ed25519: Generate, sign and verify keys.

Reviewed-by: Andreas Schneider <asn@cryptomilk.org>

6 files changed, 460 insertions, 2 deletions

diff --git a/include/libssh/pki.h b/include/libssh/pki.h
index 89a0f982..9f9ddf4a 100644
--- a/include/libssh/pki.h
+++ b/include/libssh/pki.h
@@ -21,6 +21,7 @@
 #ifndef PKI_H_
 #define PKI_H_
 
+#include "libssh/priv.h"
 #ifdef HAVE_OPENSSL_EC_H
 #include <openssl/ec.h>
 #endif
@@ -29,6 +30,7 @@
 #endif
 
 #include "libssh/crypto.h"
+#include "libssh/ed25519.h"
 
 #define MAX_PUBKEY_SIZE 0x100000 /* 1M */
 #define MAX_PRIVKEY_SIZE 0x400000 /* 4M */
@@ -55,6 +57,8 @@ struct ssh_key_struct {
     void *ecdsa;
 #endif /* HAVE_OPENSSL_EC_H */
 #endif
+    ed25519_pubkey *ed25519_pubkey;
+    ed25519_privkey *ed25519_privkey;
     void *cert;
 };
 
@@ -74,6 +78,7 @@ struct ssh_signature_struct {
     void *ecdsa_sig;
 # endif
 #endif
+    ed25519_signature *ed25519_sig;
 };
 
 typedef struct ssh_signature_struct *ssh_signature;
diff --git a/include/libssh/pki_priv.h b/include/libssh/pki_priv.h
index 0cbe8b72..0aaadb60 100644
--- a/include/libssh/pki_priv.h
+++ b/include/libssh/pki_priv.h
@@ -41,6 +41,8 @@ ssh_key pki_key_dup(const ssh_key key, int demote);
 int pki_key_generate_rsa(ssh_key key, int parameter);
 int pki_key_generate_dss(ssh_key key, int parameter);
 int pki_key_generate_ecdsa(ssh_key key, int parameter);
+int pki_key_generate_ed25519(ssh_key key);
+
 int pki_key_compare(const ssh_key k1,
                     const ssh_key k2,
                     enum ssh_keycmp_e what);
@@ -91,4 +93,16 @@ ssh_signature pki_do_sign(const ssh_key privkey,
 ssh_signature pki_do_sign_sessionid(const ssh_key key,
                                     const unsigned char *hash,
                                     size_t hlen);
+int pki_ed25519_sign(const ssh_key privkey, ssh_signature sig,
+		const unsigned char *hash, size_t hlen);
+int pki_ed25519_verify(const ssh_key pubkey, ssh_signature sig,
+		const unsigned char *hash, size_t hlen);
+int pki_ed25519_key_cmp(const ssh_key k1,
+                const ssh_key k2,
+                enum ssh_keycmp_e what);
+int pki_ed25519_key_dup(ssh_key new, const ssh_key key);
+int pki_ed25519_public_key_to_blob(ssh_buffer buffer, ssh_key key);
+ssh_string pki_ed25519_sig_to_blob(ssh_signature sig);
+int pki_ed25519_sig_from_blob(ssh_signature sig, ssh_string sig_blob);
+
 #endif /* PKI_PRIV_H_ */
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 446238ae..a4bc8595 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -139,6 +139,7 @@ set(libssh_SRCS
   packet_crypt.c
   pcap.c
   pki.c
+  pki_ed25519.c
   poll.c
   session.c
   sc25519.c
diff --git a/src/pki.c b/src/pki.c
index c64f0ec9..8fc7251a 100644
--- a/src/pki.c
+++ b/src/pki.c
@@ -157,6 +157,11 @@ void ssh_key_clean (ssh_key key){
     if(key->ecdsa) EC_KEY_free(key->ecdsa);
 #endif /* HAVE_OPENSSL_ECC */
 #endif
+    if (key->ed25519_privkey != NULL){
+        BURN_BUFFER(key->ed25519_privkey, sizeof(ed25519_privkey));
+        SAFE_FREE(key->ed25519_privkey);
+    }
+    SAFE_FREE(key->ed25519_pubkey);
     key->flags=SSH_KEY_FLAG_EMPTY;
     key->type=SSH_KEYTYPE_UNKNOWN;
     key->ecdsa_nid = 0;
@@ -207,6 +212,8 @@ const char *ssh_key_type_to_char(enum ssh_keytypes_e type) {
       return "ssh-rsa1";
     case SSH_KEYTYPE_ECDSA:
       return "ssh-ecdsa";
+    case SSH_KEYTYPE_ED25519:
+      return "ssh-ed25519";
     case SSH_KEYTYPE_UNKNOWN:
       return NULL;
   }
@@ -245,6 +252,8 @@ enum ssh_keytypes_e ssh_key_type_from_name(const char *name) {
             || strcmp(name, "ecdsa-sha2-nistp384") == 0
             || strcmp(name, "ecdsa-sha2-nistp521") == 0) {
         return SSH_KEYTYPE_ECDSA;
+    } else if (strcmp(name, "ssh-ed25519") == 0){
+        return SSH_KEYTYPE_ED25519;
     }
 
