diff --git a/Cargo.lock b/Cargo.lock
index ddbe913..f5d23f5 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -21,7 +21,7 @@ name = "atty"
 version = "0.2.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "hermit-abi 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "hermit-abi 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.68 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -64,14 +64,14 @@ dependencies = [
  "bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "cexpr 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "clang-sys 0.29.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "clang-sys 0.29.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "clap 2.33.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "env_logger 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazycell 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "peeking_take_while 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "proc-macro2 1.0.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-hash 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -118,7 +118,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "clang-sys"
-version = "0.29.2"
+version = "0.29.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "glob 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -148,6 +148,71 @@ dependencies = [
  "bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "crossbeam"
+version = "0.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-channel 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-deque 0.7.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-epoch 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-queue 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-utils 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "crossbeam-channel"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "crossbeam-utils 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "maybe-uninit 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "crossbeam-deque"
+version = "0.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "crossbeam-epoch 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-utils 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "maybe-uninit 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "crossbeam-epoch"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "autocfg 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-utils 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "maybe-uninit 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "memoffset 0.5.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "scopeguard 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "crossbeam-queue"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-utils 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "crossbeam-utils"
+version = "0.7.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "autocfg 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "csv-core"
 version = "0.1.10"
@@ -158,15 +223,16 @@ dependencies = [
 
 [[package]]
 name = "ctap_hmac"
-version = "0.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
+version = "0.3.0"
+source = "git+https://git.shimun.net/shimun/ctap.git?branch=assert_multiple#65ef57403182fce13b5266ba7838558ba2ad008f"
 dependencies = [
  "byteorder 1.3.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "cbor-codec 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam 0.7.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "csv-core 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "derive_builder 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "failure 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "failure_derive 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "hex 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-derive 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -175,6 +241,61 @@ dependencies = [
  "untrusted 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "darling"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "darling_core 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "darling_macro 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "darling_core"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "fnv 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ident_case 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "strsim 0.9.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.17 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "darling_macro"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "darling_core 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.17 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "derive_builder"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "darling 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "derive_builder_core 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.17 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "derive_builder_core"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "darling 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.17 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "either"
 version = "1.5.3"
@@ -206,7 +327,7 @@ name = "failure_derive"
 version = "0.1.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 1.0.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 1.0.17 (registry+https://github.com/rust-lang/crates.io-index)",
  "synstructure 0.12.3 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -214,9 +335,9 @@ dependencies = [
 
 [[package]]
 name = "fido2luks"
-version = "0.2.4"
+version = "0.2.6"
 dependencies = [
- "ctap_hmac 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ctap_hmac 0.3.0 (git+https://git.shimun.net/shimun/ctap.git?branch=assert_multiple)",
  "failure 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "hex 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "libcryptsetup-rs 0.3.0 (git+https://github.com/shimunn/libcryptsetup-rs.git?branch=crypt_load_ptr_null)",
@@ -225,6 +346,11 @@ dependencies = [
  "structopt 0.3.12 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "fnv"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "fuchsia-cprng"
 version = "0.1.1"
@@ -250,7 +376,7 @@ dependencies = [
 
