123456$asaltof16chars..", "a short string",
+		"$5$rounds=123456$asaltof16chars..$gP3VQ/6X7UUEW3HkBn2w1/Ptq2jxPyzV/"
+		"cZKmF/wJvD"
+	},
+	{
+		"$5$rounds=10$roundstoolow", "the minimum number is still observed",
+		"$5$rounds=1000$roundstoolow$yfvwcWrQ8l/K0DAWyuPMDNHpIVlTQebY9l/gL97"
+		"2bIC"
+	},
+};
+
+#define ntests2 (sizeof (tests2) / sizeof (tests2[0]))
+
+int
+main(void)
+{
+	SHA256_CTX ctx;
+	uint8_t sum[32];
+	int result = 0;
+	int i, cnt;
+
+	for (cnt = 0; cnt < (int)ntests; ++cnt) {
+		SHA256_Init(&ctx);
+		SHA256_Update(&ctx, tests[cnt].input, strlen(tests[cnt].input));
+		SHA256_Final(sum, &ctx);
+		if (memcmp(tests[cnt].result, sum, 32) != 0) {
+			for (i = 0; i < 32; i++)
+				printf("%02X", tests[cnt].result[i]);
+			printf("\n");
+			for (i = 0; i < 32; i++)
+				printf("%02X", sum[i]);
+			printf("\n");
+			printf("test %d run %d failed\n", cnt, 1);
+			result = 1;
+		}
+
+		SHA256_Init(&ctx);
+		for (i = 0; tests[cnt].input[i] != '\0'; ++i)
+			SHA256_Update(&ctx, &tests[cnt].input[i], 1);
+		SHA256_Final(sum, &ctx);
+		if (memcmp(tests[cnt].result, sum, 32) != 0) {
+			for (i = 0; i < 32; i++)
+				printf("%02X", tests[cnt].result[i]);
+			printf("\n");
+			for (i = 0; i < 32; i++)
+				printf("%02X", sum[i]);
+			printf("\n");
+			printf("test %d run %d failed\n", cnt, 2);
+			result = 1;
+		}
+	}
+
+	/* Test vector from FIPS 180-2: appendix B.3. */
+	char buf[1000];
+
+	memset(buf, 'a', sizeof(buf));
+	SHA256_Init(&ctx);
+	for (i = 0; i < 1000; ++i)
+		SHA256_Update(&ctx, buf, sizeof(buf));
+	SHA256_Final(sum, &ctx);
+	static const char expected[32] =
+	"\xcd\xc7\x6e\x5c\x99\x14\xfb\x92\x81\xa1\xc7\xe2\x84\xd7\x3e\x67"
+	"\xf1\x80\x9a\x48\xa4\x97\x20\x0e\x04\x6d\x39\xcc\xc7\x11\x2c\xd0";
+
+	if (memcmp(expected, sum, 32) != 0) {
+		printf("test %d failed\n", cnt);
+		result = 1;
+	}
+
+	for (cnt = 0; cnt < ntests2; ++cnt) {
+		char *cp = sha256_crypt(tests2[cnt].input, tests2[cnt].salt);
+
+		if (strcmp(cp, tests2[cnt].expected) != 0) {
+			printf("test %d: expected \"%s\", got \"%s\"\n",
+			       cnt, tests2[cnt].expected, cp);
+			result = 1;
+		}
+	}
+
+	if (result == 0)
+		puts("all tests OK");
+
+	return result;
+}
+
+#endif /* TEST */
diff --git a/lib/libcrypt/crypt-sha512.c b/lib/libcrypt/crypt-sha512.c
new file mode 100644
index 0000000..61b1e87
--- /dev/null
+++ b/lib/libcrypt/crypt-sha512.c
@@ -0,0 +1,500 @@
+/*
+ * Copyright (c) 2011 The FreeBSD Project. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/* Based on:
+ * SHA512-based Unix crypt implementation. Released into the Public Domain by
+ * Ulrich Drepper <drepper@redhat.com>. */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/endian.h>
+#include <sys/param.h>
+
+#include <errno.h>
+#include <limits.h>
