1 files changed, 242 insertions, 165 deletions

diff --git a/cipher.c b/cipher.c
index 53d9b4fb7..638ca2d97 100644
--- a/cipher.c
+++ b/cipher.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: cipher.c,v 1.97 2014/02/07 06:55:54 djm Exp $ */
+/* $OpenBSD: cipher.c,v 1.99 2014/06/24 01:13:21 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -43,21 +43,21 @@
 #include <stdarg.h>
 #include <stdio.h>
 
-#include "xmalloc.h"
-#include "log.h"
-#include "misc.h"
 #include "cipher.h"
-#include "buffer.h"
+#include "misc.h"
+#include "sshbuf.h"
+#include "ssherr.h"
 #include "digest.h"
 
-/* compatibility with old or broken OpenSSL versions */
 #include "openbsd-compat/openssl-compat.h"
 
+#ifdef WITH_SSH1
 extern const EVP_CIPHER *evp_ssh1_bf(void);
 extern const EVP_CIPHER *evp_ssh1_3des(void);
-extern void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
+extern int ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int);
+#endif
 
-struct Cipher {
+struct sshcipher {
         char    *name;
         int     number;         /* for ssh1 only */
         u_int   block_size;
@@ -68,15 +68,23 @@ struct Cipher {
         u_int   flags;
 #define CFLAG_CBC               (1<<0)
 #define CFLAG_CHACHAPOLY        (1<<1)
+#define CFLAG_AESCTR            (1<<2)
+#define CFLAG_NONE              (1<<3)
+#ifdef WITH_OPENSSL
         const EVP_CIPHER        *(*evptype)(void);
+#else
+        void    *ignored;
+#endif
 };
 
-static const struct Cipher ciphers[] = {
-        { "none",       SSH_CIPHER_NONE, 8, 0, 0, 0, 0, 0, EVP_enc_null },
+static const struct sshcipher ciphers[] = {
+#ifdef WITH_SSH1
         { "des",        SSH_CIPHER_DES, 8, 8, 0, 0, 0, 1, EVP_des_cbc },
         { "3des",       SSH_CIPHER_3DES, 8, 16, 0, 0, 0, 1, evp_ssh1_3des },
         { "blowfish",   SSH_CIPHER_BLOWFISH, 8, 32, 0, 0, 0, 1, evp_ssh1_bf },
-
+#endif /* WITH_SSH1 */
+#ifdef WITH_OPENSSL
+        { "none",       SSH_CIPHER_NONE, 8, 0, 0, 0, 0, 0, EVP_enc_null },
         { "3des-cbc",   SSH_CIPHER_SSH2, 8, 24, 0, 0, 0, 1, EVP_des_ede3_cbc },
         { "blowfish-cbc",
                         SSH_CIPHER_SSH2, 8, 16, 0, 0, 0, 1, EVP_bf_cbc },
@@ -93,26 +101,33 @@ static const struct Cipher ciphers[] = {
         { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, 0, EVP_aes_128_ctr },
         { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, 0, EVP_aes_192_ctr },
         { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, 0, EVP_aes_256_ctr },
-#ifdef OPENSSL_HAVE_EVPGCM
+# ifdef OPENSSL_HAVE_EVPGCM
         { "aes128-gcm@openssh.com",
                         SSH_CIPHER_SSH2, 16, 16, 12, 16, 0, 0, EVP_aes_128_gcm },
         { "aes256-gcm@openssh.com",
                         SSH_CIPHER_SSH2, 16, 32, 12, 16, 0, 0, EVP_aes_256_gcm },
-#endif
+# endif /* OPENSSL_HAVE_EVPGCM */
+#else /* WITH_OPENSSL */
+        { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, 0, 0, CFLAG_AESCTR, NULL },
+        { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, 0, 0, CFLAG_AESCTR, NULL },
+        { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, 0, 0, CFLAG_AESCTR, NULL },
+        { "none",       SSH_CIPHER_NONE, 8, 0, 0, 0, 0, CFLAG_NONE, NULL },
+#endif /* WITH_OPENSSL */
         { "chacha20-poly1305@openssh.com",
                         SSH_CIPHER_SSH2, 8, 64, 0, 16, 0, CFLAG_CHACHAPOLY, NULL },
+
         { NULL,         SSH_CIPHER_INVALID, 0, 0, 0, 0, 0, 0, NULL }
 };
 