 [[package]]
 name = "hermit-abi"
-version = "0.1.8"
+version = "0.1.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "libc 0.2.68 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -261,11 +387,6 @@ name = "hex"
 version = "0.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
-[[package]]
-name = "hex"
-version = "0.4.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-
 [[package]]
 name = "humantime"
 version = "1.3.0"
@@ -274,6 +395,11 @@ dependencies = [
  "quick-error 1.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "ident_case"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "itoa"
 version = "0.4.5"
@@ -304,7 +430,7 @@ dependencies = [
  "libcryptsetup-rs-sys 0.1.2 (git+https://github.com/shimunn/libcryptsetup-rs.git?branch=crypt_load_ptr_null)",
  "pkg-config 0.3.17 (registry+https://github.com/rust-lang/crates.io-index)",
  "semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_json 1.0.48 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_json 1.0.50 (registry+https://github.com/rust-lang/crates.io-index)",
  "uuid 0.7.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -336,11 +462,24 @@ dependencies = [
  "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "maybe-uninit"
+version = "2.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "memchr"
 version = "2.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "memoffset"
+version = "0.5.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "autocfg 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "nom"
 version = "5.1.1"
@@ -384,7 +523,7 @@ version = "0.4.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro-error-attr 0.4.12 (registry+https://github.com/rust-lang/crates.io-index)",
- "proc-macro2 1.0.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 1.0.17 (registry+https://github.com/rust-lang/crates.io-index)",
  "version_check 0.9.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -395,7 +534,7 @@ name = "proc-macro-error-attr"
 version = "0.4.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 1.0.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 1.0.17 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn-mid 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -412,7 +551,7 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.9"
+version = "1.0.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "unicode-xid 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -436,7 +575,7 @@ name = "quote"
 version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 1.0.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -637,6 +776,11 @@ name = "ryu"
 version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "scopeguard"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "semver"
 version = "0.9.0"
@@ -657,7 +801,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "serde_json"
-version = "1.0.48"
+version = "1.0.50"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "itoa 0.4.5 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -675,6 +819,11 @@ name = "strsim"
 version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "strsim"
+version = "0.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "structopt"
 version = "0.3.12"
@@ -692,7 +841,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "heck 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "proc-macro-error 0.4.12 (registry+https://github.com/rust-lang/crates.io-index)",
- "proc-macro2 1.0.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 1.0.17 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -712,7 +861,7 @@ name = "syn"
 version = "1.0.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 1.0.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-xid 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -722,7 +871,7 @@ name = "syn-mid"
 version = "0.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 1.0.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 1.0.17 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -732,7 +881,7 @@ name = "synstructure"
 version = "0.12.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "proc-macro2 1.0.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "proc-macro2 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "quote 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "syn 1.0.17 (registry+https://github.com/rust-lang/crates.io-index)",
  "unicode-xid 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -743,7 +892,7 @@ name = "termcolor"
 version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "winapi-util 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi-util 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -839,7 +988,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "winapi-util"
-version = "0.1.3"
+version = "0.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -865,23 +1014,35 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum cc 1.0.50 (registry+https://github.com/rust-lang/crates.io-index)" = "95e28fa049fda1c330bcf9d723be7663a899c4679724b34c81e9f5a326aab8cd"
 "checksum cexpr 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f4aedb84272dbe89af497cf81375129abda4fc0a9e7c5d317498c15cc30c0d27"
 "checksum cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)" = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
-"checksum clang-sys 0.29.2 (registry+https://github.com/rust-lang/crates.io-index)" = "f92986241798376849e1a007827041fed9bb36195822c2049d18e174420e0534"
