Implement user duo, initial version

TODO:
- At the moment each user needs to configure a DUO application and input the API keys, we need to check if multiple users can register with the same keys correctly and if so we could implement a global setting.
- Sometimes the Duo frame doesn't load correctly, but canceling, reloading the page and logging in again seems to fix it for me.

5 files changed, 312 insertions, 62 deletions

diff --git a/Cargo.lock b/Cargo.lock
index d6e357ab..b746a06a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -61,7 +61,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "backtrace"
-version = "0.3.14"
+version = "0.3.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "autocfg 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -69,7 +69,7 @@ dependencies = [
  "cfg-if 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.51 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-demangle 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -77,7 +77,7 @@ name = "backtrace-sys"
 version = "0.1.28"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "cc 1.0.32 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cc 1.0.34 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.51 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -139,8 +139,8 @@ dependencies = [
  "rmpv 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rocket 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rocket_contrib 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
  "soup 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "syslog 4.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -245,7 +245,7 @@ dependencies = [
 
 [[package]]
 name = "cc"
-version = "1.0.32"
+version = "1.0.34"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
@@ -594,7 +594,7 @@ name = "error-chain"
 version = "0.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "backtrace 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)",
+ "backtrace 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -602,7 +602,7 @@ name = "failure"
 version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "backtrace 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)",
+ "backtrace 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)",
  "failure_derive 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -771,7 +771,7 @@ dependencies = [
  "bytes 0.4.12 (registry+https://github.com/rust-lang/crates.io-index)",
  "fnv 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "futures 0.1.26 (registry+https://github.com/rust-lang/crates.io-index)",
- "http 0.1.16 (registry+https://github.com/rust-lang/crates.io-index)",
+ "http 0.1.17 (registry+https://github.com/rust-lang/crates.io-index)",
  "indexmap 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "slab 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -790,7 +790,7 @@ dependencies = [
  "pest_derive 2.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "quick-error 1.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
  "walkdir 2.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -838,7 +838,7 @@ dependencies = [
 