 /*--*/
 
-/* Returns a list of supported ciphers separated by the specified char. */
+/* Returns a comma-separated list of supported ciphers. */
 char *
 cipher_alg_list(char sep, int auth_only)
 {
-        char *ret = NULL;
+        char *tmp, *ret = NULL;
         size_t nlen, rlen = 0;
-        const Cipher *c;
+        const struct sshcipher *c;
 
         for (c = ciphers; c->name != NULL; c++) {
                 if (c->number != SSH_CIPHER_SSH2)
@@ -122,7 +137,11 @@ cipher_alg_list(char sep, int auth_only)
                 if (ret != NULL)
                         ret[rlen++] = sep;
                 nlen = strlen(c->name);
-                ret = xrealloc(ret, 1, rlen + nlen + 2);
+                if ((tmp = realloc(ret, rlen + nlen + 2)) == NULL) {
+                        free(ret);
+                        return NULL;
+                }
+                ret = tmp;
                 memcpy(ret + rlen, c->name, nlen + 1);
                 rlen += nlen;
         }
@@ -130,19 +149,19 @@ cipher_alg_list(char sep, int auth_only)
 }
 
 u_int
-cipher_blocksize(const Cipher *c)
+cipher_blocksize(const struct sshcipher *c)
 {
         return (c->block_size);
 }
 
 u_int
-cipher_keylen(const Cipher *c)
+cipher_keylen(const struct sshcipher *c)
 {
         return (c->key_len);
 }
 
 u_int
-cipher_seclen(const Cipher *c)
+cipher_seclen(const struct sshcipher *c)
 {
         if (strcmp("3des-cbc", c->name) == 0)
                 return 14;
@@ -150,13 +169,13 @@ cipher_seclen(const Cipher *c)
 }
 
 u_int
-cipher_authlen(const Cipher *c)
+cipher_authlen(const struct sshcipher *c)
 {
         return (c->auth_len);
 }
 
 u_int
-cipher_ivlen(const Cipher *c)
+cipher_ivlen(const struct sshcipher *c)
 {
         /*
          * Default is cipher block size, except for chacha20+poly1305 that
@@ -167,13 +186,13 @@ cipher_ivlen(const Cipher *c)
 }
 
 u_int
-cipher_get_number(const Cipher *c)
+cipher_get_number(const struct sshcipher *c)
 {
         return (c->number);
 }
 
 u_int
-cipher_is_cbc(const Cipher *c)
+cipher_is_cbc(const struct sshcipher *c)
 {
         return (c->flags & CFLAG_CBC) != 0;
 }
@@ -190,20 +209,20 @@ cipher_mask_ssh1(int client)
         return mask;
 }
 
-const Cipher *
+const struct sshcipher *
 cipher_by_name(const char *name)
 {
-        const Cipher *c;
+        const struct sshcipher *c;
         for (c = ciphers; c->name != NULL; c++)
                 if (strcmp(c->name, name) == 0)
                         return c;
         return NULL;
 }
 
-const Cipher *
+const struct sshcipher *
 cipher_by_number(int id)
 {
-        const Cipher *c;
+        const struct sshcipher *c;
         for (c = ciphers; c->name != NULL; c++)
                 if (c->number == id)
                         return c;
@@ -214,23 +233,22 @@ cipher_by_number(int id)
 int
 ciphers_valid(const char *names)
 {
-        const Cipher *c;
+        const struct sshcipher *c;
         char *cipher_list, *cp;
         char *p;
 