+"checksum clang-sys 0.29.3 (registry+https://github.com/rust-lang/crates.io-index)" = "fe6837df1d5cba2397b835c8530f51723267e16abbf83892e9e5af4f0e5dd10a"
 "checksum clap 2.33.0 (registry+https://github.com/rust-lang/crates.io-index)" = "5067f5bb2d80ef5d68b4c87db81601f0b75bca627bc2ef76b141d7b846a3c6d9"
 "checksum cloudabi 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "ddfc5b9aa5d4507acaf872de71051dfd0e309860e88966e1051e462a077aac4f"
+"checksum crossbeam 0.7.3 (registry+https://github.com/rust-lang/crates.io-index)" = "69323bff1fb41c635347b8ead484a5ca6c3f11914d784170b158d8449ab07f8e"
+"checksum crossbeam-channel 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)" = "cced8691919c02aac3cb0a1bc2e9b73d89e832bf9a06fc579d4e71b68a2da061"
+"checksum crossbeam-deque 0.7.3 (registry+https://github.com/rust-lang/crates.io-index)" = "9f02af974daeee82218205558e51ec8768b48cf524bd01d550abe5573a608285"
+"checksum crossbeam-epoch 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)" = "058ed274caafc1f60c4997b5fc07bf7dc7cca454af7c6e81edffe5f33f70dace"
+"checksum crossbeam-queue 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "c695eeca1e7173472a32221542ae469b3e9aac3a4fc81f7696bcad82029493db"
+"checksum crossbeam-utils 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)" = "c3c7c73a2d1e9fc0886a08b93e98eb643461230d5f1925e4036204d5f2e261a8"
 "checksum csv-core 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)" = "2b2466559f260f48ad25fe6317b3c8dac77b5bdb5763ac7d9d6103530663bc90"
-"checksum ctap_hmac 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "4d57004228e303ed0d161f081020240d969ce18b623c3f4503645e1a06b42ae7"
+"checksum ctap_hmac 0.3.0 (git+https://git.shimun.net/shimun/ctap.git?branch=assert_multiple)" = "<none>"
+"checksum darling 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)" = "0d706e75d87e35569db781a9b5e2416cff1236a47ed380831f959382ccd5f858"
+"checksum darling_core 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)" = "f0c960ae2da4de88a91b2d920c2a7233b400bc33cb28453a2987822d8392519b"
+"checksum darling_macro 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)" = "d9b5a2f4ac4969822c62224815d069952656cadc7084fdca9751e6d959189b72"
+"checksum derive_builder 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "a2658621297f2cf68762a6f7dc0bb7e1ff2cfd6583daef8ee0fed6f7ec468ec0"
+"checksum derive_builder_core 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "2791ea3e372c8495c0bc2033991d76b512cd799d07491fbd6890124db9458bef"
 "checksum either 1.5.3 (registry+https://github.com/rust-lang/crates.io-index)" = "bb1f6b1ce1c140482ea30ddd3335fc0024ac7ee112895426e0a629a6c20adfe3"
 "checksum env_logger 0.7.1 (registry+https://github.com/rust-lang/crates.io-index)" = "44533bbbb3bb3c1fa17d9f2e4e38bbbaf8396ba82193c4cb1b6445d711445d36"
 "checksum failure 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)" = "b8529c2421efa3066a5cbd8063d2244603824daccb6936b079010bb2aa89464b"
 "checksum failure_derive 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)" = "030a733c8287d6213886dd487564ff5c8f6aae10278b3588ed177f9d18f8d231"
+"checksum fnv 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)" = "2fad85553e09a6f881f739c29f0b00b0f01357c743266d478b68951ce23285f3"
 "checksum fuchsia-cprng 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "a06f77d526c1a601b7c4cdd98f54b5eaabffc14d5f2f0296febdc7f357c6d3ba"
 "checksum gcc 0.3.55 (registry+https://github.com/rust-lang/crates.io-index)" = "8f5f3913fa0bfe7ee1fd8248b6b9f42a5af4b9d65ec2dd2c3c26132b950ecfc2"
 "checksum glob 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "9b919933a397b79c37e33b77bb2aa3dc8eb6e165ad809e58ff75bc7db2e34574"
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-"checksum hermit-abi 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)" = "1010591b26bbfe835e9faeabeb11866061cc7dcebffd56ad7d0942d0e61aefd8"
+"checksum hermit-abi 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)" = "725cf19794cf90aa94e65050cb4191ff5d8fa87a498383774c47b332e3af952e"
 "checksum hex 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)" = "805026a5d0141ffc30abb3be3173848ad46a1b1664fe632428479619a3644d77"
-"checksum hex 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)" = "644f9158b2f133fd50f5fb3242878846d9eb792e445c893805ff0e3824006e35"
 "checksum humantime 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "df004cfca50ef23c36850aaaa59ad52cc70d0e90243c3c7737a4dd32dc7a3c4f"
+"checksum ident_case 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "b9e0384b61958566e926dc50660321d12159025e767c18e043daf26b70104c39"
 "checksum itoa 0.4.5 (registry+https://github.com/rust-lang/crates.io-index)" = "b8b7a7c0c47db5545ed3fef7468ee7bb5b74691498139e4b3f6a20685dc6dd8e"
 "checksum lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 "checksum lazycell 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "b294d6fa9ee409a054354afc4352b0b9ef7ca222c69b8812cbea9e7d2bf3783f"
@@ -890,7 +1051,9 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum libcryptsetup-rs-sys 0.1.2 (git+https://github.com/shimunn/libcryptsetup-rs.git?branch=crypt_load_ptr_null)" = "<none>"
 "checksum libloading 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)" = "f2b111a074963af1d37a139918ac6d49ad1d0d5e47f72fd55388619691a7d753"
 "checksum log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)" = "14b6052be84e6b71ab17edffc2eeabf5c2c3ae1fdb464aae35ac50c67a44e1f7"