 [[package]]
 name = "http"
-version = "0.1.16"
+version = "0.1.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "bytes 0.4.12 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -878,7 +878,7 @@ dependencies = [
  "futures 0.1.26 (registry+https://github.com/rust-lang/crates.io-index)",
  "futures-cpupool 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "h2 0.1.17 (registry+https://github.com/rust-lang/crates.io-index)",
- "http 0.1.16 (registry+https://github.com/rust-lang/crates.io-index)",
+ "http 0.1.17 (registry+https://github.com/rust-lang/crates.io-index)",
  "httparse 1.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "iovec 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "itoa 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -969,7 +969,7 @@ dependencies = [
  "cfg-if 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.51 (registry+https://github.com/rust-lang/crates.io-index)",
  "redox_syscall 0.1.52 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -985,8 +985,8 @@ dependencies = [
  "base64 0.9.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "chrono 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "ring 0.13.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
  "untrusted 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1029,8 +1029,8 @@ dependencies = [
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "native-tls 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "nom 4.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -1059,7 +1059,7 @@ name = "libsqlite3-sys"
 version = "0.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "cc 1.0.32 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cc 1.0.34 (registry+https://github.com/rust-lang/crates.io-index)",
  "pkg-config 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)",
  "vcpkg 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -1106,8 +1106,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "phf 0.7.24 (registry+https://github.com/rust-lang/crates.io-index)",
  "phf_codegen 0.7.24 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
  "string_cache 0.7.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "string_cache_codegen 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1198,7 +1198,7 @@ name = "miniz_oxide_c_api"
 version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "cc 1.0.32 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cc 1.0.34 (registry+https://github.com/rust-lang/crates.io-index)",
  "crc 1.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.51 (registry+https://github.com/rust-lang/crates.io-index)",
  "miniz_oxide 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1285,7 +1285,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "cfg-if 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.51 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1322,7 +1322,7 @@ dependencies = [
  "mio 0.6.16 (registry+https://github.com/rust-lang/crates.io-index)",
  "mio-extras 2.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "walkdir 2.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1404,7 +1404,7 @@ name = "openssl-sys"
 version = "0.9.43"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "cc 1.0.32 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cc 1.0.34 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.51 (registry+https://github.com/rust-lang/crates.io-index)",
  "pkg-config 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1453,7 +1453,7 @@ dependencies = [
  "libc 0.2.51 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "smallvec 0.6.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1465,7 +1465,7 @@ dependencies = [
  "rand 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "smallvec 0.6.9 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1627,7 +1627,7 @@ dependencies = [
  "libc 0.2.51 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_core 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rdrand 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1645,7 +1645,7 @@ dependencies = [
  "rand_os 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_pcg 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_xorshift 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1693,7 +1693,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "libc 0.2.51 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_core 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1706,7 +1706,7 @@ dependencies = [
  "libc 0.2.51 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_core 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rdrand 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1764,7 +1764,7 @@ name = "remove_dir_all"
 version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1777,14 +1777,14 @@ dependencies = [
  "encoding_rs 0.8.17 (registry+https://github.com/rust-lang/crates.io-index)",
  "flate2 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "futures 0.1.26 (registry+https://github.com/rust-lang/crates.io-index)",
- "http 0.1.16 (registry+https://github.com/rust-lang/crates.io-index)",
+ "http 0.1.17 (registry+https://github.com/rust-lang/crates.io-index)",
  "hyper 0.12.25 (registry+https://github.com/rust-lang/crates.io-index)",