         if (names == NULL || strcmp(names, "") == 0)
                 return 0;
-        cipher_list = cp = xstrdup(names);
+        if ((cipher_list = cp = strdup(names)) == NULL)
+                return 0;
         for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0';
             (p = strsep(&cp, CIPHER_SEP))) {
                 c = cipher_by_name(p);
                 if (c == NULL || c->number != SSH_CIPHER_SSH2) {
-                        debug("bad cipher %s [%s]", p, names);
                         free(cipher_list);
                         return 0;
                 }
         }
-        debug3("ciphers ok: [%s]", names);
         free(cipher_list);
         return 1;
 }
@@ -243,7 +261,7 @@ ciphers_valid(const char *names)
 int
 cipher_number(const char *name)
 {
-        const Cipher *c;
+        const struct sshcipher *c;
         if (name == NULL)
                 return -1;
         for (c = ciphers; c->name != NULL; c++)
@@ -255,90 +273,104 @@ cipher_number(const char *name)
 char *
 cipher_name(int id)
 {
-        const Cipher *c = cipher_by_number(id);
+        const struct sshcipher *c = cipher_by_number(id);
         return (c==NULL) ? "<unknown>" : c->name;
 }
 
-void
-cipher_init(CipherContext *cc, const Cipher *cipher,
+const char *
+cipher_warning_message(const struct sshcipher_ctx *cc)
+{
+        if (cc == NULL || cc->cipher == NULL)
+                return NULL;
+        if (cc->cipher->number == SSH_CIPHER_DES)
+                return "use of DES is strongly discouraged due to "
+                    "cryptographic weaknesses";
+        return NULL;
+}
+
+int
+cipher_init(struct sshcipher_ctx *cc, const struct sshcipher *cipher,
     const u_char *key, u_int keylen, const u_char *iv, u_int ivlen,
     int do_encrypt)
 {
-        static int dowarn = 1;
-#ifdef SSH_OLD_EVP
-        EVP_CIPHER *type;
-#else
+#ifdef WITH_OPENSSL
+        int ret = SSH_ERR_INTERNAL_ERROR;
         const EVP_CIPHER *type;
         int klen;
-#endif
         u_char *junk, *discard;
 
         if (cipher->number == SSH_CIPHER_DES) {
-                if (dowarn) {
-                        error("Warning: use of DES is strongly discouraged "
-                            "due to cryptographic weaknesses");
-                        dowarn = 0;
-                }
                 if (keylen > 8)
                         keylen = 8;
         }
+#endif
         cc->plaintext = (cipher->number == SSH_CIPHER_NONE);
         cc->encrypt = do_encrypt;
 
-        if (keylen < cipher->key_len)
-                fatal("cipher_init: key length %d is insufficient for %s.",
-                    keylen, cipher->name);
-        if (iv != NULL && ivlen < cipher_ivlen(cipher))
-                fatal("cipher_init: iv length %d is insufficient for %s.",
-                    ivlen, cipher->name);
-        cc->cipher = cipher;
+        if (keylen < cipher->key_len ||
+            (iv != NULL && ivlen < cipher_ivlen(cipher)))
+                return SSH_ERR_INVALID_ARGUMENT;
 