+"checksum maybe-uninit 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "60302e4db3a61da70c0cb7991976248362f30319e88850c487b9b95bbf059e00"
 "checksum memchr 2.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "3728d817d99e5ac407411fa471ff9800a778d88a24685968b36824eaf4bee400"
+"checksum memoffset 0.5.4 (registry+https://github.com/rust-lang/crates.io-index)" = "b4fc2c02a7e374099d4ee95a193111f72d2110197fe200272371758f6c3643d8"
 "checksum nom 5.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "0b471253da97532da4b61552249c521e01e736071f71c1a4f7ebbfbf0a06aad6"
 "checksum num-derive 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)" = "eafd0b45c5537c3ba526f79d3e75120036502bebacbb3f3220914067ce39dbf2"
 "checksum num-traits 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)" = "c62be47e61d1842b9170f0fdeec8eba98e60e90e5446449a0545e5152acd7096"
@@ -899,7 +1062,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum proc-macro-error 0.4.12 (registry+https://github.com/rust-lang/crates.io-index)" = "18f33027081eba0a6d8aba6d1b1c3a3be58cbb12106341c2d5759fcd9b5277e7"
 "checksum proc-macro-error-attr 0.4.12 (registry+https://github.com/rust-lang/crates.io-index)" = "8a5b4b77fdb63c1eca72173d68d24501c54ab1269409f6b672c85deb18af69de"
 "checksum proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)" = "cf3d2011ab5c909338f7887f4fc896d35932e29146c12c8d01da6b22a80ba759"
-"checksum proc-macro2 1.0.9 (registry+https://github.com/rust-lang/crates.io-index)" = "6c09721c6781493a2a492a96b5a5bf19b65917fe6728884e7c44dd0c60ca3435"
+"checksum proc-macro2 1.0.10 (registry+https://github.com/rust-lang/crates.io-index)" = "df246d292ff63439fea9bc8c0a270bed0e390d5ebd4db4ba15aba81111b5abe3"
 "checksum quick-error 1.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "a1d01941d82fa2ab50be1e79e6714289dd7cde78eba4c074bc5a4374f650dfe0"
 "checksum quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)" = "6ce23b6b870e8f94f81fb0a363d65d86675884b34a09043c81e5562f11c1f8e1"
 "checksum quote 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "2bdc6c187c65bca4260c9011c9e3132efe4909da44726bad24cf7572ae338d7f"
@@ -926,12 +1089,14 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum rustc-hash 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "08d43f7aa6b08d49f382cde6a7982047c3426db949b1424bc4b7ec9ae12c6ce2"
 "checksum rustc-serialize 0.3.24 (registry+https://github.com/rust-lang/crates.io-index)" = "dcf128d1287d2ea9d80910b5f1120d0b8eede3fbf1abe91c40d39ea7d51e6fda"
 "checksum ryu 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "535622e6be132bccd223f4bb2b8ac8d53cda3c7a6394944d3b2b33fb974f9d76"
+"checksum scopeguard 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
 "checksum semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1d7eb9ef2c18661902cc47e535f9bc51b78acd254da71d375c2f6720d9a40403"
 "checksum semver-parser 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "388a1df253eca08550bef6c72392cfe7c30914bf41df5269b68cbd6ff8f570a3"
 "checksum serde 1.0.105 (registry+https://github.com/rust-lang/crates.io-index)" = "e707fbbf255b8fc8c3b99abb91e7257a622caeb20a9818cbadbeeede4e0932ff"
-"checksum serde_json 1.0.48 (registry+https://github.com/rust-lang/crates.io-index)" = "9371ade75d4c2d6cb154141b9752cf3781ec9c05e0e5cf35060e1e70ee7b9c25"
+"checksum serde_json 1.0.50 (registry+https://github.com/rust-lang/crates.io-index)" = "78a7a12c167809363ec3bd7329fc0a3369056996de43c4b37ef3cd54a6ce4867"
 "checksum shlex 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "7fdf1b9db47230893d76faad238fd6097fd6d6a9245cd7a4d90dbd639536bbd2"
 "checksum strsim 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "8ea5119cdb4c55b55d432abb513a0429384878c15dde60cc77b1c99de1a95a6a"
+"checksum strsim 0.9.3 (registry+https://github.com/rust-lang/crates.io-index)" = "6446ced80d6c486436db5c078dde11a9f73d42b57fb273121e160b84f63d894c"
 "checksum structopt 0.3.12 (registry+https://github.com/rust-lang/crates.io-index)" = "c8faa2719539bbe9d77869bfb15d4ee769f99525e707931452c97b693b3f159d"
 "checksum structopt-derive 0.4.5 (registry+https://github.com/rust-lang/crates.io-index)" = "3f88b8e18c69496aad6f9ddf4630dd7d585bcaf765786cb415b9aec2fe5a0430"
 "checksum syn 0.15.44 (registry+https://github.com/rust-lang/crates.io-index)" = "9ca4b3b69a77cbe1ffc9e198781b7acb0c7365a883670e8f1c1bc66fba79a5c5"
@@ -953,5 +1118,5 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum which 3.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "d011071ae14a2f6671d0b74080ae0cd8ebf3a6f8c9589a2cd45f23126fe29724"
 "checksum winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)" = "8093091eeb260906a183e6ae1abdba2ef5ef2257a21801128899c3fc699229c6"
 "checksum winapi-i686-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
-"checksum winapi-util 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "4ccfbf554c6ad11084fb7517daca16cfdcaccbdadba4fc336f032a8b12c2ad80"
+"checksum winapi-util 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "fa515c5163a99cc82bab70fd3bfdd36d827be85de63737b40fcef2ce084a436e"
 "checksum winapi-x86_64-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
diff --git a/Cargo.toml b/Cargo.toml
index ff4594d..fc8f4db 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "fido2luks"
-version = "0.2.4"
+version = "0.2.6"
 authors = ["shimunn <shimun@shimun.net>"]
 edition = "2018"
 