     return SSH_KEYTYPE_UNKNOWN;
@@ -300,7 +309,7 @@ int ssh_key_cmp(const ssh_key k1,
     }
 
     if (k1->type != k2->type) {
-        ssh_pki_log("key types don't macth!");
+        ssh_pki_log("key types don't match!");
         return 1;
     }
 
@@ -311,6 +320,10 @@ int ssh_key_cmp(const ssh_key k1,
         }
     }
 
+    if (k1->type == SSH_KEYTYPE_ED25519) {
+        return pki_ed25519_key_cmp(k1, k2, what);
+    }
+
     return pki_key_compare(k1, k2, what);
 }
 
@@ -354,6 +367,9 @@ void ssh_signature_free(ssh_signature sig)
             ECDSA_SIG_free(sig->ecdsa_sig);
 #endif
             break;
+        case SSH_KEYTYPE_ED25519:
+            SAFE_FREE(sig->ed25519_sig);
+            break;
         case SSH_KEYTYPE_UNKNOWN:
             break;
     }
@@ -749,7 +765,26 @@ static int pki_import_pubkey_buffer(ssh_buffer buffer,
             }
             break;
 #endif
+        case SSH_KEYTYPE_ED25519:
+        {
+            ssh_string pubkey = buffer_get_ssh_string(buffer);
+
+            if (ssh_string_len(pubkey) != ED25519_PK_LEN) {
+                ssh_pki_log("Invalid public key length");
+            }
+
+            key->ed25519_pubkey = malloc(ED25519_PK_LEN);
+            if (key->ed25519_pubkey == NULL) {
+                goto fail;
+            }
+
+            memcpy(key->ed25519_pubkey, ssh_string_data(pubkey), ED25519_PK_LEN);
+            ssh_string_burn(pubkey);
+            ssh_string_free(pubkey);
+        }
+        break;
         case SSH_KEYTYPE_UNKNOWN:
+        default:
             ssh_pki_log("Unknown public key protocol %d", type);
             goto fail;
     }
@@ -1010,6 +1045,12 @@ int ssh_pki_generate(enum ssh_keytypes_e type, int parameter,
             key->type_c = ssh_pki_key_ecdsa_name(key);
             break;
 #endif
+        case SSH_KEYTYPE_ED25519:
+            rc = pki_key_generate_ed25519(key);
+            if (rc == SSH_ERROR) {
+                goto error;
+            }
+            break;
         case SSH_KEYTYPE_UNKNOWN:
             goto error;
     }
@@ -1336,6 +1377,8 @@ int ssh_pki_signature_verify_blob(ssh_session session,
                                   ehash,
                                   elen);
 #endif
+    } else if (key->type == SSH_KEYTYPE_ED25519) {
+        rc = pki_signature_verify(session, sig, key, digest, dlen);
     } else {
         unsigned char hash[SHA_DIGEST_LEN] = {0};
 