+        cc->cipher = cipher;
         if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
-                chachapoly_init(&cc->cp_ctx, key, keylen);
-                return;
+                return chachapoly_init(&cc->cp_ctx, key, keylen);
         }
-        type = (*cipher->evptype)();
-        EVP_CIPHER_CTX_init(&cc->evp);
-#ifdef SSH_OLD_EVP
-        if (type->key_len > 0 && type->key_len != keylen) {
-                debug("cipher_init: set keylen (%d -> %d)",
-                    type->key_len, keylen);
-                type->key_len = keylen;
+#ifndef WITH_OPENSSL
+        if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
+                aesctr_keysetup(&cc->ac_ctx, key, 8 * keylen, 8 * ivlen);
+                aesctr_ivsetup(&cc->ac_ctx, iv);
+                return 0;
         }
-        EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv,
-            (do_encrypt == CIPHER_ENCRYPT));
+        if ((cc->cipher->flags & CFLAG_NONE) != 0)
+                return 0;
+        return SSH_ERR_INVALID_ARGUMENT;
 #else
+        type = (*cipher->evptype)();
+        EVP_CIPHER_CTX_init(&cc->evp);
         if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv,
-            (do_encrypt == CIPHER_ENCRYPT)) == 0)
-                fatal("cipher_init: EVP_CipherInit failed for %s",
-                    cipher->name);
+            (do_encrypt == CIPHER_ENCRYPT)) == 0) {
+                ret = SSH_ERR_LIBCRYPTO_ERROR;
+                goto bad;
+        }
         if (cipher_authlen(cipher) &&
             !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_IV_FIXED,
-            -1, (u_char *)iv))
-                fatal("cipher_init: EVP_CTRL_GCM_SET_IV_FIXED failed for %s",
-                    cipher->name);
+            -1, (u_char *)iv)) {
+                ret = SSH_ERR_LIBCRYPTO_ERROR;
+                goto bad;
+        }
         klen = EVP_CIPHER_CTX_key_length(&cc->evp);
         if (klen > 0 && keylen != (u_int)klen) {
-                debug2("cipher_init: set keylen (%d -> %d)", klen, keylen);
-                if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0)
-                        fatal("cipher_init: set keylen failed (%d -> %d)",
-                            klen, keylen);
+                if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0) {
+                        ret = SSH_ERR_LIBCRYPTO_ERROR;
+                        goto bad;
+                }
+        }
+        if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0) {
+                ret = SSH_ERR_LIBCRYPTO_ERROR;
+                goto bad;
         }
-        if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0)
-                fatal("cipher_init: EVP_CipherInit: set key failed for %s",
-                    cipher->name);
-#endif
 
         if (cipher->discard_len > 0) {
-                junk = xmalloc(cipher->discard_len);
-                discard = xmalloc(cipher->discard_len);
-                if (EVP_Cipher(&cc->evp, discard, junk,
-                    cipher->discard_len) == 0)
-                        fatal("evp_crypt: EVP_Cipher failed during discard");
+                if ((junk = malloc(cipher->discard_len)) == NULL ||
+                    (discard = malloc(cipher->discard_len)) == NULL) {
+                        if (junk != NULL)
+                                free(junk);
+                        ret = SSH_ERR_ALLOC_FAIL;
+                        goto bad;
+                }
+                ret = EVP_Cipher(&cc->evp, discard, junk, cipher->discard_len);
                 explicit_bzero(discard, cipher->discard_len);
                 free(junk);
                 free(discard);
+                if (ret != 1) {
+                        ret = SSH_ERR_LIBCRYPTO_ERROR;
+ bad:
+                        EVP_CIPHER_CTX_cleanup(&cc->evp);
+                        return ret;
+                }
         }
+#endif
+        return 0;
 }
 
 /*
@@ -350,204 +382,244 @@ cipher_init(CipherContext *cc, const Cipher *cipher,
  * Use 'authlen' 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.
- * cipher_crypt() returns 0 on success and -1 if the decryption integrity
- * check fails.
  */
 int
-cipher_crypt(CipherContext *cc, u_int seqnr, u_char *dest, const u_char *src,
-    u_int len, u_int aadlen, u_int authlen)
+cipher_crypt(struct sshcipher_ctx *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_CHACHAPOLY) != 0)
-                return chachapoly_crypt(&cc->cp_ctx, seqnr, dest, src, len,
-                    aadlen, authlen, cc->encrypt);
+        if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
+                return chachapoly_crypt(&cc->cp_ctx, seqnr, dest, src,
+                    len, aadlen, authlen, cc->encrypt);
+        }
+#ifndef WITH_OPENSSL
+        if ((cc->cipher->flags & CFLAG_AESCTR) != 0) {
+                if (aadlen)
+                        memcpy(dest, src, aadlen);
+                aesctr_encrypt_bytes(&cc->ac_ctx, src + aadlen,
+                    dest + aadlen, len);
+                return 0;
+        }
+        if ((cc->cipher->flags & CFLAG_NONE) != 0) {
+                memcpy(dest, src, aadlen + len);
+                return 0;
+        }
+        return SSH_ERR_INVALID_ARGUMENT;
+#else
         if (authlen) {
                 u_char lastiv[1];
 
