Build with LibreSSL.

Index: imap/http_jwt.c
--- imap/http_jwt.c.orig
+++ imap/http_jwt.c
@@ -82,7 +82,7 @@ static EVP_PKEY *read_public_key(struct buf *pem)
     EVP_PKEY *pkey = PEM_read_bio_PUBKEY(bp, NULL, NULL, NULL);
 
     if (pkey) {
-        if (!EVP_PKEY_is_a(pkey, "RSA")) {
+        if (!(EVP_PKEY_base_id(pkey) == EVP_PKEY_RSA)) {
             xsyslog(LOG_ERR, "Unsupported public key", NULL);
             EVP_PKEY_free(pkey);
             pkey = NULL;
@@ -287,10 +287,10 @@ static int validate_pkey_type(struct jwt *jwt, EVP_PKE
     if (!jwt->nid)
         return 0;
 
-    if (jwt->nid == EVP_PKEY_HMAC && EVP_PKEY_is_a(pkey, "HMAC"))
+    if (jwt->nid == EVP_PKEY_HMAC && (EVP_PKEY_base_id(pkey) == EVP_PKEY_HMAC))
         return 1;
 
-    if (jwt->nid == EVP_PKEY_RSA && EVP_PKEY_is_a(pkey, "RSA"))
+    if (jwt->nid == EVP_PKEY_RSA && (EVP_PKEY_base_id(pkey) == EVP_PKEY_RSA))
         return 1;
 
     return 0;