@@ -14,9 +14,7 @@ categories = ["command-line-utilities"]
 license-file = "LICENSE"
 
 [dependencies]
-ctap_hmac = "0.2.1"
-
-
+ctap_hmac = { git = "https://git.shimun.net/shimun/ctap.git", branch = "assert_multiple", features = ["request_multiple"] }
 hex = "0.3.2"
 ring = "0.13.5"
 failure = "0.1.5"
diff --git a/src/cli.rs b/src/cli.rs
index c467d08..fe459b2 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -4,19 +4,19 @@ use crate::*;
 
 use structopt::StructOpt;
 
-use failure::_core::fmt::{Error, Formatter};
+use ctap::FidoCredential;
+use failure::_core::fmt::{Display, Error, Formatter};
 use failure::_core::str::FromStr;
 use failure::_core::time::Duration;
 use std::io::Write;
-
 use std::process::exit;
 use std::thread;
 
 use std::time::SystemTime;
 #[derive(Debug, Eq, PartialEq, Clone)]
-pub struct HexEncoded(Vec<u8>);
+pub struct HexEncoded(pub Vec<u8>);
 
-impl std::fmt::Display for HexEncoded {
+impl Display for HexEncoded {
     fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
         f.write_str(&hex::encode(&self.0))
     }
@@ -30,6 +30,30 @@ impl FromStr for HexEncoded {
     }
 }
 
+#[derive(Debug, Eq, PartialEq, Clone)]
+pub struct CommaSeparated<T: FromStr + Display>(pub Vec<T>);
+
+impl<T: Display + FromStr> Display for CommaSeparated<T> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
+        for i in &self.0 {
+            f.write_str(&i.to_string())?;
+            f.write_str(",")?;
+        }
+        Ok(())
+    }
+}
+
+impl<T: Display + FromStr> FromStr for CommaSeparated<T> {
+    type Err = <T as FromStr>::Err;
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Ok(CommaSeparated(
+            s.split(',')
+                .map(|part| <T as FromStr>::from_str(dbg!(part)))
+                .collect::<Result<Vec<_>, _>>()?,
+        ))
+    }
+}
+
 #[derive(Debug, StructOpt)]
 pub struct Args {
     /// Request passwords via Stdin instead of using the password helper
@@ -41,9 +65,9 @@ pub struct Args {
 
 #[derive(Debug, StructOpt, Clone)]
 pub struct SecretGeneration {
-    /// FIDO credential id, generate using fido2luks credential
+    /// FIDO credential ids, generate using fido2luks credential
     #[structopt(name = "credential-id", env = "FIDO2LUKS_CREDENTIAL_ID")]
-    pub credential_id: HexEncoded,
+    pub credential_ids: CommaSeparated<HexEncoded>,
     /// Salt for secret generation, defaults to 'ask'
     ///
     /// Options:{n}
@@ -75,6 +99,14 @@ pub struct SecretGeneration {
     pub await_authenticator: u64,
 }
 