                 if (authlen != cipher_authlen(cc->cipher))
-                        fatal("%s: authlen mismatch %d", __func__, authlen);
+                        return SSH_ERR_INVALID_ARGUMENT;
                 /* increment IV */
                 if (!EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_IV_GEN,
                     1, lastiv))
-                        fatal("%s: EVP_CTRL_GCM_IV_GEN", __func__);
+                        return SSH_ERR_LIBCRYPTO_ERROR;
                 /* set tag on decyption */
                 if (!cc->encrypt &&
                     !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_SET_TAG,
                     authlen, (u_char *)src + aadlen + len))
-                        fatal("%s: EVP_CTRL_GCM_SET_TAG", __func__);
+                        return SSH_ERR_LIBCRYPTO_ERROR;
         }
         if (aadlen) {
                 if (authlen &&
                     EVP_Cipher(&cc->evp, NULL, (u_char *)src, aadlen) < 0)
-                        fatal("%s: EVP_Cipher(aad) failed", __func__);
+                        return SSH_ERR_LIBCRYPTO_ERROR;
                 memcpy(dest, src, aadlen);
         }
         if (len % cc->cipher->block_size)
-                fatal("%s: bad plaintext length %d", __func__, len);
+                return SSH_ERR_INVALID_ARGUMENT;
         if (EVP_Cipher(&cc->evp, dest + aadlen, (u_char *)src + aadlen,
             len) < 0)
-                fatal("%s: EVP_Cipher failed", __func__);
+                return SSH_ERR_LIBCRYPTO_ERROR;
         if (authlen) {
                 /* compute tag (on encrypt) or verify tag (on decrypt) */
-                if (EVP_Cipher(&cc->evp, NULL, NULL, 0) < 0) {
-                        if (cc->encrypt)
-                                fatal("%s: EVP_Cipher(final) failed", __func__);
-                        else
-                                return -1;
-                }
+                if (EVP_Cipher(&cc->evp, NULL, NULL, 0) < 0)
+                        return cc->encrypt ?
+                            SSH_ERR_LIBCRYPTO_ERROR : SSH_ERR_MAC_INVALID;
                 if (cc->encrypt &&
                     !EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_GET_TAG,
                     authlen, dest + aadlen + len))
-                        fatal("%s: EVP_CTRL_GCM_GET_TAG", __func__);
+                        return SSH_ERR_LIBCRYPTO_ERROR;
         }
         return 0;
+#endif
 }
 
 /* Extract the packet length, including any decryption necessary beforehand */
 int
-cipher_get_length(CipherContext *cc, u_int *plenp, u_int seqnr,
+cipher_get_length(struct sshcipher_ctx *cc, u_int *plenp, u_int seqnr,
     const u_char *cp, u_int len)
 {
         if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
                 return chachapoly_get_length(&cc->cp_ctx, plenp, seqnr,
                     cp, len);
         if (len < 4)
-                return -1;
+                return SSH_ERR_MESSAGE_INCOMPLETE;
         *plenp = get_u32(cp);
         return 0;
 }
 
-void
-cipher_cleanup(CipherContext *cc)
+int
+cipher_cleanup(struct sshcipher_ctx *cc)
 {
+        if (cc == NULL || cc->cipher == NULL)
+                return 0;
         if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
                 explicit_bzero(&cc->cp_ctx, sizeof(cc->cp_ctx));
+        else if ((cc->cipher->flags & CFLAG_AESCTR) != 0)
+                explicit_bzero(&cc->ac_ctx, sizeof(cc->ac_ctx));
+#ifdef WITH_OPENSSL
         else if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0)
-                error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed");
+                return SSH_ERR_LIBCRYPTO_ERROR;
+#endif
+        return 0;
 }
 