  "hyper-tls 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "mime 0.3.13 (registry+https://github.com/rust-lang/crates.io-index)",
  "mime_guess 2.0.0-alpha.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "native-tls 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_urlencoded 0.5.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "tokio 0.1.18 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1801,7 +1801,7 @@ name = "ring"
 version = "0.13.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "cc 1.0.32 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cc 1.0.34 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.51 (registry+https://github.com/rust-lang/crates.io-index)",
  "untrusted 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1866,7 +1866,7 @@ dependencies = [
  "log 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "notify 4.0.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "rocket 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -1948,7 +1948,7 @@ version = "0.1.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "lazy_static 1.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -2009,12 +2009,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "serde"
-version = "1.0.89"
+version = "1.0.90"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "serde_derive"
-version = "1.0.89"
+version = "1.0.90"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "proc-macro2 0.4.27 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2029,7 +2029,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "itoa 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "ryu 0.2.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -2039,7 +2039,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "dtoa 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "itoa 0.4.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)",
  "url 1.7.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -2142,7 +2142,7 @@ dependencies = [
  "new_debug_unreachable 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "phf_shared 0.7.24 (registry+https://github.com/rust-lang/crates.io-index)",
  "precomputed-hash 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)",
  "string_cache_codegen 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "string_cache_shared 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
@@ -2234,7 +2234,7 @@ dependencies = [
  "rand 0.6.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "redox_syscall 0.1.52 (registry+https://github.com/rust-lang/crates.io-index)",
  "remove_dir_all 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -2270,7 +2270,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "libc 0.2.51 (registry+https://github.com/rust-lang/crates.io-index)",
  "redox_syscall 0.1.52 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -2399,7 +2399,7 @@ name = "toml"
 version = "0.4.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "serde 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -2440,8 +2440,8 @@ dependencies = [
  "bytes 0.4.12 (registry+https://github.com/rust-lang/crates.io-index)",
  "chrono 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "ring 0.13.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
- "serde_derive 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)",
+ "serde_derive 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)",
  "serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)",
  "time 0.1.42 (registry+https://github.com/rust-lang/crates.io-index)",
  "untrusted 0.6.2 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2549,7 +2549,7 @@ version = "2.2.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "same-file 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
  "winapi-util 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -2588,7 +2588,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
 name = "winapi"
-version = "0.3.6"
+version = "0.3.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
  "winapi-i686-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2610,7 +2610,7 @@ name = "winapi-util"
 version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -2623,7 +2623,7 @@ name = "winutil"
 version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -2691,7 +2691,7 @@ dependencies = [
 "checksum arrayvec 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)" = "92c7fb76bc8826a8b33b4ee5bb07a247a81e76764ab4d55e8f73e3a4d8808c71"
 "checksum ascii_utils 0.9.3 (registry+https://github.com/rust-lang/crates.io-index)" = "71938f30533e4d95a6d17aa530939da3842c2ab6f4f84b9dae68447e4129f74a"
 "checksum autocfg 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "a6d640bee2da49f60a4068a7fae53acde8982514ab7bae8b8cea9e88cbcfd799"
-"checksum backtrace 0.3.14 (registry+https://github.com/rust-lang/crates.io-index)" = "cd5a90e2b463010cd0e0ce9a11d4a9d5d58d9f41d4a6ba3dcaf9e68b466e88b4"
+"checksum backtrace 0.3.15 (registry+https://github.com/rust-lang/crates.io-index)" = "f106c02a3604afcdc0df5d36cc47b44b55917dbaf3d808f71c163a0ddba64637"
 "checksum backtrace-sys 0.1.28 (registry+https://github.com/rust-lang/crates.io-index)" = "797c830ac25ccc92a7f8a7b9862bde440715531514594a6154e3d4a54dd769b6"