+#[derive(Debug, StructOpt, Clone)]
+pub struct LuksSettings {
+    /// Number of milliseconds required to derive the volume decryption key
+    /// Defaults to 10ms when using an authenticator or the default by cryptsetup when using a password
+    #[structopt(long = "kdf-time", name = "kdf-time")]
+    kdf_time: Option<u64>,
+}
+
 impl SecretGeneration {
     pub fn patch(&self, args: &Args) -> Self {
         let mut me = self.clone();
@@ -101,8 +133,18 @@ impl SecretGeneration {
             }
             thread::sleep(Duration::from_millis(500));
         }
+        let credentials = &self
+            .credential_ids
+            .0
+            .iter()
+            .map(|HexEncoded(id)| FidoCredential {
+                id: id.to_vec(),
+                public_key: None,
+            })
+            .collect::<Vec<_>>();
+        let credentials = credentials.iter().collect::<Vec<_>>();
         Ok(assemble_secret(
-            &perform_challenge(&self.credential_id.0, &salt)?,
+            &perform_challenge(&credentials[..], &salt)?,
             &salt,
         ))
     }
@@ -131,6 +173,8 @@ pub enum Command {
         keyfile: Option<PathBuf>,
         #[structopt(flatten)]
         secret_gen: SecretGeneration,
+        #[structopt(flatten)]
+        luks_settings: LuksSettings,
     },
     /// Replace a previously added key with a password
     #[structopt(name = "replace-key")]
@@ -145,6 +189,8 @@ pub enum Command {
         keyfile: Option<PathBuf>,
         #[structopt(flatten)]
         secret_gen: SecretGeneration,
+        #[structopt(flatten)]
+        luks_settings: LuksSettings,
     },
     /// Open the LUKS device
     #[structopt(name = "open")]
@@ -200,6 +246,7 @@ pub fn run_cli() -> Fido2LuksResult<()> {
             exclusive,
             keyfile,
             ref secret_gen,
+            luks_settings,
         } => {
             let secret = secret_gen.patch(&args).obtain_secret()?;
             let old_secret = if let Some(keyfile) = keyfile.clone() {
@@ -207,7 +254,12 @@ pub fn run_cli() -> Fido2LuksResult<()> {
             } else {
                 util::read_password("Old password", false).map(|p| p.as_bytes().to_vec())
             }?;
-            let added_slot = luks::add_key(device.clone(), &secret, &old_secret[..], Some(10))?;
+            let added_slot = luks::add_key(
+                device.clone(),
+                &secret,
+                &old_secret[..],
+                luks_settings.kdf_time.or(Some(10)),
+            )?;
             if *exclusive {
                 let destroyed = luks::remove_keyslots(&device, &[added_slot])?;
                 println!(
@@ -230,6 +282,7 @@ pub fn run_cli() -> Fido2LuksResult<()> {
             add_password,
             keyfile,
             ref secret_gen,
+            luks_settings,
         } => {
             let secret = secret_gen.patch(&args).obtain_secret()?;
             let new_secret = if let Some(keyfile) = keyfile.clone() {
@@ -238,9 +291,9 @@ pub fn run_cli() -> Fido2LuksResult<()> {
                 util::read_password("Password to add", *add_password).map(|p| p.as_bytes().to_vec())
             }?;
             let slot = if *add_password {
-                luks::add_key(device, &new_secret[..], &secret, None)
+                luks::add_key(device, &new_secret[..], &secret, luks_settings.kdf_time)
             } else {
-                luks::replace_key(device, &new_secret[..], &secret, Some(5))
+                luks::replace_key(device, &new_secret[..], &secret, luks_settings.kdf_time)
             }?;
             println!(
                 "Added to password to device {}, slot: {}",
diff --git a/src/device.rs b/src/device.rs
index 221d1fd..e71dfb0 100644
--- a/src/device.rs
+++ b/src/device.rs
@@ -1,91 +1,42 @@
 use crate::error::*;
-use crate::util::sha256;
 
 use ctap::{
-    self,
-    extensions::hmac::{FidoHmacCredential, HmacExtension},
-    AuthenticatorOptions, FidoDevice, FidoError, FidoErrorKind, PublicKeyCredentialRpEntity,
-    PublicKeyCredentialUserEntity,
+    self, extensions::hmac::HmacExtension, request_multiple_devices, FidoAssertionRequestBuilder,
+    FidoCredential, FidoCredentialRequestBuilder, FidoDevice, FidoError, FidoErrorKind,
 };
 
 const RP_ID: &'static str = "fido2luks";
 