+#include <sha512.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "crypt.h"
+
+/* Define our magic string to mark salt for SHA512 "encryption" replacement. */
+static const char sha512_salt_prefix[] = "$6$";
+
+/* Prefix for optional rounds specification. */
+static const char sha512_rounds_prefix[] = "rounds=";
+
+/* Maximum salt string length. */
+#define SALT_LEN_MAX 16
+/* Default number of rounds if not explicitly specified. */
+#define ROUNDS_DEFAULT 5000
+/* Minimum number of rounds. */
+#define ROUNDS_MIN 1000
+/* Maximum number of rounds. */
+#define ROUNDS_MAX 999999999
+
+static char *
+sha512_crypt_r(const char *key, const char *salt, char *buffer, int buflen)
+{
+	u_long srounds;
+	int n;
+	uint8_t alt_result[64], temp_result[64];
+	SHA512_CTX ctx, alt_ctx;
+	size_t salt_len, key_len, cnt, rounds;
+	char *cp, *copied_key, *copied_salt, *p_bytes, *s_bytes, *endp;
+	const char *num;
+	bool rounds_custom;
+
+	copied_key = NULL;
+	copied_salt = NULL;
+
+	/* Default number of rounds. */
+	rounds = ROUNDS_DEFAULT;
+	rounds_custom = false;
+
+	/* Find beginning of salt string. The prefix should normally always
+	 * be present. Just in case it is not. */
+	if (strncmp(sha512_salt_prefix, salt, sizeof(sha512_salt_prefix) - 1) == 0)
+		/* Skip salt prefix. */
+		salt += sizeof(sha512_salt_prefix) - 1;
+
+	if (strncmp(salt, sha512_rounds_prefix, sizeof(sha512_rounds_prefix) - 1)
+	    == 0) {
+		num = salt + sizeof(sha512_rounds_prefix) - 1;
+		srounds = strtoul(num, &endp, 10);
+
+		if (*endp == '$') {
+			salt = endp + 1;
+			rounds = MAX(ROUNDS_MIN, MIN(srounds, ROUNDS_MAX));
+			rounds_custom = true;
+		}
+	}
+
+	salt_len = MIN(strcspn(salt, "$"), SALT_LEN_MAX);
+	key_len = strlen(key);
+
+	/* Prepare for the real work. */
+	SHA512_Init(&ctx);
+
+	/* Add the key string. */
+	SHA512_Update(&ctx, key, key_len);
+
+	/* The last part is the salt string. This must be at most 8
+	 * characters and it ends at the first `$' character (for
+	 * compatibility with existing implementations). */
+	SHA512_Update(&ctx, salt, salt_len);
+
+	/* Compute alternate SHA512 sum with input KEY, SALT, and KEY. The
+	 * final result will be added to the first context. */
+	SHA512_Init(&alt_ctx);
+
+	/* Add key. */
+	SHA512_Update(&alt_ctx, key, key_len);
+
+	/* Add salt. */
+	SHA512_Update(&alt_ctx, salt, salt_len);
+
+	/* Add key again. */
+	SHA512_Update(&alt_ctx, key, key_len);
+
+	/* Now get result of this (64 bytes) and add it to the other context. */
+	SHA512_Final(alt_result, &alt_ctx);
+
+	/* Add for any character in the key one byte of the alternate sum. */
+	for (cnt = key_len; cnt > 64; cnt -= 64)
+		SHA512_Update(&ctx, alt_result, 64);
+	SHA512_Update(&ctx, alt_result, cnt);
+