 "checksum base64 0.10.1 (registry+https://github.com/rust-lang/crates.io-index)" = "0b25d992356d2eb0ed82172f5248873db5560c4721f564b13cb5193bda5e668e"
 "checksum base64 0.9.3 (registry+https://github.com/rust-lang/crates.io-index)" = "489d6c0ed21b11d038c31b6ceccca973e65d73ba3bd8ecb9a2babf5546164643"
@@ -2710,7 +2710,7 @@ dependencies = [
 "checksum byte-tools 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "e3b5ca7a04898ad4bcd41c90c5285445ff5b791899bb1b0abdd2a2aa791211d7"
 "checksum byteorder 1.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "a019b10a2a7cdeb292db131fc8113e57ea2a908f6e7894b0c3c671893b65dbeb"
 "checksum bytes 0.4.12 (registry+https://github.com/rust-lang/crates.io-index)" = "206fdffcfa2df7cbe15601ef46c813fce0965eb3286db6b56c583b814b51c81c"
-"checksum cc 1.0.32 (registry+https://github.com/rust-lang/crates.io-index)" = "ad0daef304fa0b4238f5f7ed7178774b43b06f6a9b6509f6642bef4ff1f7b9b2"
+"checksum cc 1.0.34 (registry+https://github.com/rust-lang/crates.io-index)" = "30f813bf45048a18eda9190fd3c6b78644146056740c43172a5a3699118588fd"
 "checksum cfg-if 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)" = "11d43355396e872eefb45ce6342e4374ed7bc2b3a502d1b28e36d6e23c05d1f4"
 "checksum chashmap 2.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "ff41a3c2c1e39921b9003de14bf0439c7b63a9039637c291e1a64925d8ddfa45"
 "checksum chrono 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)" = "45912881121cb26fad7c38c17ba7daa18764771836b34fab7d3fbd93ed633878"
@@ -2778,7 +2778,7 @@ dependencies = [
 "checksum hmac 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f127a908633569f208325f86f71255d3363c79721d7f9fe31cd5569908819771"
 "checksum hostname 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "21ceb46a83a85e824ef93669c8b390009623863b5c195d1ba747292c0c72f94e"
 "checksum html5ever 0.22.5 (registry+https://github.com/rust-lang/crates.io-index)" = "c213fa6a618dc1da552f54f85cba74b05d8e883c92ec4e89067736938084c26e"
-"checksum http 0.1.16 (registry+https://github.com/rust-lang/crates.io-index)" = "fe67e3678f2827030e89cc4b9e7ecd16d52f132c0b940ab5005f88e821500f6a"
+"checksum http 0.1.17 (registry+https://github.com/rust-lang/crates.io-index)" = "eed324f0f0daf6ec10c474f150505af2c143f251722bf9dbd1261bd1f2ee2c1a"
 "checksum httparse 1.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "e8734b0cfd3bc3e101ec59100e101c2eecd19282202e87808b3037b442777a83"
 "checksum hyper 0.10.15 (registry+https://github.com/rust-lang/crates.io-index)" = "df0caae6b71d266b91b4a83111a61d2b94ed2e2bea024c532b933dcff867e58c"
 "checksum hyper 0.12.25 (registry+https://github.com/rust-lang/crates.io-index)" = "7d5b6658b016965ae301fa995306db965c93677880ea70765a84235a96eae896"
@@ -2902,8 +2902,8 @@ dependencies = [
 "checksum security-framework-sys 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "3d6696852716b589dff9e886ff83778bb635150168e83afa8ac6b8a78cb82abc"
 "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 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)" = "92514fb95f900c9b5126e32d020f5c6d40564c27a5ea6d1d7d9f157a96623560"
-"checksum serde_derive 1.0.89 (registry+https://github.com/rust-lang/crates.io-index)" = "bb6eabf4b5914e88e24eea240bb7c9f9a2cbc1bbbe8d961d381975ec3c6b806c"
+"checksum serde 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)" = "aa5f7c20820475babd2c077c3ab5f8c77a31c15e16ea38687b4c02d3e48680f4"
+"checksum serde_derive 1.0.90 (registry+https://github.com/rust-lang/crates.io-index)" = "58fc82bec244f168b23d1963b45c8bf5726e9a15a9d146a067f9081aeed2de79"
 "checksum serde_json 1.0.39 (registry+https://github.com/rust-lang/crates.io-index)" = "5a23aa71d4a4d43fdbfaac00eff68ba8a06a51759a89ac3304323e800c4dd40d"
 "checksum serde_urlencoded 0.5.4 (registry+https://github.com/rust-lang/crates.io-index)" = "d48f9f99cd749a2de71d29da5f948de7f2764cc5a9d7f3c97e3514d4ee6eabf2"
 "checksum sha-1 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)" = "8347606816471548cd60f0abd5ef0d513a81f5202dbdab9c09f17a15b5248484"
@@ -2970,7 +2970,7 @@ dependencies = [
 "checksum webpki 0.18.1 (registry+https://github.com/rust-lang/crates.io-index)" = "17d7967316d8411ca3b01821ee6c332bde138ba4363becdb492f12e514daa17f"
 "checksum webpki-roots 0.15.0 (registry+https://github.com/rust-lang/crates.io-index)" = "85d1f408918fd590908a70d36b7ac388db2edc221470333e4d6e5b598e44cabf"
 "checksum winapi 0.2.8 (registry+https://github.com/rust-lang/crates.io-index)" = "167dc9d6949a9b857f3451275e911c3f44255842c1f7a76f33c55103a909087a"
-"checksum winapi 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)" = "92c1eb33641e276cfa214a0522acad57be5c56b10cb348b3c5117db75f3ac4b0"
+"checksum winapi 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)" = "f10e386af2b13e47c89e7236a7a14a086791a2b88ebad6df9bf42040195cf770"
 "checksum winapi-build 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "2d315eee3b34aca4797b2da6b13ed88266e6d612562a0c46390af8299fc699bc"
 "checksum winapi-i686-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
 "checksum winapi-util 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "7168bab6e1daee33b4557efd0e95d5ca70a03706d39fa5f3fe7a236f584b03c9"
diff --git a/Cargo.toml b/Cargo.toml
index 506f5f62..1e844fa8 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -38,8 +38,8 @@ rmpv = "0.4.0"
 chashmap = "2.2.2"
 