@@ -1402,6 +1445,25 @@ ssh_string ssh_pki_do_sign(ssh_session session,
 
         sig = pki_do_sign(privkey, ehash, elen);
 #endif
+    } else if (privkey->type == SSH_KEYTYPE_ED25519){
+        ssh_buffer buf;
+
+        buf = ssh_buffer_new();
+        if (buf == NULL){
+            ssh_string_free(session_id);
+            return NULL;
+        }
+
+        ssh_buffer_set_secure(buf);
+        ssh_buffer_pack(buf,
+                        "SP",
+                        session_id,
+                        buffer_get_rest_len(sigbuf), buffer_get_rest(sigbuf));
+
+        sig = pki_do_sign(privkey,
+                          ssh_buffer_get_begin(buf),
+                          ssh_buffer_get_len(buf));
+        ssh_buffer_free(buf);
     } else {
         unsigned char hash[SHA_DIGEST_LEN] = {0};
         SHACTX ctx;
@@ -1525,6 +1587,23 @@ ssh_string ssh_srv_pki_do_sign_sessionid(ssh_session session,
             return NULL;
         }
 #endif
+    } else if (privkey->type == SSH_KEYTYPE_ED25519) {
+        sig = ssh_signature_new();
+        if (sig == NULL){
+            return NULL;
+        }
+
+        sig->type = privkey->type;
+        sig->type_c = privkey->type_c;
+
+        rc = pki_ed25519_sign(privkey,
+                              sig,
+                              crypto->secret_hash,
+                              crypto->digest_len);
+        if (rc != SSH_OK){
+            ssh_signature_free(sig);
+            sig = NULL;
+        }
     } else {
         unsigned char hash[SHA_DIGEST_LEN] = {0};
         SHACTX ctx;
diff --git a/src/pki_crypto.c b/src/pki_crypto.c
index 425e535d..5706fdf0 100644
--- a/src/pki_crypto.c
+++ b/src/pki_crypto.c
@@ -214,6 +214,7 @@ int pki_pubkey_build_ecdsa(ssh_key key, int nid, ssh_string e)
 ssh_key pki_key_dup(const ssh_key key, int demote)
 {
     ssh_key new;
+    int rc;
 
     new = ssh_key_new();
     if (new == NULL) {
@@ -371,7 +372,14 @@ ssh_key pki_key_dup(const ssh_key key, int demote)
         }
         break;
 #endif
+    case SSH_KEYTYPE_ED25519:
+        rc = pki_ed25519_key_dup(new, key);
+        if (rc != SSH_OK) {
+            goto fail;
+        }
+        break;
     case SSH_KEYTYPE_UNKNOWN:
+    default:
         ssh_key_free(new);
         return NULL;
     }
@@ -533,7 +541,10 @@ int pki_key_compare(const ssh_key k1,
                 break;
             }
 #endif
+        case SSH_KEYTYPE_ED25519:
+            /* ed25519 keys handled globaly */
         case SSH_KEYTYPE_UNKNOWN:
+        default:
             return 1;
     }
 
@@ -636,6 +647,7 @@ ssh_string pki_private_key_to_pem(const ssh_key key,
             }
             break;
 #endif
+        case SSH_KEYTYPE_ED25519:
         case SSH_KEYTYPE_UNKNOWN:
             BIO_free(mem);
             ssh_pki_log("Unkown or invalid private key type %d", key->type);
@@ -759,6 +771,7 @@ ssh_key pki_private_key_from_base64(const char *b64_key,
 
             break;
 #endif
+        case SSH_KEYTYPE_ED25519:
         case SSH_KEYTYPE_UNKNOWN:
             BIO_free(mem);
             ssh_pki_log("Unkown or invalid private key type %d", type);
@@ -997,7 +1010,14 @@ ssh_string pki_publickey_to_blob(const ssh_key key)
 
             break;
 #endif
+        case SSH_KEYTYPE_ED25519:
+            rc = pki_ed25519_public_key_to_blob(buffer, key);
+            if (rc == SSH_ERROR){
+                goto fail;
+            }
+            break;
         case SSH_KEYTYPE_UNKNOWN:
+        default:
             goto fail;
     }
 