+	/* Take the binary representation of the length of the key and for
+	 * every 1 add the alternate sum, for every 0 the key. */
+	for (cnt = key_len; cnt > 0; cnt >>= 1)
+		if ((cnt & 1) != 0)
+			SHA512_Update(&ctx, alt_result, 64);
+		else
+			SHA512_Update(&ctx, key, key_len);
+
+	/* Create intermediate result. */
+	SHA512_Final(alt_result, &ctx);
+
+	/* Start computation of P byte sequence. */
+	SHA512_Init(&alt_ctx);
+
+	/* For every character in the password add the entire password. */
+	for (cnt = 0; cnt < key_len; ++cnt)
+		SHA512_Update(&alt_ctx, key, key_len);
+
+	/* Finish the digest. */
+	SHA512_Final(temp_result, &alt_ctx);
+
+	/* Create byte sequence P. */
+	cp = p_bytes = alloca(key_len);
+	for (cnt = key_len; cnt >= 64; cnt -= 64) {
+		memcpy(cp, temp_result, 64);
+		cp += 64;
+	}
+	memcpy(cp, temp_result, cnt);
+
+	/* Start computation of S byte sequence. */
+	SHA512_Init(&alt_ctx);
+
+	/* For every character in the password add the entire password. */
+	for (cnt = 0; cnt < 16 + alt_result[0]; ++cnt)
+		SHA512_Update(&alt_ctx, salt, salt_len);
+
+	/* Finish the digest. */
+	SHA512_Final(temp_result, &alt_ctx);
+
+	/* Create byte sequence S. */
+	cp = s_bytes = alloca(salt_len);
+	for (cnt = salt_len; cnt >= 64; cnt -= 64) {
+		memcpy(cp, temp_result, 64);
+		cp += 64;
+	}
+	memcpy(cp, temp_result, cnt);
+
+	/* Repeatedly run the collected hash value through SHA512 to burn CPU
+	 * cycles. */
+	for (cnt = 0; cnt < rounds; ++cnt) {
+		/* New context. */
+		SHA512_Init(&ctx);
+
+		/* Add key or last result. */
+		if ((cnt & 1) != 0)
+			SHA512_Update(&ctx, p_bytes, key_len);
+		else
+			SHA512_Update(&ctx, alt_result, 64);
+
+		/* Add salt for numbers not divisible by 3. */
+		if (cnt % 3 != 0)
+			SHA512_Update(&ctx, s_bytes, salt_len);
+
+		/* Add key for numbers not divisible by 7. */
+		if (cnt % 7 != 0)
+			SHA512_Update(&ctx, p_bytes, key_len);
+
+		/* Add key or last result. */
+		if ((cnt & 1) != 0)
+			SHA512_Update(&ctx, alt_result, 64);
+		else
+			SHA512_Update(&ctx, p_bytes, key_len);
+
+		/* Create intermediate result. */
+		SHA512_Final(alt_result, &ctx);
+	}
+
+	/* Now we can construct the result string. It consists of three
+	 * parts. */
+	cp = stpncpy(buffer, sha512_salt_prefix, MAX(0, buflen));
+	buflen -= sizeof(sha512_salt_prefix) - 1;
+
+	if (rounds_custom) {
+		n = snprintf(cp, MAX(0, buflen), "%s%zu$",
+			 sha512_rounds_prefix, rounds);
+
+		cp += n;
+		buflen -= n;
+	}
+
+	cp = stpncpy(cp, salt, MIN((size_t)MAX(0, buflen), salt_len));
+	buflen -= MIN((size_t)MAX(0, buflen), salt_len);
+
+	if (buflen > 0) {
+		*cp++ = '$';
+		--buflen;
+	}
+