 # A generic serialization/deserialization framework
-serde = "1.0.89"
-serde_derive = "1.0.89"
+serde = "1.0.90"
+serde_derive = "1.0.90"
 serde_json = "1.0.39"
 
 # Logging
diff --git a/src/api/core/two_factor.rs b/src/api/core/two_factor.rs
index c097c78b..31cca499 100644
--- a/src/api/core/two_factor.rs
+++ b/src/api/core/two_factor.rs
@@ -1,4 +1,4 @@
-use data_encoding::BASE32;
+use data_encoding::{BASE32, BASE64};
 use rocket_contrib::json::Json;
 use serde_json;
 use serde_json::Value;
@@ -31,6 +31,9 @@ pub fn routes() -> Vec<Route> {
         generate_yubikey,
         activate_yubikey,
         activate_yubikey_put,
+        get_duo,
+        activate_duo,
+        activate_duo_put,
     ]
 }
 
@@ -231,7 +234,6 @@ pub fn validate_totp_code_str(totp_code: &str, secret: &str) -> EmptyResult {
 }
 
 pub fn validate_totp_code(totp_code: u64, secret: &str) -> EmptyResult {
-    use data_encoding::BASE32;
     use oath::{totp_raw_now, HashType};
 
     let decoded_secret = match BASE32.decode(secret.as_bytes()) {
@@ -714,3 +716,217 @@ pub fn validate_yubikey_login(response: &str, twofactor_data: &str) -> EmptyResu
         Err(_e) => err!("Failed to verify Yubikey against OTP server"),
     }
 }
+
+#[derive(Serialize, Deserialize, Default)]
+pub struct DuoData {
+    pub host: String,
+    sk: String,
+    ik: String,
+    ak: String,
+}
+
+#[post("/two-factor/get-duo", data = "<data>")]
+fn get_duo(data: JsonUpcase<PasswordData>, headers: Headers, conn: DbConn) -> JsonResult {
+    let data: PasswordData = data.into_inner().data;
+
+    if !headers.user.check_valid_password(&data.MasterPasswordHash) {
+        err!("Invalid password");
+    }
+
+    let type_ = TwoFactorType::Duo as i32;
+    let twofactor = TwoFactor::find_by_user_and_type(&headers.user.uuid, type_, &conn);
+
+    let (enabled, data) = match twofactor {
+        Some(tf) => (true, serde_json::from_str(&tf.data)?),
+        _ => (false, DuoData::default()),
+    };
+
+    // TODO: It's probably not the best idea to return the keys here
+
+    Ok(Json(json!({
+        "Enabled": enabled,
+        "Host": data.host,
+        "SecretKey": data.sk,
+        "IntegrationKey": data.ik,
+        "Object": "twoFactorDuo"
+    })))
+}
+
+#[derive(Deserialize)]
+#[allow(non_snake_case)]
+struct EnableDuoData {
+    MasterPasswordHash: String,
+    Host: String,
+    SecretKey: String,
+    IntegrationKey: String,
+}
+
+#[post("/two-factor/duo", data = "<data>")]
+fn activate_duo(data: JsonUpcase<EnableDuoData>, headers: Headers, conn: DbConn) -> JsonResult {
+    let data: EnableDuoData = data.into_inner().data;
+
+    if !headers.user.check_valid_password(&data.MasterPasswordHash) {
+        err!("Invalid password");
+    }
+
+    let data = DuoData {
+        host: data.Host,
+        sk: data.SecretKey,
+        ik: data.IntegrationKey,
+        ak: BASE64.encode(&crypto::get_random_64()),
+    };
+
+    // Validate parameters with the server
+    duo_api_request("GET", "/auth/v2/check", "", &data)?;
+
+    let data_json = serde_json::to_string(&data)?;
+    let type_ = TwoFactorType::Duo;
+    let twofactor = TwoFactor::new(headers.user.uuid.clone(), type_, data_json);
+    twofactor.save(&conn)?;
+
+    // TODO: It's probably not the best idea to return the keys here
+    Ok(Json(json!({
+        "Enabled": true,
+        "Host": data.host,
+        "SecretKey": data.sk,
+        "IntegrationKey": data.ik,
+        "Object": "twoFactorDuo"
+    })))
+}
+
+#[put("/two-factor/duo", data = "<data>")]
+fn activate_duo_put(data: JsonUpcase<EnableDuoData>, headers: Headers, conn: DbConn) -> JsonResult {
+    activate_duo(data, headers, conn)
+}
+
+fn duo_api_request(method: &str, path: &str, params: &str, data: &DuoData) -> EmptyResult {
+    const AGENT: &str = "bitwarden_rs:Duo/1.0 (Rust)";
+
+    use std::str::FromStr;
+
+    use chrono::Utc;
+    use reqwest::{header::*, Client, Method};
+
+    let url = format!("https://{}{}", data.host, path);
+
+    let date = Utc::now().to_rfc2822();