@@ -1216,6 +1236,10 @@ ssh_string pki_signature_to_blob(const ssh_signature sig)
             break;
         }
 #endif
+        case SSH_KEYTYPE_ED25519:
+            sig_blob = pki_ed25519_sig_to_blob(sig);
+            break;
+        default:
         case SSH_KEYTYPE_UNKNOWN:
             ssh_pki_log("Unknown signature key type: %s", sig->type_c);
             return NULL;
@@ -1293,6 +1317,7 @@ ssh_signature pki_signature_from_blob(const ssh_key pubkey,
     ssh_string r;
     ssh_string s;
     size_t len;
+    int rc;
 
     sig = ssh_signature_new();
     if (sig == NULL) {
@@ -1369,7 +1394,6 @@ ssh_signature pki_signature_from_blob(const ssh_key pubkey,
             { /* build ecdsa siganature */
                 ssh_buffer b;
                 uint32_t rlen;
-                int rc;
 
                 b = ssh_buffer_new();
                 if (b == NULL) {
@@ -1437,6 +1461,14 @@ ssh_signature pki_signature_from_blob(const ssh_key pubkey,
 
             break;
 #endif
+        case SSH_KEYTYPE_ED25519:
+            rc = pki_ed25519_sig_from_blob(sig, sig_blob);
+            if (rc == SSH_ERROR){
+                ssh_signature_free(sig);
+                return NULL;
+            }
+            break;
+        default:
         case SSH_KEYTYPE_UNKNOWN:
             ssh_pki_log("Unknown signature type");
             ssh_signature_free(sig);
@@ -1484,6 +1516,15 @@ int pki_signature_verify(ssh_session session,
                 return SSH_ERROR;
             }
             break;
+        case SSH_KEYTYPE_ED25519:
+            rc = pki_ed25519_verify(key, sig, hash, hlen);
+            if (rc != SSH_OK){
+                ssh_set_error(session,
+                              SSH_FATAL,
+                              "ed25519 signature verification error");
+                return SSH_ERROR;
+            }
+            break;
         case SSH_KEYTYPE_ECDSA:
 #ifdef HAVE_OPENSSL_ECC
             rc = ECDSA_do_verify(hash,
@@ -1500,6 +1541,7 @@ int pki_signature_verify(ssh_session session,
             break;
 #endif
         case SSH_KEYTYPE_UNKNOWN:
+        default:
             ssh_set_error(session, SSH_FATAL, "Unknown public key type");
             return SSH_ERROR;
     }
@@ -1511,6 +1553,7 @@ ssh_signature pki_do_sign(const ssh_key privkey,
                           const unsigned char *hash,
                           size_t hlen) {
     ssh_signature sig;
+    int rc;
 
     sig = ssh_signature_new();
     if (sig == NULL) {
@@ -1558,7 +1601,15 @@ ssh_signature pki_do_sign(const ssh_key privkey,
 