+	b64_from_24bit(alt_result[0], alt_result[21], alt_result[42], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[22], alt_result[43], alt_result[1], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[44], alt_result[2], alt_result[23], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[3], alt_result[24], alt_result[45], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[25], alt_result[46], alt_result[4], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[47], alt_result[5], alt_result[26], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[6], alt_result[27], alt_result[48], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[28], alt_result[49], alt_result[7], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[50], alt_result[8], alt_result[29], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[9], alt_result[30], alt_result[51], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[31], alt_result[52], alt_result[10], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[53], alt_result[11], alt_result[32], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[12], alt_result[33], alt_result[54], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[34], alt_result[55], alt_result[13], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[56], alt_result[14], alt_result[35], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[15], alt_result[36], alt_result[57], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[37], alt_result[58], alt_result[16], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[59], alt_result[17], alt_result[38], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[18], alt_result[39], alt_result[60], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[40], alt_result[61], alt_result[19], 4, &buflen, &cp);
+	b64_from_24bit(alt_result[62], alt_result[20], alt_result[41], 4, &buflen, &cp);
+	b64_from_24bit(0, 0, alt_result[63], 2, &buflen, &cp);
+
+	if (buflen <= 0) {
+		errno = ERANGE;
+		buffer = NULL;
+	}
+	else
+		*cp = '\0';	/* Terminate the string. */
+
+	/* Clear the buffer for the intermediate result so that people
+	 * attaching to processes or reading core dumps cannot get any
+	 * information. We do it in this way to clear correct_words[] inside
+	 * the SHA512 implementation as well. */
+	SHA512_Init(&ctx);
+	SHA512_Final(alt_result, &ctx);
+	memset(temp_result, '\0', sizeof(temp_result));
+	memset(p_bytes, '\0', key_len);
+	memset(s_bytes, '\0', salt_len);
+	memset(&ctx, '\0', sizeof(ctx));
+	memset(&alt_ctx, '\0', sizeof(alt_ctx));
+	if (copied_key != NULL)
+		memset(copied_key, '\0', key_len);
+	if (copied_salt != NULL)
+		memset(copied_salt, '\0', salt_len);
+
+	return buffer;
+}
+
+/* This entry point is equivalent to crypt(3). */
+char *
+sha512_crypt(const char *key, const char *salt)
+{
+	/* We don't want to have an arbitrary limit in the size of the