+
+    let username = &data.ik;
+    let fields = [&date, method, &data.host, path, params];
+    let password = crypto::hmac_sign(&data.sk, &fields.join("\n"));
+
+    let m = Method::from_str(method).unwrap_or_default();
+
+    Client::new()
+        .request(m, &url)
+        .basic_auth(username, Some(password))
+        .header(USER_AGENT, AGENT)
+        .header(DATE, date)
+        .send()?
+        .error_for_status()?;
+
+    Ok(())
+}
+
+const DUO_EXPIRE: i64 = 300;
+const APP_EXPIRE: i64 = 3600;
+
+const AUTH_PREFIX: &str = "AUTH";
+const DUO_PREFIX: &str = "TX";
+const APP_PREFIX: &str = "APP";
+
+use chrono::Utc;
+
+pub fn generate_duo_signature(data: &DuoData, email: &str) -> String {
+    let now = Utc::now().timestamp();
+
+    let duo_sign = sign_duo_values(&data.sk, email, &data.ik, DUO_PREFIX, now + DUO_EXPIRE);
+    let app_sign = sign_duo_values(&data.ak, email, &data.ik, APP_PREFIX, now + APP_EXPIRE);
+
+    format!("{}:{}", duo_sign, app_sign)
+}
+
+fn sign_duo_values(key: &str, email: &str, ikey: &str, prefix: &str, expire: i64) -> String {
+    let val = format!("{}|{}|{}", email, ikey, expire);
+    let cookie = format!("{}|{}", prefix, BASE64.encode(val.as_bytes()));
+
+    format!("{}|{}", cookie, crypto::hmac_sign(key, &cookie))
+}
+
+pub fn validate_duo_login(response: &str, twofactor_data: &str) -> EmptyResult {
+    let data: DuoData = serde_json::from_str(twofactor_data)?;
+
+    let split: Vec<&str> = response.split(":").collect();
+    if split.len() != 2 {
+        err!("Invalid response length");
+    }
+
+    let auth_sig = split[0];
+    let app_sig = split[1];
+
+    let now = Utc::now().timestamp();
+
+    let auth_user = parse_duo_values(&data.sk, auth_sig, &data.ik, AUTH_PREFIX, now)?;
+    let app_user = parse_duo_values(&data.ak, app_sig, &data.ik, APP_PREFIX, now)?;
+
+    if !crypto::ct_eq(auth_user, app_user) {
+        err!("Error validating duo authentication")
+    }
+
+    Ok(())
+}
+
+fn parse_duo_values(key: &str, val: &str, ikey: &str, prefix: &str, time: i64) -> ApiResult<String> {
+    let split: Vec<&str> = val.split("|").collect();
+    if split.len() != 3 {
+        err!("Invalid value length")
+    }
+
+    let u_prefix = split[0];
+    let u_b64 = split[1];
+    let u_sig = split[2];
+
+    let sig = crypto::hmac_sign(key, &format!("{}|{}", u_prefix, u_b64));
+
+    if !crypto::ct_eq(crypto::hmac_sign(key, &sig), crypto::hmac_sign(key, u_sig)) {
+        err!("Duo signatures don't match")
+    }
+
+    if u_prefix != prefix {
+        err!("Prefixes don't match")
+    }
+
+    let cookie_vec = match BASE64.decode(u_b64.as_bytes()) {
+        Ok(c) => c,
+        Err(_) => err!("Invalid Duo cookie encoding"),
+    };
+
+    let cookie = match String::from_utf8(cookie_vec) {
+        Ok(c) => c,
+        Err(_) => err!("Invalid Duo cookie encoding"),
+    };
+
+    let cookie_split: Vec<&str> = cookie.split("|").collect();
+    if cookie_split.len() != 3 {
+        err!("Invalid cookie length")
+    }
+
+    let username = cookie_split[0];
+    let u_ikey = cookie_split[1];
+    let expire = cookie_split[2];
+
+    if !crypto::ct_eq(ikey, u_ikey) {
+        err!("Invalid ikey")
+    }
+
+    let expire = match expire.parse() {
+        Ok(e) => e,
+        Err(_) => err!("Invalid expire time"),
+    };
+
+    if time >= expire {
+        err!("Expired authorization")
+    }
+
+    Ok(username.into())
+}
diff --git a/src/api/identity.rs b/src/api/identity.rs
index 309613f2..b881cbe9 100644
--- a/src/api/identity.rs
+++ b/src/api/identity.rs
@@ -178,6 +178,7 @@ fn twofactor_auth(
         Some(TwoFactorType::Authenticator) => _tf::validate_totp_code_str(twofactor_code, &selected_data?)?,
         Some(TwoFactorType::U2f) => _tf::validate_u2f_login(user_uuid, twofactor_code, conn)?,
         Some(TwoFactorType::YubiKey) => _tf::validate_yubikey_login(twofactor_code, &selected_data?)?,
+        Some(TwoFactorType::Duo) => _tf::validate_duo_login(twofactor_code, &selected_data?)?,
 