 /*
  * Selects the cipher, and keys if by computing the MD5 checksum of the
  * passphrase and using the resulting 16 bytes as the key.
  */
-
-void
-cipher_set_key_string(CipherContext *cc, const Cipher *cipher,
+int
+cipher_set_key_string(struct sshcipher_ctx *cc, const struct sshcipher *cipher,
     const char *passphrase, int do_encrypt)
 {
         u_char digest[16];
+        int r = SSH_ERR_INTERNAL_ERROR;
 
-        if (ssh_digest_memory(SSH_DIGEST_MD5, passphrase, strlen(passphrase),
-            digest, sizeof(digest)) < 0)
-                fatal("%s: md5 failed", __func__);
-
-        cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
+        if ((r = ssh_digest_memory(SSH_DIGEST_MD5,
+            passphrase, strlen(passphrase),
+            digest, sizeof(digest))) != 0)
+                goto out;
 
+        r = cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt);
+ out:
         explicit_bzero(digest, sizeof(digest));
+        return r;
 }
 
 /*
- * Exports an IV from the CipherContext required to export the key
+ * Exports an IV from the sshcipher_ctx required to export the key
  * state back from the unprivileged child to the privileged parent
  * process.
  */
-
 int
-cipher_get_keyiv_len(const CipherContext *cc)
+cipher_get_keyiv_len(const struct sshcipher_ctx *cc)
 {
-        const Cipher *c = cc->cipher;
-        int ivlen;
+        const struct sshcipher *c = cc->cipher;
+        int ivlen = 0;
 
         if (c->number == SSH_CIPHER_3DES)
                 ivlen = 24;
         else if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
                 ivlen = 0;
+#ifdef WITH_OPENSSL
         else
                 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp);
+#endif /* WITH_OPENSSL */
         return (ivlen);
 }
 
-void
-cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len)
+int
+cipher_get_keyiv(struct sshcipher_ctx *cc, u_char *iv, u_int len)
 {
-        const Cipher *c = cc->cipher;
-        int evplen;
+        const struct sshcipher *c = cc->cipher;
+#ifdef WITH_OPENSSL
+        int evplen;
+#endif
 
         if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0) {
                 if (len != 0)
-                        fatal("%s: wrong iv length %d != %d", __func__, len, 0);
-                return;
+                        return SSH_ERR_INVALID_ARGUMENT;
+                return 0;
         }
+        if ((cc->cipher->flags & CFLAG_NONE) != 0)
+                return 0;
 
         switch (c->number) {
+#ifdef WITH_OPENSSL
         case SSH_CIPHER_SSH2:
         case SSH_CIPHER_DES:
         case SSH_CIPHER_BLOWFISH:
                 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
-                if (evplen <= 0)
-                        return;
+                if (evplen == 0)
+                        return 0;
+                else if (evplen < 0)
+                        return SSH_ERR_LIBCRYPTO_ERROR;
                 if ((u_int)evplen != len)
-                        fatal("%s: wrong iv length %d != %d", __func__,
-                            evplen, len);
-#ifdef USE_BUILTIN_RIJNDAEL
-                if (c->evptype == evp_rijndael)
-                        ssh_rijndael_iv(&cc->evp, 0, iv, len);
-                else
-#endif
+                        return SSH_ERR_INVALID_ARGUMENT;
 #ifndef OPENSSL_HAVE_EVPCTR
                 if (c->evptype == evp_aes_128_ctr)
                         ssh_aes_ctr_iv(&cc->evp, 0, iv, len);
                 else
 #endif
-                memcpy(iv, cc->evp.iv, len);
+                if (cipher_authlen(c)) {
+                        if (!EVP_CIPHER_CTX_ctrl(&cc->evp, EVP_CTRL_GCM_IV_GEN,
+                           len, iv))
+                               return SSH_ERR_LIBCRYPTO_ERROR;
+                } else
+                        memcpy(iv, cc->evp.iv, len);
                 break;
+#endif
+#ifdef WITH_SSH1
         case SSH_CIPHER_3DES:
-                ssh1_3des_iv(&cc->evp, 0, iv, 24);
-                break;
+                return ssh1_3des_iv(&cc->evp, 0, iv, 24);
+#endif
         default:
-                fatal("%s: bad cipher %d", __func__, c->number);
+                return SSH_ERR_INVALID_ARGUMENT;
         }
+        return 0;
 }
 