+	 * password. We can compute an upper bound for the size of the
+	 * result in advance and so we can prepare the buffer we pass to
+	 * `sha512_crypt_r'. */
+	static char *buffer;
+	static int buflen;
+	int needed;
+	char *new_buffer;
+
+	needed = (sizeof(sha512_salt_prefix) - 1
+	      + sizeof(sha512_rounds_prefix) + 9 + 1
+	      + strlen(salt) + 1 + 86 + 1);
+
+	if (buflen < needed) {
+		new_buffer = (char *)realloc(buffer, needed);
+
+		if (new_buffer == NULL)
+			return NULL;
+
+		buffer = new_buffer;
+		buflen = needed;
+	}
+
+	return sha512_crypt_r(key, salt, buffer, buflen);
+}
+
+#ifdef TEST
+
+static const struct {
+	const char *input;
+	const char result[64];
+} tests[] =
+{
+	/* Test vectors from FIPS 180-2: appendix C.1. */
+	{
+		"abc",
+		"\xdd\xaf\x35\xa1\x93\x61\x7a\xba\xcc\x41\x73\x49\xae\x20\x41\x31"
+		"\x12\xe6\xfa\x4e\x89\xa9\x7e\xa2\x0a\x9e\xee\xe6\x4b\x55\xd3\x9a"
+		"\x21\x92\x99\x2a\x27\x4f\xc1\xa8\x36\xba\x3c\x23\xa3\xfe\xeb\xbd"
+		"\x45\x4d\x44\x23\x64\x3c\xe8\x0e\x2a\x9a\xc9\x4f\xa5\x4c\xa4\x9f"
+	},
+	/* Test vectors from FIPS 180-2: appendix C.2. */
+	{
+		"abcdefghbcdefghicdefghijdefghijkefghijklfghijklmghijklmn"
+		"hijklmnoijklmnopjklmnopqklmnopqrlmnopqrsmnopqrstnopqrstu",
+		"\x8e\x95\x9b\x75\xda\xe3\x13\xda\x8c\xf4\xf7\x28\x14\xfc\x14\x3f"
+		"\x8f\x77\x79\xc6\xeb\x9f\x7f\xa1\x72\x99\xae\xad\xb6\x88\x90\x18"
+		"\x50\x1d\x28\x9e\x49\x00\xf7\xe4\x33\x1b\x99\xde\xc4\xb5\x43\x3a"
+		"\xc7\xd3\x29\xee\xb6\xdd\x26\x54\x5e\x96\xe5\x5b\x87\x4b\xe9\x09"
+	},
+	/* Test vectors from the NESSIE project. */
+	{
+		"",
+		"\xcf\x83\xe1\x35\x7e\xef\xb8\xbd\xf1\x54\x28\x50\xd6\x6d\x80\x07"
+		"\xd6\x20\xe4\x05\x0b\x57\x15\xdc\x83\xf4\xa9\x21\xd3\x6c\xe9\xce"
+		"\x47\xd0\xd1\x3c\x5d\x85\xf2\xb0\xff\x83\x18\xd2\x87\x7e\xec\x2f"
+		"\x63\xb9\x31\xbd\x47\x41\x7a\x81\xa5\x38\x32\x7a\xf9\x27\xda\x3e"
+	},
+	{
+		"a",
+		"\x1f\x40\xfc\x92\xda\x24\x16\x94\x75\x09\x79\xee\x6c\xf5\x82\xf2"
+		"\xd5\xd7\xd2\x8e\x18\x33\x5d\xe0\x5a\xbc\x54\xd0\x56\x0e\x0f\x53"
+		"\x02\x86\x0c\x65\x2b\xf0\x8d\x56\x02\x52\xaa\x5e\x74\x21\x05\x46"
+		"\xf3\x69\xfb\xbb\xce\x8c\x12\xcf\xc7\x95\x7b\x26\x52\xfe\x9a\x75"
+	},
+	{
+		"message digest",
+		"\x10\x7d\xbf\x38\x9d\x9e\x9f\x71\xa3\xa9\x5f\x6c\x05\x5b\x92\x51"
+		"\xbc\x52\x68\xc2\xbe\x16\xd6\xc1\x34\x92\xea\x45\xb0\x19\x9f\x33"
+		"\x09\xe1\x64\x55\xab\x1e\x96\x11\x8e\x8a\x90\x5d\x55\x97\xb7\x20"
+		"\x38\xdd\xb3\x72\xa8\x98\x26\x04\x6d\xe6\x66\x87\xbb\x42\x0e\x7c"
+	},
+	{
+		"abcdefghijklmnopqrstuvwxyz",
+		"\x4d\xbf\xf8\x6c\xc2\xca\x1b\xae\x1e\x16\x46\x8a\x05\xcb\x98\x81"
+		"\xc9\x7f\x17\x53\xbc\xe3\x61\x90\x34\x89\x8f\xaa\x1a\xab\xe4\x29"
+		"\x95\x5a\x1b\xf8\xec\x48\x3d\x74\x21\xfe\x3c\x16\x46\x61\x3a\x59"
+		"\xed\x54\x41\xfb\x0f\x32\x13\x89\xf7\x7f\x48\xa8\x79\xc7\xb1\xf1"