-fn authenticator_options() -> Option<AuthenticatorOptions> {
-    Some(AuthenticatorOptions {
-        uv: false, //TODO: should get this from config
-        rk: true,
-    })
+pub fn make_credential_id(name: Option<&str>) -> Fido2LuksResult<FidoCredential> {
+    let mut request = FidoCredentialRequestBuilder::default().rp_id(RP_ID);
+    if let Some(user_name) = name {
+        request = request.user_name(user_name);
+    }
+    let request = request.build().unwrap();
+    let make_credential = |device: &mut FidoDevice| device.make_hmac_credential(&request);
+    Ok(request_multiple_devices(
+        get_devices()?
+            .iter_mut()
+            .map(|device| (device, &make_credential)),
+    )?)
 }
 
-fn authenticator_rp() -> PublicKeyCredentialRpEntity<'static> {
-    PublicKeyCredentialRpEntity {
-        id: RP_ID,
-        name: None,
-        icon: None,
-    }
-}
-
-fn authenticator_user(name: Option<&str>) -> PublicKeyCredentialUserEntity {
-    PublicKeyCredentialUserEntity {
-        id: &[0u8],
-        name: name.unwrap_or(""),
-        icon: None,
-        display_name: name,
-    }
-}
-
-pub fn make_credential_id(name: Option<&str>) -> Fido2LuksResult<FidoHmacCredential> {
-    let mut errs = Vec::new();
-    match get_devices()? {
-        ref devs if devs.is_empty() => Err(Fido2LuksError::NoAuthenticatorError)?,
-        devs => {
-            for mut dev in devs.into_iter() {
-                match dev
-                    .make_hmac_credential_full(
-                        authenticator_rp(),
-                        authenticator_user(name),
-                        &[0u8; 32],
-                        &[],
-                        authenticator_options(),
-                    )
-                    .map(|cred| cred.into())
-                {
-                    //TODO: make credentials device specific
-                    Ok(cred) => {
-                        return Ok(cred);
-                    }
-                    Err(e) => {
-                        errs.push(e);
-                    }
-                }
-            }
-        }
-    }
-    Err(errs.pop().ok_or(Fido2LuksError::NoAuthenticatorError)?)?
-}
-
-pub fn perform_challenge(credential_id: &[u8], salt: &[u8; 32]) -> Fido2LuksResult<[u8; 32]> {
-    let cred = FidoHmacCredential {
-        id: credential_id.to_vec(),
-        rp_id: RP_ID.to_string(),
-    };
-    let mut errs = Vec::new();
-    match get_devices()? {
-        ref devs if devs.is_empty() => Err(Fido2LuksError::NoAuthenticatorError)?,
-        devs => {
-            for mut dev in devs.into_iter() {
-                match dev.get_hmac_assertion(&cred, &sha256(&[&salt[..]]), None, None) {
-                    Ok(secret) => {
-                        return Ok(secret.0);
-                    }
-                    Err(e) => {
-                        errs.push(e);
-                    }
-                }
-            }
-        }
-    }
-    Err(errs.pop().ok_or(Fido2LuksError::NoAuthenticatorError)?)?
+pub fn perform_challenge(
+    credentials: &[&FidoCredential],
+    salt: &[u8; 32],
+) -> Fido2LuksResult<[u8; 32]> {
+    let request = FidoAssertionRequestBuilder::default()
+        .rp_id(RP_ID)
+        .credentials(credentials)
+        .build()
+        .unwrap();
+    let get_assertion = |device: &mut FidoDevice| device.get_hmac_assertion(&request, &salt, None);
+    let (_, (secret, _)) = request_multiple_devices(
+        get_devices()?
+            .iter_mut()
+            .map(|device| (device, &get_assertion)),
+    )?;
+    Ok(secret)
 }
 
 pub fn get_devices() -> Fido2LuksResult<Vec<FidoDevice>> {
diff --git a/src/setup.rs b/src/setup.rs
deleted file mode 100644
index e69de29..0000000