-void
-cipher_set_keyiv(CipherContext *cc, u_char *iv)
+int
+cipher_set_keyiv(struct sshcipher_ctx *cc, const u_char *iv)
 {
-        const Cipher *c = cc->cipher;
-        int evplen = 0;
+        const struct sshcipher *c = cc->cipher;
+#ifdef WITH_OPENSSL
+        int evplen = 0;
+#endif
 
         if ((cc->cipher->flags & CFLAG_CHACHAPOLY) != 0)
-                return;
+                return 0;
+        if ((cc->cipher->flags & CFLAG_NONE) != 0)
+                return 0;
 
         switch (c->number) {
+#ifdef WITH_OPENSSL
         case SSH_CIPHER_SSH2:
         case SSH_CIPHER_DES:
         case SSH_CIPHER_BLOWFISH:
                 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp);
-                if (evplen == 0)
-                        return;
-#ifdef USE_BUILTIN_RIJNDAEL
-                if (c->evptype == evp_rijndael)
-                        ssh_rijndael_iv(&cc->evp, 1, iv, evplen);
-                else
-#endif
-#ifndef OPENSSL_HAVE_EVPCTR
-                if (c->evptype == evp_aes_128_ctr)
-                        ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen);
-                else
-#endif
-                memcpy(cc->evp.iv, iv, evplen);
+                if (evplen <= 0)
+                        return SSH_ERR_LIBCRYPTO_ERROR;
+                if (cipher_authlen(c)) {
+                        /* XXX iv arg is const, but EVP_CIPHER_CTX_ctrl isn't */
+                        if (!EVP_CIPHER_CTX_ctrl(&cc->evp,
+                            EVP_CTRL_GCM_SET_IV_FIXED, -1, (void *)iv))
+                                return SSH_ERR_LIBCRYPTO_ERROR;
+                } else
+                        memcpy(cc->evp.iv, iv, evplen);
                 break;
+#endif
+#ifdef WITH_SSH1
         case SSH_CIPHER_3DES:
-                ssh1_3des_iv(&cc->evp, 1, iv, 24);
-                break;
+                return ssh1_3des_iv(&cc->evp, 1, (u_char *)iv, 24);
+#endif
         default:
-                fatal("%s: bad cipher %d", __func__, c->number);
+                return SSH_ERR_INVALID_ARGUMENT;
         }
+        return 0;
 }
 
+#ifdef WITH_OPENSSL
+#define EVP_X_STATE(evp)        (evp).cipher_data
+#define EVP_X_STATE_LEN(evp)    (evp).cipher->ctx_size
+#endif
+
 int
-cipher_get_keycontext(const CipherContext *cc, u_char *dat)
+cipher_get_keycontext(const struct sshcipher_ctx *cc, u_char *dat)
 {
-        const Cipher *c = cc->cipher;
+#ifdef WITH_OPENSSL
+        const struct sshcipher *c = cc->cipher;
         int plen = 0;
 
         if (c->evptype == EVP_rc4) {
@@ -557,16 +629,21 @@ cipher_get_keycontext(const CipherContext *cc, u_char *dat)
                 memcpy(dat, EVP_X_STATE(cc->evp), plen);
         }
         return (plen);
+#else
+        return 0;
+#endif
 }
 
 void
-cipher_set_keycontext(CipherContext *cc, u_char *dat)
+cipher_set_keycontext(struct sshcipher_ctx *cc, const u_char *dat)
 {
-        const Cipher *c = cc->cipher;
+#ifdef WITH_OPENSSL
+        const struct sshcipher *c = cc->cipher;
         int plen;
 
         if (c->evptype == EVP_rc4) {
                 plen = EVP_X_STATE_LEN(cc->evp);
                 memcpy(EVP_X_STATE(cc->evp), dat, plen);
         }
+#endif
 }