+	},
+	{
+		"abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq",
+		"\x20\x4a\x8f\xc6\xdd\xa8\x2f\x0a\x0c\xed\x7b\xeb\x8e\x08\xa4\x16"
+		"\x57\xc1\x6e\xf4\x68\xb2\x28\xa8\x27\x9b\xe3\x31\xa7\x03\xc3\x35"
+		"\x96\xfd\x15\xc1\x3b\x1b\x07\xf9\xaa\x1d\x3b\xea\x57\x78\x9c\xa0"
+		"\x31\xad\x85\xc7\xa7\x1d\xd7\x03\x54\xec\x63\x12\x38\xca\x34\x45"
+	},
+	{
+		"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789",
+		"\x1e\x07\xbe\x23\xc2\x6a\x86\xea\x37\xea\x81\x0c\x8e\xc7\x80\x93"
+		"\x52\x51\x5a\x97\x0e\x92\x53\xc2\x6f\x53\x6c\xfc\x7a\x99\x96\xc4"
+		"\x5c\x83\x70\x58\x3e\x0a\x78\xfa\x4a\x90\x04\x1d\x71\xa4\xce\xab"
+		"\x74\x23\xf1\x9c\x71\xb9\xd5\xa3\xe0\x12\x49\xf0\xbe\xbd\x58\x94"
+	},
+	{
+		"123456789012345678901234567890123456789012345678901234567890"
+		"12345678901234567890",
+		"\x72\xec\x1e\xf1\x12\x4a\x45\xb0\x47\xe8\xb7\xc7\x5a\x93\x21\x95"
+		"\x13\x5b\xb6\x1d\xe2\x4e\xc0\xd1\x91\x40\x42\x24\x6e\x0a\xec\x3a"
+		"\x23\x54\xe0\x93\xd7\x6f\x30\x48\xb4\x56\x76\x43\x46\x90\x0c\xb1"
+		"\x30\xd2\xa4\xfd\x5d\xd1\x6a\xbb\x5e\x30\xbc\xb8\x50\xde\xe8\x43"
+	}
+};
+
+#define ntests (sizeof (tests) / sizeof (tests[0]))
+
+static const struct {
+	const char *salt;
+	const char *input;
+	const char *expected;
+} tests2[] =
+{
+	{
+		"$6$saltstring", "Hello world!",
+		"$6$saltstring$svn8UoSVapNtMuq1ukKS4tPQd8iKwSMHWjl/O817G3uBnIFNjnQJu"
+		"esI68u4OTLiBFdcbYEdFCoEOfaS35inz1"
+	},
+	{
+		"$6$rounds=10000$saltstringsaltstring", "Hello world!",
+		"$6$rounds=10000$saltstringsaltst$OW1/O6BYHV6BcXZu8QVeXbDWra3Oeqh0sb"
+		"HbbMCVNSnCM/UrjmM0Dp8vOuZeHBy/YTBmSK6H9qs/y3RnOaw5v."
+	},
+	{
+		"$6$rounds=5000$toolongsaltstring", "This is just a test",
+		"$6$rounds=5000$toolongsaltstrin$lQ8jolhgVRVhY4b5pZKaysCLi0QBxGoNeKQ"
+		"zQ3glMhwllF7oGDZxUhx1yxdYcz/e1JSbq3y6JMxxl8audkUEm0"
+	},
+	{
+		"$6$rounds=1400$anotherlongsaltstring",
+		"a very much longer text to encrypt.  This one even stretches over more"
+		"than one line.",
+		"$6$rounds=1400$anotherlongsalts$POfYwTEok97VWcjxIiSOjiykti.o/pQs.wP"
+		"vMxQ6Fm7I6IoYN3CmLs66x9t0oSwbtEW7o7UmJEiDwGqd8p4ur1"
+	},
+	{
+		"$6$rounds=77777$short",
+		"we have a short salt string but not a short password",
+		"$6$rounds=77777$short$WuQyW2YR.hBNpjjRhpYD/ifIw05xdfeEyQoMxIXbkvr0g"
+		"ge1a1x3yRULJ5CCaUeOxFmtlcGZelFl5CxtgfiAc0"
+	},
+	{
+		"$6$rounds=123456$asaltof16chars..", "a short string",
+		"$6$rounds=123456$asaltof16chars..$BtCwjqMJGx5hrJhZywWvt0RLE8uZ4oPwc"
+		"elCjmw2kSYu.Ec6ycULevoBK25fs2xXgMNrCzIMVcgEJAstJeonj1"
+	},
+	{
+		"$6$rounds=10$roundstoolow", "the minimum number is still observed",
+		"$6$rounds=1000$roundstoolow$kUMsbe306n21p9R.FRkW3IGn.S9NPN0x50YhH1x"
+		"hLsPuWGsUSklZt58jaTfF4ZEQpyUNGc0dqbpBYYBaHHrsX."
