Implement a PEM-like format for Ed25519 keys.

We don't require compatibility with any other software, but we do want Ed25519 keys to work
the same as RSA keys for now.

diff --git a/src/ed25519/ecdsa.c b/src/ed25519/ecdsa.c
index 4515131..bfdabc1 100644 (file)
--- a/src/ed25519/ecdsa.c
+++ b/src/ed25519/ecdsa.c
@@ -62,9 +62,52 @@ char *ecdsa_get_base64_public_key(ecdsa_t *ecdsa) {
 
 // Read PEM ECDSA keys
 
+static bool read_pem(FILE *fp, const char *type, void *buf, size_t size) {
+       char line[1024];
+       bool data = false;
+       size_t typelen = strlen(type);
+
+       while(fgets(line, sizeof line, fp)) {
+               if(!data) {
+                       if(strncmp(line, "-----BEGIN ", 11))
+                               continue;
+                       if(strncmp(line + 11, type, typelen))
+                               continue;
+                       data = true;
+                       continue;
+               }
+
+               if(!strncmp(line, "-----END ", 9))
+                       break;
+
+               size_t linelen = strcspn(line, "\r\n");
+               size_t len = b64decode(line, line, linelen);
+               if(!len) {
+                       logger(DEBUG_ALWAYS, LOG_ERR, "Invalid base64 data in PEM file\n");
+                       return false;
+               }
+
+               if(len > size) {
+                       logger(DEBUG_ALWAYS, LOG_ERR, "Too much base64 data in PEM file\n");
+                       return false;
+               }
+
+               memcpy(buf, line, len);
+               buf += len;
+               size -= len;
+       }
+
+       if(size) {
+               logger(DEBUG_ALWAYS, LOG_ERR, "Too little base64 data in PEM file\n");
+               return false;
+       }
+
+       return true;
+}
+
 ecdsa_t *ecdsa_read_pem_public_key(FILE *fp) {
        ecdsa_t *ecdsa = xzalloc(sizeof *ecdsa);
-       if(fread(ecdsa->public, sizeof ecdsa->public, 1, fp) == 1)
+       if(read_pem(fp, "ED25519 PUBLIC KEY", ecdsa->public, sizeof ecdsa->public))
                return ecdsa;
        free(ecdsa);
        return 0;
@@ -72,7 +115,7 @@ ecdsa_t *ecdsa_read_pem_public_key(FILE *fp) {
 
 ecdsa_t *ecdsa_read_pem_private_key(FILE *fp) {
        ecdsa_t *ecdsa = xmalloc(sizeof *ecdsa);
-       if(fread(ecdsa, sizeof *ecdsa, 1, fp) == 1)
+       if(read_pem(fp, "ED25519 PRIVATE KEY", ecdsa->private, sizeof *ecdsa))
                return ecdsa;
        free(ecdsa);
        return 0;

diff --git a/src/ed25519/ecdsagen.c b/src/ed25519/ecdsagen.c
index 4184573..d2a1489 100644 (file)
--- a/src/ed25519/ecdsagen.c
+++ b/src/ed25519/ecdsagen.c
@@ -46,10 +46,26 @@ ecdsa_t *ecdsa_generate(void) {
 
 // Write PEM ECDSA keys
 
+static bool write_pem(FILE *fp, const char *type, void *buf, size_t size) {
+       fprintf(fp, "-----BEGIN %s-----\n", type);
+
+       char base64[65];
+       while(size) {
+               size_t todo = size > 48 ? 48 : size;
+               b64encode(buf, base64, todo);
+               fprintf(fp, "%s\n", base64);
+               buf += todo;
+               size -= todo;
+       }
+
+       fprintf(fp, "-----END %s-----\n", type);
+       return !ferror(fp);
+}
+
 bool ecdsa_write_pem_public_key(ecdsa_t *ecdsa, FILE *fp) {
-       return fwrite(ecdsa->public, sizeof ecdsa->public, 1, fp) == 1;
+       return write_pem(fp, "ED25519 PUBLIC KEY", ecdsa->public, sizeof ecdsa->public);
 }
 
 bool ecdsa_write_pem_private_key(ecdsa_t *ecdsa, FILE *fp) {
-       return fwrite(ecdsa, sizeof *ecdsa, 1, fp) == 1;
+       return write_pem(fp, "ED25519 PRIVATE KEY", ecdsa->private, sizeof *ecdsa);
 }

diff --git a/src/tincctl.c b/src/tincctl.c
index 5f2b135..7a3195e 100644 (file)
--- a/src/tincctl.c
+++ b/src/tincctl.c
@@ -246,7 +246,7 @@ static void disable_old_keys(const char *filename, const char *what) {
 
        while(fgets(buf, sizeof buf, r)) {
                if(!block && !strncmp(buf, "-----BEGIN ", 11)) {
-                       if((strstr(buf, " RSA ") && strstr(what, "RSA"))) {
+                       if((strstr(buf, " ED25519 ") && strstr(what, "Ed25519")) || (strstr(buf, " RSA ") && strstr(what, "RSA"))) {
                                disabled = true;
                                block = true;
                        }