             break;
 #endif /* HAVE_OPENSSL_ECC */
+        case SSH_KEYTYPE_ED25519:
+            rc = pki_ed25519_sign(privkey, sig, hash, hlen);
+            if (rc != SSH_OK){
+                ssh_signature_free(sig);
+                return NULL;
+            }
+            break;
         case SSH_KEYTYPE_UNKNOWN:
+        default:
             ssh_signature_free(sig);
             return NULL;
     }
@@ -1605,7 +1656,10 @@ ssh_signature pki_do_sign_sessionid(const ssh_key key,
             }
             break;
 #endif
+        case SSH_KEYTYPE_ED25519:
+            /* ED25519 handled in caller */
         case SSH_KEYTYPE_UNKNOWN:
+        default:
             ssh_signature_free(sig);
             return NULL;
     }
diff --git a/src/pki_ed25519.c b/src/pki_ed25519.c
new file mode 100644
index 00000000..918db843
--- /dev/null
+++ b/src/pki_ed25519.c
@@ -0,0 +1,305 @@
+/*
+ * pki_ed25519 .c - PKI infrastructure using ed25519
+ *
+ * This file is part of the SSH Library
+ *
+ * Copyright (c) 2014 by Aris Adamantiadis
+ *
+ * The SSH 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 SSH 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 SSH Library; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+#include "libssh/pki.h"
+#include "libssh/pki_priv.h"
+#include "libssh/ed25519.h"
+#include "libssh/buffer.h"
+
+int pki_key_generate_ed25519(ssh_key key)
+{
+    int rc;
+
+    key->ed25519_privkey = malloc(sizeof (ed25519_privkey));
+    if (key->ed25519_privkey == NULL) {
+        goto error;
+    }
+
+    key->ed25519_pubkey = malloc(sizeof (ed25519_privkey));
+    if (key->ed25519_privkey == NULL) {
+        goto error;
+    }
+
+    rc = crypto_sign_ed25519_keypair(*key->ed25519_pubkey,
+                                     *key->ed25519_privkey);
+    if (rc != 0) {
+        goto error;
+    }
+
+    return SSH_OK;
+error:
+    SAFE_FREE(key->ed25519_privkey);
+    SAFE_FREE(key->ed25519_pubkey);
+
+    return SSH_ERROR;
+}
+
+int pki_ed25519_sign(const ssh_key privkey,
+                     ssh_signature sig,
+                     const unsigned char *hash,
+                     size_t hlen)
+{
+    uint8_t *buffer = malloc(hlen + ED25519_SIG_LEN);
+    unsigned long long dlen = 0;
+    int rc;
+
+    buffer = malloc(hlen + ED25519_SIG_LEN);
+    if (buffer == NULL) {
+        return SSH_ERROR;
+    }
+
+    rc = crypto_sign_ed25519(buffer,
+                             &dlen,
+                             hash,
+                             hlen,
+                             *privkey->ed25519_privkey);
+    if (rc != 0) {
+        goto error;
+    }
+    sig->ed25519_sig = malloc(ED25519_SIG_LEN);
+    if (sig->ed25519_sig == NULL) {
+        goto error;
+    }
+
+    /* This shouldn't happen */
+    if (dlen - hlen != ED25519_SIG_LEN) {
+        goto error;
+    }
+    memcpy(sig->ed25519_sig, buffer, dlen - hlen);
+    SAFE_FREE(buffer);
+
+    return SSH_OK;
+error:
+    SAFE_FREE(buffer);
+    return SSH_ERROR;
+}
+
+int pki_ed25519_verify(const ssh_key pubkey,
+                       ssh_signature sig,
+                       const unsigned char *hash,
+                       size_t hlen)
+{
+    unsigned long long mlen = 0;
+    uint8_t *buffer;
+    uint8_t *buffer2;
+    int rc;
+
+    if (pubkey == NULL || sig == NULL ||
+        hash == NULL || sig->ed25519_sig == NULL) {
+        return SSH_ERROR;
+    }
+
+    buffer = malloc(hlen + ED25519_SIG_LEN);
+    if (buffer == NULL) {
+        return SSH_ERROR;
+    }
+
+    buffer2 = malloc(hlen + ED25519_SIG_LEN);
+    if (buffer2 == NULL) {
+        goto error;
+    }
+
+    memcpy(buffer, sig->ed25519_sig, ED25519_SIG_LEN);
+    memcpy(buffer + ED25519_SIG_LEN, hash, hlen);
+
+    rc = crypto_sign_ed25519_open(buffer2,
+                                  &mlen,
+                                  buffer,
+                                  hlen + ED25519_SIG_LEN,
+                                  *pubkey->ed25519_pubkey);
+
+    BURN_BUFFER(buffer, hlen + ED25519_SIG_LEN);
+    BURN_BUFFER(buffer2, hlen);
+    SAFE_FREE(buffer);