+	},
+};
+
+#define ntests2 (sizeof (tests2) / sizeof (tests2[0]))
+
+int
+main(void)
+{
+	SHA512_CTX ctx;
+	uint8_t sum[64];
+	int result = 0;
+	int i, cnt;
+
+	for (cnt = 0; cnt < (int)ntests; ++cnt) {
+		SHA512_Init(&ctx);
+		SHA512_Update(&ctx, tests[cnt].input, strlen(tests[cnt].input));
+		SHA512_Final(sum, &ctx);
+		if (memcmp(tests[cnt].result, sum, 64) != 0) {
+			printf("test %d run %d failed\n", cnt, 1);
+			result = 1;
+		}
+
+		SHA512_Init(&ctx);
+		for (i = 0; tests[cnt].input[i] != '\0'; ++i)
+			SHA512_Update(&ctx, &tests[cnt].input[i], 1);
+		SHA512_Final(sum, &ctx);
+		if (memcmp(tests[cnt].result, sum, 64) != 0) {
+			printf("test %d run %d failed\n", cnt, 2);
+			result = 1;
+		}
+	}
+
+	/* Test vector from FIPS 180-2: appendix C.3. */
+	char buf[1000];
+
+	memset(buf, 'a', sizeof(buf));
+	SHA512_Init(&ctx);
+	for (i = 0; i < 1000; ++i)
+		SHA512_Update(&ctx, buf, sizeof(buf));
+	SHA512_Final(sum, &ctx);
+	static const char expected[64] =
+	"\xe7\x18\x48\x3d\x0c\xe7\x69\x64\x4e\x2e\x42\xc7\xbc\x15\xb4\x63"
+	"\x8e\x1f\x98\xb1\x3b\x20\x44\x28\x56\x32\xa8\x03\xaf\xa9\x73\xeb"
+	"\xde\x0f\xf2\x44\x87\x7e\xa6\x0a\x4c\xb0\x43\x2c\xe5\x77\xc3\x1b"
+	"\xeb\x00\x9c\x5c\x2c\x49\xaa\x2e\x4e\xad\xb2\x17\xad\x8c\xc0\x9b";
+
+	if (memcmp(expected, sum, 64) != 0) {
+		printf("test %d failed\n", cnt);
+		result = 1;
+	}
+
+	for (cnt = 0; cnt < ntests2; ++cnt) {
+		char *cp = sha512_crypt(tests2[cnt].input, tests2[cnt].salt);
+
+		if (strcmp(cp, tests2[cnt].expected) != 0) {
+			printf("test %d: expected \"%s\", got \"%s\"\n",
+			       cnt, tests2[cnt].expected, cp);
+			result = 1;
+		}
+	}
+
+	if (result == 0)
+		puts("all tests OK");
+
+	return result;
+}
+
+#endif /* TEST */
diff --git a/lib/libcrypt/crypt.c b/lib/libcrypt/crypt.c
index a6b91f5..89d427f 100644
--- a/lib/libcrypt/crypt.c
+++ b/lib/libcrypt/crypt.c
@@ -63,6 +63,16 @@ static const struct {
 		"$3$"
 	},
 	{
+		"sha256",
+		sha256_crypt,
+		"$5$"
+	},
+	{
+		"sha512",
+		sha512_crypt,
+		"$6$"
+	},
+	{
 		NULL,
 		NULL,
 		NULL
diff --git a/lib/libcrypt/crypt.h b/lib/libcrypt/crypt.h
index c677160..6a73fc9 100644
--- a/lib/libcrypt/crypt.h
+++ b/lib/libcrypt/crypt.h
@@ -36,5 +36,8 @@ char *crypt_des(const char *pw, const char *salt);
 char *crypt_md5(const char *pw, const char *salt);
 char *crypt_nthash(const char *pw, const char *salt);
 char *crypt_blowfish(const char *pw, const char *salt);
+char *sha256_crypt (const char *pw, const char *salt);
+char *sha512_crypt (const char *pw, const char *salt);
 
 extern void _crypt_to64(char *s, u_long v, int n);
+extern void b64_from_24bit(uint8_t B2, uint8_t B1, uint8_t B0, int n, int *buflen, char **cp);
diff --git a/lib/libcrypt/misc.c b/lib/libcrypt/misc.c
index 594c580..0f63ce0 100644
--- a/lib/libcrypt/misc.c
+++ b/lib/libcrypt/misc.c
@@ -45,3 +45,19 @@ _crypt_to64(char *s, u_long v, int n)
 		v >>= 6;
 	}
 }
+
+void
+b64_from_24bit(uint8_t B2, uint8_t B1, uint8_t B0, int n, int *buflen, char **cp)
+{
+	uint32_t w;
+	int i;
+
+	w = (B2 << 16) | (B1 << 8) | B0;
+	for (i = 0; i < n; i++) {
+		**cp = itoa64[w&0x3f];
+		(*cp)++;
+		if ((*buflen)-- < 0)
+			break;
+		w >>= 6;
+	}
+}