         Some(TwoFactorType::Remember) => {
             match device.twofactor_remember {
@@ -237,13 +238,33 @@ fn _json_err_twofactor(providers: &[i32], user_uuid: &str, conn: &DbConn) -> Api
                 }
 
                 let mut map = JsonMap::new();
-                use serde_json;
                 let challenge_list_str = serde_json::to_string(&challenge_list).unwrap();
 
                 map.insert("Challenges".into(), Value::String(challenge_list_str));
                 result["TwoFactorProviders2"][provider.to_string()] = Value::Object(map);
             }
 
+            Some(tf_type @ TwoFactorType::Duo) => {
+                let twofactor = match TwoFactor::find_by_user_and_type(user_uuid, tf_type as i32, &conn) {
+                    Some(tf) => tf,
+                    None => err!("No Duo devices registered"),
+                };        
+
+                let duo_data: two_factor::DuoData = serde_json::from_str(&twofactor.data)?;
+
+                let email = match User::find_by_uuid(user_uuid, &conn) {
+                    Some(u) => u.email,
+                    None => err!("User does not exist")
+                };
+
+                let signature = two_factor::generate_duo_signature(&duo_data, &email);
+
+                let mut map = JsonMap::new();
+                map.insert("Host".into(), Value::String(duo_data.host));
+                map.insert("Signature".into(), Value::String(signature));
+                result["TwoFactorProviders2"][provider.to_string()] = Value::Object(map);     
+            }
+
             Some(tf_type @ TwoFactorType::YubiKey) => {
                 let twofactor = match TwoFactor::find_by_user_and_type(user_uuid, tf_type as i32, &conn) {
                     Some(tf) => tf,
@@ -251,7 +272,7 @@ fn _json_err_twofactor(providers: &[i32], user_uuid: &str, conn: &DbConn) -> Api
                 };
 
                 let yubikey_metadata: two_factor::YubikeyMetadata =
-                    serde_json::from_str(&twofactor.data).expect("Can't parse Yubikey Metadata");
+                    serde_json::from_str(&twofactor.data)?;
 
                 let mut map = JsonMap::new();
                 map.insert("Nfc".into(), Value::Bool(yubikey_metadata.Nfc));
diff --git a/src/crypto.rs b/src/crypto.rs
index 628afcd0..4cb46c41 100644
--- a/src/crypto.rs
+++ b/src/crypto.rs
@@ -20,6 +20,19 @@ pub fn verify_password_hash(secret: &[u8], salt: &[u8], previous: &[u8], iterati
 }
 
 //
+// HMAC
+//
+pub fn hmac_sign(key: &str, data:&str) -> String {
+    use data_encoding::HEXLOWER;
+    use ring::{digest, hmac};
+
+    let key = hmac::SigningKey::new(&digest::SHA1, key.as_bytes());
+    let signature = hmac::sign(&key, data.as_bytes());
+
+    HEXLOWER.encode(signature.as_ref())
+}
+
+//
 // Random values
 //