+    SAFE_FREE(buffer2);
+    if (rc == 0) {
+        return SSH_OK;
+    } else {
+        return SSH_ERROR;
+    }
+error:
+    SAFE_FREE(buffer);
+    SAFE_FREE(buffer2);
+
+    return SSH_ERROR;
+}
+
+/**
+ * @internal
+ *
+ * @brief Compare ed25519 keys if they are equal.
+ *
+ * @param[in] k1        The first key to compare.
+ *
+ * @param[in] k2        The second key to compare.
+ *
+ * @param[in] what      What part or type of the key do you want to compare.
+ *
+ * @return              0 if equal, 1 if not.
+ */
+int pki_ed25519_key_cmp(const ssh_key k1,
+                        const ssh_key k2,
+                        enum ssh_keycmp_e what)
+{
+    int cmp;
+
+    switch(what) {
+    case SSH_KEY_CMP_PRIVATE:
+        if (k1->ed25519_privkey == NULL || k2->ed25519_privkey == NULL) {
+            return 1;
+        }
+        cmp = memcmp(k1->ed25519_privkey, k2->ed25519_privkey, ED25519_SK_LEN);
+        if (cmp != 0) {
+            return 1;
+        }
+        /* FALL THROUGH */
+    case SSH_KEY_CMP_PUBLIC:
+        if (k1->ed25519_pubkey == NULL || k2->ed25519_pubkey == NULL) {
+            return 1;
+        }
+        cmp = memcmp(k1->ed25519_pubkey, k2->ed25519_pubkey, ED25519_PK_LEN);
+        if (cmp != 0) {
+            return 1;
+        }
+    }
+
+    return 0;
+}
+
+/**
+ * @internal
+ *
+ * @brief duplicate an ed25519 key
+ *
+ * @param[out\ new preinitialized output ssh_ke
+ *
+ * @param[in] key key to copy
+ *
+ * @return SSH_ERROR on error, SSH_OK on success
+ */
+int pki_ed25519_key_dup(ssh_key new, const ssh_key key)
+{
+    if (key->ed25519_privkey == NULL || key->ed25519_pubkey == NULL) {
+        return SSH_ERROR;
+    }
+
+    new->ed25519_privkey = malloc(ED25519_SK_LEN);
+    if (new->ed25519_privkey == NULL) {
+        return SSH_ERROR;
+    }
+
+    new->ed25519_pubkey = malloc(ED25519_PK_LEN);
+    if (new->ed25519_privkey == NULL || new->ed25519_pubkey == NULL){
+        SAFE_FREE(new->ed25519_privkey);
+        return SSH_ERROR;
+    }
+
+    memcpy(new->ed25519_privkey, key->ed25519_privkey, ED25519_SK_LEN);
+    memcpy(new->ed25519_pubkey, key->ed25519_pubkey, ED25519_PK_LEN);
+
+    return SSH_OK;
+}
+
+/**
+ * @internal
+ *
+ * @brief outputs an ed25519 public key in a blob buffer.
+ *
+ * @param[out] buffer output buffer
+ *
+ * @param[in] key key to output
+ *
+ * @return SSH_ERROR on error, SSH_OK on success
+ */
+int pki_ed25519_public_key_to_blob(ssh_buffer buffer, ssh_key key)
+{
+    int rc;
+
+    if (key->ed25519_pubkey == NULL){
+        return SSH_ERROR;
+    }
+
+    rc = ssh_buffer_pack(buffer,
+                         "dP",
+                         (uint32_t)ED25519_PK_LEN,
+                         (size_t)ED25519_PK_LEN, key->ed25519_pubkey);
+
+    return rc;
+}
+
+/**
+ * @internal
+ *
+ * @brief output a signature blob from an ed25519 signature
+ *
+ * @param[in] sig signature to convert
+ *
+ * @return Signature blob in SSH string, or NULL on error
+ */
+ssh_string pki_ed25519_sig_to_blob(ssh_signature sig)
+{
+    ssh_string sig_blob;
+
+    if (sig->ed25519_sig == NULL) {
+        return NULL;
+    }
+
+    sig_blob = ssh_string_new(ED25519_SIG_LEN);
+    if (sig_blob == NULL) {
+        return NULL;
+    }
+    ssh_string_fill(sig_blob, sig->ed25519_sig, ED25519_SIG_LEN);
+
+    return sig_blob;
+}
+
+/**
+ * @internal
+ *
+ * @brief Convert a signature blob in an ed25519 signature.
+ *
+ * @param[out] sig a preinitialized signature
+ *
+ * @param[in] sig_blob a signature blob
+ *
+ * @return SSH_ERROR on error, SSH_OK on success
+ */
+int pki_ed25519_sig_from_blob(ssh_signature sig, ssh_string sig_blob)
+{
+    size_t len;
+
+    len = ssh_string_len(sig_blob);
+    if (len != ED25519_SIG_LEN){
+        ssh_pki_log("Invalid ssh-ed25519 signature len: %zu", len);
+        return SSH_ERROR;
+    }
+
+    sig->ed25519_sig = malloc(ED25519_SIG_LEN);
+    if (sig->ed25519_sig == NULL){
+        return SSH_ERROR;
+    }
+
+    memcpy(sig->ed25519_sig, ssh_string_data(sig_blob), ED25519_SIG_LEN);
+
+    return SSH_OK;
+}